阅读说明：本技术 发光元件、发光装置、电子设备、照明装置、照明系统及引导系统 (Light-emitting element, light-emitting device, electronic apparatus, lighting device, lighting system, and guidance system ) 是由 泷田悠介 濑尾哲史 铃木恒德 尾坂晴惠 于 2016-12-06 设计创作，主要内容包括：目的是提供一种寿命长的发光元件。发光元件包括：第一电极；第二电极；以及EL层,其中,EL层包括空穴注入层以及第一层至第四层,空穴注入层包含有机受体且位于第一电极与第一层之间,第一层包含第一空穴传输材料,第二层包含第二空穴传输材料且位于第一层与第三层之间,第三层包含第三空穴传输材料,第四层包含主体材料以及发光材料且位于第三层与第二电极之间,第二空穴传输材料的HOMO能级深于第一空穴传输材料的HOMO能级,主体材料的HOMO能级深于第二空穴传输材料的HOMO能级,第三空穴传输材料的HOMO能级相等于或深于主体材料的HOMO能级,第二空穴传输材料的HOMO能级与第三空穴传输材料的HOMO能级之差为0.3eV以下,并且,第二空穴传输材料是具有二苯并呋喃骨架或二苯并噻吩骨架直接或通过二价芳香烃基团键合于胺的氮的结构的三芳基胺化合物。(The purpose is to provide a light emitting element having a long lifetime. The light emitting element includes: a first electrode; a second electrode; and an EL layer, wherein the EL layer includes a hole injection layer containing an organic acceptor and located between the first electrode and the first layer, the first layer contains a first hole transport material, the second layer contains a second hole transport material and located between the first layer and the third layer, the third layer contains a third hole transport material, the fourth layer contains a host material and a light emitting material and located between the third layer and the second electrode, the HOMO level of the second hole transport material is deeper than the HOMO level of the first hole transport material, the HOMO level of the host material is deeper than the HOMO level of the second hole transport material, the HOMO level of the third hole transport material is equal to or deeper than the HOMO level of the host material, the difference between the HOMO level of the second hole transport material and the HOMO level of the third hole transport material is 0.3eV or less, and the second hole transport material has a dibenzofuran skeleton or a dibenzothiophene skeleton and is bonded to the first layer or second layer through a divalent aromatic hydrocarbon group Triarylamine compounds having the structure of amine nitrogen.)

1. A light emitting element comprising:

a first electrode;

a second electrode; and

an EL layer is formed on the substrate,

wherein the EL layer is located between the first electrode and the second electrode,

the EL layer includes a hole injection layer, a first layer, a second layer, a third layer, and a fourth layer,

the hole injection layer contains an organic acceptor,

the hole injection layer is located between the first electrode and the first layer,

the second layer is located between the first layer and the third layer,

the fourth layer is located between the third layer and the second electrode,

the first layer comprises a first hole transport material,

the second layer comprises a second hole transport material,

the third layer comprises a third hole transport material,

the fourth layer comprises a host material and a light emitting material,

the HOMO level of the second hole transporting material is deeper than the HOMO level of the first hole transporting material,

the host material has a HOMO energy level that is deeper than the HOMO energy level of the second hole-transporting material,

the HOMO energy level of the third hole-transporting material is deeper than the HOMO energy level of the host material,

the difference between the HOMO level of the second hole-transporting material and the HOMO level of the third hole-transporting material is 0.3eV or less,

and the second hole transport material is a triarylamine compound having a structure in which a dibenzofuran skeleton or a dibenzothiophene skeleton is bonded to the nitrogen of an amine directly or through a divalent aromatic hydrocarbon group.

2. The light-emitting element according to claim 1,

wherein the second hole-transporting material is a substance having one or two structures in each of which the dibenzofuran skeleton or the dibenzothiophene skeleton is bonded to the nitrogen of the amine directly or through the divalent aromatic hydrocarbon group.

3. The light-emitting element according to claim 1 or claim 2,

wherein the 4-position of the dibenzofuran skeleton or the dibenzothiophene skeleton is bonded to the nitrogen of the amine directly or through the divalent aromatic hydrocarbon group.

4. The light-emitting element according to claim 1 or claim 2,

wherein the second hole transporting material is an organic compound having a partial structure represented by the general formula (g1-1),

wherein Z represents an oxygen atom or a sulfur atom,

n represents an integer of 0 to 3,

and, R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

5. The light-emitting element according to claim 1 or claim 2,

wherein the second hole transporting material is an organic compound having a partial structure represented by the general formula (g1-2),

wherein Z represents an oxygen atom or a sulfur atom,

n represents an integer of 0 to 3,

and, R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

6. The light-emitting element according to claim 1 or claim 2,

wherein the second hole-transporting material is a monoamine compound.

7. The light-emitting element according to claim 1 or claim 2,

wherein the second hole transporting material is an organic compound represented by the general formula (G1-1),

wherein X represents an oxygen atom or a sulfur atom,

n represents an integer of 0 to 3,

Ar¹represents any of aromatic hydrocarbon groups having 6 to 18 nuclear atoms,

Ar²represents any one of an aromatic hydrocarbon group having 6 to 18 nuclear atoms and a group represented by the general formula (g2-1),

and, R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms,

wherein Z represents an oxygen atom or a sulfur atom,

m represents an integer of 0 to 3,

and, R²¹To R³¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

8. The light-emitting element according to claim 1 or claim 2,

wherein the second hole transporting material is an organic compound represented by the general formula (G1-2),

wherein Z represents an oxygen atom or a sulfur atom,

n represents an integer of 0 to 3,

Ar¹represents any of aromatic hydrocarbon groups having 6 to 18 nuclear atoms,

Ar²represents any one of an aromatic hydrocarbon group having 6 to 18 nuclear atoms and a group represented by the general formula (g2-2),

and, R¹To R¹¹Are respectively independentRepresents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms,

wherein Z represents an oxygen atom or a sulfur atom,

m represents an integer of 0 to 3,

and, R²¹To R³¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

9. The light-emitting element according to claim 8,

wherein the second hole transport material is an organic compound represented by a structural formula shown below,

10. the light-emitting element according to claim 1 or claim 2,

wherein the organic acceptor is 2,3, 6, 7, 10, 11-hexacyano-1, 4, 5, 8, 9, 12-hexaazatriphenylene.

11. The light-emitting element according to claim 10,

wherein the HOMO level of the second hole transport material is-5.7 eV or more and-5.4 eV or less.

12. The light-emitting element according to claim 1 or claim 2,

wherein a difference between the HOMO level of the first hole-transporting material and the HOMO level of the second hole-transporting material is 0.3eV or less.

13. The light-emitting element according to claim 1 or claim 2,

wherein a difference between the HOMO level of the second hole-transporting material and the HOMO level of the third hole-transporting material is 0.2eV or less.

14. The light-emitting element according to claim 1 or claim 2,

wherein a difference between the HOMO level of the first hole-transporting material and the HOMO level of the second hole-transporting material is 0.2eV or less.

15. The light-emitting element according to claim 1 or claim 2,

wherein the HOMO energy level of the light emitting material is higher than the HOMO energy level of the host material.

16. The light-emitting element according to claim 1 or claim 2,

wherein the first hole transporting material is a substance which is a triarylamine and has a fluoreneamine skeleton.

17. The light-emitting element according to claim 1 or claim 2,

wherein the third hole transport material is a non-amine containing substance.

18. The light-emitting element according to claim 17,

wherein the third hole transport material comprises a carbazole skeleton.

19. The light-emitting element according to claim 18,

wherein the carbazole skeleton is an N-phenylcarbazole skeleton.

20. The light-emitting element according to claim 17,

wherein the third hole transport material comprises a triphenylene backbone.

21. The light-emitting element according to claim 17,

wherein the third hole transport material comprises a naphthalene skeleton.

22. The light-emitting element according to claim 1 or claim 2,

wherein the host material comprises an anthracene skeleton.

23. The light-emitting element according to claim 22,

wherein the host material comprises a diphenylanthracene skeleton.

24. The light-emitting element according to claim 22,

wherein the host material comprises a carbazole skeleton.

25. The light-emitting element according to claim 24,

wherein the carbazole skeleton comprises a benzocarbazole skeleton.

26. The light-emitting element according to claim 25,

wherein the carbazole skeleton is a dibenzocarbazole skeleton.

27. The light-emitting element according to claim 1 or claim 2,

wherein the luminescent material is a fluorescent luminescent material.

28. The light-emitting element according to claim 1 or claim 2,

wherein the luminescent material emits blue fluorescence.

29. The light-emitting element according to claim 1 or claim 2,

wherein the light-emitting material is a condensed aromatic diamine compound.

30. The light-emitting element according to claim 1 or claim 2,

wherein the luminescent material is a pyrene diamine compound.

31. A light emitting device comprising:

the light-emitting element according to claim 1 or claim 2; and

a transistor or a substrate.

32. An electronic device, comprising:

the light emitting device of claim 31; and

sensors, operating buttons, speakers or microphones.

33. An illumination device, comprising:

the light emitting device of claim 31; and

a housing.

34. An illumination system, comprising:

a control unit;

a sensor section; and

a lighting part for lighting the light source and the light source,

wherein the illumination section includes a plurality of light emitting device sections,

the light emitting device section includes one or more light emitting elements,

further, the light-emitting element is the light-emitting element according to any one of claim 1 to claim 30.

35. The lighting system as set forth in claim 34,

wherein the sensor part senses presence information or position information of a user and transmits the information to the control part, so that the control part causes the light emitting device part to emit light with an appropriate light emission intensity.

36. The lighting system of claim 34 or claim 35,

wherein the light emission intensity of the light emitting device section is sequentially changed according to a change in the positional information of the user.

37. A guidance system using the lighting system of claim 34 or claim 35.

38. The guidance system of claim 37, wherein the guidance system,

wherein the sensor unit has a function of detecting attribute information possessed by the user,

and the guiding system guides the user in an appropriate direction by changing the light emission intensity of the light emitting device section based on the attribute information and the position information of the user.

39. A light emitting element comprising:

an anode;

a cathode;

a light-emitting layer having a host material and a guest material between the anode and the cathode;

a hole injection layer having an organic acceptor between the anode and the light emitting layer;

a first layer having a first organic compound between the hole injection layer and the light-emitting layer;

a second layer having a second organic compound between the first layer and the light-emitting layer; and

a third layer having a third organic compound between the second layer and the light-emitting layer,

wherein the HOMO level of the second organic compound is deeper than the HOMO level of the first organic compound,

the HOMO level of the host material is deeper than the HOMO level of the second organic compound,

the HOMO level of the third organic compound is deeper than the HOMO level of the host material,

a difference between the HOMO level of the second organic compound and the HOMO level of the third organic compound is 0.3eV or less,

the second organic compound has a band gap with an energy greater than a singlet energy of the guest material,

the second organic compound is a monoamine compound having a dibenzofuran skeleton or a dibenzothiophene skeleton,

and the dibenzofuran skeleton or the dibenzothiophene skeleton is bonded to the nitrogen of the amine directly or through a divalent aromatic hydrocarbon group.

40. The light-emitting element according to claim 39, wherein a wavelength of the singlet energy of the guest material is longer than an absorption edge of the second organic compound.

41. The light-emitting element according to claim 40, wherein the guest material emits fluorescence.

42. A method of synthesizing an organic compound, the method comprising:

the reaction was carried out according to the following scheme (F-1):

wherein Y represents a halogen atom or a trifluoromethanesulfonate,

R¹to R⁷And R³⁵To R⁴⁸Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms,

alpha represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms,

z represents an oxygen atom or a sulfur atom,

and k represents 1 or 2.

43. The method for synthesizing an organic compound according to claim 42, wherein the reaction condition is a Buhward-Hartmann reaction or an Ullmann reaction.

Technical Field

One embodiment of the present invention relates to a light-emitting element, a display module, an illumination module, a display device, a light-emitting device, an electronic device, and an illumination device. Note that one embodiment of the present invention is not limited to the above-described technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a program (process), a machine (machine), a product (manufacture), or a composition (machine). Therefore, more specifically, as an example of the technical field of one embodiment of the present invention disclosed in the present specification, a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, an illumination device, a power storage device, a storage device, an imaging device, driving methods thereof, and manufacturing methods thereof can be given.

Background

In recent years, light-emitting elements (organic EL elements) using organic compounds and utilizing Electroluminescence (EL) have been actively put into practical use. In the basic structure of these light-emitting elements, an organic compound layer (EL layer) containing a light-emitting material is interposed between a pair of electrodes. By applying a voltage to the element, carriers are injected, and light emission from the light-emitting material can be obtained by recombination energy of the carriers.

Since such a light-emitting element is a self-light-emitting type light-emitting element, there are advantages such as higher visibility, no need for a backlight, and the like when used for a pixel of a display device, compared with a liquid crystal. Therefore, the light-emitting element is suitable for a flat panel display element. In addition, a display using such a light emitting element can be manufactured to be thin and light, which is also a great advantage. Further, a very high speed response is one of the characteristics of the light emitting element.

Since the light-emitting layers of such a light-emitting element can be formed continuously in two dimensions, surface light emission can be obtained. This is a feature that is difficult to obtain in a point light source represented by an incandescent lamp or an LED or a line light source represented by a fluorescent lamp, and therefore, the light emitting element has high utility value as a surface light source applicable to illumination or the like.

As described above, although displays and lighting devices using light-emitting elements are applied to various electronic devices, research and development have been actively conducted to obtain light-emitting elements having higher efficiency and longer life.

As a material of the hole injection layer used for facilitating injection of carriers (particularly holes) into the EL layer, there is an organic acceptor. The organic acceptor can be easily formed by vapor deposition, and is suitable for mass production and widely used. However, when there is a distance between the LUMO level of the organic acceptor and the HOMO level of the organic compound constituting the hole transport layer, it is difficult to inject holes into the EL layer. Therefore, in order to make the LUMO level of the organic acceptor close to the HOMO level of the organic compound constituting the hole transport layer, the HOMO level of the organic compound constituting the hole transport layer is made shallow. However, when the HOMO level of the organic compound constituting the hole transport layer is shallow, the difference between the HOMO level of the organic compound and the HOMO level of the light emitting layer becomes large, and holes can be injected into the EL layer, but it is difficult to inject holes from the hole transport layer into the host material of the light emitting layer.

Patent document 1 discloses a structure in which a hole-transporting material having a HOMO level between the HOMO level of the first hole-injecting layer and the HOMO level of the host material is provided between the first hole-transporting layer in contact with the hole-injecting layer and the light-emitting layer.

The characteristics of the light-emitting element are remarkably improved, but it is not enough to meet high demands for various characteristics such as efficiency and durability.

[ patent document 1] International publication No. 2011/065136 pamphlet

Disclosure of Invention

An object of one embodiment of the present invention is to provide a novel light-emitting element. Another object of one embodiment of the present invention is to provide a light-emitting element having a long lifetime. Another object of one embodiment of the present invention is to provide a light-emitting element having excellent light-emitting efficiency.

Another object of the present invention is to provide a light-emitting device, an electronic device, and a display device with high reliability. Another object of the present invention is to provide a light-emitting device, an electronic device, and a display device with low power consumption.

It is an object of an embodiment of the present invention to provide a novel lighting system and a novel guidance system.

The present invention can achieve any of the above objects.

One embodiment of the present invention is a light-emitting element including: a first electrode; a second electrode; and an EL layer, wherein the EL layer is located between the first electrode and the second electrode, the EL layer includes a hole injection layer containing an organic acceptor, the hole injection layer is located between the first electrode and the first layer, the second layer is located between the first layer and the third layer, the fourth layer is located between the third layer and the second electrode, the first layer contains a first hole transport material, the second layer contains a second hole transport material, the third layer contains a third hole transport material, the fourth layer contains a host material having a HOMO level deeper than that of the first hole transport material, and a light emitting material, the host material has a HOMO level deeper than that of the second hole transport material, the third hole transport material has a HOMO level equal to or deeper than that of the host material, the difference between the HOMO level of the second hole transport material and that of the third hole transport material is 0.3eV or less, and the second hole transport material is a triarylamine compound having a structure in which a dibenzofuran skeleton or a dibenzothiophene skeleton is bonded to nitrogen of an amine directly or through a divalent aromatic hydrocarbon group.

Another embodiment of the present invention is a light-emitting element including 1 or 2 light-emitting materials having a structure in which the dibenzofuran skeleton or the dibenzothiophene skeleton is bonded to nitrogen of an amine directly or through a divalent aromatic hydrocarbon group in the second hole-transporting material.

Another embodiment of the present invention is a light-emitting element in which the 4-position of the dibenzofuran skeleton or dibenzothiophene skeleton is bonded to the nitrogen of an amine directly or through a divalent aromatic hydrocarbon group.

Another embodiment of the present invention is a light-emitting element in which the second hole-transporting material is an organic compound having a partial structure represented by the following general formula (g 1-1).

[ solution 1]

Note that, in the general formula (g1-1), Z represents an oxygen atomOr a sulfur atom. Further, n represents an integer of 0 to 3. In addition, R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

Another embodiment of the present invention is a light-emitting element in which the second hole-transporting material is an organic compound having a partial structure represented by the following general formula (g 1-2).

[ solution 2]

Note that, in the general formula (g1-2), Z represents an oxygen atom or a sulfur atom. n represents an integer of 0 to 3. R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

Another embodiment of the present invention is a light-emitting element, wherein the second hole-transporting material is a monoamine compound.

Another embodiment of the present invention is a light-emitting element in which the second hole-transporting material is an organic compound represented by the following general formula (G1-1).

[ solution 3]

Note that, in the general formula (G1-1), X represents an oxygen atom or a sulfur atom, and n represents an integer of 0 to 3. Ar (Ar)¹Represents any one of aromatic hydrocarbon groups having 6 to 18 nuclear atoms, Ar²Represents an aromatic hydrocarbon group having 6 to 18 nuclear atoms or a group represented by the following general formula (g 2-1). R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

[ solution 4]

In the general formula (g2-1), Z represents an oxygen atom or a sulfur atom, and m represents an integer of 0 to 3. R²¹To R³¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

Another embodiment of the present invention is a light-emitting element in which the second hole-transporting material is an organic compound represented by the following general formula (G1-2).

[ solution 5]

Note that, in the general formula (G1-2), Z represents an oxygen atom or a sulfur atom, and n represents an integer of 0 to 3. Ar (Ar)¹Represents any one of aromatic hydrocarbon groups having 6 to 18 nuclear atoms, Ar²Represents an aromatic hydrocarbon group having 6 to 18 nuclear atoms or a group represented by the following general formula (g 2-2). R¹To R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

[ solution 6]

In the general formula (g2-2), Z represents an oxygen atom or a sulfur atom, and m represents an integer of 0 to 3. R²¹To R³¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

Another embodiment of the present invention is a light-emitting element in which the organic acceptor is 2,3, 6, 7, 10, 11-hexacyan-1, 4, 5, 8, 9, 12-hexaazatriphenylene in the above structure.

Another embodiment of the present invention is a light-emitting element in which the second hole-transporting material has a HOMO level of-5.7 eV or more and-5.4 eV or less in the above structure.

