阅读说明：本技术 发光器件 (Light emitting device ) 是由 渡部刚吉 植田蓝莉 大泽信晴 濑尾哲史 于 2020-02-24 设计创作，主要内容包括：提供一种发光器件。该发光器件包括中间层、第一发光单元及第二发光单元。中间层具有夹在第一发光单元和第二发光单元之间的区域,中间层具有将电子供应给第一发光单元和第二发光单元中的一个且将空穴供应给第一发光单元和第二发光单元中的另一个的功能。第一发光单元包括第一发光层,第一发光层包含第一发光材料,第二发光单元包括第二发光层,第二发光层包含第二发光材料,第二发光层和第一发光层之间有第一距离,第一距离为5nm以上且65nm以下。(A light emitting device is provided. The light emitting device includes an intermediate layer, a first light emitting unit, and a second light emitting unit. The intermediate layer has a region sandwiched between the first light emitting unit and the second light emitting unit, and the intermediate layer has a function of supplying electrons to one of the first light emitting unit and the second light emitting unit and supplying holes to the other of the first light emitting unit and the second light emitting unit. The first light-emitting unit includes a first light-emitting layer containing a first light-emitting material, the second light-emitting unit includes a second light-emitting layer containing a second light-emitting material, and a first distance is provided between the second light-emitting layer and the first light-emitting layer, the first distance being 5nm or more and 65nm or less.)

1. A light emitting device comprising:

an intermediate layer;

a first light emitting unit; and

a second light-emitting unit for emitting light,

wherein the intermediate layer has a region sandwiched between the first light emitting unit and the second light emitting unit,

the intermediate layer has a function of supplying electrons to one of the first light emitting unit and the second light emitting unit and supplying holes to the other of the first light emitting unit and the second light emitting unit,

the first light-emitting unit includes a first light-emitting layer,

the first light-emitting layer comprises a first light-emitting material,

the second light emitting unit includes a second light emitting layer,

the second light-emitting layer comprises a second light-emitting material,

a first distance is provided between the second light-emitting layer and the first light-emitting layer,

the first distance is 5nm to 65 nm.

2. A light emitting device comprising:

an intermediate layer;

a first light emitting unit;

a second light emitting unit;

a first electrode; and

a second electrode for applying a second voltage to the substrate,

wherein the light emitting device has a function of emitting light,

the intermediate layer has a function of supplying electrons to one of the first light emitting unit and the second light emitting unit and supplying holes to the other of the first light emitting unit and the second light emitting unit,

the first light emitting unit has a region sandwiched between the first electrode and the intermediate layer,

the first light-emitting unit includes a first light-emitting layer,

the first light-emitting layer comprises a first light-emitting material,

the second light emitting unit has a region sandwiched between the intermediate layer and the second electrode,

the second light emitting unit includes a second light emitting layer,

the second light-emitting layer comprises a second light-emitting material,

the light exhibits a spectrum that is largely at the first wavelength,

the first electrode has a higher reflectivity at the first wavelength than the second electrode,

the second electrode has a higher transmittance at the first wavelength than the first electrode,

the second electrode transmits a portion of the light and reflects another portion of the light at the first wavelength,

the second electrode is spaced from the first electrode by a second distance,

and a value obtained by multiplying the second distance by 1.8 is included in a range of 0.3 times or more and 0.6 times or less of the first wavelength.

3. A light emitting device comprising:

an intermediate layer;

a first light emitting unit;

a second light emitting unit;

a first electrode;

a second electrode; and

a reflective film having a first surface and a second surface,

wherein the light emitting device has a function of emitting light,

the intermediate layer has a function of supplying electrons to one of the first light emitting unit and the second light emitting unit and supplying holes to the other of the first light emitting unit and the second light emitting unit,

the first light emitting unit has a region sandwiched between the first electrode and the intermediate layer,

the first light-emitting unit includes a first light-emitting layer,

the first light-emitting layer comprises a first light-emitting material,

the second light emitting unit has a region sandwiched between the intermediate layer and the second electrode,

the second light emitting unit includes a second light emitting layer,

the second light-emitting layer comprises a second light-emitting material,

the light exhibits a spectrum that is largely at the first wavelength,

the reflective film has a higher reflectivity at the first wavelength than the second electrode,

the first electrode has a region sandwiched between the first light emitting unit and the reflective film,

the first electrode has a higher transmittance at the first wavelength than the second electrode,

the second electrode transmits a portion of the light and reflects another portion of the light at the first wavelength,

the second electrode is a second distance from the reflective film,

and a value obtained by multiplying the second distance by 1.8 is included in a range of 0.3 times or more and 0.6 times or less of the first wavelength.

4. The light emitting device according to claim 2 or 3,

wherein the second light-emitting layer is spaced apart from the first light-emitting layer by the first distance D1,

and the first distance D1 and the first wavelength EL1 satisfy a relationship expressed by equation (i):

(6.3×10^-3)×EL1≤D1≤(81.3×10^-3)×EL1 (i)。

5. the light emitting device according to any one of claims 2 to 4,

wherein the first luminescent material exhibits a first emission spectrum in solution which is at its maximum at a second wavelength,

the second luminescent material exhibits a second emission spectrum in solution which is at its maximum at a third wavelength,

there is a difference of 100nm or less between the first wavelength and the second wavelength PL1,

and a difference of 100nm or less between the first wavelength and the third wavelength.

6. The light emitting device according to any one of claims 1 to 5,

wherein the second light emitting layer comprises the first light emitting material.

7. The light emitting device according to any one of claims 1 to 6,

wherein the intermediate layer is at a third distance from the first light-emitting layer,

the intermediate layer is spaced from the second light-emitting layer by a fourth distance,

the third distance is 5nm or more,

and the fourth distance is 5nm or more.

Technical Field

One embodiment of the present invention relates to a light-emitting device, a light-emitting apparatus, a light-emitting module, an electronic apparatus, or a lighting apparatus.

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. In addition, one embodiment of the present invention relates to a process (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 light-emitting device, a power storage device, a memory device, and a method for driving or manufacturing the above-described devices can be given.

Background

Research and development of light emitting devices (also referred to as organic EL devices and organic EL elements) using an organic Electro Luminescence (EL) phenomenon are becoming more and more popular. The basic structure of an organic EL device is a structure in which a layer containing a light-emitting organic compound (hereinafter also referred to as a light-emitting layer) is interposed between a pair of electrodes. By applying a voltage to the organic EL device, light emission from a light-emitting organic compound can be obtained.

Examples of the light-emitting organic compound include compounds capable of converting a triplet excited state into light emission (also referred to as phosphorescent compounds and phosphorescent materials). Patent document 1 discloses an organometallic complex containing iridium or the like as a central metal as a phosphorescent material.

In addition, the image sensor is used for various purposes such as personal identification, defect analysis, medical diagnosis, security field, and the like. The wavelength of the light source used is appropriately selected according to the purpose of use. For example, light of various wavelengths such as light of a short wavelength such as visible light or X-ray, light of a long wavelength such as near-infrared light, and the like is used for the image sensor.

In addition to the display device, the light emitting device is also expected to be applied to the light source of the image sensor as described above.

[ Prior Art document ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2007-137872

Disclosure of Invention

Technical problem to be solved by the invention

An object of one embodiment of the present invention is to provide a novel light-emitting device with high convenience and reliability. Another object of one embodiment of the present invention is to provide a novel light-emitting device or a novel semiconductor device.

Note that the description of these objects does not hinder the existence of other objects. It is not necessary for one embodiment of the invention to achieve all of the above objectives. Objects other than those mentioned above will become apparent from the description of the specification, drawings, claims, and the like, and objects other than those mentioned above can be extracted from the description.

Means for solving the problems

(1) One embodiment of the present invention includes an intermediate layer, a first light-emitting unit, and a second light-emitting unit.

The intermediate layer has a region sandwiched between the first light emitting unit and the second light emitting unit, and the intermediate layer has a function of supplying electrons to one of the first light emitting unit and the second light emitting unit and supplying holes to the other of the first light emitting unit and the second light emitting unit.

The first light-emitting unit includes a first light-emitting layer containing a first light-emitting material.

The second light emitting unit includes a second light emitting layer containing a second light emitting material.

There is a first distance D1 between the second light-emitting layer and the first light-emitting layer. The first distance D1 is 5nm or more and 65nm or less.