Another embodiment of the present invention is a light-emitting element in the above structure, wherein a difference between the HOMO level of the first hole-transporting material and the HOMO level of the second hole-transporting material is 0.3eV or less.

Another embodiment of the present invention is a light-emitting element in the above structure, wherein a difference between the HOMO level of the second hole-transporting material and the HOMO level of the third hole-transporting material is 0.2eV or less.

Another embodiment of the present invention is a light-emitting element in the above structure, wherein a difference between the HOMO level of the first hole-transporting material and the HOMO level of the second hole-transporting material is 0.2eV or less.

Another embodiment of the present invention is a light-emitting element in which the HOMO level of the light-emitting material is higher than the HOMO level of the host material.

Another embodiment of the present invention is a light-emitting element in the above structure, wherein the first hole-transporting material is a triarylamine and has a fluoreneamine skeleton.

Another embodiment of the present invention is a light-emitting element in which the third hole-transporting material is a substance containing no amine.

Another embodiment of the present invention is a light-emitting element in which the third hole-transporting material has a carbazole skeleton.

Another embodiment of the present invention is a light-emitting element in which the carbazole skeleton is an N-phenylcarbazole skeleton in the above structure.

Another embodiment of the present invention is a light-emitting element in which the third hole-transporting material has a triphenylene skeleton.

Another embodiment of the present invention is a light-emitting element, in which the third hole-transporting material has a naphthalene skeleton.

Another embodiment of the present invention is a light-emitting element in which the host material has an anthracene skeleton.

Another embodiment of the present invention is a light-emitting element in which the host material has a diphenylanthracene skeleton.

Another embodiment of the present invention is a light-emitting element, in which the host material includes a carbazole skeleton.

Another embodiment of the present invention is a light-emitting element in which the carbazole skeleton includes a benzocarbazole skeleton in the above structure.

Another embodiment of the present invention is a light-emitting element in which the carbazole skeleton is a dibenzocarbazole skeleton in the above structure.

Another embodiment of the present invention is a light-emitting element in which the light-emitting material is a fluorescent substance in the above structure.

Another embodiment of the present invention is a light-emitting element in which the light emitted by the light-emitting material is blue fluorescence.

Another embodiment of the present invention is a light-emitting element, in which the light-emitting material is a condensed aromatic diamine compound.

Another embodiment of the present invention is a light-emitting element, in which the light-emitting material is a pyrene diamine compound.

Another aspect of the present invention is a lighting system including: a control unit; a sensor section; and an illumination section including a plurality of light emitting device sections, the light emitting device sections including one or more light emitting elements, the light emitting elements being the light emitting elements described in any one of the above.

Another aspect of the present invention is an illumination system having the above-described configuration, wherein the sensor unit senses presence information or position information of a user and transmits the information to the control unit, and the control unit causes the light emitting device unit to emit light with an appropriate light emission intensity.

Another aspect of the present invention is an illumination system having the above configuration, wherein the light emission intensity of the light emitting device portion is sequentially changed in accordance with a change in the positional information of the user.

Another aspect of the present invention is a guidance system in which the sensor unit has a function of detecting attribute information of a user, and changes the light emission intensity of the light-emitting device unit based on the attribute information and position information of the user to guide the user in an appropriate direction.

Another aspect of the present invention is a light-emitting device including the light-emitting element described in any one of the above; and a transistor or substrate.

Another aspect of the present invention is an electronic device including: the above light-emitting device; and a sensor, an operation button, a speaker, or a microphone.

Another aspect of the present invention is a lighting device including: the above light-emitting device; and a housing.

Another embodiment of the present invention is an organic compound represented by the following general formula (G2).

[ solution 7]

Note that, in the general formula (G2), R¹To R7 and R³⁵To R⁴⁸Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms. Further, α represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms in the core, and Z represents an oxygen atom or a sulfur atom. Further, k represents 1 or 2.

Another embodiment of the present invention is an organic compound represented by the following general formula (G3).

[ solution 8]

Note that, in the general formula (G3), R¹To R7 and R³⁵To R⁴⁸Each independently represents hydrogen, a saturated hydrocarbon having 1 to 6 carbon atomsAny one of a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. α represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and Z represents an oxygen atom or a sulfur atom.

Another embodiment of the present invention is an organic compound represented by the following general formula (G4).

[ solution 9]

Note that, in the general formula (G4), R¹To R⁷Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. α represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and Z represents an oxygen atom or a sulfur atom.

Another embodiment of the present invention is an organic compound represented by the following general formula (G5).

[ solution 10]

Note that, in the general formula (G5), R¹To R⁷Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. α represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and Z represents an oxygen atom or a sulfur atom.

Another embodiment of the present invention is an organic compound in which α in the above structure is any one of groups represented by the following structural formulae (α -1) to (α -5).

[ solution 11]

Another embodiment of the present invention is an organic compound represented by the following general formula (G6).

[ solution 12]

Another embodiment of the present invention is an organic compound represented by the following structural formula (100).

[ solution 13]

Another embodiment of the present invention is an organic compound represented by the following structural formula (101).

[ solution 14]

In addition, a light-emitting device in this specification includes an image display device using a light-emitting element. In addition, the following modules sometimes include a light emitting device: a module in which a connector such as an anisotropic conductive film or TCP (Tape Carrier Package) is mounted on the light emitting element; a module of a printed circuit board is arranged at the end part of the TCP; or a module in which an IC (integrated circuit) is directly mounted On a light-emitting element by a COG (Chip On Glass) method. Further, a lighting fixture or the like may include a light-emitting device.

One embodiment of the present invention can provide a novel light-emitting element. In addition, one embodiment of the present invention can provide a light-emitting element having a long lifetime. In addition, one embodiment of the present invention can provide a light-emitting element with excellent light-emitting efficiency.

In addition, another embodiment of the present invention can provide a light-emitting device, an electronic device, and a display device with high reliability. In addition, another embodiment of the present invention can provide a light-emitting device, an electronic device, and a display device with low power consumption.

One aspect of the present invention may provide a novel lighting system and a novel guidance system.

Note that the description of these effects does not hinder the existence of other effects. In addition, one embodiment of the present invention does not necessarily have all of the above effects. Further, effects other than these effects are obvious from the descriptions of the specification, the drawings, the claims, and the like, and the effects other than these effects can be extracted from the descriptions of the specification, the drawings, the claims, and the like.

Drawings

FIG. 1 is a schematic view of a light emitting element;

fig. 2 is a schematic diagram of an active matrix light-emitting device;

fig. 3 is a schematic diagram of an active matrix light-emitting device;

fig. 4 is a schematic diagram of an active matrix light-emitting device;

fig. 5 is a schematic diagram of a passive matrix light-emitting device;

fig. 6 is a diagram showing a lighting device;

fig. 7 is a diagram showing an electronic apparatus;

fig. 8 is a diagram showing a light source device;

fig. 9 is a diagram showing a lighting device;

fig. 10 is a diagram showing a lighting device;

fig. 11 is a diagram showing an in-vehicle display device and an illumination device;

fig. 12 is a diagram showing an electronic apparatus;

fig. 13 is a diagram showing an electronic apparatus;

FIG. 14 is a 1H NMR spectrum of mThBA1 BP-II;

FIG. 15 is a 1H NMR spectrum of ThBA1 BP-II;

FIG. 16 is a 1H NMR spectrum of ThBB1 BP-II;

FIG. 17 is an absorption spectrum in toluene solutions of mThBA1BP-II, ThBA1BP-II, and ThBB1 BP-II;

FIG. 18 is an emission spectrum in toluene solutions of mThBA1BP-II, ThBA1BP-II, and ThBB1 BP-II;

FIG. 19 is an absorption spectrum of a thin film of mThBA1BP-II, ThBA1BP-II, and ThBB1 BP-II;

FIG. 20 is a film and emission spectra of mThBA1BP-II, ThBA1BP-II, and ThBB1 BP-II;

fig. 21 is a luminance-current density characteristic of the light emitting element 1;

fig. 22 is a current efficiency-luminance characteristic of the light emitting element 1;

fig. 23 is a luminance-voltage characteristic of the light emitting element 1;

fig. 24 is a current-voltage characteristic of the light emitting element 1;

fig. 25 is an external quantum efficiency-luminance characteristic of the light emitting element 1;

fig. 26 is an emission spectrum of the light emitting element 1;

fig. 27 is a normalized luminance-time variation characteristic of the light emitting element 1;

fig. 28 is a sectional view illustrating a method of manufacturing an EL layer;

fig. 29 is a schematic view illustrating a liquid droplet ejection apparatus;

fig. 30 is a block diagram of a lighting system.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art can easily understand that the mode and details thereof can be changed into various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below.

Embodiment mode 1

Fig. 1A is a diagram illustrating a light-emitting element according to an embodiment of the present invention. A light-emitting element according to one embodiment of the present invention includes a first electrode 101, a second electrode 102, and an EL layer 103, and the EL layer 103 includes a hole injection layer 111, a first hole transport layer 112-1, a second hole transport layer 112-2, a third hole transport layer 112-3, and a light-emitting layer 113 from the first electrode 101 side. Further, an electron transport layer 114 and an electron injection layer 115 may be further included.

The light-emitting layer 113 of the light-emitting element according to one embodiment of the present invention includes a host material and a light-emitting material, the hole-injecting layer 111 includes an organic acceptor, and the first hole-transporting layer 112-1, the second hole-transporting layer 112-2, and the third hole-transporting layer 112-3 include a first hole-transporting material, a second hole-transporting material, and a third hole-transporting material, respectively.

The HOMO level of the host material is deeper than the HOMO level of the second hole transport material, and the HOMO level of the second hole transport material is deeper than the HOMO level of the first hole transport material. In addition, the HOMO level of the third hole transport material exists at a position deeper than or equal to the HOMO level of the host material. Note that the difference between the HOMO level of the second hole-transporting material and the HOMO level of the third hole-transporting material is 0.3eV or less.

The organic acceptor is an organic compound having a deep LUMO level, and holes are generated in the organic compound by charge separation between the organic acceptor and the organic compound having a HOMO level close to the LUMO level of the organic acceptor. In other words, the light-emitting element of this embodiment generates holes in the first hole-transporting material in contact with the organic acceptor. As the organic acceptor, a compound having an electron-withdrawing group (halogen group or cyano group) is preferably used, and for example, 7,8, 8-tetracyano-2, 3,5, 6-tetrafluoroquinodimethane (abbreviated as F) is preferably used₄-TCNQ), 3, 6-difluoro-2, 5, 7, 7,8, 8-hexacyano-p-quinodimethane, chloranil, and 2,3, 6, 7, 10, 11-hexacyan-1, 4, 5, 8, 9, 12-hexaazatriphenylene (HAT-CN), and the like. In particular, HAT-CN is preferable because it has a high acceptor property and a stable film quality.

Since the difference between the LUMO level of the organic acceptor and the HOMO level of the first hole transporting material varies depending on the level of the acceptor property of the organic acceptor, holes can be injected without any particular limitation as long as the difference is about 1eV or less. In the case of using HAT-CN as the organic acceptor, the LUMO level of HAT-CN can be estimated to be-4.41 eV by cyclic voltammetry, and therefore the HOMO level of the first hole transporting material is preferably-5.4 eV or more. Note that if the HOMO level of the first hole transporting material is too high, the hole injecting property into the second hole transporting material is lowered. Further, since the work function of the anode such as ITO is about-5 eV, the HOMO energy level of the first hole transporting material is disadvantageously higher than-5 eV. Therefore, the HOMO level of the first hole transporting material is preferably-5.0 eV or less.

The holes generated in the first hole transport material are moved to the second electrode 102 side by the electric field and injected into the second hole transport layer 112-2. When the second hole transporting material contained in the second hole transporting layer 112-2 is a triarylamine compound having a structure in which a dibenzofuran skeleton or a dibenzothiophene skeleton is bonded to nitrogen of an amine directly or through a divalent aromatic hydrocarbon group, the reliability of the light-emitting element is good, and thus the light-emitting element is preferable.

The triarylamine compound of the second hole transport material is preferably a compound in which a dibenzofuran skeleton or a dibenzothiophene skeleton is bonded to nitrogen of an amine directly or through a divalent aromatic hydrocarbon group, and has a wide optical band gap and is less likely to absorb in the visible region. Further, since the HOMO level of this substance is located at a deep position, i.e., -5.4eV to-5.7 eV or so, it is suitable for use as the second hole transporting material. Note that in this specification, the aryl group in the triarylamine also includes a heteroaryl group.

The triarylamine compound of the second hole transport material is preferably a compound in which the 4-position of the dibenzofuran skeleton or the 4-position of the dibenzothiophene skeleton is bonded to the nitrogen of the amine directly or through a divalent aromatic hydrocarbon group because the compound is easy to synthesize. Further, the value of the HOMO level tends to be smaller (deeper) than that of the substituent at the 2-position, and therefore, this is preferable.

The divalent aromatic hydrocarbon group in the triarylamine compound is preferably a divalent aromatic hydrocarbon group having 6 or more nuclear atoms to 18 carbon atoms.

The triarylamine compound of the second hole transport material may be represented by an organic compound having a partial structure represented by the following general formula (g 1-1).

[ solution 15]

Note that, in the general formula (g1-1), Z represents an oxygen atom or a sulfur atom. Further, n represents an integer of 0 to 3. In addition, the first and second substrates are,R¹to R¹¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

As described above, it is preferable that the dibenzofuran skeleton or dibenzothiophene skeleton in the organic compound of the above-mentioned second hole transporting material is bonded to the nitrogen of the amine directly or through a divalent aromatic hydrocarbon group at the 4-position.

In other words, an organic compound having a partial structure represented by the following general formula (g1-2) is preferable.

[ solution 16]

Note that Z, n and R in the general formula (g1-2)¹To R¹¹The same as in the general formula (g 1-1).

The second hole-transporting material is a monoamine rather than a diamine, and therefore has an appropriately deep HOMO level, and can be further preferably applied to the light-emitting element of this embodiment mode.

More specifically, the second hole transporting material is preferably an organic compound represented by the following general formula (G1-1).

[ solution 17]

Note that Z, n and R in the general formula (G1-1)¹To R¹¹The same as in the general formula (g 1-1). Further, Ar¹Represents any one of aromatic hydrocarbon groups having 6 to 18 nuclear atoms, Ar²Represents an aromatic hydrocarbon group having 6 to 18 nuclear atoms or a group represented by the following general formula (g 2-1).

[ solution 18]

Note that, in the general formula (g2-1),z represents an oxygen atom or a sulfur atom, and m represents an integer of 0 to 3. Furthermore, R²¹To R³¹Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms.

As described above, it is preferable that the dibenzofuran skeleton or dibenzothiophene skeleton in the above-mentioned second hole transporting material is bonded to the nitrogen of the amine at the 4-position directly or through a divalent aromatic hydrocarbon group.

That is, another embodiment of the present invention is preferably an organic compound represented by the following general formula (G1-2).

[ solution 19]

Note that in the general formula (G1-2), Z, n, R¹To R¹⁰And Ar¹And Z, n, R of the above general formula (G1-1)¹To R¹⁰And Ar¹The same is true. Further, Ar²Is an aromatic hydrocarbon group having 6 to 18 nuclear atoms or a group represented by the following general formula (g 2-2).

[ solution 20]

In the general formula (g2-2), Z, m and R²¹To R³¹Z, m and R of the above general formula (g2-1)²¹To R³¹The same is true.

In the present specification, specific examples of the saturated hydrocarbon group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylpropyl group, a1, 1-dimethylpropyl group, a1, 2-dimethylpropyl group, a2, 2-dimethylpropyl group, a branched or unbranched hexyl group, and the like.

Examples of the cyclic saturated hydrocarbon group having 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.

Examples of the aromatic hydrocarbon group having 1 to 18 carbon atoms include a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and a fluorenyl group. When the group is a fluorenyl group, it is preferably substituted, and the fluorenyl group is more preferably a 9, 9-dialkylfluorenyl group, a 9, 9-diarylfluorenyl group or a diphenylfluorenyl group. Further, the alkyl group of the 9, 9-dialkylfluorenyl group is preferably an alkyl group having 1 to 6 carbon atoms. The 9, 9-diarylfluorene group is preferably a phenyl group, and may be a 9, 9' -spirobifluorene group in which diphenylfluorene groups and phenyl groups are bonded to each other.

Examples of the divalent aromatic hydrocarbon group having 6 to 18 carbon atoms include phenylene, biphenyl-diyl, naphthylene, fluorene-diyl, and the like. When the group is a fluorene-diyl group, it preferably has a substituent, and the fluorene-diyl group is more preferably a 9, 9-dialkylfluorene-diyl group or a 9, 9-diphenylfluorene-diyl group. Further, the alkyl group of the 9, 9-dialkylfluorenyl group is preferably an alkyl group having 1 to 6 carbon atoms. Further, the 9, 9-diphenylfluorene-diyl group is preferably a 9, 9' -spirobifluorene-diyl group in which phenyl groups are bonded to each other.

In the present specification, when the number of nuclear atoms in a certain substituent is specified, the number of atoms in the skeleton in the substituent is specified, and the substituent may further include a substituent. As the substituent in this case, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, a phenyl group, or the like can be used.

The HOMO level of the second hole transport material constituting the second hole transport layer 112-2 is located between the HOMO level of the first hole transport material and the HOMO level of the host material by using the triarylamine compound or the organic compound, and thus holes can be easily injected from the first hole transport layer 112-1 to the second hole transport layer 112-2. The difference in HOMO levels between the first hole-transporting material and the second hole-transporting material is preferably 0.3eV or less in order to smoothly inject holes, and more preferably 0.2eV or less in order to further smoothly inject holes.

The holes injected into the second hole transport layer 112-2 are further moved toward the second electrode 102 by the electric field, and are injected into the third hole transport layer 112-3. The HOMO level of the third hole transport material contained in the third hole transport layer 112-3 is deeper than or equal to the HOMO level of the host material and the difference between the HOMO level of the third hole transport material and the HOMO level of the second hole transport material is less than 0.3 eV. Since the difference between the HOMO level of the second hole transport material and the HOMO level of the third hole transport material is 0.3eV or less, holes are smoothly injected from the second hole transport layer 112-2 to the third hole transport layer 112-3. In order to further smoothly inject holes, the difference between the HOMO level of the third hole transporting material and the HOMO level of the second hole transporting material is preferably less than 0.2 eV. The hole transport material having the HOMO level equal to the HOMO level of the host material is a material having a HOMO level within a range of ± 0.1eV of the HOMO level of the host material, and preferably within a range of ± 0.05 eV.