Thereby, a plurality of regions (specifically, a plurality of light emitting layers) that emit light can be brought close to each other. In addition, optical design becomes easy. In addition, the degree of freedom of optical design is improved. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, an increase in driving voltage due to the use of the intermediate layer can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

(2) In addition, one embodiment of the present invention includes an intermediate layer, a first light-emitting unit, a second light-emitting unit, a first electrode, and a second electrode, and has a function of emitting light.

The intermediate layer has a function of supplying electrons to one of the first and second light emitting units and supplying holes to the other of the first and second light emitting units.

The first light-emitting unit has a region sandwiched between the first electrode and the intermediate layer, and includes a first light-emitting layer containing a first light-emitting material.

The second light emitting unit has a region sandwiched between the intermediate layer and the second electrode, and includes a second light emitting layer containing a second light emitting material.

The emitted light exhibits a spectrum whose maximum is at the first wavelength EL 1.

The first electrode has a higher reflectivity at the first wavelength EL1 than the second electrode.

The second electrode has a higher transmittance at the first wavelength EL1 than the first electrode, and transmits a part of light and reflects another part of light at the first wavelength EL 1. In addition, a second distance D2 exists between the second electrode and the first electrode.

A value obtained by multiplying the second distance D2 by 1.8 is included in a range of 0.3 times or more and 0.6 times or less of the wavelength EL 1.

(3) In addition, one embodiment of the present invention includes an intermediate layer, a first light-emitting unit, a second light-emitting unit, a first electrode, a second electrode, and a reflective film, and has a function of emitting light.

The intermediate layer has a function of supplying electrons to one of the first and second light emitting units and supplying holes to the other of the first and second light emitting units.

The first light-emitting unit has a region sandwiched between the first electrode and the intermediate layer, and includes a first light-emitting layer containing a first light-emitting material.

The second light emitting unit has a region sandwiched between the intermediate layer and the second electrode, and includes a second light emitting layer containing a second light emitting material.

The emitted light exhibits a spectrum that is largely at the first wavelength.

The reflective film has a reflectivity at the first wavelength that is higher than the second electrode.

The first electrode has a region sandwiched between the first light emitting unit and the reflective film, and has a higher transmittance at the first wavelength than the second electrode.

The second electrode transmits a portion of the light at the first wavelength and reflects another portion of the light.

The second electrode and the reflective film have a second distance therebetween, and a value obtained by multiplying the second distance by 1.8 is included in a range of 0.3 times or more and 0.6 times or less of the first wavelength.

This facilitates optical design. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, the half width of the spectrum of the emitted light can be narrowed. In addition, a microcavity resonator structure may be constructed. In addition, an increase in driving voltage due to the use of the intermediate layer can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

(4) In addition, one embodiment of the present invention is the light-emitting device described above, wherein the second light-emitting layer and the first light-emitting layer have a first distance D1 therebetween.

The relationship expressed by equation (i) holds between the first distance D1 and the first wavelength EL 1.

[ equation 1]

(6.3×10^-3)×EL1≤D1≤(81.3×10^-3)×EL1 (i)

Thereby, a plurality of regions emitting light can be brought close to each other. In addition, optical design becomes easy. In addition, the degree of freedom of optical design is improved. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, an increase in driving voltage due to the use of the intermediate layer can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

(5) In addition, an embodiment of the present invention is the above light-emitting device, wherein the first light-emitting material exhibits a first emission spectrum in a solution, the first emission spectrum being at the second wavelength PL1 at its maximum.

In addition, the second luminescent material exhibits a second emission spectrum in solution, which is largely at the third wavelength PL 2.

The first wavelength EL1 differs from the second wavelength PL1 by 100nm or less, and the first wavelength EL1 differs from the third wavelength PL2 by 100nm or less.

Thereby, the light emitting efficiency of the light emitting device can be improved. In addition, light can be extracted efficiently. As a result, a novel light emitting device with high convenience or reliability can be provided.

(6) In addition, an embodiment of the present invention is the light-emitting device described above, wherein the second light-emitting layer contains a first light-emitting material.

Thereby, the light emitting efficiency of the light emitting device can be improved. In addition, high luminance can be obtained. As a result, a novel light emitting device with high convenience or reliability can be provided.

(7) Another embodiment of the present invention is the light-emitting device described above, wherein the intermediate layer is spaced apart from the first light-emitting layer by a third distance D31 and spaced apart from the second light-emitting layer by a fourth distance D32.

The third distance D31 is 5nm or more, and the fourth distance D32 is 5nm or more.

Thereby, for example, the light-emitting layer can be kept away from the intermediate layer. In addition, for example, a decrease in light emission efficiency due to the light-emitting layer being close to the intermediate layer can be suppressed. In addition, the light emitting efficiency of the light emitting device can be improved. As a result, a novel light emitting device with high convenience or reliability can be provided.

In this specification, the EL layer refers to a layer provided between a pair of electrodes of a light-emitting device. Therefore, a light-emitting layer which is sandwiched between electrodes and contains an organic compound which is a light-emitting material is one embodiment of an EL layer.

In this specification, when a substance a is dispersed in a matrix composed of another substance B, the substance B constituting the matrix is referred to as a host material, and the substance a dispersed in the matrix is referred to as a guest material. Note that the substance a and the substance B may be a single substance or a mixture of two or more substances, respectively.

Note that a light-emitting device in this specification refers to an image display device or a light source (including a lighting device). In addition, the light emitting device also includes a module in which a connector such as an FPC (Flexible printed circuit) or a TCP (Tape Carrier Package) is mounted in the light emitting device; a module of a printed circuit board is arranged at the end part of the TCP; an IC (integrated circuit) is directly mounted On a module On a substrate On which a light emitting device is formed by a COG (Chip On Glass) method.

Effects of the invention

According to one embodiment of the present invention, a novel light-emitting device with high convenience and reliability can be provided. In addition, a novel light-emitting device or a novel semiconductor device can be provided according to one embodiment of the present invention.

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 achieve all of the above effects. Effects other than the above-described effects are apparent from and can be extracted from the description of the specification, the drawings, the claims, and the like.

Brief description of the drawings

Fig. 1A and 1B are diagrams illustrating a structure of a light emitting device according to an embodiment.

Fig. 2 is a diagram illustrating a structure of a light emitting device according to an embodiment.

Fig. 3A to 3C are views illustrating a structure of a light emitting device according to an embodiment.

Fig. 4A and 4B are diagrams illustrating a structure of a light-emitting device according to an embodiment.

Fig. 5A to 5E are diagrams illustrating a structure of an electronic apparatus according to an embodiment.

Fig. 6 is a diagram illustrating a structure of a light emitting device according to an embodiment.

Fig. 7A and 7B are views illustrating a structure of a light emitting device according to an embodiment.

Fig. 8 is a graph showing the current density-radiance characteristics of the light-emitting device 1.

Fig. 9 is a graph showing the voltage-current density characteristics of the light emitting device 1.

Fig. 10 is a graph showing a current density-radiant flux characteristic of the light emitting device 1.

Fig. 11 is a graph showing the voltage-emittance characteristics of the light-emitting device 1.

Fig. 12 is a graph showing the current density-external quantum efficiency characteristic of the light-emitting device 1.

Fig. 13 is a graph showing the emission spectrum of the light-emitting device 1.

Fig. 14 is a graph showing the current density-radiance characteristics of the light-emitting device 2.

Fig. 15 is a graph showing the voltage-current density characteristics of the light emitting device 2.

Fig. 16 is a graph showing a current density-radiant flux characteristic of the light emitting device 2.

Fig. 17 is a graph showing the voltage-emittance characteristics of the light-emitting device 2.

Fig. 18 is a graph showing the current density-external quantum efficiency characteristic of the light-emitting device 2.

Fig. 19 is a graph showing the emission spectrum of the light-emitting device 2.

Fig. 20 is a graph showing the current density-radiance characteristics of the light-emitting device 3.

Fig. 21 is a graph showing the voltage-current density characteristics of the light emitting device 3.

Fig. 22 is a graph showing a current density-radiant flux characteristic of the light-emitting device 3.

Fig. 23 is a graph showing the voltage-emittance characteristics of the light-emitting device 3.

Fig. 24 is a graph showing the current density-external quantum efficiency characteristics of the light-emitting device 3.

Fig. 25 is a graph showing an emission spectrum of the light-emitting device 3.

Fig. 26 is a diagram illustrating a structure of a light emitting device according to an embodiment.

Fig. 27 is a diagram illustrating a calculation result of the light emitting device according to the embodiment.

Fig. 28 is an ultraviolet-visible absorption spectrum and an emission spectrum of the organometallic complex represented by the structural formula (100).

Fig. 29 is an emission spectrum of the organometallic complex represented by the structural formula (100).

Fig. 30 is a graph showing the current density-radiance characteristics of the light-emitting device 4.

Fig. 31 is a graph showing the voltage-current density characteristics of the light-emitting device 4.

Fig. 32 is a graph showing a current density-radiant flux characteristic of the light-emitting device 4.

Fig. 33 is a graph showing the voltage-emittance characteristics of the light-emitting device 4.

Fig. 34 is a graph showing the current density-external quantum efficiency characteristic of the light-emitting device 4.

Fig. 35 is a graph showing an emission spectrum of the light-emitting device 4.

Fig. 36 is a graph showing the angular dependence of the relative intensity of the light-emitting device 4.

Fig. 37 is a graph showing the angular dependence of the normalized photon intensity of the light-emitting device 4.

Modes for carrying out the invention

The light-emitting device according to one embodiment of the present invention includes an intermediate layer, a first light-emitting unit, and a second light-emitting unit. The intermediate layer has a region sandwiched between the first light emitting unit and the second light emitting unit, and the intermediate layer has a function of supplying electrons to one of the first light emitting unit and the second light emitting unit and supplying holes to the other of the first light emitting unit and the second light emitting unit. The first light-emitting unit includes a first light-emitting layer containing a first light-emitting material, the second light-emitting unit includes a second light-emitting layer containing a second light-emitting material, and a first distance is provided between the second light-emitting layer and the first light-emitting layer, the first distance being 5nm or more and 65nm or less.

Thereby, a plurality of regions emitting light can be brought close to each other. In addition, optical design becomes easy. In addition, the degree of freedom of optical design is improved. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

The embodiments are described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and those skilled in the art can easily understand that the form 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. Note that in the following description of the present invention, the same reference numerals are used in common in different drawings to denote the same portions or portions having the same functions, and repetitive description thereof will be omitted.

(embodiment mode 1)

In this embodiment mode, a structure of a light-emitting device which is one embodiment of the present invention will be described with reference to fig. 1.

Fig. 1 is a diagram illustrating a structure of a light-emitting device according to one embodiment of the present invention. Fig. 1A is a cross-sectional view of a light-emitting device according to an embodiment of the present invention, and fig. 1B is a schematic view illustrating an emission spectrum of the light-emitting device according to the embodiment of the present invention.

Note that in this specification, a variable taking a value of an integer of 1 or more is sometimes used for a symbol. For example, (p) including a variable p having a value of an integer of 1 or more may be used to designate a part of a symbol of at most any one of p constituent elements. For example, (m, n) including a variable m and a variable n each having a value of an integer of 1 or more may be used to designate a part of a symbol of at most any one of m × n components.

< structural example 1 of light emitting device >

The light-emitting device described in this embodiment mode includes an intermediate layer 104, a light-emitting unit 103a, and a light-emitting unit 103b (see fig. 1A).

< structural example 1 of intermediate layer >

The intermediate layer 104 has a region sandwiched between the light emitting cells 103a and 103 b. In addition, the intermediate layer 104 has a function of supplying electrons to one of the light emitting unit 103a and the light emitting unit 103b and supplying holes to the other of the light emitting unit 103a and the light emitting unit 103 b. For example, electrons are supplied to the light emitting unit 103a disposed on the anode side and holes are supplied to the light emitting unit 103b disposed on the cathode side. Further, the intermediate layer 104 may be referred to as a charge generation layer, for example.

< structural example 1 of light emitting Unit >

The light emitting unit 103a includes a light emitting layer 113a, and the light emitting layer 113a contains a first light emitting material. The light-emitting unit 103a includes a region in which electrons injected from one side recombine with holes injected from the other side. Note that a structure including a plurality of light-emitting cells and an intermediate layer is sometimes referred to as a tandem light-emitting device. In addition, the first light-emitting material emits energy generated by recombination of electrons and holes as light.

The light emitting unit 103b includes a light emitting layer 113b, and the light emitting layer 113b contains a second light emitting material.

< structural example 1 of light-emitting layer >

The light-emitting layer 113b is spaced apart from the light-emitting layer 113a by a distance D1. The distance D1 is 5nm to 65nm inclusive. The distance D1 is preferably 5nm or more and 50nm or less, and more preferably 5nm or more and 40nm or less. The distance D1 is preferably 10nm or more.

This makes it possible to bring a plurality of regions (for example, the light-emitting layers 113a and 113b) emitting light close to each other. In addition, optical design becomes easy. In addition, the degree of freedom of optical design is improved. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

< structural example 2 of light emitting device >

The light-emitting device described in this embodiment mode includes an electrode 101 and an electrode 102, and has a function of emitting light (see fig. 1A).

< emission Spectrum >

The light emitted by the light-emitting device according to one embodiment of the present invention has a spectrum whose maximum is at the first wavelength EL1, for example (see fig. 1B). Note that, when there are a plurality of maxima in the spectrum, the maximum wavelength having the maximum intensity is defined as the wavelength EL 1.

< example 1 of the structures of electrode 101 and electrode 102>

The electrode 101 has a higher reflectance at the wavelength EL1 than the electrode 102.

The electrode 102 has a higher transmittance at the wavelength EL1 than the electrode 101, and the electrode 102 transmits a part of light and reflects another part of light at the wavelength EL 1.

There is a distance D2 between electrode 102 and electrode 101. The value obtained by multiplying the distance D2 by 1.8 is included in the range of 0.3 times or more and 0.6 times or less of the wavelength EL 1.

For example, in the case where the distance D2 is 180nm, (1.8X 180) nm is 324 nm. When the wavelength EL1 was 800nm, the wavelength (0.3X 800) nm was 240nm and the wavelength (0.6X 800) nm was 480 nm. Thus, 324nm is included in the range of 240nm or more and 480nm or less.

This facilitates optical design. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, the half width of the spectrum of the emitted light can be narrowed. In addition, a microcavity resonator structure may be constructed. In addition, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

In addition, in the light-emitting device, a conductive film having transparency to light of the wavelength EL1 and a film having reflectivity to light of the wavelength EL1 can be used.

For example, a conductive film having transparency to light of the wavelength EL1 may be used for the electrode 101, and a first film having reflectivity to light of the wavelength EL1 may be disposed so as to sandwich the electrode 101 with the light-emitting layer 113 a. In other words, the first film having reflectivity and the light-emitting layer 113a sandwich a conductive film having light transmittance. Alternatively, the conductive film having light-transmitting property has not only a function as the electrode 101 but also a function of adjusting the distance between the electrode 102 and the first film having reflectivity. In such a configuration, there is a distance D2 between the electrode 102 and the reflective first film.

Further, a conductive film having transparency to light of the wavelength EL1 may be used for the electrode 102, and a second film having reflectivity to light of the wavelength EL1 may be disposed so as to sandwich the electrode 102 with the light-emitting layer 113 b. In other words, the second film having reflectivity and the light-emitting layer 113b sandwich a conductive film having light-transmitting properties. Alternatively, the conductive film having light-transmitting property has not only a function as the electrode 102 but also a function of adjusting the distance between the electrode 101 and the second film having reflectivity. In such a configuration, the second film, which is reflective, is spaced a distance D2 from the electrode 101.

< structural example 3 of light emitting device >

In the light-emitting device described in the embodiment, the relationship expressed by the equation (i) is established between the distance D1 and the wavelength EL1 (see fig. 1A).

[ equation 2]

(6.3×10^-3)×EL1≤D1≤(81.3×10^-3)×EL1 (i)

For example, when the wavelength EL1 is 800nm, (6.3X 10)^-3) X 800nm is 5.04nm, (81.3X 10)^-3) X 800nm is 65.04 nm. Therefore, in the case where the wavelength EL1 is 800nm, the appropriate distance D1 is included in the range of 5.04nm or more and 65.04nm or less.

Thereby, a plurality of regions emitting light can be brought close to each other. In addition, optical design becomes easy. In addition, the degree of freedom of optical design is improved. In addition, optical design for efficiently extracting light becomes easy. In addition, light can be extracted efficiently. In addition, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light emitting device with high convenience or reliability can be provided.