The HOMO level of the third hole transport material is deeper than or equal to the HOMO level of the host material, and thus there is no injection barrier for holes from the third hole transport layer 112-3 to the light emitting layer 113. Also, the HOMO level of the third hole transport material is deeper than or equal to the HOMO level of the host material, so holes are directly injected not only into the light emitting material but also easily into the host material. In the case where holes are preferentially injected into the light-emitting material, the holes in the light-emitting layer are extremely unlikely to move, and the light-emitting region is concentrated at the interface between the hole-transporting layer and the light-emitting layer. As a result, the element life is adversely affected. In one embodiment of the present invention, since holes are also injected into the host material, holes are transported mainly in the host material in the light-emitting layer, and are appropriately affected by hole traps in the light-emitting material, so that the light-emitting region can be appropriately enlarged, and high efficiency and long lifetime can be obtained. Appropriately enlarging the light-emitting region refers to a state where holes are transported to some extent in the light-emitting layer but do not pass through the light-emitting layer. Therefore, the host material preferably has a hole-transporting property, and specifically preferably has an anthracene skeleton or a carbazole skeleton. In addition, the host material preferably also has an electron-transporting property, and therefore an anthracene skeleton is particularly preferable. In other words, the host material preferably has both an anthracene skeleton and a carbazole skeleton. The carbazole skeleton is preferably a benzocarbazole skeleton or dibenzocarbazole. This is because these structures have HOMO levels about 0.1eV higher than carbazole, and holes are easily injected into the host material (therefore, as described above, the light emitting region which is appropriately enlarged as described above is easily formed). As described above, the inclusion of the third hole transport layer 112-3 is one of the features of the light-emitting element according to one embodiment of the present invention.

In the case where the HOMO level of the light-emitting material is shallower than that of the host material, if holes are injected into the light-emitting layer from a hole-transporting material whose HOMO level is shallower than that of the host material, hole injection into the light-emitting material is dominant over hole injection into the host material. In the case where holes are injected into a light-emitting material having a shallow HOMO level, the holes are trapped. When holes are trapped and movement of holes is inhibited, problems such as deterioration of a light-emitting layer and reduction in light emission efficiency due to accumulation of charges or concentration of recombination regions occur.

However, the light-emitting element of this embodiment mode includes the third hole transport layer 112-3 and has a HOMO level deeper than or equal to that of the host material, and therefore hole injection into the host material is dominant over hole injection into the light-emitting material. As a result, it is possible to avoid blocking the movement of holes, to trap holes appropriately in the light-emitting material, and to obtain various effects such as dispersion of recombination regions, improvement in reliability, and improvement in light-emitting efficiency.

Next, a detailed structure and material example of the light-emitting element will be described. As described above, the light-emitting element according to one embodiment of the present invention includes the EL layer 103 formed of a plurality of layers between the pair of the first electrode 101 and the second electrode 102, and the EL layer 103 includes the hole injection layer 111, the first hole transport layer 112-1, the second hole transport layer 112-2, the third hole transport layer 112-3, and the light-emitting layer 113 at least from the first electrode 101 side.

The other layers in the EL layer 103 are not particularly limited, and various layer structures such as a hole injection layer, a hole transport layer, an electron injection layer, a carrier blocking layer, an exciton blocking layer, and a charge generation layer can be applied.

The first electrode 101 is preferably formed using a metal, an alloy, a conductive compound, a mixture thereof, or the like having a large work function (specifically, 4.0eV or more). Specific examples thereof include Indium Tin Oxide (ITO), Indium Tin Oxide containing silicon or silicon Oxide, Indium zinc Oxide, and Indium Oxide containing tungsten Oxide and zinc Oxide (IWZO). Although these conductive metal oxide films are generally formed by a sputtering method, they may be formed by applying a sol-gel method or the like. Examples of the formation method include the following methods: a method of forming indium oxide-zinc oxide by a sputtering method using a target to which zinc oxide is added in an amount of 1 wt% to 20 wt% relative to indium oxide, and the like. In addition, indium oxide (IWZO) including tungsten oxide and zinc oxide may also be formed by a sputtering method using a target to which 0.5 wt% to 5 wt% of tungsten oxide and 0.1 wt% to 1 wt% of zinc oxide are added with respect to indium oxide. Further, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or a nitride of a metal material (e.g., titanium nitride), and the like can be given. Further, graphene may also be used. Further, by using a composite material described later for a layer in contact with the first electrode 101 in the EL layer 103, it is possible to select an electrode material without considering a work function.

In this embodiment, the following two structures are described as the stacked structure of the EL layer 103: as shown in fig. 1A, a structure including a hole injection layer 111, a first hole transport layer 112-1, a second hole transport layer 112-2, a third hole transport layer 112-3, a light emitting layer 113, an electron transport layer 114, and an electron injection layer 115; and as shown in fig. 1B, a structure including a hole injection layer 111, a first hole transport layer 112-1, a second hole transport layer 112-2, a third hole transport layer 112-3, a light emitting layer 113, an electron transport layer 114, and a charge generation layer 116. Examples of specific materials constituting the respective layers are shown below.

The hole injection layer 111 is a layer containing an organic acceptor. As the organic acceptor, a compound having an electron-withdrawing group (halogen group or cyano group) can be used, and for example, 7,8, 8-tetracyano-2, 3,5, 6-tetrafluoroquinodimethane (abbreviated as F) can be used₄-TCNQ), 3, 6-difluoro-2, 5, 7, 7,8, 8-hexacyano-p-quinodimethane, chloranil and 2,3, 6, 7, 10, 11-hexacyano-1, 4, 5, 8, 9, 12-hexaazatriphenylene (HAT-CN), and the like. As the organic acceptor, a compound in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of hetero atoms such as HAT-CN or the like has thermal stability, and is therefore preferable. The organic acceptor can extract electrons from at least the adjacent hole transport layer (or hole transport material) by application of an electric field.

By forming the hole injection layer 111, hole injection properties can be improved, and a light-emitting element with a small driving voltage can be obtained. In addition, the organic acceptor is a material that is easy to use because it is easy to form a film by vapor deposition.

The hole transport layer is composed of a first hole transport layer 112-1, a second hole transport layer 112-2, and a third hole transport layer 112-3. The first to third hole transport layers 112-1 to 112-3 each contain a hole transport material having a hole transport property, the first hole transport layer 112-1 contains a first hole transport material, the second hole transport layer 112-2 contains a second hole transport material, and the third hole transport layer 112-1 contains a third hole transport material. The hole-transporting material preferably has a density of 1X 10^-6cm²A hole mobility of Vs or higher. In addition, the following relationships exist between the materials: the HOMO level of the second hole transporting material is deeper than the HOMO level of the first hole transporting material, the HOMO level of the host material contained in the light emitting layer 113 is deeper than the HOMO level of the second hole transporting material, the HOMO level of the third hole transporting material is deeper than or equal to the HOMO level of the host material, and the difference between the HOMO level of the second hole transporting material and the HOMO level of the third hole transporting material is 0.3eV or less. Note that the difference between the HOMO level of the second hole transporting material and the HOMO level of the third hole transporting material is preferably 0.2eV or less.

As the first hole transporting material, a hole transporting material having a relatively shallow HOMO level is preferably used, and as the organic compound, a material having a triarylamine and a fluorenylamine skeleton is preferably used.

As the third hole transport material, a hole transport material having a relatively deep HOMO level is preferably used. Since the HOMO level of the organic compound containing an amine tends to be shallow, it is preferable to use a hole transport material containing no amine. As such a hole transporting material, a hole transporting material having a carbazole skeleton is preferably used. Organic compounds having a carbazole skeleton and a triphenylene skeleton, organic compounds having a carbazole skeleton and a phenanthrene skeleton, organic compounds having a carbazole skeleton and a naphthalene skeleton, and the like are preferably used.

The second hole-transporting material has already been described in detail, and therefore, redundant description is omitted. Please refer to the above description.

The light-emitting layer 113 is a layer containing a host material and a light-emitting material. The light-emitting material may be any of a fluorescent substance, a phosphorescent substance, and a substance exhibiting Thermally Activated Delayed Fluorescence (TADF). The light-emitting layer may be a single layer or may be composed of a plurality of layers containing different light-emitting materials. In one embodiment of the present invention, the layer is preferably used as a layer exhibiting fluorescence emission, and particularly, a layer exhibiting blue fluorescence emission.

In the light-emitting layer 113, the following materials can be used as a fluorescent light-emitting substance. In addition, other fluorescent substances may be used.

For example, 5, 6-bis [4- (10-phenyl-9-anthryl) phenyl group]-2, 2 '-bipyridine (PAP 2BPy for short), 5, 6-bis [4' - (10-phenyl-9-anthryl) biphenyl-4-yl]-2, 2' -bipyridine (PAPP 2BPy), (N, N ' -diphenyl-N, N ' -bis [4- (9-phenyl-9H-fluoren-9-yl) phenyl]Pyrene-1, 6-diamine) (abbreviation: 1, 6FLPAPRn), N '-bis (3-methylphenyl) -N, N' -bis [3- (9-phenyl-9H-fluoren-9-yl) phenyl]Pyrene-1, 6-diamine (1, 6mM FLPAPPrn), N' -bis [4- (9H-carbazol-9-yl) phenyl]-N, N '-diphenylstilbene-4, 4' -diamine (abbreviation: YGA2S), 4- (9H-carbazol-9-yl) -4'- (10-phenyl-9-anthracenyl) triphenylamine (abbreviation: YGAPA), 4- (9H-carbazol-9-yl) -4' - (9, 10-diphenyl-2-anthracenyl) triphenylamine (abbreviation: 2YGAPPA), N, 9-diphenyl-N- [4- (10-phenyl-9-anthracenyl) phenyl]-9H-carbazole-3-amine (PCAPA), perylene, 2, 5, 8, 11-tetra-tert-butyl perylene (TBP), 4- (10-phenyl-9-anthryl) -4'- (9-phenyl-9H-carbazole-3-yl) triphenylamine (PCBAPA), N' - (2-tert-butylanthracene-9, 10-diyl di-4, 1-phenylene) bis [ N, N ', N' -triphenyl-1, 4-phenylenediamine](DPABPA), N, 9-diphenylphenyl-N- [4- (9, 10-diphenyl-2-anthryl)]-9H-carbazole-3-amine (2 PCAPPA for short), N- [4- (9, 10-diphenyl-2-anthryl) phenyl]-N, N ', N ' -triphenyl-1, 4-phenylenediamine (abbreviated as 2DPAPPA), N, N, N ', N ', N ' -octaphenyldibenzo [ g, p ]](chrysene) -2, 7, 10, 15-tetramine (abbreviation: DBC1), coumarin 30, N- (9, 10-diphenyl-2-anthryl) -N, 9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N- [9, 10-bis (1, 1' -biphenyl-2-yl) -2-anthryl]-N, 9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N- (9, 10-diphenyl-2-anthracenyl) -N, N ', N ' -triphenyl-1, 4-phenylenediamine (abbreviation: 2DPAPA), N- [9, 10-bis (1, 1' -biphenyl-2-yl) -2-anthracenyl]-N, N ', N ' -triphenyl-1, 4-phenylenediamine (2 DPABPhA for short), 9, 10-bis (1, 1' -biphenyl-2-yl) -N- [4- (9H-carbazol-9-yl) phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N, 9-triphenylanthracene-9-amine (abbreviation: DPhAPHA), coumarin 545T, N, N '-diphenylquinacridone (abbreviation: DPQd), rubrene, 5, 12-bis (1, 1' -biphenyl-4-yl) -6, 11-diphenyltetracene (abbreviation: BPT), 2- (2- {2- [4- (dimethylamino) phenyl ] tetraphenyl]Vinyl } -6-methyl-4H-pyran-4-ylidene) malononitrile (abbreviation: DCM1), 2- { 2-methyl-6- [2- (2,3, 6, 7-tetrahydro-1H, 5H-benzo [ ij ]]Quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene malononitrile (abbreviation: DCM2), N, N, N ', N' -tetrakis (4-methylphenyl) naphthacene-5, 11-diamine (abbreviation: p-mPTHTD), 7, 14-diphenyl-N, N, N ', N' -tetrakis (4-methylphenyl) acenaphtho [1, 2-a ]]Fluoranthene-3, 10-diamine (p-mPHAFD for short), 2- { 2-isopropyl-6- [2- (1, 1, 7, 7-tetramethyl-2, 3,6, 7-tetrahydro-1H, 5H-benzo [ ij ]]Quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene malononitrile (abbreviated as DCJTI), 2- { 2-tert-butyl-6- [2- (1, 1, 7, 7-tetramethyl-2, 3,6, 7-tetrahydro-1H, 5H-benzo [ ij ]]Quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene malononitrile (abbreviated as DCJTB), 2- (2, 6-bis {2- [4- (dimethylamino) phenyl group)]Vinyl } -4H-pyran-4-ylidene) malononitrile (abbreviation: BisDCM), 2- {2, 6-bis [2- (8-methoxy-1, 1, 7, 7-tetramethyl-2, 3,6, 7-tetrahydro-1H, 5H-benzo [ ij ]]Quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene malononitrile (abbreviated: BisDCJTM), and the like. In particular, fused aromatic diamine compounds represented by pyrene diamine derivative compounds such as 1, 6FLPAPrn and 1, 6mMemFLPAPrn are preferable because they have suitable hole-trapping properties and good luminous efficiency and reliability.

In the light-emitting layer 113, the following materials can be used as a phosphorescent material.

For example, there may be mentioned: tris {2- [5- (2-methylphenyl) -4- (2, 6-dimethylphenyl) -4H-1,2, 4-triazol-3-yl- } - κ N2]Phenyl-kappa C iridium (III) (abbreviation: [ Ir (mpptz-dmp) ]₃]) Tris (5-methyl-3, 4-diphenyl-4H-1, 2, 4-triazole) iridium (III) (abbreviation: [ Ir (Mptz)₃]) Tris [4- (3-biphenyl) -5-isopropyl-3-phenyl-4H-1, 2, 4-triazole]Iridium (III) (abbreviation: [ Ir (iPrptz-3b)₃]) And the like organometallic iridium complexes having a 4H-triazole skeleton; tris [ 3-methyl-1- (2-methylphenyl) -5-phenyl-1H-1, 2, 4-triazole]Iridium (III) (abbreviation: [ Ir (Mptz1-mp)₃]) Tris (1-methyl-5-phenyl-3-propyl-1H-1, 2, 4-triazole) iridium (III) (abbreviation: [ Ir (Prptz1-Me)₃]) And the like organometallic iridium complexes having a 1H-triazole skeleton; fac-tris [ (1-2, 6-diisopropylphenyl) -2-phenyl-1H-imidazole]Iridium (III) (abbreviation: [ Ir (iPrpmi)₃]) Tris [3- (2, 6-dimethylphenyl) -7-methylimidazo [1,2-f ]]Phenanthridino (phenanthrinato)]Iridium (III) (abbreviation: [ Ir (dmpimpt-Me)₃]) And the like organometallic iridium complexes having an imidazole skeleton; and bis [2- (4',6' -difluorophenyl) pyridinato-N, C²']Iridium (III) tetrakis (1-pyrazolyl) borate (FIr 6 for short), bis [2- (4',6' -difluorophenyl) pyridinato-N, C²']Iridium (III) picolinate (FIrpic), bis {2- [3',5' -bis (trifluoromethyl) phenyl]pyridinato-N, C²' } Iridium (III) picolinate (abbreviation: [ Ir (CF)₃ppy)₂(pic)]) Bis [2- (4',6' -difluorophenyl) pyridinato-N, C²']And organometallic iridium complexes having, as a ligand, a phenylpyridine derivative having an electron-withdrawing group, such as iridium (III) acetylacetonate (abbreviated as "FIRacac"). The above substance is a compound emitting blue phosphorescence, and has a peak of light emission at 440nm to 520 nm.

In addition, there may be mentioned: three (4-Methyl-6-phenylpyrimidine) iridium (III) (abbreviation: [ Ir (mppm)₃]) Tris (4-tert-butyl-6-phenylpyrimidinate) iridium (III) (abbreviation: [ Ir (tBuppm)₃]) And (acetylacetonate) bis (6-methyl-4-phenylpyrimidinate) iridium (III) (abbreviation: [ Ir (mppm)₂(acac)]) And (acetylacetonate) bis (6-tert-butyl-4-phenylpyrimidinate) iridium (III) (abbreviation: [ Ir (tBuppm)₂(acac)]) And (acetylacetonate) bis [6- (2-norbornyl) -4-phenylpyrimidine]Iridium (III) (abbreviation: [ Ir (nbppm)₂(acac)]) And (acetylacetonate) bis [ 5-methyl-6- (2-methylphenyl) -4-phenylpyrimidine]Iridium (III) (simply: Ir (mppm))₂(acac)), (acetylacetonate) bis (4, 6-diphenylpyrimidinate) iridium (III) (abbreviation: [ Ir (dppm)₂(acac)]) And the like organometallic iridium complexes having a pyrimidine skeleton; (Acetylacetonato) bis (3, 5-dimethyl-2-phenylpyrazinato) iridium (III) (abbreviation: [ Ir (mppr-Me)₂(acac)]) And (acetylacetonate) bis (5-isopropyl-3-methyl-2-phenylpyrazinato) iridium (III) (abbreviation: [ Ir (mppr-iPr)₂(acac)]) And the like organometallic iridium complexes having a pyrazine skeleton; tris (2-phenylpyridinato-N, C)²') Iridium (III) (abbreviation: [ Ir (ppy)₃]) Bis (2-phenylpyridinato-N, C)²') Iridium (III) acetylacetone (abbreviation: [ Ir (ppy)₂(acac)]) Bis (benzo [ h ]]Quinoline) iridium (III) acetylacetone (abbreviation: [ Ir (bzq)₂(acac)]) Tris (benzo [ h ]) or a salt thereof]Quinoline) iridium (III) (abbreviation: [ Ir (bzq)₃]) Tris (2-phenylquinoline-N, C)²']Iridium (III) (abbreviation: [ Ir (pq))₃]) Bis (2-phenylquinoline-N, C)²') Iridium (III) acetylacetone (abbreviation: [ Ir (pq)₂(acac)]) And the like organometallic iridium complexes having a pyridine skeleton; and tris (acetylacetonate) (monophenanthroline) terbium (III) (abbreviation: [ Tb (acac))₃(Phen)]) And the like. The above substances are mainly green phosphorescent emitting compounds, and have a peak of light emission at 500nm to 600 nm. In addition, an organometallic iridium complex having a pyrimidine skeleton is particularly preferable because of its particularly excellent reliability and light emission efficiency.

In addition, there may be mentioned: (diisobutyl methanolate) bis [4, 6-bis (3-methylphenyl) pyrimidinyl]Iridium (III) (abbreviation: [ Ir (5mdppm)₂(dibm)]) Bis [4, 6-bis (3-methylphenyl) pyrimidino) (dipivaloylmethanato) iridium (III) (abbreviation: [ Ir (5 mddppm)₂(dpm)]) Bis [4, 6-di (naphthalen-1-yl) pyrimidinium radical](Dipivaloylmethanato) iridium (III) (abbreviation: [ Ir (d1npm)₂(dpm)]) And the like organometallic iridium complexes having a pyrimidine skeleton; (Acetylacetonato) bis (2,3, 5-triphenylpyrazinato) iridium (III) (abbreviation: [ Ir (tppr)₂(acac)]) Bis (2,3, 5-triphenylpyrazinyl) (dipivaloylmethanyl) iridium (III) (abbreviation: [ Ir (tppr)₂(dpm)]) (acetylacetonate) bis [2, 3-bis (4-fluorophenyl) quinoxalinyl]Iridium (III) (abbreviation: [ Ir (Fdpq)₂(acac)]) And the like organometallic iridium complexes having a pyrazine skeleton; tris (1-phenylisoquinoline-N, C)^2’) Iridium (III) (abbreviation: [ Ir (piq)₃]) Bis (1-phenylisoquinoline-N, C)^2’) Iridium (III) acetylacetone (abbreviation: [ Ir (piq)₂(acac)]) And the like organometallic iridium complexes having a pyridine skeleton; platinum complexes such as 2,3,7,8,12,13,17, 18-octaethyl-21H, 23H-porphyrin platinum (II) (abbreviated as PtOEP); and tris (1, 3-diphenyl-1, 3-propanedione (panediatoo)) (monophenanthroline) europium (III) (abbreviation: [ Eu (DBM))₃(Phen)]) Tris [1- (2-thenoyl) -3,3, 3-trifluoroacetone](Monophenanthroline) europium (III) (abbreviation: [ Eu (TTA))₃(Phen)]) And the like. The above substance is a compound that emits red phosphorescence, and has a peak of light emission at 600nm to 700 nm. In addition, the organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

In addition to the phosphorescent compound, a known phosphorescent material may be selected and used.