< light-emitting Material >

The first luminescent material exhibits a first emission spectrum in solution, which is at its maximum at the wavelength PL1 (refer to fig. 1B). Note that, when there are a plurality of maxima in the spectrum, the maximum wavelength having the maximum intensity is defined as the wavelength PL 1. In addition, for example, the first emission spectrum may be measured in a solution in which dichloromethane is used as a solvent and the first luminescent material is used as a solute. Furthermore, as solvents there may be used: ketones such as methyl ethyl ketone and cyclohexanone; fatty acid esters such as ethyl acetate; halogenated aromatic hydrocarbons such as dichlorobenzene; aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene; aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane; dimethylformamide (DMF), Dimethylsulfoxide (DMSO), etc.

The second luminescent material exhibits a second emission spectrum in solution, which is at its maximum at the wavelength PL 2. Note that, when there are a plurality of maxima in the spectrum, the maximum wavelength having the maximum intensity is defined as the wavelength PL 2.

< emission Spectrum >

The difference between the wavelength EL1 and the wavelength PL1 is 100nm or less. Further, there is a difference of 100nm or less between the wavelength EL1 and the wavelength PL 2. For example, when the wavelength EL1 is 800nm and the wavelengths PL1 and PL2 are 780nm, there is a difference of 20nm between the wavelength EL1 and the wavelength PL 1.

Thereby, the light emitting efficiency of the light emitting device can be improved. In addition, light can be extracted efficiently. As a result, a novel light emitting device with high convenience or reliability can be provided.

< structural example 2 of light-emitting layer >

The light-emitting layer 113b contains a first light-emitting material. In addition, the same material as the first light emitting material may be used as the second light emitting material.

Thereby, the light emitting efficiency of the light emitting device can be improved. In addition, high luminance can be obtained. As a result, a novel light emitting device with high convenience or reliability can be provided.

< structural example 1 of intermediate layer >

The intermediate layer 104 is spaced apart from the light-emitting layer 113a by a distance D31, and the intermediate layer 104 is spaced apart from the light-emitting layer 113b by a distance D32 (see fig. 1A). The distance D31 is 5nm or more, and the distance D32 is 5nm or more.

Thereby, for example, the light-emitting layer 113a can be separated from the intermediate layer 104. Alternatively, for example, a decrease in light emission efficiency due to the light-emitting layer 113a being close to the intermediate layer 104 can be suppressed. In addition, the light emitting efficiency of the light emitting device can be improved. As a result, a novel light emitting device with high convenience or reliability can be provided.

< structural example 2 of intermediate layer 104 >

The intermediate layer 104 may be configured to include a hole-transporting material and an acceptor material (electron-receiving material). As the intermediate layer 104, a structure including an electron-transporting material and a donor material can be used.

Specifically, materials that can be used for the light-emitting unit (a hole-transporting material, an acceptor material, an electron-transporting material, and a donor material) can be used for the intermediate layer 104. Note that, as for a material which can be used for the light-emitting unit, description of a structural example of the light-emitting unit described later can be referred to.

By adopting a structure in which the intermediate layer 104 is sandwiched between the plurality of light emitting cells, an increase in driving voltage can be suppressed as compared with a structure in which the intermediate layer 104 is not used. Alternatively, power consumption can be suppressed.

< example 2 of the structures of electrode 101 and electrode 102>

The resistivity of the electrodes 101 and 102 is preferably 1 × 10^-2Omega cm or less. In the light-emitting device shown in fig. 2, an electrode 101 is formed on a substrate by a sputtering method. The electrode 102 is formed on the light-emitting unit by a sputtering method or a vacuum evaporation method.

In addition, at least one of the electrode 101 and the electrode 102 has a light-transmitting property to light emitted from the light-emitting device. For example, at least one of the electrode 101 and the electrode 102 has a transmittance of 5% or more with respect to light emitted from the light-emitting device.

In addition, for example, the reflectance of at least one of the electrode 101 and the electrode 102 with respect to light emitted from the light-emitting device is 20% or more and 95% or less, and preferably 40% or more and 70% or less.

One or more conductive materials may be used for the electrodes 101 and 102 in a single layer or a stacked layer. The following materials may be used in combination as appropriate as materials for forming the electrodes 101 and 102. For example, metals, alloys, conductive compounds, mixtures thereof, and the like can be suitably used. Specific examples thereof include an In-Sn oxide (also referred to as ITO), an In-Si-Sn oxide (also referred to as ITSO), an In-Zn oxide, and an In-W-Zn oxide. In addition to the above, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), neodymium (Nd), and alloys appropriately combining these metals may be mentioned. In addition to the above, elements belonging to group 1 or group 2 of the periodic table (for example, rare earth metals such as lithium (Li), cesium (Cs), calcium (Ca), strontium (Sr)), europium (Eu), ytterbium (Yb)) which are not listed above, alloys in which these are appropriately combined, graphene, and the like can be used.

< structural example 2 of light-emitting Unit >

The light-emitting device described in this embodiment mode includes a light-emitting unit 103a and a light-emitting unit 103 b.

The light emitting unit 103a may include a hole injection layer 111a, a hole transport layer 112a, a light emitting layer 113a, an electron transport layer 114a, and an electron injection layer 115 a.

In addition, the light emitting unit 103b may include a hole transport layer 112b, a light emitting layer 113b, an electron transport layer 114b, and an electron injection layer 115 b. In addition, a material that can be used for the light emitting unit 103a may be used for the light emitting unit 103 b.

In addition, when the light-emitting device described in this embodiment mode is manufactured, a vacuum process such as a vapor deposition method or a solution process such as a spin coating method or an ink jet method can be used. When the vapor deposition method is used, a physical vapor deposition method (PVD method) such as a sputtering method, an ion plating method, an ion beam vapor deposition method, a molecular beam vapor deposition method, or a vacuum vapor deposition method, a chemical vapor deposition method (CVD method), or the like can be used. In particular, the functional layer (the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer) and the charge generation layer included in the EL layer can be formed by a method such as an evaporation method (a vacuum evaporation method), a coating method (a dip coating method, a dye coating method, a bar coating method, a spin coating method, a spray coating method, or the like), a printing method (an ink jet method, a screen printing (stencil printing) method, an offset printing (lithography printing) method, a flexographic printing (relief printing) method, a gravure printing method, a micro contact printing method, or the like), or the like.

In addition, the materials of the functional layer and the charge generation layer are not limited to the above materials. For example, as the material of the functional layer, a high molecular compound (oligomer, dendrimer, polymer, or the like), a medium molecular compound (a compound between a low molecule and a high molecule: molecular weight of 400 to 4000), an inorganic compound (quantum dot material, or the like), or the like can be used. As the quantum dot material, a colloidal quantum dot material, an alloy type quantum dot material, a Core Shell (Core Shell) type quantum dot material, a Core type quantum dot material, or the like can be used.

[ hole injection layer and hole transport layer ]

For example, the hole injection layer 111a is a layer that injects holes from the anode into the light-emitting unit 103a, and contains a material having a high hole injection property. Further, the electrode 101 may be used as an anode. For example, in the light-emitting device shown in fig. 2, a hole injection layer 111a and a hole transport layer 112a are sequentially formed on an electrode 101 by a vacuum evaporation method.

As the material having a high hole-injecting property, transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide and manganese oxide, phthalocyanine (abbreviated as H)₂Pc), copper phthalocyanine (abbreviation: CuPc), and the like.

As the material having a high hole-injecting property, aromatic amine compounds such as 4,4 '-tris (N, N-diphenylamino) triphenylamine (abbreviated as TDATA), 4' -tris [ N- (3-methylphenyl) -N-phenylamino ] triphenylamine (abbreviated as MTDATA), 4 '-bis [ N- (4-diphenylaminophenyl) -N-phenylamino ] biphenyl (abbreviated as DPAB), 4' -bis (N- {4- [ N '- (3-methylphenyl) -N' -phenylamino ] phenyl } -N-phenylamino) biphenyl (abbreviated as DNTPD), 1,3, 5-tris [ N- (4-diphenylaminophenyl) -N-phenylamino ] benzene (abbreviated as DPA3B), and the like can be used, 3- [ N- (9-phenylcarbazol-3-yl) -N-phenylamino ] -9-phenylcarbazole (abbreviated as PCzPCA1), 3, 6-bis [ N- (9-phenylcarbazol-3-yl) -N-phenylamino ] -9-phenylcarbazole (abbreviated as PCzPCA2), 3- [ N- (1-naphthyl) -N- (9-phenylcarbazol-3-yl) amino ] -9-phenylcarbazole (abbreviated as PCzPCN1), and the like.