As the TADF material, fullerene and a derivative thereof, an acridine derivative such as pullulan, eosin, or the like can be used. And metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), or the like. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complexes (SnF) represented by the following structural formula₂(Proto IX)), mesoporphyrin-tin fluoride complex (SnF)₂(Meso IX)), hematoporphyrin-tin fluoride complex (SnF)₂(Hemato IX)), coproporphyrin tetramethyl esterTin fluoride complexes (SnF)₂(Copro III-4Me), octaethylporphyrin-tin fluoride complex (SnF)₂(OEP)), protoporphyrin-tin fluoride complex (SnF)₂(Etio I)) and octaethylporphyrin-platinum chloride complex (PtCl)₂OEP), and the like.

[ solution 21]

In addition, 2-biphenyl-4, 6-bis (12-phenylindole [2, 3-a) represented by the following structural formula can also be used]Carbazol-11-yl) -1,3, 5-triazine (abbreviation: PIC-TRZ), 9- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -9 ' -phenyl-9H, 9 ' H-3, 3' -bicarbazole (abbreviation: PCCzTzn), 9- [4- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) phenyl]-9 ' -phenyl-9H, 9 ' H-3, 3' -bicarbazole (PCCzPTzn), 2- [4- (10H-phenoxazin-10-yl) phenyl]-4, 6-diphenyl-1, 3, 5-triazine (abbreviation: PXZ-TRZ), 3- [4- (5-phenyl-5, 10-dihydrophenazine-10-yl) phenyl]-4, 5-diphenyl-1, 2, 4-triazole (abbreviated as PPZ-3TPT), 3- (9, 9-dimethyl-9H-acridin-10-yl) -9H-xanthen-9-one (abbreviated as ACRXTN), bis [4- (9, 9-dimethyl-9, 10-dihydroacridine) phenyl]Sulfosulfone (DMAC-DPS), 10-phenyl-10H, 10 'H-spiro [ acridine-9, 9' -anthracene]Heterocyclic compounds having both of a pi-electron-rich aromatic heterocycle and a pi-electron-deficient aromatic heterocycle, such as-10' -ketone (ACRSA). The heterocyclic compound preferably has a pi-electron-rich aromatic heterocycle and a pi-electron-deficient aromatic heterocycle, and has high electron-transporting property and hole-transporting property. In the substance in which the pi-electron-rich aromatic heterocycle and the pi-electron-deficient aromatic heterocycle are directly bonded, the donor property and the acceptor property of the pi-electron-rich aromatic heterocycle and the pi-electron-deficient aromatic heterocycle are both high and S is₁Energy level and T₁The energy difference between the energy levels becomes small, and thermally activated delayed fluorescence can be obtained efficiently, so that it is particularly preferable. In addition, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used instead of the pi-electron deficient aromatic heterocycle.

[ solution 22]

As the host material of the light-emitting layer, various carrier-transporting materials such as a material having an electron-transporting property and a material having a hole-transporting property can be used.

Examples of the material having a hole-transporting property include: 4,4 '-bis [ N- (1-naphthyl) -N-phenylamino ] biphenyl (abbreviated to NPB), N' -bis (3-methylphenyl) -N, N '-diphenyl- [1,1' -biphenyl ] -4,4 '-diamine (abbreviated to TPD), 4' -bis [ N- (spiro-9, 9 '-bifluoren-2-yl) -N-phenylamino ] biphenyl (abbreviated to BSPB), 4-phenyl-4' - (9-phenylfluoren-9-yl) triphenylamine (abbreviated to BPAFLP), 4-phenyl-3 '- (9-phenylfluoren-9-yl) triphenylamine (abbreviated to mBPAFLP), 4-phenyl-4' - (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviated to mBPAFLP) For short: PCBA1BP), 4' -diphenyl-4 "- (9-phenyl-9-H-carbazol-3-yl) triphenylamine (abbreviation: PCBBi1BP), 4- (1-naphthyl) -4' - (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBANB), 4' -bis (1-naphthyl) -4 "- (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBNBB), 9-dimethyl-N-phenyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] -spiro-9, 9-bifluoren-2-amine (abbreviation: PCBASF), and the like having an aromatic amine skeleton; compounds having a carbazole skeleton such as 1, 3-bis (N-carbazolyl) benzene (abbreviated as mCP), 4 '-bis (N-carbazolyl) biphenyl (abbreviated as CBP), 3, 6-bis (3, 5-diphenylphenyl) -9-phenylcarbazole (abbreviated as CzTP), 3' -bis (9-phenyl-9H-carbazole) (abbreviated as PCCP); compounds having a thiophene skeleton such as 4,4',4 "- (benzene-1, 3, 5-triyl) tris (dibenzothiophene) (abbreviated as DBT3P-II), 2, 8-diphenyl-4- [4- (9-phenyl-9H-fluoren-9-yl) phenyl ] dibenzothiophene (abbreviated as DBTFLP-III), 4- [4- (9-phenyl-9H-fluoren-9-yl) phenyl ] -6-phenyldibenzothiophene (abbreviated as DBTFLP-IV); and compounds having a furan skeleton such as 4,4' - (benzene-1, 3, 5-triyl) tris (dibenzofuran) (abbreviated as DBF3P-II) and 4- {3- [3- (9-phenyl-9H-fluoren-9-yl) phenyl ] phenyl } dibenzofuran (abbreviated as mmDBFFLBi-II). Among them, a compound having an aromatic amine skeleton and a compound having a carbazole skeleton are preferable because they have good reliability and high hole-transporting property and contribute to reduction of driving voltage.

Examples of the material having an electron-transporting property include: bis (10-hydroxybenzo [ h ]]Quinoline) beryllium (II) (abbreviation: BeBq₂) Bis (2-methyl-8-quinolinol) (4-phenylphenol) aluminum (III) (abbreviation: BAlq), bis (8-hydroxyquinoline) zinc (II) (abbreviation: znq), bis [2- (2-benzoxazolyl) phenol]Zinc (II) (ZnPBO for short), bis [2- (2-benzothiazolyl) phenol]Metal complexes such as zinc (II) (ZnBTZ for short); 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3, 4-oxadiazole (abbreviated as PBD), 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2, 4-triazole (abbreviated as TAZ), 1, 3-bis [5- (p-tert-butylphenyl) -1,3, 4-oxadiazol-2-yl]Benzene (abbreviated as OXD-7), 9- [4- (5-phenyl-1, 3, 4-oxadiazole-2-yl) phenyl]-9H-carbazole (abbreviation: CO11), 2' - (1,3, 5-benzenetriyl) tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2- [3- (dibenzothiophen-4-yl) phenyl]Heterocyclic compounds having a polyazole skeleton such as-1-phenyl-1H-benzimidazole (abbreviated as mDBTBIm-II); 2- [3- (dibenzothiophen-4-yl) phenyl]Dibenzo [ f, h ]]Quinoxaline (abbreviation: 2mDBTPDBq-II), 2- [3' - (dibenzothiophen-4-yl) biphenyl-3-yl]Dibenzo [ f, h ]]Quinoxaline (abbreviation: 2mDBTBPDBq-II), 2- [3' - (9H-carbazol-9-yl) biphenyl-3-yl]Dibenzo [ f, h ]]Quinoxaline (abbreviation: 2mCZBPDBq), 4, 6-bis [3- (phenanthrene-9-yl) phenyl]Pyrimidine (abbreviation: 4,6mPnP2Pm), 4, 6-bis [3- (4-dibenzothienyl) phenyl]Heterocyclic compounds having a diazine skeleton such as pyrimidine (4, 6mDBTP2 Pm-II); and 3, 5-bis [3- (9H-carbazol-9-yl) phenyl]Pyridine (35 DCzPPy for short), 1,3, 5-tri [3- (3-pyridyl) -phenyl]And heterocyclic compounds having a pyridine skeleton such as benzene (abbreviated as TmPyPB). Among them, a heterocyclic compound having a diazine skeleton or a heterocyclic compound having a pyridine skeleton is preferable because it has good reliability. In particular, a heterocyclic compound having a diazine (pyrimidine or pyrazine) skeleton has a high electron-transporting property and also contributes to a reduction in driving voltage.

In the case where a fluorescent light-emitting substance is used as a light-emitting material, a material having an anthracene skeleton is preferably used as a host material. By using a substance having an anthracene skeleton as a host material of a fluorescent substance, a light-emitting layer having excellent light-emitting efficiency and durability can be realized. A material having an anthracene skeleton often has a deep HOMO level, and thus is preferably used in one embodiment of the present invention. Among the substances having an anthracene skeleton used as a host material, a substance having a diphenylanthracene skeleton (particularly, a 9, 10-diphenylanthracene skeleton) is chemically stable, and is therefore preferable. In addition, when the host material has a carbazole skeleton, the hole injection/transport properties are improved, which is preferable. In particular, in the case of a benzocarbazole skeleton in which a benzene ring is fused to carbazole, the HOMO level is higher by about 0.1eV than carbazole, and holes are easily injected, which is more preferable. In particular, when the host material has a dibenzocarbazole skeleton, the HOMO level thereof is preferably higher than that of carbazole by about 0.1eV, and not only holes are easily injected, but also the hole-transporting property and heat resistance are improved. Therefore, a substance having a 9, 10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton) is more preferably used as the host material. Note that, from the viewpoint of the above-described hole injecting/transporting property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton. Examples of such a substance include 9-phenyl-3- [4- (10-phenyl-9-anthryl) phenyl ] -9H-carbazole (abbreviated as PCzPA), 3- [4- (1-naphthyl) -phenyl ] -9-phenyl-9H-carbazole (abbreviated as PCPN), 9- [4- (10-phenylanthracen-9-yl) phenyl ] -9H-carbazole (abbreviated as CzPA), 7- [4- (10-phenyl-9-anthryl) phenyl ] -7H-dibenzo [ c, g ] carbazole (abbreviated as cgDBCzPA), 6- [3- (9, 10-diphenyl-2-anthryl) phenyl ] -benzo [ b ] naphtho [1,2-d ] furan (abbreviated as 2mBnfPPA), 9-phenyl-10- {4- (9-phenyl-9H-fluoren-9-yl) -biphenyl-4' -yl } -anthracene (abbreviated as FLPPA), and the like. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferable because they exhibit very good characteristics.

The light-emitting element according to one embodiment of the present invention is particularly preferably used for a light-emitting element which exhibits blue fluorescence.

The host material may be a mixture of a plurality of substances, and when a mixed host material is used, it is preferable to mix a material having an electron-transporting property and a material having a hole-transporting property. By mixing a material having an electron-transporting property and a material having a hole-transporting property, the transport property of the light-emitting layer 113 can be adjusted more easily, and the recombination region can be controlled more easily. The content ratio of the material having a hole-transporting property to the material having an electron-transporting property may be 1:9 to 9: 1.

In addition, an exciplex can be formed using a mixture of these materials. It is preferable to select a mixed material so as to form an exciplex that emits light with a wavelength overlapping with the wavelength of the absorption band on the lowest energy side of the light-emitting material, because energy transfer can be smoothly performed and light emission can be efficiently obtained. In addition, the driving voltage can be reduced, and therefore, it is preferable.

The electron transport layer 114 is a layer containing a substance having an electron transport property. As the substance having an electron-transporting property, the substance having an electron-transporting property which can be used for the host material described above can be used.

A layer of lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF) may be disposed between the electron transport layer 114 and the second electrode 102₂) And the like, an alkali metal, an alkaline earth metal, or a compound thereof. As the electron injection layer 115, a layer containing an alkali metal, an alkaline earth metal, or a compound thereof in a layer made of a substance having an electron-transporting property, or an electron compound (electrode) can be used. Examples of the electron compound include a compound in which electrons are added to a mixed oxide of calcium and aluminum at a high concentration.

In addition, a charge generation layer 116 may be provided instead of the electron injection layer 115 (see fig. 1B). The charge generation layer 116 is a layer which can inject holes into a layer in contact with the cathode side of the layer and can inject electrons into a layer in contact with the anode side of the layer by applying an electric potential. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using the composite material constituting the hole injection layer 111 described above. The P-type layer 117 may be formed by laminating films each containing the above-described acceptor material and hole transport material as materials constituting the composite material. By applying a potential to the P-type layer 117, electrons and holes are injected into the electron transport layer 114 and the second electrode 102 serving as a cathode, respectively, so that the light-emitting element operates.

In addition, the charge generation layer 116 preferably includes one or both of an electron relay layer 118 and an electron injection buffer layer 119 in addition to the P-type layer 117.

The electron relay layer 118 contains at least a substance having an electron-transporting property, and can prevent interaction between the electron injection buffer layer 119 and the P-type layer 117 and smoothly transfer electrons. The LUMO level of the substance having an electron-transporting property included in the electron relay layer 118 is preferably set between the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance included in the layer in contact with the charge generation layer 116 in the electron transport layer 114. Specifically, the LUMO level of the substance having an electron-transporting property in the electron relay layer 118 is preferably-5.0 eV or more, and more preferably-5.0 eV or more and-3.0 eV or less. In addition, as the substance having an electron-transporting property in the electron relay layer 118, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.

The electron injection buffer layer 119 may be formed using a substance having a high electron injection property, such as an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (an alkali metal compound (including an oxide such as lithium oxide, a halide, a carbonate such as lithium carbonate or cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, or a carbonate), or a compound of a rare earth metal (including an oxide, a halide, or a carbonate)).

In the case where the electron injection buffer layer 119 contains a substance having an electron-transporting property and a donor substance, the donor substance may be an alkali metal, an alkaline earth metal, a rare earth metal, or a compound of these substances (an alkali metal compound (including an oxide such as lithium oxide, a halide, a carbonate such as lithium carbonate or cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, and a carbonate), or a compound of a rare earth metal (including an oxide, a halide, and a carbonate)), or an organic compound such as tetrathianaphthacene (abbreviated as TTN), nickelocene, or decamethylnickelocene. As the substance having an electron-transporting property, the same materials as those used for the electron-transporting layer 114 described above can be used.

As a substance forming the second electrode 102, a metal, an alloy, a conductive compound, a mixture thereof, or the like having a small work function (specifically, 3.8eV or less) can be used. Specific examples of such a cathode material include alkali metals such as lithium (Li) and cesium (Cs), elements belonging to group 1 or group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing them (MgAg, AlLi), rare earth metals such as europium (Eu), and ytterbium (Yb), and alloys containing them. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, indium oxide-tin oxide containing silicon or silicon oxide, or the like can be used as the second electrode 102 regardless of the magnitude of the work function ratio. These conductive materials can be formed by a dry method such as a vacuum evaporation method or a sputtering method, an ink jet method, a spin coating method, or the like. The electrode can be formed by a wet method such as a sol-gel method or a wet method using a paste of a metal material.

As a method for forming the EL layer 103, various methods can be used, regardless of a dry method or a wet method. For example, a vacuum vapor deposition method, a gravure printing method, a screen printing method, an ink jet method, a spin coating method, or the like may be used.

In addition, the electrodes or layers described above may be formed by using different film formation methods.

Note that the structure of the layer provided between the first electrode 101 and the second electrode 102 is not limited to the above-described structure. However, it is preferable to adopt a structure in which a light-emitting region where holes and electrons are recombined is provided in a portion away from the first electrode 101 and the second electrode 102 in order to suppress quenching that occurs due to the proximity of the light-emitting region to a metal used for the electrode or the carrier injection layer.

In addition, in order to suppress energy transfer from excitons generated in the light-emitting layer, a carrier transport layer such as a hole transport layer and an electron transport layer which are in contact with the light-emitting layer 113, particularly a carrier transport layer near a recombination region in the light-emitting layer 113, is preferably formed using a substance having a band gap larger than that of a light-emitting material constituting the light-emitting layer or a light-emitting material contained in the light-emitting layer.

Next, a mode of a light-emitting element (hereinafter, also referred to as a stacked element or a series element) having a structure in which a plurality of light-emitting units are stacked will be described with reference to fig. 1C. The light-emitting element is a light-emitting element having a plurality of light-emitting units between an anode and a cathode. One light-emitting unit has substantially the same structure as the EL layer 103 shown in fig. 1A. In other words, it can be said that the light-emitting element shown in fig. 1C is a light-emitting element having a plurality of light-emitting units, and the light-emitting element shown in fig. 1A or 1B is a light-emitting element having one light-emitting unit.

In fig. 1C, a first light emitting unit 511 and a second light emitting unit 512 are stacked between a first electrode 501 and a second electrode 502, and a charge generation layer 513 is disposed between the first light emitting unit 511 and the second light emitting unit 512. The first electrode 501 and the second electrode 502 correspond to the first electrode 101 and the second electrode 102 in fig. 1A, respectively, and the same material as the description of fig. 1A can be applied. In addition, the first and second light emitting units 511 and 512 may have the same structure or different structures.

The charge generation layer 513 has a function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied to the first electrode 501 and the second electrode 502. That is, in fig. 1C, when a voltage is applied so that the potential of the first electrode is higher than the potential of the second electrode, the charge generation layer 513 may be a layer that injects electrons into the first light-emitting unit 511 and injects holes into the second light-emitting unit 512.

The charge generation layer 513 preferably has the same structure as the charge generation layer 116 shown in fig. 1B. Since the composite material of the organic compound and the metal oxide has good carrier injection property and carrier transport property, low voltage driving and low current driving can be realized. Note that in the case where the anode-side surface of the light-emitting unit is in contact with the charge generation layer 513, the charge generation layer 513 may function as a hole injection layer of the light-emitting unit, and therefore the light-emitting unit may not be provided with a hole injection layer.

In addition, in the case where the electron injection buffer layer 119 is provided, since the electron injection buffer layer 119 has a function of an electron injection layer in the light emitting cell on the anode side, the electron injection layer does not necessarily have to be provided in the light emitting cell on the anode side.

Although the light-emitting element having two light-emitting units is illustrated in fig. 1C, a light-emitting element in which three or more light-emitting units are stacked may be similarly applied. As in the light-emitting element according to the present embodiment, by disposing a plurality of light-emitting cells with the charge generation layer 513 being separated between a pair of electrodes, the element can realize high-luminance light emission while maintaining a low current density, and can realize an element having a long lifetime. In addition, a light-emitting device which can be driven at low voltage and has low power consumption can be realized.