As the material having a high hole-injecting property, Poly (N-vinylcarbazole) (abbreviated as PVK), Poly (4-vinyltriphenylamine) (abbreviated as PVTPA), Poly [ N- (4- { N '- [4- (4-diphenylamino) phenyl ] phenyl-N' -phenylamino } phenyl) methacrylamide ] (abbreviated as PTPDMA), Poly [ N, N '-bis (4-butylphenyl) -N, N' -bis (phenyl) benzidine ] (abbreviated as Poly-TPD) and the like can be used. Alternatively, a polymer compound to which an acid is added, such as poly (3, 4-ethylenedioxythiophene)/poly (styrenesulfonic acid) (abbreviated as PEDOT/PSS) or polyaniline/poly (styrenesulfonic acid) (PANI/PSS), may also be used.

As the material having a high hole-injecting property, a composite material including a hole-transporting material and an acceptor material (electron-acceptor material) may be used. In this case, electrons are extracted from the hole-transporting material by the acceptor material to generate holes in the hole injection layer 111a, and the holes are injected into the light-emitting layer 113a through the hole-transporting layer 112 a. The hole injection layer 111a may be a single layer made of a composite material including a hole-transporting material and an acceptor material, or may be a stack of layers formed using a hole-transporting material and an acceptor material, respectively.

The hole transport layer 112a is a layer that transports holes injected from the electrode 101 through the hole injection layer 111a into the light emitting layer 113 a. The hole-transporting layer 112 is a layer containing a hole-transporting material. As the hole-transporting material used for the hole-transporting layer 112a, a material having the HOMO energy level that is the same as or close to the HOMO energy level of the hole-injecting layer 111a is particularly preferably used.

As the acceptor material used for the hole injection layer 111a, an oxide of a metal belonging to groups 4 to 8 in the periodic table of elements can be used. Specifically, molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide can be given. Among these, molybdenum oxide is preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. In addition to the above, examples include organic acceptors such as quinodimethane derivatives, tetrachlorobenzoquinone derivatives, and hexaazatriphenylene derivatives. Examples of the compound having an electron-absorbing group (halogen group, cyano group) include 7, 7, 8, 8-tetracyano-2, 3,5, 6-tetrafluoroquinodimethane (abbreviated as F)₄TCNQ), chloranil, 2,3, 6, 7, 10, 11-hexacyan-1, 4, 5, 8, 9, 12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3, 4, 5, 7, 8-hexafluorotetracyanoquinodimethane (abbreviation: F6-TCNNQ), and the like. In particular, a compound in which an electron-withdrawing group such as HAT-CN is bonded to a condensed aromatic ring having a plurality of hetero atoms is thermally stable, and is therefore preferable. Further, [ 3] comprising an electron-withdrawing group (particularly, a halogen group such as a fluoro group, a cyano group)]The axiene derivative is preferable because it has a very high electron-accepting property, and specific examples thereof include: alpha, alpha' -1, 2, 3-cyclopropane triylidene tris [ 4-cyano-2, 3,5, 6-tetrafluorophenylacetonitrile]Alpha, alpha' -1, 2, 3-cyclopropane triylidenetris [2, 6-dichloro-3, 5-difluoro-4- (trifluoromethyl) benzeneacetonitrile]Alpha, alpha' -1, 2, 3-cyclopropane triylidene tris [2, 3,4, 5, 6-pentafluorophenylacetonitrile]And the like.

The hole-transporting material used for the hole injection layer 111a and the hole transport layer 112a preferably has a hole-transporting property of 10^{- 6}cm²A substance having a hole mobility of greater than/Vs. Note that as long as the hole transporting property is higher than the electron transporting property, a substance other than the above may be used.

As the hole-transporting material, a material having high hole-transporting property such as a pi-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, or the like) or an aromatic amine compound (a compound having an aromatic amine skeleton) is preferably used.

Examples of the carbazole derivative (compound having a carbazole skeleton) include a biscarbazole derivative (for example, 3, 3' -biscarbazole derivative), an aromatic amine compound having a carbazole group, and the like.

Specific examples of the bicarbazole derivative (for example, 3,3 '-bicarbazole derivative) include 3, 3' -bis (9-phenyl-9H-carbazole) (PCCP), 9 '-bis (1, 1' -biphenyl-4-yl) -3,3 '-bi-9H-carbazole, 9' -bis (1,1 '-biphenyl-3-yl) -3, 3' -bi-9H-carbazole, 9- (1,1 '-biphenyl-3-yl) -9' - (1,1 '-biphenyl-4-yl) -9H, 9' H-3,3 '-bicarbazole (mBPCCBP), 9- (2-naphthyl) -9' -phenyl-9H, 9 'H-3, 3' -bicarbazole (abbreviated as. beta. NCCP), and the like.

Specific examples of the aromatic amine compound having a carbazole group include 4-phenyl-4 '- (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviated as PCBA1BP), N- (4-biphenyl) -N- (9, 9-dimethyl-9H-fluoren-2-yl) -9-phenyl-9H-carbazol-3-amine (abbreviated as pcpef), N- (1, 1' -biphenyl-4-yl) -N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] -9, 9-dimethyl-9H-fluoren-2-amine (abbreviated as PCBBiF), and 4,4' -diphenyl-4 ' - (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviated as PCBBi1BP), 4- (1-naphthyl) -4' - (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviated as PCBANB), 4' -bis (1-naphthyl) -4' - (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviated as PCBNBB), 4-phenyldiphenyl- (9-phenyl-9H-carbazol-3-yl) amine (abbreviated as PCA1BP), N ' -bis (9-phenylcarbazol-3-yl) -N, N ' -diphenylbenzene-1, 3-diamine (PCA 2B), N ' -triphenyl-N, N ' -tris (9-phenylcarbazol-3-yl) benzene-1, 3, 5-triamine (PCA 3B), 9-dimethyl-N-phenyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] fluorene-2-amine (PCBAF), N-phenyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] spiro-9, 9 ' -bifluorene-2-amine (PCBASF), PCzPCA1, PCzPCA2, PCzPCN1, 3- [ N- (4-diphenylaminophenyl) -N-phenylamino ] -9-phenylcarbazole (PCzDPA 1), 3, 6-bis [ N- (4-diphenylaminophenyl) -N-phenylamino ] -9-phenylcarbazole (abbreviation: PCzDPA2), 3, 6-bis [ N- (4-diphenylaminophenyl) -N- (1-naphthyl) amino ] -9-phenylcarbazole (abbreviation: PCzTPN2), 2- [ N- (9-phenylcarbazol-3-yl) -N-phenylamino ] spiro-9, 9 '-bifluorene (abbreviation: PCASF), N- [4- (9H-carbazol-9-yl) phenyl ] -N- (4-phenyl) phenylaniline (abbreviation: YGA1BP), N' -bis [4- (carbazol-9-yl) phenyl ] -N, n '-diphenyl-9, 9-dimethylfluorene-2, 7-diamine (abbreviation: YGA2F), 4' -tris (carbazol-9-yl) triphenylamine (abbreviation: TCTA), and the like.

As the carbazole derivative, in addition to the above, examples thereof include 3- [4- (9-phenanthryl) -phenyl ] -9-phenyl-9H-carbazole (abbreviated as PCPPn), 3- [4- (1-naphthyl) -phenyl ] -9-phenyl-9H-carbazole (abbreviated as PCPN), 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), 1,3, 5-tris [4- (N-carbazolyl) phenyl ] benzene (abbreviated as TCPB), 9- [4- (10-phenyl-9-anthracyl) phenyl ] -9H-carbazole (abbreviated as CZPA) and the like.

Specific examples of the thiophene derivative (compound having a thiophene skeleton) and the furan derivative (compound having a furan skeleton) include compounds having a thiophene skeleton such as 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 4,4' - (benzene-1, 3, 5-triyl) tris (dibenzofuran) (abbreviated as DBF3P-II), 4- {3- [3- (9-phenyl-9H-fluoren-9-yl) phenyl ] phenyl } dibenzofuran (mmDBFFLBi-II).

Specific examples of the aromatic amine compound include 4,4' -bis [ N- (1-naphthyl) -N-phenylamino ] biphenyl (abbreviated as NPB or. alpha. -NPD), N ' -bis (3-methylphenyl) -N, N ' -diphenyl- [1, 1 ' -biphenyl ] -4, 4' -diamine (abbreviated as TPD), 4' -bis [ N- (spiro-9, 9 ' -difluoren-2-yl) -N-phenylamino ] biphenyl (abbreviated as BSPB), 4-phenyl-4 ' - (9-phenylfluoren-9-yl) triphenylamine (abbreviated as BPAFLP), 4-phenyl-3 ' - (9-phenylfluoren-9-yl) triphenylamine (abbreviated as mBPAFLP), N- (9, 9-dimethyl-9H-fluoren-2-yl) -N- {9, 9-dimethyl-2- [ N ' -phenyl-N ' - (9, 9-dimethyl-9H-fluoren-2-yl) amino ] -9H-fluoren-7-yl } phenylamine (abbreviated: DFLADFL), N- (9, 9-dimethyl-2-diphenylamino-9H-fluoren-7-yl) diphenylamine (abbreviated: DPNF), 2- [ N- (4-diphenylaminophenyl) -N-phenylamino ] spiro-9, 9 ' -bifluorene (abbreviated: DPASF), 2, 7-bis [ N- (4-diphenylaminophenyl) -N-phenylamino ] spiro-9, 9 ' -bifluorene (abbreviated as DPA2SF), 4' -tris [ N- (1-naphthyl) -N-phenylamino ] triphenylamine (abbreviated as 1 ' -TNATA), TDATA, m-MTDATA, N ' -di (p-tolyl) -N, N ' -diphenyl-p-phenylenediamine (abbreviated as DTDPPA), DPAB, DNTPD, DPA3B and the like.

As the hole transporting material, a polymer compound such as PVK, PVTPA, PTPDMA, Poly-TPD or the like can be used.

The hole-transporting material is not limited to the above-described materials, and one or a combination of a plurality of known materials can be used for the hole injection layer 111a and the hole transport layer 112 a.

[ luminescent layer ]

The light-emitting layer 113a is a layer containing a light-emitting material. For example, in the light-emitting device shown in fig. 2, the light-emitting layer 113a is formed on the hole transport layer 112a by a vacuum evaporation method.

A light-emitting device according to one embodiment of the present invention includes a light-emitting organic compound as a light-emitting material. The light-emitting organic compound emits near-infrared light. Specifically, the maximum peak wavelength of light emitted from the light-emitting organic compound is greater than 780nm and not more than 900 nm.

As the light-emitting organic compound, for example, the organometallic complex described in embodiment 1 can be used. Further, as the light-emitting organic compound, an organometallic complex shown in the following examples can be used.

The light emitting layer 113a may include one or more light emitting materials.

The light-emitting layer 113a may contain one or more organic compounds (host materials, auxiliary materials, and the like) in addition to a light-emitting material (guest material). As the one or more organic compounds, one or both of the hole-transporting material and the electron-transporting material described in this embodiment can be used. Further, as the one or more organic compounds, bipolar materials may also be used.

The light-emitting material that can be used for the light-emitting layer 113a is not particularly limited, and a light-emitting material that converts singlet excitation energy into light in the near-infrared region or a light-emitting material that converts triplet excitation energy into light in the near-infrared region can be used.

Examples of the light-emitting material that converts the singlet excitation energy into light include a substance that emits fluorescence (fluorescent material), and examples thereof include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives.

Examples of the light-emitting material that converts triplet excitation energy into light emission include a substance that emits phosphorescence (phosphorescent material) and a Thermally Activated Delayed Fluorescence (TADF) material that exhibits Thermally activated delayed fluorescence.

Examples of the phosphorescent material include organic metal complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, and a pyridine skeleton, organic metal complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand, platinum complexes, and rare earth metal complexes.

Further, the light-emitting device according to one embodiment of the present invention may include a light-emitting material other than a light-emitting material that emits near infrared light. For example, the light-emitting device according to one embodiment of the present invention may include a light-emitting material that emits visible light (red, blue, green, and the like) in addition to a light-emitting material that emits near-infrared light.

As the organic compound (a host material, an auxiliary material, or the like) used for the light-emitting layer 113a, one or more kinds of substances having a larger energy gap than that of the light-emitting material can be selected and used.

When the light-emitting material used in the light-emitting layer 113a is a fluorescent material, it is preferable to use an organic compound having a large singlet excited state and a small triplet excited state as an organic compound used in combination with the light-emitting material.

Although some of the organic compounds overlap with the above specific examples, specific examples of the organic compounds are shown below from the viewpoint of preferable combination with a light-emitting material (fluorescent material, phosphorescent material).

When the light-emitting material is a fluorescent material, examples of the organic compound which can be used in combination with the light-emitting material include anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, and the like,(chrysene) derivatives, dibenzo [ g, p ]]Derivatives, and the like.

Specific examples of the organic compound (host material) used in combination with the fluorescent material include 9-phenyl-3- [4- (10-phenyl-9-anthryl) phenyl]-9H-carbazole (PCzPA), 3, 6-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl]-9H-carbazole (DPCzPA), PCPN, 9, 10-diphenylanthracene (DPAnth), N-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl]-9H-carbazole-3-amine (CzA 1-1 PA for short), 4- (10-phenyl-9-anthryl) triphenylamine (DPhPA for short), 4- (9H-carbazole-9-yl) -4' - (10-phenyl-9-anthryl) triphenylamine (YGAPA for short), N, 9-diphenyl-N- [4- (10-phenyl-9-anthryl) phenyl]-9H-carbazole-3-amine (PCAPA), N, 9-diphenyl-N- {4- [4- (10-phenyl-9-anthryl) phenyl]Phenyl } -9H-carbazole-3-amine (PCAPBA), N- (9, 10-diphenyl-2-anthryl) -N, 9-diphenyl-9H-carbazole-3-amine (2 PCAPA), 6, 12-dimethoxy-5, 11-diphenylN, N, N ', N ', N ", N", N ' "-octaphenyldibenzo [ g, p]-2,7, 10, 15-tetramine (DBC 1 for short), CzPA, 7- [4- (10-phenyl-9-anthryl) phenyl]-7H-dibenzo [ c, g]Carbazole (short for: cgDBCzPA), 6- [3- (9, 10-diphenyl-2-anthryl) phenyl]-benzo [ b ]]Naphtho [1,2-d ]]Furan (abbreviation: 2mBnfPPA), 9-phenyl-10- {4- (9-phenyl group)-9H-fluoren-9-yl) biphenyl-4' -yl } anthracene (abbreviation: FLPPA), 9, 10-bis (3, 5-diphenylphenyl) anthracene (abbreviation: DPPA), 9, 10-di (2-naphthyl) anthracene (abbreviation: DNA), 2-tert-butyl-9, 10-di (2-naphthyl) anthracene (abbreviation: t-bundna), 9' -bianthracene (abbreviation: BANT), 9 '- (stilbene-3, 3' -diyl) phenanthrene (abbreviation: DPNS), 9 '- (stilbene-4, 4' -diyl) phenanthrene (abbreviation: DPNS2), 1,3, 5-tris (1-pyrene) benzene (abbreviation: TPB3), 5, 12-diphenyltetracene, 5, 12-bis (biphenyl-2-yl) tetracene, and the like.

In the case where the light-emitting material is a phosphorescent material, an organic compound having triplet excitation energy larger than triplet excitation energy (energy difference between an underlying state and a triplet excited state) of the light-emitting material may be selected as the organic compound used in combination with the light-emitting material.

When a plurality of organic compounds (for example, a first host material and a second host material (or an auxiliary material) are used together with a light-emitting material in order to form an exciplex combination, it is preferable to use the plurality of organic compounds in a mixture with a phosphorescent material (particularly, an organometallic complex).

By adopting such a structure, it is possible to efficiently obtain light emission of EXTET (excimer-Triplet Energy Transfer) utilizing Energy Transfer from the Exciplex to the light-emitting material. As the combination of a plurality of organic compounds, a combination in which an exciplex is easily formed is preferably used, and a combination of a compound which easily receives holes (a hole-transporting material) and a compound which easily receives electrons (an electron-transporting material) is particularly preferable. As specific examples of the hole-transporting material and the electron-transporting material, materials described in this embodiment can be used. Since this structure can realize high efficiency, low voltage, and long life of the light emitting device at the same time.

Examples of the organic compound that can be used in combination with a light-emitting material when the light-emitting material is a phosphorescent material include aromatic amine compounds, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, zinc-based metal complexes or aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives, and the like.

As specific examples of the aromatic amine compound (compound having an aromatic amine skeleton), carbazole derivative, dibenzothiophene derivative (thiophene derivative), and dibenzofuran derivative (furan derivative) of the organic compound having a high hole-transporting property, the same materials as those of the hole-transporting material can be given.