Further, by making the emission colors of the light-emitting units different, light emission of a desired color can be obtained from the entire light-emitting element. For example, by obtaining the emission colors of red and green from the first light-emitting unit and the emission color of blue from the second light-emitting unit in a light-emitting element having two light-emitting units, a light-emitting element that emits white light in the entire light-emitting element can be obtained.

Each of the EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512, the charge generation layer, and the like, and the electrode can be formed by a method such as vapor deposition (including vacuum vapor deposition), droplet discharge (also referred to as an ink jet method), coating, or gravure printing. In addition, it may also contain low molecular materials, medium molecular materials (including oligomers, dendrimers) or high molecular materials.

Here, a method of forming the EL layer 786 by a droplet discharge method will be described with reference to fig. 28. Fig. 28A to 28D are sectional views illustrating a method of manufacturing the EL layer 786.

First, a conductive film 772 is formed over the planarizing insulating film 770, and an insulating film 730 is formed so as to cover a part of the conductive film 772 (see fig. 28A).

Next, a droplet 784 is ejected by a droplet ejection apparatus 783 onto an exposed portion of the conductive film 772 which is an opening of the insulating film 730, thereby forming a layer 785 containing a composition. The droplet 784 is a composition containing a solvent, and is attached to the conductive film 772 (see fig. 28B).

The step of ejecting the droplet 784 may be performed under reduced pressure.

Next, the solvent in the layer 785 containing the composition is removed and cured, whereby an EL layer 786 is formed (see fig. 28C).

As a method for removing the solvent, a drying step or a heating step may be performed.

Next, a conductive film 788 is formed over the EL layer 786, and a light-emitting element 782 is formed (see fig. 28D).

As described above, by forming the EL layer 786 by the droplet discharge method, a composition can be selectively discharged, and thus, material loss can be reduced. Further, since it is not necessary to perform a photolithography step or the like for processing a shape, the steps can be simplified, and an EL layer can be formed at low cost.

The droplet discharge method is a generic term including a unit such as a nozzle having a discharge port of the composition or a head having one or more nozzles.

Next, a droplet discharge apparatus used in the droplet discharge method will be described with reference to fig. 29. Fig. 29 is a schematic diagram illustrating the droplet ejection apparatus 1400.

The droplet ejection apparatus 1400 includes a droplet ejection unit 1403. The droplet ejection unit 1403 includes a head 1405, a head 1412, and a head 1416.

A pre-programmed pattern can be drawn by controlling the control unit 1407 connected to the head 1405 and the head 1412 by the computer 1410.

Note that the timing of drawing may be, for example, drawing with reference to the mark 1411 formed over the substrate 1402. Alternatively, the reference point may be determined with reference to the edge of the substrate 1402. Here, the mark 1411 is detected by the imaging unit 1404, and the mark 1411 converted into a digital signal by the image processing unit 1409 is recognized by the computer 1410 to generate a control signal to be transmitted to the control unit 1407.

As the imaging unit 1404, an image sensor using a Charge Coupled Device (CCD), a Complementary Metal Oxide Semiconductor (CMOS), or the like can be used. Data of a pattern to be formed over the substrate 1402 is stored in the storage medium 1408, and a control signal is transmitted to the control unit 1407 based on the data to control the heads 1405, 1412 and 1416 of the droplet discharge unit 1403, respectively. The ejected materials are supplied from the material supply source 1413, the material supply source 1414, and the material supply source 1415 to the head 1405, the head 1412, and the head 1416, respectively, through pipes.

The heads 1405, 1412 and 1416 include a space filled with a liquid material and a nozzle for ejecting an ejection orifice, which are indicated by a broken line 1406. Although not shown here, the head 1412 has the same internal structure as the head 1405. By making the size of the nozzles of the head 1405 different from that of the nozzles of the head 1412, patterns having different widths can be simultaneously drawn using different materials. Since a plurality of light-emitting materials can be ejected and a pattern can be drawn by using one head, when a pattern is drawn over a wide area, the same light-emitting material can be ejected and a pattern can be drawn by using a plurality of nozzles at the same time in order to increase throughput. In the case of using a large-sized substrate, the head 1405, the head 1412, and the head 1416 can freely scan the substrate in the direction of arrow X, Y or Z shown in fig. 29, and can freely set a drawing area, thereby drawing a plurality of identical patterns on one substrate.

Further, the step of spraying the composition may be performed under reduced pressure. The composition may be sprayed in a state where the substrate is heated. After the composition is sprayed, one or both of a drying process and a firing process are performed. The drying step and the firing step are both heating steps, and the purpose, temperature, and time of each step are different. The drying step and the firing step are performed by irradiation with a laser, rapid thermal annealing, use of a heating furnace, or the like under normal pressure or reduced pressure. Note that the timing of performing the heat treatment and the number of times of the heat treatment are not particularly limited. The temperature of the drying step and the firing step depends on the material of the substrate and the properties of the composition in order to perform a satisfactory drying step and firing step.

As described above, the EL layer 786 can be formed using a droplet discharge apparatus.

In addition, the above-described structure can be combined with other embodiments or other structures in this embodiment as appropriate.

Embodiment mode 2

In this embodiment, an organic compound which is one embodiment of the present invention will be described.

Since some of the organic compounds that can be used for the second hole-transporting material described in embodiment 1 are novel compounds, the organic compounds described above are also an embodiment of the present invention. Next, an organic compound according to an embodiment of the present invention will be described.

An organic compound according to one embodiment of the present invention is an organic compound represented by the following general formula (G2).

[ solution 23]

Note that, in the general formula (G2), R¹To R7 and R³⁵To R⁴⁸Each independently represents any of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms. Further, α represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms in the core, and Z represents an oxygen atom or a sulfur atom. Further, k represents 1 or 2.

When R is³⁵To R⁴⁸The saturated hydrocarbon group or cyclic saturated hydrocarbon group is preferable because the solubility is improved and the compound can be easily used in a wet state or the like. When the substituent is present, the molecular structure is a three-dimensional structure and the intermolecular interaction can be reduced, and therefore, the structure is preferable because the membranous and sublimation properties are good. The substituent is preferably methyl, tert-butyl, cyclohexyl, phenyl, tolyl, or the like.

Among the organic compounds represented by (G2), those having a structure in which k is 1 are preferable because they can be synthesized easily and produced at low cost. In other words, an organic compound represented by the following general formula (G3) is preferably used.

[ solution 24]

Note that, in the organic compound represented by the above general formula (G3), R¹To R7 and R³⁵To R⁴⁸Z and alpha are the same as R in the above general formula (G2)¹To R7 and R³⁵To R⁴⁸Z and α are the same.

Among the organic compounds represented by the above general formula (G2), biphenyl and phenyl groups having no substituent are preferable because they are inexpensive in raw materials and simple in synthesis. In other words, an organic compound represented by the following general formula (G4) is preferably used.

[ solution 25]

Note that, of the organic compounds represented by the above general formula (G4), Z, R¹To R⁷And alpha and Z, R in the above general formula (G2)¹To R⁷And α are the same.

In the general formula (G4), when Z is a sulfur atom, the glass transition temperature is increased and the heat resistance is improved, which is preferable. In other words, an organic compound represented by the following general formula (G5) is preferable.

[ solution 26]

Note that, in the organic compound represented by the above general formula (G5), R¹To R⁷And alpha and R in the above general formula (G2)¹To R⁷And α are the same.

In the above organic compound, α may be a phenylene group, a biphenylene group, a fluorenylene group, a naphthylene group, or the like. Further, the substituent as α may have a saturated hydrocarbon group having 1 to 6 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, and an aromatic hydrocarbon group having 6 to 18 nuclear atoms. When the substituent is a saturated hydrocarbon group or a cyclic saturated hydrocarbon group, the solubility is improved, and the compound can be easily used in a wet state, and the like, and thus is preferable. When the substituent is present, the molecular structure is a three-dimensional structure and the intermolecular interaction can be reduced, and therefore, the structure is preferable because the membranous and sublimation properties are good. The substituent is preferably methyl, tert-butyl, cyclohexyl, phenyl, tolyl, or the like. Note that when having no substituent, it is inexpensive and simple to synthesize, and is therefore preferable. It is preferable that the optical band gap be kept high when α is a group represented by the following structural formulae (α -1) to (α -5).

[ solution 27]

The organic compounds using (alpha-1) and (alpha-2) are simple to synthesize and can be synthesized at low cost, and therefore, they are preferable structures. Further, when (. alpha. -1) is used, the carrier transporting property is improved, and therefore, it is preferable. Further, the molecular structures (. alpha. -2) to (. alpha. -5) are preferably steric structures because they can suppress intermolecular interaction and provide good membranous and sublimation properties. Further, the organic compounds using (α -2) and (α -3) are preferable because the triplet excitation level is higher than that of the organic compound using (α -1).

Among the organic compounds represented by the above general formula (G5), α is a phenylene group having no substituent, and when the dibenzothiophene skeleton has no substituent, it is easy to obtain a raw material or to synthesize it easily, and therefore, it can be produced at low cost, which is preferable. In other words, an organic compound represented by the following general formula (G6) is preferable.

[ solution 28]

Examples of the organic compounds represented by the above general formulae (G2) to (G6) are given below. Note that the following is only an example, and the organic compound of the present invention is not limited to the organic compound having the following structure.

[ solution 29]

[ solution 30]

The organic compounds as described above can be synthesized in the following synthetic schemes (F-1) to (F-3).

[ solution 31]

In the synthesis scheme (F-1), Y represents a halogen atom, and as the halogen atom, iodine, bromine, and chlorine are preferably used in this order from the viewpoint of high reactivity. Alternatively, Y may also be trifluoromethanesulfonate.

In the present synthesis scheme, the amine compound represented by (G2) can be synthesized by coupling the halide represented by (a1) and the amine compound represented by (a 2).

In the synthesis, various reaction conditions can be used, and as an example thereof, a synthesis method using a metal catalyst in the presence of a base can be used. Specifically, a Buhward-Hartvich reaction or a Ullmann reaction may be used.

The reaction is preferably carried out under an inert atmosphere such as nitrogen or argon. In addition, heating may be performed by electromagnetic waves.

[ solution 32]

In the synthesis scheme (F-2), Y represents a halogen atom, and as the halogen atom, iodine, bromine, and chlorine are preferably used in this order from the viewpoint of high reactivity. Alternatively, Y may also be trifluoromethanesulfonate.

In the present synthesis scheme, the amine compound represented by (G2) can be synthesized by coupling the amine compound represented by (b1) and the halide compound represented by (b 2).

In the synthesis, various reaction conditions can be used, and as an example thereof, a synthesis method using a metal catalyst in the presence of a base can be used. Specifically, a Buhward-Hartvich reaction or a Ullmann reaction may be used.

The reaction is preferably carried out under an inert atmosphere such as nitrogen or argon. In addition, heating may be performed by electromagnetic waves.

[ solution 33]

In the above synthesis scheme (F-3), B represents a boron atom, and R represents hydrogen or an alkyl group. Y represents a halogen atom, and iodine, bromine, and chlorine are preferably used in this order as the halogen atom from the viewpoint of high reactivity. Alternatively, Y may also be trifluoromethanesulfonate.

In the present synthesis scheme, the amine compound represented by (G2) can be synthesized by a coupling reaction of a boride represented by (c1) and a halide represented by (c 2).

In the synthesis, various reaction conditions can be used, and as an example thereof, a synthesis method using a metal catalyst in the presence of a base can be used. Specifically, the suzuki-miyaura coupling reaction can be used.

Furthermore, a leaving group B (OR)₂In place of the arylboron compound (c1), an arylaluminum, an arylzirconium, an arylzinc, an aryltin or the like may be used as part of (a).

The reaction is preferably carried out under an inert atmosphere such as nitrogen or argon. In addition, heating may be performed by electromagnetic waves.

Embodiment 3

In this embodiment, a light-emitting device using the light-emitting element described in embodiment 1 will be described.

In this embodiment, a light-emitting device manufactured using the light-emitting element described in embodiment 1 will be described with reference to fig. 2. Note that fig. 2A is a plan view showing the light-emitting device, and fig. 2B is a sectional view taken along line a-B and line C-D in fig. 2A. The light-emitting device includes a driver circuit portion (source line driver circuit) 601, a pixel portion 602, and a driver circuit portion (gate line driver circuit) 603, which are indicated by broken lines, as means for controlling light emission of the light-emitting element. In addition, reference numeral 604 denotes a sealing substrate, reference numeral 605 denotes a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

Note that the lead wiring 608 is a wiring for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, and the like from an FPC (flexible printed circuit) 609 serving as an external input terminal. Note that although only the FPC is illustrated here, the FPC may be mounted with a Printed Wiring Board (PWB). The light-emitting device in this specification includes not only a light-emitting device main body but also a light-emitting device on which an FPC or a PWB is mounted.

Next, a cross-sectional structure is explained with reference to fig. 2B. Although a driver circuit portion and a pixel portion are formed over the element substrate 610, one pixel of the source line driver circuit 601 and the pixel portion 602 which are the driver circuit portion is illustrated here.

The element substrate 610 may be formed using a substrate made of glass, quartz, an organic resin, a metal, an alloy, a semiconductor, or the like, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic, or the like.

There is no particular limitation on the structure of the transistor used for the pixel or the driver circuit. For example, an inverted staggered transistor or a staggered transistor may be employed. In addition, either a top gate type transistor or a bottom gate type transistor may be used. The semiconductor material used for the transistor is not particularly limited, and for example, silicon, germanium, silicon carbide, gallium nitride, or the like can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc such as an In-Ga-Zn metal oxide can be used.

The crystallinity of a semiconductor material used for a transistor is also not particularly limited, and an amorphous semiconductor or a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor in which a part thereof has a crystalline region) can be used. When a crystalline semiconductor is used, deterioration in characteristics of the transistor can be suppressed, and therefore, the crystalline semiconductor is preferable.

Here, the oxide semiconductor is preferably used for a semiconductor device such as a transistor provided in the pixel or the driver circuit and a transistor used in a touch sensor or the like described later. It is particularly preferable to use an oxide semiconductor whose band gap is wider than that of silicon. By using an oxide semiconductor having a wider band gap than silicon, off-state current of the transistor can be reduced.

The oxide semiconductor preferably contains at least indium (In) or zinc (Zn). The oxide semiconductor is more preferably an oxide semiconductor including an oxide represented by an In-M-Zn based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

In particular, as the semiconductor layer, the following oxide semiconductor films are preferably used: the semiconductor device includes a plurality of crystal portions, each of which has a c-axis oriented in a direction perpendicular to a surface of the semiconductor layer to be formed or a top surface of the semiconductor layer and has no grain boundary between adjacent crystal portions.

By using the above-described material for the semiconductor layer, a highly reliable transistor in which variation in electrical characteristics is suppressed can be realized.

In addition, since the off-state current of the transistor having the semiconductor layer is low, the charge stored in the capacitor through the transistor can be held for a long period of time. By using such a transistor for a pixel, the driving circuit can be stopped while the gradation of an image displayed in each display region is maintained. As a result, an electronic apparatus with extremely low power consumption can be realized.

In order to stabilize the characteristics of a transistor or the like, a base film is preferably provided. The base film can be formed using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film in a single layer or stacked layers. The base film can be formed by a sputtering method, a CVD (Chemical Vapor Deposition) method (a plasma CVD method, a thermal CVD method, an MOCVD (Metal Organic Chemical Vapor Deposition) method, or the like), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the base film may not be provided if it is not necessary.

Note that the FET623 shows one of transistors formed in the driver circuit portion 601. The driver circuit may be formed using various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, although this embodiment mode shows a driver-integrated type in which a driver circuit is formed over a substrate, this structure is not always necessary, and the driver circuit may be formed outside without being formed over the substrate.

The pixel portion 602 is formed of a plurality of pixels each including a switching FET 611, a current controlling FET 612, and a first electrode 613 electrically connected to the drain of the current controlling FET 612, but the present invention is not limited to this, and a pixel portion in which three or more FETs and a capacitor element are combined may be employed.

Note that an insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 may be formed using a positive photosensitive acrylic resin film.

In addition, the upper end portion or the lower end portion of the insulator 614 is formed into a curved surface having a curvature to obtain good coverage of an EL layer or the like formed later. For example, in the case of using a positive photosensitive acrylic resin as a material of the insulator 614, it is preferable that only the upper end portion of the insulator 614 includes a curved surface having a radius of curvature (0.2 μm to 3 μm). As the insulator 614, a negative photosensitive resin or a positive photosensitive resin can be used.

An EL layer 616 and a second electrode 617 are formed over the first electrode 613. Here, a material having a high work function is preferably used as a material of the first electrode 613 functioning as an anode. For example, in addition to a single-layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing zinc oxide in an amount of 2 to 20 wt%, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, or the like, a stacked-layer film composed of a titanium nitride film and a film containing aluminum as a main component, a three-layer structure composed of a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film, or the like can be used. Note that if a stacked-layer structure is employed here, since the resistance value of the wiring is low, a good ohmic contact can be obtained, and it can also be used as an anode.

The EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an ink jet method, and a spin coating method. The EL layer 616 has the structure described in embodiment 1. As another material constituting the EL layer 616, a low molecular compound or a high molecular compound (including an oligomer and a dendrimer) may be used.

As a material of the second electrode 617 which is formed over the EL layer 616 and functions as a cathode, a material having a small work function (Al, Mg, Li, Ca, an alloy thereof, a compound thereof (MgAg, MgIn, AlLi, or the like)), or the like is preferably used. Note that when light generated in the EL layer 616 is transmitted through the second electrode 617, a stack of a thin metal film having a reduced thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% to 20 wt% of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), or the like) is preferably used as the second electrode 617.

The light-emitting element is formed of a first electrode 613, an EL layer 616, and a second electrode 617. The light-emitting element is the light-emitting element described in embodiment 1. The pixel portion is formed of a plurality of light-emitting elements, and the light-emitting device of this embodiment may include both the light-emitting element described in embodiment 1 and a light-emitting element having another structure.

Further, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filler, and as the filler, an inert gas (nitrogen, argon, or the like) may be used, or a sealant may be used. By forming a recess in the sealing substrate and providing a drying agent therein, deterioration due to moisture can be suppressed, and therefore, this is preferable.

In addition, epoxy resin or glass frit is preferably used as the sealing material 605. These materials are preferably materials that are as impermeable as possible to water and oxygen. As a material for the sealing substrate 604, a glass substrate or a quartz substrate, and a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic resin, or the like can be used.

Although not shown in fig. 2, a protective film may be provided on the second electrode. The protective film may be formed of an organic resin film or an inorganic insulating film. Further, a protective film may be formed so as to cover the exposed portion of the sealing material 605. The protective film may be provided so as to cover the surfaces and side surfaces of the pair of substrates, and the exposed side surfaces of the sealing layer, the insulating layer, and the like.

As the protective film, a material that is not easily permeable to impurities such as water can be used. Therefore, it is possible to effectively suppress diffusion of impurities such as water from the outside to the inside.