Specific examples of the zinc-based metal complex and the aluminum-based metal complex of the organic compound having a high electron-transporting property include: tris (8-quinolinolato) aluminum (III) (Alq for short), tris (4-methyl-8-quinolinolato) aluminum (III) (Almq for short)₃) 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) and the like having a quinoline skeleton or a benzoquinoline skeleton.

In addition, metal complexes having an oxazole-based ligand or a thiazole-based ligand, such as bis [2- (2-benzoxazolyl) phenol ] zinc (II) (abbreviated as ZnPBO) and bis [2- (2-benzothiazolyl) phenol ] zinc (II) (abbreviated as ZnBTZ), can be used.

Specific examples of the oxadiazole derivative, triazole derivative, benzimidazole derivative, quinoxaline derivative, dibenzoquinoxaline derivative, and phenanthroline derivative of the organic compound having a high electron-transporting property include 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3, 4-oxadiazole (abbreviated as PBD), 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-oxadiazol-2-yl) phenyl ] -9H-carbazole (abbreviated as CO11), 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -1, 2, 4-Triazole (TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenyl) -1, 2, 4-triazole (p-EtTAZ), 2 '- (1, 3, 5-benzenetriyl) tris (1-phenyl-1H-benzimidazole) (TPBI), 2- [3- (dibenzothiophen-4-yl) phenyl ] -1-phenyl-1H-benzimidazole (mDBTBIm-II), 4' -bis (5-methylbenzoxazol-2-yl) stilbene (BzOs), bathophenanthroline (Bphen), Bathocuproin (BCP), 2, 9-bis (naphthalen-2-yl) -4, 7-diphenyl-1, 10-phenanthroline (abbreviated as NBphen), 2- [3- (dibenzothiophen-4-yl) phenyl ] dibenzo [ f, H ] quinoxaline (abbreviated as 2mDBTPDBq-II), 2- [ 3'- (dibenzothiophen-4-yl) biphenyl-3-yl ] dibenzo [ f, H ] quinoxaline (abbreviated as 2mDBTBPDBq-II), 2- [ 3' - (9H-carbazol-9-yl) biphenyl-3-yl ] dibenzo [ f, H ] quinoxaline (abbreviated as 2mCZBPDBq), 2- [4- (3, 6-diphenyl-9H-carbazol-9-yl) phenyl ] dibenzo [ f, h ] quinoxaline (abbreviated as 2CzPDBq-III), 7- [3- (dibenzothiophene-4-yl) phenyl ] dibenzo [ f, h ] quinoxaline (abbreviated as 7mDBTPDBq-II), and 6- [3- (dibenzothiophene-4-yl) phenyl ] dibenzo [ f, h ] quinoxaline (abbreviated as 6 mDBTPDBq-II).

Specific examples of the heterocyclic compound having a diazine skeleton, the heterocyclic compound having a triazine skeleton, and the heterocyclic compound having a pyridine skeleton, which are organic compounds having a high electron-transporting property, include 4, 6-bis [3- (phenanthren-9-yl) phenyl ] pyrimidine (abbreviated as 4,6mPnP2Pm), 4, 6-bis [3- (4-dibenzothienyl) phenyl ] pyrimidine (abbreviated as 4,6mDBTP2Pm-II), 4, 6-bis [3- (9H-carbazol-9-yl) phenyl ] pyrimidine (abbreviated as 4,6mCzP2Pm), 2- {4- [3- (N-phenyl-9H-carbazol-3-yl) -9H-carbazol-9-yl ] phenyl } -4, 6-diphenyl-1, 3, 5-triazine (abbreviated as PCCzPTzn), 9- [3- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) phenyl ] -9 '-phenyl-2, 3' -bi-9H-carbazole (abbreviated as mPCzPTzn-02), 3, 5-bis [3- (9H-carbazol-9-yl) phenyl ] pyridine (abbreviated as 35DCzPPy), 1,3, 5-tris [3- (3-pyridine) phenyl ] benzene (abbreviated as TmPyPB), and the like.

As the organic compound having a high electron-transporting property, a polymer compound such as poly (2, 5-pyridyldiyl) (abbreviated as PPy), poly [ (9, 9-dihexylfluorene-2, 7-diyl) -co- (pyridine-3, 5-diyl) ] (abbreviated as PF-Py), poly [ (9, 9-dioctylfluorene-2, 7-diyl) -co- (2,2 '-bipyridine-6, 6' -diyl) ] (abbreviated as PF-BPy) can be used.

The TADF material is a material capable of converting (up-convert) a triplet excited state into a singlet excited state (reverse intersystem crossing) by a small amount of thermal energy and efficiently exhibiting luminescence from the singlet excited state(fluorescent) material. In addition, the conditions under which the thermally activated delayed fluorescence can be obtained with high efficiency are as follows: the energy difference between the triplet excitation level and the singlet excitation level is 0eV or more and 0.2eV or less, and preferably 0eV or more and 0.1eV or less. The delayed fluorescence exhibited by the TADF material means luminescence having a spectrum similar to that of general fluorescence but having a very long lifetime. Having a life of 10^-6Second or more, preferably 10^-3For more than a second.

Examples of the TADF material include fullerene or a derivative thereof, an acridine derivative such as luteolin, and eosin. Further, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), or the like can be cited. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (abbreviated as SnF)₂(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF₂(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF₂(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF₂(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF₂(OEP)), protoporphyrin-tin fluoride complex (abbreviation: SnF₂(Etio I)) and octaethylporphyrin-platinum chloride complex (abbreviation: PtCl₂OEP), and the like.

In addition to the above, 2- (biphenyl-4-yl) -4, 6-bis (12-phenylindolo [2, 3-a ] carbazol-11-yl) -1,3, 5-triazine (abbreviation: PIC-TRZ), PCCZPTzn, 2- [4- (10H-phenoxazin-10-yl) phenyl ] -4, 6-diphenyl-1, 3, 5-triazine (abbreviation: PXZ-TRZ), 3- [4- (5-phenyl-5, 10-dihydrophenazin-10-yl) phenyl ] -4, 5-diphenyl-1, 2, 4-triazole (abbreviation: PPZ-3TPT), 3- (9, 9-dimethyl-9H-acridin-10-yl) -9H-xanthen-9-one Heterocyclic compounds having a pi-electron-rich heteroaromatic ring and a pi-electron-deficient heteroaromatic ring, such as (ACRXTN for short), bis [4- (9, 9-dimethyl-9, 10-dihydroacridine) phenyl ] sulfone (DMAC-DPS for short), 10-phenyl-10H, 10 ' H-spiro [ acridine-9, 9 ' -anthracene ] -10 ' -one (ACRSA for short), and the like. In addition, in the case where a pi-electron-rich heteroaromatic ring and a pi-electron-deficient heteroaromatic ring are directly bonded to each other, both donor and acceptor of the pi-electron-rich heteroaromatic ring are strong, and the energy difference between a singlet excited state and a triplet excited state is small, which is particularly preferable.

In addition, in the case of using the TADF material, other organic compounds may be used in combination. Particularly, the TADF material may be combined with the above-described host material, hole-transporting material, and electron-transporting material.

In addition, the above-described materials can be used for formation of the light-emitting layer 113a by combination with a low-molecular material or a high-molecular material. For the film formation, a known method (vapor deposition method, coating method, printing method, or the like) can be suitably used.

[ Electron transport layer ]

The electron transport layer 114a is a layer that transports electrons injected from the electrode 102 by the electron injection layer 115a into the light emitting layer 113 a. In addition, the electron transporting layer 114a is a layer containing an electron transporting material. The electron-transporting material for the electron-transporting layer 114a preferably has a thickness of 1 × 10^-6cm²A substance having an electron mobility of greater than/Vs. Note that substances other than the above may be used as long as the electron-transporting property is higher than the hole-transporting property. For example, in the light-emitting device shown in fig. 2, an electron transport layer 114a is formed on the light-emitting layer 113 a.

As the electron transporting material, a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, a metal complex having a thiazole skeleton, or the like can be used, and a material having high electron transporting properties such as an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative having a quinoline ligand, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, a nitrogen-containing heteroaromatic compound, or the like which lacks pi-electron type heteroaromatic compound can be used.

As a specific example of the electron transporting material, the above-mentioned material can be used.