As a material constituting the protective film, an oxide, a nitride, a fluoride, a sulfide, a ternary compound, a metal, a polymer, or the like can be used. For example, the material may contain aluminum oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, gallium nitride, a nitride containing titanium and aluminum, an oxide containing aluminum and zinc, a sulfide containing manganese and zinc, a sulfide containing cerium and strontium, an oxide containing erbium and aluminum, an oxide containing yttrium and zirconium, and the like.

The protective film is preferably formed by a film formation method having good step coverage (step coverage). One such method is the Atomic Layer Deposition (ALD) method. A material that can be formed by the ALD method is preferably used for the protective film. The protective film having a high density, reduced defects such as cracks and pinholes, and a uniform thickness can be formed by the ALD method. In addition, damage to the processing member when the protective film is formed can be reduced.

For example, a protective film having a uniform and small number of defects can be formed on a surface having a complicated uneven shape or on the top surface, side surfaces, and back surface of a touch panel by the ALD method.

As described above, a light-emitting device manufactured using the light-emitting element described in embodiment mode 1 can be obtained.

The light-emitting device in this embodiment mode can have excellent characteristics because the light-emitting element described in embodiment mode 1 is used. Specifically, the light-emitting element described in embodiment 1 has a long lifetime, and thus a light-emitting device with high reliability can be realized. Further, a light-emitting device using the light-emitting element described in embodiment 1 has good light-emitting efficiency, and thus can realize a light-emitting device with low power consumption.

Fig. 3 shows an example of a light-emitting device which realizes full color by providing a colored layer (color filter) or the like for forming a light-emitting element which emits white light. Fig. 3A illustrates a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driver circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 1024B of a light emitting element, a partition wall 1025, an EL layer 1028, a second electrode 1029 of a light emitting element, a sealing substrate 1031, a sealing material 1032, and the like.

In fig. 3A, colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are provided on the transparent base 1033. In addition, a black matrix 1035 may be provided. The transparent base 1033 provided with the colored layer and the black matrix is aligned and fixed to the substrate 1001. The color layer and the black matrix 1035 are covered with a protective layer 1036. Fig. 3A shows that light having a light-emitting layer that is transmitted to the outside without passing through the colored layer and a light-emitting layer that is transmitted to the outside with passing through the colored layer of each color, and that the light that is not transmitted through the colored layer is white light and the light that is transmitted through the colored layer is red light, green light, and blue light, and therefore, an image can be displayed by pixels of four colors.

Fig. 3B shows an example in which colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As described above, the coloring layer may be provided between the substrate 1001 and the sealing substrate 1031.

In addition, although the light-emitting device having the structure (bottom emission type) in which light is extracted from the side of the substrate 1001 where the FET is formed has been described above, a light-emitting device having the structure (top emission type) in which light is extracted from the side of the sealing substrate 1031 may be employed. Fig. 4 illustrates a cross-sectional view of a top emission type light emitting device. In this case, a substrate which does not transmit light can be used as the substrate 1001. The steps up to the production of the connection electrode for connecting the FET to the anode of the light-emitting element are performed in the same manner as in the bottom emission type light-emitting device. Then, the third interlayer insulating film 1037 is formed so as to cover the electrode 1022. The third interlayer insulating film 1037 may have a function of flattening. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film or another known material.

Although the first electrodes 1024W, 1024R, 1024G, 1024B of the light emitting elements are anodes here, they may be cathodes. In addition, in the case of using a top emission type light-emitting device as shown in fig. 4, the first electrode is preferably a reflective electrode. The EL layer 1028 has the structure of the EL layer 103 described in embodiment 1, and has an element structure capable of emitting white light.

In the case of employing the top emission structure shown in fig. 4, sealing may be performed using a sealing substrate 1031 provided with coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B). The sealing substrate 1031 may also be provided with a black matrix 1035 between pixels. The color layers (red color layer 1034R, green color layer 1034G, and blue color layer 1034B) and the black matrix 1035 may be covered with a protective layer 1036. As the sealing substrate 1031, a substrate having light-transmitting properties is used. Here, an example in which full-color display is performed in four colors of red, green, blue, and white is shown, but the present invention is not limited to this. Full-color display may be performed with four colors of red, yellow, green, and blue, or three colors of red, green, and blue.

In a top emission type light emitting device, a microcavity structure may be preferably applied. A light-emitting element having a microcavity structure can be obtained by using the reflective electrode as the first electrode and the semi-transmissive/semi-reflective electrode as the second electrode. At least an EL layer is provided between the reflective electrode and the semi-transmissive/semi-reflective electrode, and at least a light-emitting layer which is a light-emitting region is provided.

Note that the reflective electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%, and a resistivity of 1 × 10^-2Omega cm or less. In addition, the semi-transmissive and semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1 × 10^-2Omega cm or less.

Light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transmissive/semi-reflective electrode, and resonates.

In this light-emitting element, the optical length between the reflective electrode and the semi-transmissive/semi-reflective electrode can be changed by changing the thickness of the transparent conductive film, the composite material, the carrier transporting material, or the like. This makes it possible to attenuate light of a wavelength not resonating while strengthening light of a wavelength resonating between the reflective electrode and the semi-transmissive/semi-reflective electrode.

Since the light (first reflected light) reflected by the reflective electrode greatly interferes with the light (first incident light) directly entering the semi-transmissive and semi-reflective electrode from the light-emitting layer, it is preferable to adjust the optical path length between the reflective electrode and the light-emitting layer to (2n-1) λ/4 (note that n is a natural number of 1 or more, and λ is the wavelength of light to be amplified). By adjusting the optical path length, the phase of the first reflected light can be made to coincide with that of the first incident light, whereby the light emitted from the light-emitting layer can be further amplified.

In the above structure, the EL layer may include a plurality of light-emitting layers, or may include only one light-emitting layer. For example, the above-described structure may be combined with a structure of the above-described tandem-type light-emitting element in which a plurality of EL layers are provided with a charge generation layer interposed therebetween in one light-emitting element, and one or more light-emitting layers are formed in each EL layer.

By adopting the microcavity structure, the emission intensity in the front direction of a predetermined wavelength can be enhanced, and thus low power consumption can be achieved. Note that in the case of a light-emitting device which displays an image using subpixels of four colors of red, yellow, green, and blue, a luminance improvement effect due to yellow light emission can be obtained, and a microcavity structure suitable for the wavelength of each color can be employed in all subpixels, so that a light-emitting device having good characteristics can be realized.

The light-emitting device in this embodiment mode can have excellent characteristics because the light-emitting element described in embodiment mode 1 is used. Specifically, the light-emitting element described in embodiment 1 has a long lifetime, and thus a light-emitting device with high reliability can be realized. Further, a light-emitting device using the light-emitting element described in embodiment 1 has good light-emitting efficiency, and thus can realize a light-emitting device with low power consumption.

Although the active matrix light-emitting device has been described so far, the passive matrix light-emitting device will be described below. Fig. 5 shows a passive matrix light-emitting device manufactured by using the present invention. Note that fig. 5A is a perspective view illustrating the light-emitting device, and fig. 5B is a sectional view obtained by cutting along the line X-Y of fig. 5A. In fig. 5, an EL layer 955 is provided between an electrode 952 and an electrode 956 over a substrate 951. The ends of the electrodes 952 are covered by an insulating layer 953. An insulating layer 954 is provided over the insulating layer 953. The sidewalls of the isolation layer 954 have such an inclination that the closer to the substrate surface, the narrower the interval between the two sidewalls. In other words, the cross section of the partition layer 954 in the short side direction is trapezoidal, and the base (the side which faces the same direction as the surface direction of the insulating layer 953 and is in contact with the insulating layer 953) is shorter than the upper side (the side which faces the same direction as the surface direction of the insulating layer 953 and is not in contact with the insulating layer 953). Thus, by providing the partition layer 954, defects of the light-emitting element due to static electricity or the like can be prevented. In addition, in a passive matrix light-emitting device, a light-emitting device with high reliability or a light-emitting device with low power consumption can be obtained by using the light-emitting element described in embodiment 1.

The light-emitting device described above can control each of a plurality of minute light-emitting elements arranged in a matrix, and therefore can be suitably used as a display device for displaying an image.

In addition, this embodiment mode can be freely combined with other embodiment modes.

Embodiment 4

In this embodiment, an example in which the light-emitting element described in embodiment 1 is used in a lighting device will be described with reference to fig. 6. Fig. 6B is a plan view of the lighting device, and fig. 6A is a sectional view taken along line e-f of fig. 6B.

In the lighting device of this embodiment mode, a first electrode 401 is formed over a substrate 400 having a light-transmitting property, which serves as a support. The first electrode 401 corresponds to the first electrode 101 in embodiment 1. When light is extracted from the first electrode 401 side, the first electrode 401 is formed using a material having light-transmitting properties.

A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400.

An EL layer 403 is formed over the first electrode 401. The EL layer 403 corresponds to the structure of the EL layer 103 in embodiment 1, the structure of the combined light-emitting units 511 and 512, and the charge generation layer 513, and the like. Note that, as their structures, the respective descriptions are referred to.

The second electrode 404 is formed so as to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in embodiment 1. When light is extracted from the first electrode 401 side, the second electrode 404 is formed using a material having high reflectance. By connecting the second electrode 404 to the pad 412, a voltage is supplied to the second electrode 404.

As described above, the lighting device shown in this embodiment mode includes the light-emitting element including the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting element has high light-emitting efficiency, the lighting device of the present embodiment can provide a lighting device with low power consumption.

The substrate 400 on which the light-emitting element having the above-described structure is formed and the sealing substrate 407 are fixed and sealed with the sealing materials 405 and 406, whereby an illumination device is manufactured. Further, only one of the sealing materials 405 and 406 may be used. Further, the inner sealing material 406 (not shown in fig. 6B) may be mixed with a desiccant, thereby absorbing moisture and improving reliability.

In addition, by providing the pad 412 and a part of the first electrode 401 so as to extend to the outside of the sealing materials 405 and 406, they can be used as external input terminals. Further, an IC chip 420 or the like on which a converter or the like is mounted may be provided on the external input terminal.

In the lighting device described in this embodiment mode, the light-emitting element described in embodiment mode 1 is used as an EL element, and a light-emitting device with high reliability can be realized. In addition, a light-emitting device with low power consumption can be realized.

Embodiment 5

In this embodiment, an example of an electronic device including the light-emitting element described in embodiment 1 in part will be described. The light-emitting element described in embodiment 1 has a long life and is highly reliable. As a result, the electronic device described in this embodiment can realize an electronic device including a light-emitting portion with high reliability.

Examples of electronic devices using the light-emitting element include television devices (also referred to as televisions or television receivers), monitors of computers and the like, digital cameras, digital video cameras, digital photo frames, cellular phones (also referred to as cellular phones or cellular phone devices), portable game machines, portable information terminals, audio reproducing devices, large-sized game machines such as pachinko machines, and the like. Specific examples of these electronic devices are shown below.

Fig. 7A shows an example of a television device. In the television device, a display portion 7103 is incorporated in a housing 7101. In addition, a structure in which the housing 7101 is supported by a bracket 7105 is shown here. The display portion 7103 can be configured such that an image is displayed on the display portion 7103 and the light-emitting elements described in embodiment 1 are arranged in a matrix.

The television apparatus can be operated by using an operation switch provided in the housing 7101 or a remote controller 7110 provided separately. By using the operation keys 7109 of the remote controller 7110, channels and volume can be controlled, and thus, an image displayed on the display portion 7103 can be controlled. In addition, the remote controller 7110 may be provided with a display portion 7107 for displaying information output from the remote controller 7110.

The television device is configured to include a receiver, a modem, and the like. General television broadcasts can be received by a receiver. Further, by connecting the modem to a wired or wireless communication network, information communication can be performed in one direction (from a sender to a receiver) or in two directions (between a sender and a receiver or between receivers).

Fig. 7B1 shows a computer including a main body 7201, a housing 7202, a display portion 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. The computer is manufactured by arranging the light-emitting elements described in embodiment 1 in a matrix and using the light-emitting elements for the display portion 7203. The computer in FIG. 7B1 may also be in the manner shown in FIG. 7B 2. The computer shown in fig. 7B2 is provided with a second display portion 7210 instead of the keyboard 7204 and the pointing device 7206. The second display unit 7210 is a touch panel, and input can be performed by operating an input display displayed on the second display unit 7210 with a finger or a dedicated pen. In addition, the second display portion 7210 can display not only an input display but also other images. The display portion 7203 may be a touch panel. Since the two panels are connected by the hinge portion, it is possible to prevent problems such as damage, breakage, etc. of the panels when stored or carried.

Fig. 7C shows a portable game machine which is constituted by two housings of a housing 7301 and a housing 7302, and is openably and closably connected by a connecting portion 7303. A display portion 7304 formed by arranging the light-emitting elements described in embodiment 1 in a matrix is incorporated in the housing 7301, and a display portion 7305 is incorporated in the housing 7302. The portable game machine shown in fig. 7C further includes a speaker portion 7306, a recording medium insertion portion 7307, an LED lamp 7308, an input unit (an operation key 7309, a connection terminal 7310, a sensor 7311 (including a function of measuring a force, a displacement, a position, a velocity, an acceleration, an angular velocity, a rotation number, a distance, light, liquid, magnetism, a temperature, a chemical substance, sound, time, hardness, an electric field, a current, a voltage, electric power, radiation, a flow rate, humidity, a gradient, vibration, odor, or infrared ray), a microphone 7312), and the like. Needless to say, the configuration of the portable game machine is not limited to the above configuration, and any configuration may be employed as long as a display portion manufactured by arranging light-emitting elements described in embodiment 1 in a matrix is used for at least one or both of the display portion 7304 and the display portion 7305, and other accessory devices may be appropriately provided. The portable game machine shown in fig. 7C has the following functions: reading out the program or data stored in the recording medium and displaying it on the display section; and information sharing by wireless communication with other portable game machines. The functions of the portable game machine shown in fig. 7C are not limited to these, and various functions may be provided.

Fig. 7D shows an example of a portable terminal. The mobile phone includes a display portion 7402, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like, which are incorporated in a housing 7401. The mobile phone 7400 includes a display portion 7402 manufactured by arranging the light-emitting elements described in embodiment 1 in a matrix.

The mobile terminal shown in fig. 7D may be configured to input information by touching the display portion 7402 with a finger or the like. In this case, an operation such as making a call or writing an email can be performed by touching the display portion 7402 with a finger or the like.

The display portion 7402 mainly has three screen modes. The first is a display mode mainly in which images are displayed, the second is an input mode mainly in which information such as characters is input, and the third is a display input mode in which two modes, namely a mixed display mode and an input mode, are displayed.

For example, in the case of making a call or composing an e-mail, characters displayed on the screen may be input in a character input mode in which the display portion 7402 is mainly used for inputting characters. In this case, it is preferable that a keyboard or number buttons be displayed in most of the screen of the display portion 7402.

Further, by providing a detection device having a sensor for detecting inclination, such as a gyroscope or an acceleration sensor, in the mobile terminal, the direction (vertical or horizontal) of the mobile terminal can be determined, and the screen display of the display portion 7402 can be automatically switched.

Further, the screen mode is switched by touching the display portion 7402 or operating an operation button 7403 of the housing 7401. Alternatively, the screen mode may be switched depending on the type of image displayed on the display portion 7402. For example, when the image signal displayed on the display portion is data of a moving image, the screen mode is switched to the display mode, and when the image signal is text data, the screen mode is switched to the input mode.

In the input mode, when it is known that no touch operation input is made to the display portion 7402 for a certain period of time by detecting a signal detected by the optical sensor of the display portion 7402, the screen mode may be controlled to be switched from the input mode to the display mode.

The display portion 7402 can also be used as an image sensor. For example, by touching the display portion 7402 with the palm or the fingers, a palm print, a fingerprint, or the like is captured, and personal recognition can be performed. Further, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light in the display portion, it is also possible to image finger veins, palm veins, and the like.

Note that the structure described in this embodiment can be used in combination with the structures described in embodiments 1 to 5 as appropriate.

As described above, the light-emitting device including the light-emitting element described in embodiment 1 has a very wide range of applications, and the light-emitting device can be used in electronic devices in various fields. By using the light-emitting element described in embodiment 1, an electronic device with high reliability can be obtained.

Fig. 8 shows an example of a liquid crystal display device in which the light-emitting element described in embodiment 1 is used as a backlight. The liquid crystal display device shown in fig. 8 includes a housing 901, a liquid crystal layer 902, a backlight unit 903, and a housing 904, and the liquid crystal layer 902 is connected to a driver IC 905. In addition, the light emitting element shown in embodiment mode 1 is used in the backlight unit 903, and a current is supplied to the backlight unit 903 through the terminal 906.

By using the light-emitting element described in embodiment 1 for a backlight of a liquid crystal display device, a backlight with reduced power consumption can be obtained. Further, by using the light-emitting element described in embodiment 1, a surface-emitting lighting device can be manufactured, and a large area can be achieved. This makes it possible to increase the area of the backlight and the area of the liquid crystal display device. Further, since the light-emitting device using the light-emitting element described in embodiment 1 can be thinner than a conventional light-emitting device, the display device can be thinned.

Fig. 9 shows an example in which the light-emitting element described in embodiment 1 is used for a desk lamp as an illumination device. The desk lamp shown in fig. 9 includes a housing 2001 and a light source 2002, and the lighting device described in embodiment 4 is used as the light source 2002.

Fig. 10 shows an example of an illumination device 3001 in which the light-emitting element described in embodiment 1 is used indoors. The light-emitting element described in embodiment 1 is a highly reliable light-emitting element, and thus a highly reliable lighting device can be realized. In addition, the light-emitting element described in embodiment 1 can be used for a lighting device having a large area because it can have a large area. In addition, since the light-emitting element described in embodiment 1 has a small thickness, a lighting device which can be thinned can be manufactured.

The illumination system 1 of the present invention is specifically explained with reference to the drawings. Fig. 30 is a functional block diagram of the lighting system 1 of the present invention.

The illumination system 1 is composed of at least a control unit 2, a sensor unit 3, and an illumination unit 4. Further, the illumination section 4 includes a plurality of light emitting device sections 6. In addition, a database 5 may also be included. The database 5 may be a database such as a cloud database via the internet.

The control unit 2 sets the light emission intensity of each light emitting device 6 based on the result of detection by the sensor unit 3, information of the database 5, and the like.

Here, the light emitting devices 6 may be divided into a plurality of groups. Therefore, the control section 2 sets the light emission intensity for each group and drives the light emitting elements included in the light emitting device section 6. Since the light-emitting element is a current-driven element, the light-emission intensity can be set by controlling the current flowing therethrough.

The sensor unit 3 can drive the light emitting device unit 6 at an appropriate luminance by detecting the presence and position of a user and supplying information to the control unit 2. In other words, the lighting system 1 detects the presence and the position of the user by the sensor unit 3, and starts emitting light or changes the light emission intensity. By changing the light emission intensities of the plurality of light emitting elements included in the light emitting device section 6 according to the movement of the user, the power consumption can be reduced while maintaining the appropriate luminance at the required portion. The detection of the user may be performed by a known method such as an infrared sensor.

The sensor unit 3 may detect the brightness of the area irradiated with light by the ambient brightness control illumination system 1. When the user is not present, the light is irradiated with a minimum brightness, and when the user enters the area, the user does not feel uneasy or fast to the darkness, and the power consumption can be reduced to a minimum. The control unit 2 may set in advance the luminance corresponding to the detected luminance or may determine the light emission intensity corresponding to the detected luminance with reference to the database 5. The sensor for detecting the luminance may be a known optical sensor.

The detection unit 3 may detect a signal from the IC tag. By detecting or discriminating the attribute of the user by the IC tag, the light emission intensity of the light emitting element can be appropriately changed. The user can be guided by causing the light emitting device in the direction in which the user is going to travel to emit bright light and causing the light emitting device in the direction in which the user is not going to travel to emit dark light. The user can be guided by applying a sensor for detecting the position of the user and by detecting or identifying the attribute of the user by an IC tag or the like. The attribute and discrimination of the user is performed by the IC tag, and the setting and guidance of the light emission intensity can be appropriately performed by referring to the database 5. Since the brightness of the light for guiding changes according to the surrounding brightness or the visibility of the user, it is preferable to use the sensor together with the above-mentioned sensor for detecting brightness.

When the light emitting element included in the light emitting device section 6 is a set of a plurality of light emitting elements which exhibit different colors, not only the luminance but also the emission color thereof may be used to guide a plurality of persons at the same time. In other words, a color notified to the user in advance, for example, notifying one person to proceed in a red direction, notifying the other person to proceed in a blue direction, and then showing a place to go in an appropriate direction using the light emission color, can guide a plurality of users at the same time. In addition, the region colors may be used as the emission colors, and the three RGB colors may be arranged in a matrix of a certain degree of fineness, so that when it is not necessary to guide a large number of persons, natural white light is emitted as illumination, and when it is necessary to guide a large number of persons, a large number of persons may be guided with a plurality of emission colors that can be recognized.

By using such a lighting system, it is possible to guide each user accurately in the order of examination or in the order of health examination, for example, in a hospital. Further, since no characters are used, it is possible to reliably guide a user who has weak eyesight or a user who does not understand characters in a country where the system is used.

The light-emitting element described in embodiment 1 can be mounted on a windshield or an instrument panel of an automobile. Fig. 11 shows an embodiment in which the light-emitting element described in embodiment 1 is used for a windshield or an instrument panel of an automobile. The display regions 5000 to 5005 are provided using the light-emitting elements described in embodiment mode 1.

The display region 5000 and the display region 5001 are display devices provided on a windshield of an automobile and having the light-emitting element described in embodiment 1 mounted thereon. By forming the first electrode and the second electrode using light-transmitting electrodes, the light-emitting element described in embodiment 1 can be formed as a so-called see-through display device in which a scene opposite to the light-emitting element can be seen. If the see-through display is adopted, the field of view is not obstructed even if the display is arranged on the windshield of the automobile. In addition, in the case where a transistor or the like for driving is provided, a transistor having light transmittance such as an organic transistor using an organic semiconductor material or a transistor using an oxide semiconductor is preferably used.

The display region 5002 is a display device provided in a column portion and to which the light-emitting element described in embodiment mode 1 is mounted. By displaying an image from an imaging unit provided on the vehicle compartment on the display area 5002, the view blocked by the pillar can be supplemented. Similarly, the display area 5003 provided on the dashboard portion displays an image from an imaging unit provided outside the vehicle, thereby compensating for a blind spot in the field of view blocked by the vehicle cabin and improving safety. By displaying an image to supplement an invisible part, security is confirmed more naturally and simply.

The display area 5004 and the display area 5005 may provide navigation information, a speedometer, a tachometer, a running distance, a fuel amount, a gear state, setting of an air conditioner, and other various information. The user can change the display contents and arrangement appropriately. In addition, these pieces of information may be displayed in the display regions 5000 to 5003. In addition, the display regions 5000 to 5005 may be used as illumination devices.

Fig. 12A and 12B are an example of a flip type tablet terminal. Fig. 12A is an opened state, and the tablet terminal includes a housing 9630, a display portion 9631a, a display portion 9631b, a display mode changeover switch 9034, a power switch 9035, a power saving mode changeover switch 9036, a clip 9033, and an operation switch 9038. The tablet terminal is manufactured by using a light-emitting device including the light-emitting element described in embodiment 1 for one or both of the display portion 9631a and the display portion 9631 b.

In the display portion 9631a, a part thereof can be used as a touch panel region 9632a, and data can be input by contacting the displayed operation key 9637. In addition, the following structure is shown as an example: one half of the display portion 9631a has only a display function and the other half has a touch panel function, but is not limited to this structure. Note that the entire region of the display portion 9631a may have a function of a touch panel. For example, the entire surface of the display portion 9631a may be used as a touch panel by displaying keyboard buttons, and the display portion 9631b may be used as a display screen.

In the display portion 9631b, a part thereof may be used as the touch panel region 9632b, similarly to the display portion 9631 a. Further, by touching the position of the keyboard display switching button 9639 on the touch panel with a finger, a stylus pen, or the like, the keyboard button can be displayed on the display portion 9631 b.

Further, touch input may be performed simultaneously to the touch panel region 9632a and the touch panel region 9632 b.

The display mode changeover switch 9034 can switch between black-and-white display and color display by changing over the display direction of the portrait display and the landscape display. The power saving mode switch 9036 can set the displayed luminance to the optimum luminance in accordance with the amount of external light during use detected by an optical sensor incorporated in the tablet terminal. The tablet terminal may incorporate other detection means such as a sensor for detecting inclination, such as an optical sensor, a gyroscope, and an acceleration sensor.

In addition, although fig. 12A shows an example in which the display area of the display portion 9631b is equal to the display area of the display portion 9631a, the display quality may be different by making the size of one display portion different from the size of the other display portion. For example, one of the display portion 9631a and the display portion 9631b can perform higher-definition display than the other.

Fig. 12B is a closed state, and the tablet terminal in this embodiment shows an example including a housing 9630, a solar cell 9633, a charge and discharge control circuit 9634, a battery 9635, and a DCDC converter 9636. In fig. 12B, a configuration including a battery 9635 and a DCDC converter 9636 is shown as an example of the charge/discharge control circuit 9634.

In addition, the flip-type tablet terminal can close the housing 9630 when not in use. Therefore, the display portion 9631a and the display portion 9631b can be protected, and a tablet terminal which is excellent in durability and reliability from the viewpoint of long-term use can be provided.

In addition, the tablet terminal shown in fig. 12A and 12B may also have the following functions: displaying various information (still images, moving images, text images, and the like); displaying a calendar, a date, a time, and the like on the display section; a touch input for performing a touch input operation or editing on information displayed on the display unit; the processing is controlled by various software (programs).

By using the solar cell 9633 mounted on the surface of the tablet terminal, power can be supplied to the touch screen, the display portion, the image signal processing portion, or the like. Note that the solar cell 9633 may be provided on one surface or both surfaces of the housing 9630, and the battery 9635 can be charged with high efficiency.

The configuration and operation of the charge/discharge control circuit 9634 shown in fig. 12B will be described with reference to a block diagram shown in fig. 12C. Fig. 12C shows the solar cell 9633, the battery 9635, the DCDC converter 9636, the converter 9638, the switches SW1 to SW3, and the display portion 9631, and the battery 9635, the DCDC converter 9636, the converter 9638, the switches SW1 to SW3 correspond to the charge/discharge control circuit 9634 shown in fig. 12B.

First, an example of an operation when the solar cell 9633 generates power by external light will be described. The electric power generated by the solar cell is boosted or stepped down using the DCDC converter 9636 to be a voltage for charging the battery 9635. When the display portion 9631 is operated by the power from the solar cell 9633, the switch SW1 is turned on, and the power from the solar cell 9633 is stepped up or down to a voltage required for the display portion 9631 by the converter 9638. In addition, when display on the display portion 9631 is not performed, the SW 9635 may be charged by turning off the SW1 and turning on the SW 2.

Note that the solar cell 9633 is shown as an example of the power generation unit, but the power generation unit is not limited to this, and the battery 9635 may be charged using another power generation unit such as a piezoelectric element (piezoelectric element) or a thermoelectric conversion element (peltier element). The charging may be performed using a contactless power transmission module that transmits and receives power wirelessly (without contact) or in combination with another charging unit, and the power generation unit may not be included.

The display portion 9631 is not limited to the tablet terminal having the shape shown in fig. 12.

Fig. 13A to 13C illustrate a foldable portable information terminal 9310. Fig. 13A shows the portable information terminal 9310 in an expanded state. Fig. 13B shows the portable information terminal 9310 in the middle of changing from one state to the other state of the expanded state and the folded state. Fig. 13C shows a portable information terminal 9310 in a folded state. The portable information terminal 9310 has good portability in the folded state and has a large display area seamlessly connected in the unfolded state, so that it has a high display list.

The display panel 9311 is supported by three housings 9315 to which hinge portions 9313 are connected. The display panel 9311 may be a touch panel (input/output device) on which a touch sensor (input device) is mounted. By bending the display panel 9311 at the hinge portion 9313 between the two housings 9315, the portable information terminal 9310 can be reversibly changed from the unfolded state to the folded state. The light-emitting device according to one embodiment of the present invention can be used for the display panel 9311. A display region 9312 in the display panel 9311 is a display region 9312 located on a side surface of the portable information terminal 9310 in a folded state. The display region 9312 can display the software or the shortcut of the program that is used a large number of times, and can check information or turn on the software by a suitable method.

In addition, the triarylamine compound having a structure in which a dibenzofuran skeleton or a dibenzothiophene skeleton is bonded to nitrogen of an amine directly or through a divalent aromatic hydrocarbon group according to one embodiment of the present invention can be used for an organic thin-film solar cell. Specifically, it has a carrier transporting property, and therefore, it can be used for a carrier transporting layer and a carrier injecting layer. In addition, a mixed film with an acceptor substance can be used as the charge generation layer. In addition, it can be optically excited, so it can be used for an electric generation layer.

Example 1

Synthesis example 1

In this synthetic example, a synthetic method of N- [3- (dibenzothiophen-4-yl) phenyl ] -N-phenyl-4-biphenylylamine (abbreviated as mThBA1BP-II) represented by the following structural formula (101) is explained.

[ chemical 34]

A50 mL three-necked flask was charged with 1.7g (5mmol) of 4- (3-bromophenyl) -dibenzothiophene, 1.2g (5mmol) of N-phenyl-4-biphenylamine, 0.7g (7mmol) of sodium tert-butoxide, 30mg (50. mu. mol) of bis (dibenzylideneacetone) palladium (0), and after the atmosphere in the flask was replaced with nitrogen, 20mL of dehydrated xylene was added. After the mixture was degassed while stirring under reduced pressure, 0.3mL (150. mu. mol) of tri (tert-butyl) phosphine (10 wt% hexane solution) was added to the mixture. The mixture was stirred with heating at 130 ℃ for 6.5 hours under a nitrogen atmosphere to effect a reaction.

After the reaction, 250mL of toluene was added to the reaction mixture, and the suspension was filtered through magnesium silicate and Celite. The obtained filtrate was concentrated and purified by silica gel column chromatography (developing solvent toluene: hexane ═ 1: 4). The obtained filtrate was concentrated, acetone and methanol were added and the mixture was irradiated with ultrasonic waves, and then the mixture was recrystallized to obtain a white powder with a yield of 1.6g in a yield of 64%. The above reaction scheme is shown below.

[ solution 35]

Rf values in silica gel Thin Layer Chromatography (TLC) (developing solvent ethyl acetate: hexane ═ 1: 10) were as follows: the target was 0.48; and 4- (3-bromophenyl) -dibenzothiophene 0.50; n-phenyl-4-biphenylamine was 0.30.

The resulting compound was measured by Nuclear Magnetic Resonance (NMR). The measurement data are shown below.

¹H NMR(CDCl₃，300MHz)：δ(ppm)＝7.09(1H，t，J＝7.5Hz)，7.23-7.66(21H，m)，7.83-7.86(1H，m)，8.13(1H，dd，J＝1.5Hz，7.8Hz)，8.17-8.20(1H，m)。

FIGS. 14A and 14B show¹H NMR spectrum. Fig. 14B is an enlarged view of the spectrum shown in fig. 14A. From the measurement results, it was confirmed that mThBA1BP-II as the object was obtained.

The molecular weight of the resulting compound was measured by using a GC-MS detector (ITQ 1100 ion trap GC/MS system manufactured by Thermo Fisher Scientific K.K, seimer feishell). Thus, a peak mainly having the mass number 503 (mode is EI +) was detected, and it was confirmed that the target was obtained.

Example 2

Synthesis example 2

In this synthesis example, a synthesis method of N- [4- (dibenzothiophen-4-yl) phenyl ] -N-phenyl-4-biphenylylamine (abbreviated as ThBA1BP-II) represented by the following structural formula (100) is described.

[ solution 36]

The 4- (3-bromophenyl) -dibenzothiophene used in synthesis example 1 of example 1 was synthesized in the same manner as in synthesis example 1, except for using 4- (4-bromophenyl) -dibenzothiophene, and a white powder of the target product was obtained in a yield of 56%. The reaction scheme is shown below.

[ solution 37]

Rf values in silica gel Thin Layer Chromatography (TLC) (developing solvent ethyl acetate: hexane ═ 1: 10) were as follows: the target was 0.37; 4- (4-bromophenyl) -dibenzothiophene was 0.51; and N-phenyl-4-biphenylamine was 0.26.

The resulting compound was measured by Nuclear Magnetic Resonance (NMR). The measurement data are shown below.

¹H NMR(CDCl₃，300MHz)：δ(ppm)＝7.06(1H，t，J＝7.2Hz)，7.17(21H，m)，7.80-7.83(1H，m)，8.10-8.17(2H，m)。

FIGS. 15A and 15B show¹H NMR spectrum. Fig. 15B is an enlarged view of the spectrum shown in fig. 15A. From the measurement results, it was confirmed that ThBA1BP-II as the object was obtained.

The molecular weight of the resulting compound was measured by using a GC-MS detector (ITQ 1100 ion trap GC/MS system manufactured by seimer feishell technologies ltd.). Thus, a peak mainly having the mass number 503 (mode is EI +) was detected, and it was confirmed that the target was obtained.

Example 3

Synthesis example 3

In this synthesis example, a synthesis method of N, N-bis [4- (dibenzothiophen-4-yl) phenyl ] -4-biphenylamine (abbreviated as ThBB1BP-II) represented by the following structural formula is described.

[ solution 38]

In a 100mL three-necked flask, 1.5g (3mmmol) of N, N-bis (4-bromophenyl) -4-biphenylamine, 1.3g (6mmol) of dibenzothiophene-4-boronic acid, 13mg (60. mu. mol) of palladium (II) acetate, 37mg (120. mu. mol) of tri (o-tolyl) phosphine, 30mL of toluene, 5mL of ethanol, and 5mL of a 2mol/L aqueous potassium carbonate solution were mixed, and the mixture was degassed while being stirred under reduced pressure, and then heated and stirred at 90 ℃ for 5 hours under a nitrogen atmosphere to effect a reaction.

After the reaction, 250mL of toluene was added to the reaction mixture, and the suspension was filtered through magnesium silicate and Celite. The obtained filtrate was concentrated and purified by silica gel column chromatography (developing solvent toluene: hexane ═ 1: 4). A yield of 1.8g of white powder was obtained in 90%. The reaction scheme is shown below.

[ solution 39]

Rf values in silica gel Thin Layer Chromatography (TLC) (developing solvent ethyl acetate: hexane ═ 1: 10) were as follows: the target was 0.39; and N, N-bis (4-bromophenyl) -4-biphenylamine was 0.72.

The resulting compound was measured by Nuclear Magnetic Resonance (NMR). The measurement data are shown below.

¹H NMR(CDCl₃，300MHz)：δ(ppm)＝7.33-7.64(21H，m)，7.71(4H，d，J＝6.3Hz)，7.84-7.87(2H，m)，8.14(2H，dd，J＝2.1Hz，7.8Hz)，8.17-8.20(2H，m)。

FIGS. 16A and 16B show¹H NMR spectrum. Fig. 16B is an enlarged view of the spectrum shown in fig. 16A. From the measurement results, it was confirmed that ThBB1BP-II as the objective compound was obtained.

The molecular weight of the resulting compound was measured by using a GC-MS detector (ITQ 1100 ion trap GC/MS system manufactured by seimer feishell technologies ltd.). Thus, a peak mainly having the mass number 685 (mode is EI +) is detected, and it is confirmed that the target is obtained.

The glass transition temperature was examined using a differential scanning calorimetry analyzer (DSC, Pyris 1DSC manufactured by PerkinElmer, inc.). From the measurement results, the glass transition temperature was 130 ℃. Thus, ThBB1BP-II was found to exhibit a high glass transition temperature and to have good heat resistance.

Example 4

In this example, the characteristics of the energy levels of mThBA1BP-II, ThBA1BP-II and ThBB1BP-II synthesized in the above synthesis example will be described.

The redox reaction characteristics of mThBA1BP-II, ThBA1BP-II and ThBB1BP-II were measured by Cyclic Voltammetry (CV). The measurement was performed by an electrochemical analyzer (ALS model 600A or 600C, manufactured by BAS Inc.). Further, in the measurement solution, as a solvent, dehydrated Dimethylformamide (DMF) was used, and tetra-n-butylammonium perchlorate (n-Bu) as a supporting electrolyte₄NClO₄) Dissolved at a concentration of 100mmol/L and the object to be measured was dissolved at a concentration of 2 mmol/L. As the working electrode, a platinum electrode (PTE platinum electrode manufactured by BAS Co., Ltd.) was used, and as the auxiliary electrode, a platinum electrode (Pt counter electrode (5cm) for VC-3 manufactured by BAS Co., Ltd.) was usedUsing Ag/Ag for the reference electrode⁺An electrode (RE 7 non-aqueous solution type reference electrode manufactured by BAS Co., Ltd.). The scanning speed was set to 0.1V/sec.

Table 1 shows the HOMO energy level calculated from the oxidation potential as the measurement result. From these results, it is understood that the organic compound according to one embodiment of the present invention has a HOMO level of about-5.5 to-5.6 eV. Therefore, it is known that the organic compound is preferably suitable for an energy level close to this value, and preferably injects holes from a material having a HOMO level within ± 0.3eV, and injects holes to a material having a HOMO level within ± 0.3 eV. These HOMO levels are preferable because a light-emitting element having particularly good characteristics can be obtained when used in a fluorescent light-emitting element using a host material having an anthracene skeleton or a carbazole skeleton. Further, it is found that the organic compound according to one embodiment of the present invention is also suitable for a hole-transporting host in a hole-transporting layer or a light-emitting layer.

[ Table 1]

The HOMO level of mThBA1BP-II is slightly deeper than ThBA1BP-II, and when dibenzothiophene is bonded to aniline, preferably with meta substitution, holes between layers with deeper HOMO levels move.

ThBA1BP-II has a shallower HOMO level than ThBB1BP-II, and when aniline is preferentially bound to multiple dibenzothiophenes, holes between layers with shallower HOMO levels move.

Next, absorption spectra and emission spectra were measured in solutions and films of mThBA1BP-II, ThBA1BP-II, and ThBB1 BP-II. The absorption spectrum was measured using an ultraviolet-visible spectrophotometer (manufactured by japan spectrophotometers, model V550). The emission spectrum was measured using a fluorescence spectrophotometer (FS 920, manufactured by hamamatsu photonics corporation, japan). The spectra of the solutions were measured using a quartz cell. The thin film sample was produced by vacuum vapor depositing the above compound on a quartz substrate. Further, the absorption spectrum is represented by subtracting the absorption spectrum of quartz from the spectrum of the measured sample.

As the measurement results, fig. 17 shows an absorption spectrum in the toluene solution, and fig. 18 shows an emission spectrum. Fig. 19 shows an absorption spectrum in the thin film, and fig. 20 shows an emission spectrum.

As can be seen from the figure, absorption bands of mThBA1BP-II, ThBA1BP-II and ThBB1BP-II are in a very short wavelength region, i.e., 400nm or less, and the optical band gap is very wide. It is found that mThBA1BP-II has a larger absorption end and a shorter wavelength side than the other two substances, and has a particularly wide band gap.

These facts show that when these materials are used in a light-emitting layer or a layer adjacent to the light-emitting layer, a light-emitting element which is less likely to absorb a singlet excitation level of a dopant or the like and can provide good light-emitting efficiency can be provided.

Further, these present organic compounds emit blue-violet light, and thus are known to be useful as blue-violet dopants. Further, it is known that the organic compound is suitable for a host material of a dopant which emits light having a longer wavelength than bluish violet.

In this example, the HOMO, LUMO and T1 levels of various structures of mThBA1BP-II, ThBA1BP-II and ThBB1BP-II were simulated by quantum chemical calculation.

The most stable structures in the singlet and triplet states were calculated using the density functional theory. At this time, vibration analysis in each of the most stable structures was further performed. 6-311G was applied to all atoms as a basis function. In order to improve the calculation accuracy, p functions are added to hydrogen atoms and d functions are added to atoms other than hydrogen atoms as polarization bases. B3LYP was used as a generic function. In addition, the HOMO level and LUMO level of the singlet structure were calculated, respectively. Next, the T1 level was calculated for the energy difference between the singlet ground state and the triplet excited state, which was zero-point corrected for the most stable structure. As a quantum chemical calculation program, Gaussian09 was used. Further, the singlet lowest excitation level is calculated by a time-dependent (TD) calculation method using the most stable structure of the singlet ground state (S1).

Table 2 shows values obtained by calculation.

[ Table 2]

For short	HOMO	LUMO	S1	T1
					mThBA1BP-II	-5.21	-1.31	3.43	2.69
ThBA1BP-II	-5.19	-1.32	3.42	2.53
					ThBB1BP-II	-5.20	-1.36	3.38	2.55

Unit: [ eV ]

From the calculated S1 level (excitation energy from S0 to S1), it is found that these organic compounds have a high S1 level, and when used in a light-emitting layer or a layer in contact with the light-emitting layer, various elements in the visible region such as a light-emitting element having a short wavelength from blue to red can be suitably used as a fluorescent element. Further, ThBA1BP-II having the second highest S1 energy level to mThBA1BP-II was confirmed, and the magnitude relation of the energy values of the absorption edge in the solution or film was found to be relevant.

From the calculated T1 level (the most stable energy difference between the S0 and T1 states), it is found that the amine material according to one embodiment of the present invention has a high T1 level, and when used in a light-emitting layer or a layer in contact with the light-emitting layer, an element in the visible region such as a long-wavelength light-emitting element of blue or the like to red or the like can be suitably used as a phosphorescent element. Further, having a high T1 energy level next to mThBA1BP-II is ThBA1BP-II, and a higher T1 energy level is more suitable for an element emitting light at a short wavelength.

The calculated HOMO energy level tends to be shallow (its value is large) compared to the actual measurement, but it can be confirmed that the order of the calculated 3 materials is correlated with the actual measurement. The LUMO level is also predicted to be shallower than this value, and the LUMO level of these organic compounds is higher. Therefore, when these organic compounds are used for a hole transport layer, they are also used as an electron blocking layer, and hence a highly efficient light-emitting element can be expected.

Example 5

In this example, a light-emitting element 1 according to one embodiment of the present invention described in embodiment 1 and a comparative light-emitting element 1 will be described. The structural formulae of the organic compounds used in the light-emitting element 1 and the comparative light-emitting element 1 are shown below.

[ solution 40]

(method for manufacturing light-emitting element 1)

First, an indium tin oxide (ITSO) film containing silicon oxide was formed over a glass substrate by a sputtering method, whereby the first electrode 101 was formed. Note that the thickness thereof was set to 110nm, and the electrode area thereof was 2mm × 2 mm.

Next, as a pretreatment step for forming a light emitting element on the substrate, the surface of the substrate was washed with water, baked at 200 ℃ for 1 hour, and subjected to UV ozone treatment for 370 seconds.

Then, the pressure of the substrate introduced into the chamber is reduced to 10^-4In the vacuum vapor deposition apparatus of about Pa, vacuum baking was performed at 170 ℃ for 30 minutes in a heating chamber in the vacuum vapor deposition apparatus, and then the substrate was cooled for about 30 minutes.

Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 101 was formed faced downward, and 2,3, 6, 7, 10, 11-hexacyano-1, 4, 5, 8, 9, 12-hexaazatriphenylene (HAT-CN) represented by the structural formula (i) was evaporated on the first electrode 101 to a thickness of 5nm by an evaporation method using resistance heating, thereby forming the hole injection layer 111.

Then, N- (1, 1' -biphenyl-4-yl) -9, 9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] -9H-fluoren-2-amine (abbreviated as PCBBiF) represented by the above structural formula (II) was deposited on the hole injection layer 111 to a thickness of 20nm to form a first hole transporting layer 112-1, N-bis [4- (dibenzothiophen-4-yl) phenyl ] -4-biphenylamine (abbreviated as ThBB1BP-II) represented by the above structural formula (iii) was deposited on the first hole transporting layer 112-1 to a thickness of 5nm to form a second hole transporting layer 112-2, and N, N-bis [4- (dibenzothiophen-4-yl) phenyl ] -4-biphenylamine (abbreviated as ThBB1BP-II) represented by the above structural formula (iv) was deposited on the second hole transporting layer 112-2 to a thickness of 5nm And 3- [4- (9-phenanthryl) -phenyl ] -9-phenyl-9H-carbazole (abbreviated as PCPPn) to form the third hole transport layer 112-3.

Next, 7- [4- (10-phenyl-9-anthryl) phenyl ] -7H-dibenzo [ c, g ] carbazole represented by the above structural formula (v) (abbreviated as cgDBCzPA) and N, N '-bis (3-methylphenyl) -N, N' -bis [3- (9-phenyl-9H-fluoren-9-yl) phenyl ] -pyrene-1, 6-diamine represented by the above structural formula (vi) (abbreviated as 1, 6mMemFLPAPrn) were co-evaporated to form the light-emitting layer 113. The thickness of the light-emitting layer 113 was set to 25nm, and the weight ratio of cgDBCzPA to 1, 6mMemFLPAPRn was adjusted to 1: 0.03.

Then, cgDBCzPA was deposited on the light-emitting layer 113 to a thickness of 10nm, and then bathophenanthroline (BPhen) represented by the above structural formula (vii) was deposited to a thickness of 15nm, thereby forming an electron transporting layer 114.

After the electron transit layer 114 was formed, an electron injection layer 115 was formed by depositing lithium fluoride (LiF) to a thickness of 1nm, and then the second electrode 102 was formed by depositing aluminum to a thickness of 200nm, thereby manufacturing the light-emitting element 1 of the present embodiment.

(method of manufacturing comparative light-emitting element 1)

In the comparative light-emitting element 1, the first hole-transporting layer 112-1 was formed in the light-emitting element 1 with a thickness of 25nm, and the second hole-transporting layer 112-2 was not formed, and other components were manufactured in the same manner as in the light-emitting element 1. That is, the comparative light-emitting element 1 can be said to be a light-emitting element as follows: the second hole transport layer 112-2 is not formed and has a thickness corresponding to the thickness of the second hole transport layer 112-2 plus the thickness of the first hole transport layer 112-1.

(method of manufacturing comparative light-emitting element 2)

In the comparative light-emitting element 2, the first hole-transporting layer 112-1 was formed in the light-emitting element 1 with a thickness of 30nm, and the second hole-transporting layer 112-2 and the third hole-transporting layer 112-3 were not formed, and the other components were manufactured in the same manner as in the light-emitting element 1. That is, the comparative light-emitting element 2 can be said to be a light-emitting element as follows: the second hole transport layer 112-2 and the third hole transport layer 112-3 are not formed, and have a thickness corresponding to the sum of the thicknesses of the second hole transport layer 112-2 and the third hole transport layer 112-3 and the thickness of the first hole transport layer 112-1.

(method of manufacturing comparative light-emitting element 3)

In the comparative light-emitting element 3, the first hole-transporting layer 112-1 was formed in the light-emitting element 1 with a thickness of 25nm, and the third hole-transporting layer 112-3 was not formed, and the other components were manufactured in the same manner as in the light-emitting element 1. That is, the comparative light-emitting element 3 can be said to be a light-emitting element as follows: the third hole transport layer 112-3 is not formed and has a thickness corresponding to the thickness of the third hole transport layer 112-3 plus the thickness of the first hole transport layer 112-1.

The purpose of the hole transport layers 112 being of the same thickness is to eliminate the effect of the difference in thickness of the organic layers.

The following table shows the element structures of the light-emitting element 1 and the comparative light-emitting elements 1 to 3.

[ Table 3]

In a glove box in a nitrogen atmosphere, sealing treatment (coating a sealing material around the elements, UV treatment at the time of sealing, and heat treatment at a temperature of 80 ℃ for 1 hour) was performed using a glass substrate so as not to expose the light-emitting elements 1 and the comparative light-emitting elements 1 to 3 to the atmosphere, and then initial characteristics and reliability of these light-emitting elements were measured. In addition, the measurement was performed at room temperature (atmosphere maintained at 25 ℃).

Fig. 21 to 26 show luminance-current density characteristics, current efficiency-luminance characteristics, luminance-voltage characteristics, current-voltage characteristics, external quantum efficiency-luminance characteristics, and emission spectra of the light-emitting element 1 and the comparative light-emitting elements 1 to 3, respectively. Table 4 shows 1000cd/m of each light-emitting element²Nearby main characteristic values.

[ Table 4]

As is apparent from fig. 21 to 26 and table 2, the light-emitting element 1 according to one embodiment of the present invention is a blue light-emitting element, in which the driving voltage is good as compared with the comparative light-emitting element 1 in which the second hole transport layer 112-2 is not provided, the efficiency is good as compared with the comparative light-emitting element 1 and the comparative light-emitting element 2, and the characteristics are good as in the comparative light-emitting element 3.

In addition, FIG. 27 shows that the initial luminance is 5000cd/m²And the current density is a graph of the luminance change with respect to the driving time under the condition of being constant. As shown in FIG. 27, it is known that it is not providedThe light-emitting element 1 of the light-emitting element according to one embodiment of the present invention is a light-emitting element having a long lifetime with less luminance degradation due to accumulation of driving time, as compared with the comparative light-emitting element 1 of the second hole transport layer 112-2, the comparative light-emitting element 2 in which only the first hole transport layer 112-1 is formed, and the comparative light-emitting element 3 in which the third hole transport layer 112-3 is not provided.

The following table shows respective HOMO levels of the first to third hole transporting materials, the host material, and the light emitting material in the light emitting element of this embodiment. Note that the HOMO level and LUMO level were calculated by Cyclic Voltammetry (CV) measurement. The calculation method is shown below. The calculation method is the same as in example 4.

[ Table 5]

As shown in the table, in the materials used for the light-emitting element 1, the HOMO level of the second hole-transporting material was deeper than the HOMO level of the first hole-transporting material, the HOMO level of the host material was deeper than the HOMO level of the second hole-transporting material, and the HOMO level of the third hole-transporting material was deeper than the HOMO level of the host material. In addition, the HOMO level of the light-emitting material is shallower than the HOMO level of the host material.

PCBBiF of the first hole transport material has a shallow HOMO level of-5.36 eV, and readily interacts with HAT-CN having a LUMO level of-4.41 eV, thereby causing charge separation. However, since the HOMO level of cgDBCzPA of the host material was-5.69 eV, which is a large difference from the HOMO level of PCBBiF, that is, 0.33eV, it was difficult to directly inject holes from the first hole transport layer 112-1 into the host material of the light-emitting layer. Since the HOMO level of the light-emitting material 1, 6mm flpaprn is-5.40 eV and the difference from the HOMO level of the first hole transport material is small, holes may be injected into the light-emitting material and, when holes are directly injected into the light-emitting material, the holes may be trapped at the interface between the first hole transport layer 112-1 and the light-emitting layer, leading to concentration of light-emitting regions and accelerating degradation. In addition, at this time, holes are not easily injected from the hole transport material of the first hole transport layer 112-1 to the host material of the light emitting layer, and thus holes are accumulated in the hole transport material and electrons are accumulated in the host material. In this case, an exciplex having energy lower than that of the light-emitting material may be formed between the hole-transporting material and the host material, and thus problems such as a decrease in light-emitting efficiency are likely to occur. This is one of the reasons why the characteristics of the comparative light-emitting element 2 are lower than those of the light-emitting element 1.

In the light-emitting element 1, a second hole transport material having a lower HOMO level than the host material and a higher HOMO level than the first hole transport material is used for the second hole transport layer 112-2, and holes are injected from the first hole transport layer 112-1 into the second hole transport layer 112-2. The HOMO level of ThBB1BP-II of the second hole-transporting material was-5.54 eV, which is a small difference from PCBBiF of the first hole-transporting material, and was 0.18 eV. Therefore, holes are smoothly injected from the first hole transport layer 112-1 to the second hole transport layer 112-2.

Here, a case where holes are injected from the second hole transport layer 112-2 to the light emitting layer 113 is considered. A potential barrier of about 0.15eV exists between the second hole transporting material and the host material. In general, holes are smoothly injected, but the HOMO level of the light-emitting material included in the light-emitting layer 113 is-5.40 eV, and no potential barrier exists. Therefore, hole injection into the light-emitting material is dominant over hole injection into the host material. In the case where holes are directly injected into the light-emitting material, as described above, problems such as promotion of deterioration and reduction in light-emitting efficiency tend to occur. This is one of the reasons why the reliability of the comparative light-emitting element 3 is lower than that of the light-emitting element 1.

In view of the above, in the light-emitting element 1 which is a light-emitting element according to one embodiment of the present invention, the third hole-transport layer 112-3 is provided between the second hole-transport layer 112-2 and the light-emitting layer 113. The HOMO level of the PCPPn of the third hole transport material included in the third hole transport layer 112-3 is-5.80 eV, which is deeper than the HOMO level of the host material. Therefore, there is no hole injection barrier to the host material, and holes are also preferentially injected into the host material by the mixing ratio of the host material and the light-emitting material. Although a part of the holes injected into the host material is trapped by the light-emitting material, the holes can move to the second electrode while being appropriately trapped, and the drive voltage does not increase because the host material is an anthracene compound having an electron-transporting property. Further, since the light-emitting region is not concentrated and spreads in the light-emitting layer 113, the promotion of degradation can be avoided, and a light-emitting element having a long life and excellent light-emitting efficiency can be realized.

Note that since the second hole transporting layer 112-2 is not provided in the comparative light emitting element 1, holes are injected from the first hole transporting layer 112-1 into the third hole transporting layer 112-3, and the difference in HOMO levels between the first hole transporting material and the third hole transporting material is large, that is, 0.44eV, which results in a significant decrease in both efficiency and reliability.

Description of the symbols

1 illumination system

2 control part

3 sensor part

4 illumination part

5 database

6 light emitting device section

101 first electrode

102 second electrode

103 EL layer

111 hole injection layer

112-1 first hole transport layer

112-2 second hole transport layer

112-3 third hole transport layer

113 light emitting layer

114 electron transport layer

115 electron injection layer

116 charge generation layer

117P type layer

118 electron relay layer

119 electron injection buffer layer

400 substrate

401 first electrode

403 EL layer

404 second electrode

405 sealing Material

406 sealing material

407 sealing substrate

412 bonding pad

420 IC chip

501 first electrode

502 second electrode

511 first light emitting unit

512 second light emitting unit

513 Charge generating layer

601 driver circuit section (Source line driver circuit)

602 pixel section

603 drive circuit section (gate line drive circuit)

604 sealing substrate

605 sealing material

607 space

608 routing

609 FPC (Flexible printed circuit)

610 element substrate

611 switch FET

612 Current control FET

613 first electrode

614 insulator

616 EL layer

617 second electrode

618 luminous element

730 insulating film

770 planarizing the insulating film

772 conductive film

782 light-emitting element

783 droplet jetting apparatus

784 droplet

785 layers

786 EL layer

788 conducting film

901 outer casing

902 liquid crystal layer

903 backlight unit

904 outer cover

905 driver IC

906 terminal

951 substrate

952 electrode

953 insulating layer

954 partition wall layer

955 EL layer

956 electrodes

1001 substrate

1002 base insulating film

1003 gate insulating film

1006 gate electrode

1007 gate electrode

1008 gate electrode

1020 first interlayer insulating film

1021 second interlayer insulating film

1022 electrode

1024W first electrode

1024R first electrode

1024G first electrode

1024B first electrode

1025 dividing wall

1028 EL layer

1029 second electrode

1031 sealing substrate

1032 sealing material

1033 transparent substrate

1034R red coloring layer

1034G green coloring layer

1034B blue coloring layer

1035 Black matrix

1036 protective layer

1037 third interlayer insulating film

1040 pixel part

1041 drive circuit unit

1042 of the front edge

1400 droplet ejection apparatus

1402 substrate

1403 droplet ejection unit

1404 imaging unit

1405 head

1406 dotted line

1407 control unit

1408 storage medium

1409 image processing unit

1410 computer

1411 marking

1412 head

1413 Material supply

1414 material supply source

1415 supply of material

1416 head

2001 casing

2002 light source

3001 Lighting device

5000 display area

5001 display area

5002 display area

5003 display area

5004 display area

5005 display area

7101 casing

7103 display unit

7105 support

7107 display unit

7109 operation key

7110 remote control operating machine

7201 the main body

7202 outer casing

7203 display unit

7204 keyboard

7205 external connection port

7206 pointing device

7210A second display unit

7301 outer casing

7302 outer casing

7303 joining part

7304 display unit

7305 display unit

7306 speaker unit

7307 recording medium insertion part

7308 LED lamp

7309 operating keys

7310 connecting terminal

7311 sensor

7401 outer shell

7402 display part

7403 operating button

7404 external connection port

7405 speaker

7406 microphone

7400 Mobile phone

9033 clip

9034 switch

9035 power switch

9036 switch

9038 operating switch

9310 Portable information terminal

9311 display panel

9312 display region

9313 hinge part

9315 outer cover

9630 outer shell

9631 display unit

9631a display unit

9631b display unit

9632a touch screen area

9632b touch screen area

9633 solar cell

9634 charging and discharging control circuit

9635 batteries

9636 DCDC converter

9637 operating keys

9638 converter

9639 button.