[ Electron injection layer ]

The electron injection layer 115a is a layer containing a substance having a high electron injection property. For example, in the light-emitting device shown in fig. 2, the electron injection layer 115a is formed on the electron transit layer 114a by a vacuum evaporation method.

As the electron injection layer 115a, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), or the like can be used₂) And lithium oxide (LiO)_x) And the like, alkali metals, alkaline earth metals, or compounds thereof. In addition, erbium fluoride (ErF) may be used₃) And the like. In addition, an electron salt (electrode) may be used for the electron injection layer 115 a. Examples of the electron salt include a mixed oxide of calcium and aluminum to which electrons are added at a high concentration. Further, the electron transport layer 114a may be formed using the above-described materials.

In addition, a composite material including an electron transporting material and a donor material (an electron donating material) may be used for the electron injection layer 115 a. Such a composite material is excellent in electron injection property and electron transport property, and generates electrons in an organic compound by an electron donor. In this case, the organic compound is preferably a material excellent in transporting generated electrons. In this case, the organic compound is preferably a material excellent in transporting generated electrons, and specifically, for example, an electron transporting material (metal complex, heteroaromatic compound, or the like) used for the electron transporting layer 114a as described above can be used. As the electron donor, a substance which exhibits an electron donor to an organic compound may be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferably used, and examples thereof include lithium, cesium, magnesium, calcium, erbium, and ytterbium. In addition, alkali metal oxides or alkaline earth metal oxides are preferably used, and examples thereof include lithium oxide, calcium oxide, barium oxide, and the like. In addition, lewis bases such as magnesium oxide can be used. Further, an organic compound such as tetrathiafulvalene (TTF) may be used.

Note that this embodiment mode can be combined with other embodiment modes shown in this specification as appropriate.

(embodiment mode 2)

In this embodiment, a structure of a light-emitting device according to an embodiment of the present invention will be described with reference to fig. 3 and 4.

Fig. 3 is a diagram illustrating a structure of a light-emitting device according to an embodiment of the present invention. Fig. 3A is a plan view of a light-emitting device according to one embodiment of the present invention, and fig. 3B is a sectional view of the light-emitting device taken along the cut lines X1-Y1 and X2-Y2 in fig. 3A.

Fig. 4 is a diagram illustrating a structure of a light-emitting device according to an embodiment of the present invention. Fig. 4A is a plan view of a light-emitting device according to an embodiment of the present invention, and fig. 4B is a sectional view of the light-emitting device along a cut-off line a-a' in fig. 4A.

< structural example 1 of light-emitting device >

The light-emitting device shown in fig. 3A to 3C can be used, for example, for a lighting device. The light emitting device may also have a bottom emission structure, a top emission structure, or a double-sided emission structure.

The light-emitting device shown in fig. 3B includes a substrate 490a, a substrate 490B, a conductive layer 406, a conductive layer 416, an insulating layer 405, an organic EL device 450 (a first electrode 401, an EL layer 402, and a second electrode 403), and an adhesive layer 407. The organic EL device 450 may be referred to as a light emitting element, an organic EL element, a light emitting device, or the like. The EL layer 402 preferably contains the organometallic complex shown in embodiment 1 as a light-emitting organic compound in a light-emitting layer.

The organic EL device 450 includes a first electrode 401 on a substrate 490a, an EL layer 402 on the first electrode 401, and a second electrode 403 on the EL layer 402. The organic EL device 450 is sealed by the substrate 490a, the adhesive layer 407, and the substrate 490 b.

Ends of the first electrode 401, the conductive layer 406, and the conductive layer 416 are covered with an insulating layer 405. The conductive layer 406 is electrically connected to the first electrode 401, and the conductive layer 416 is electrically connected to the second electrode 403. A conductive layer 406 covered with an insulating layer 405 with a first electrode 401 interposed therebetween is used as an auxiliary wiring, and the conductive layer 406 is electrically connected to the first electrode 401. When the auxiliary wiring electrically connected to the electrode of the organic EL device 450 is included, a voltage drop due to the resistance of the electrode can be suppressed, which is preferable. A conductive layer 406 may also be disposed on the first electrode 401. An auxiliary wiring electrically connected to the second electrode 403 may be provided on the insulating layer 405 or the like.

The substrate 490a and the substrate 490b may be made of glass, quartz, ceramic, sapphire, an organic resin, or the like. By using a material having flexibility for the substrate 490a and the substrate 490b, flexibility of the display device can be improved.

The light-emitting surface of the light-emitting device may be provided with a light extraction structure for improving light extraction efficiency, an antistatic film for suppressing adhesion of dust, a film having water repellency and being less likely to be stained, a hard coat film for suppressing damage during use, an impact absorption layer, and the like.

Examples of an insulating material that can be used for the insulating layer 405 include a resin such as an acrylic resin or an epoxy resin, and an inorganic insulating material such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, or aluminum oxide.

As the adhesive layer 407, various curable adhesives such as a light curable adhesive such as an ultraviolet curable adhesive, a reaction curable adhesive, a heat curable adhesive, and an anaerobic adhesive can be used. Examples of the binder include epoxy resins, acrylic resins, silicone resins, phenol resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, EVA (ethylene vinyl acetate) resins, and the like. Particularly, a material having low moisture permeability such as epoxy resin is preferably used. In addition, a two-liquid mixed type resin may also be used. Further, an adhesive sheet or the like may also be used.

The light-emitting device shown in fig. 3C includes a barrier layer 490C, a conductive layer 406, a conductive layer 416, an insulating layer 405, an organic EL device 450, an adhesive layer 407, a barrier layer 423, and a substrate 490 b.

The barrier layer 490C shown in fig. 3C comprises a substrate 420, an adhesion layer 422, and a high barrier insulating layer 424.

In the light-emitting device shown in fig. 3C, the organic EL device 450 is disposed between the insulating layer 424 and the barrier layer 423 having high barrier properties. Therefore, even if a resin film or the like having low water repellency is used for the substrate 420 and the substrate 490b, impurities such as water can be prevented from entering the organic EL device and causing a reduction in lifetime.

As the substrate 420 and the substrate 490b, for example, the following materials can be used: polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resins, acrylic resins, polyimide resins, polymethyl methacrylate resins, Polycarbonate (PC) resins, polyether sulfone (PES) resins, polyamide resins (nylon, aramid, and the like), polysiloxane resins, cycloolefin resins, polystyrene resins, polyamide-imide resins, polyurethane resins, polyvinyl chloride resins, polyvinylidene chloride resins, polypropylene resins, Polytetrafluoroethylene (PTFE) resins, ABS resins, cellulose nanofibers, and the like. Glass having a thickness of a degree of flexibility may also be used for the substrate 420 and the substrate 490 b.

An inorganic insulating film is preferably used as the insulating layer 424 having high barrier properties. As the inorganic insulating film, for example, an inorganic insulating film such as a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, or an aluminum nitride film can be used. Further, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like may be used. Further, two or more of the insulating films may be stacked.

The barrier layer 423 preferably includes at least one inorganic film. For example, the barrier layer 423 may have a single-layer structure of an inorganic film or a stacked-layer structure of an inorganic film and an organic film. As the inorganic film, the above inorganic insulating film is preferable. Examples of the stacked structure include a structure in which a silicon oxynitride film, a silicon oxide film, an organic film, a silicon oxide film, and a silicon nitride film are sequentially formed. By adopting a stacked-layer structure of an inorganic film and an organic film as a protective layer, impurities (typically, hydrogen, water, or the like) that may enter the organic EL device 450 can be appropriately suppressed.

The insulating layer 424 and the organic EL device 450 having high barrier properties can be formed directly over the substrate 420 having flexibility. At this time, the adhesive layer 422 is not required. The insulating layer 424 and the organic EL device 450 may be formed over a rigid substrate with a release layer interposed therebetween and then transferred to the substrate 420. For example, the insulating layer 424 and the organic EL device 450 can be transferred to the substrate 420 by peeling the insulating layer 424 and the organic EL device 450 from the rigid substrate by applying heat, force, laser, or the like to the peeling layer, and then attaching the substrate 420 with the adhesive layer 422. As the release layer, for example, a laminate of inorganic films including a tungsten film and a silicon oxide film, an organic resin film such as polyimide, or the like can be used. When a rigid substrate is used, the insulating layer 424 can be formed at a higher temperature than a resin substrate or the like, and therefore, the insulating layer 424 which is dense and has extremely high barrier properties can be realized.

< structural example 2 of light-emitting device >

The light-emitting device according to one embodiment of the present invention may be a passive matrix light-emitting device or an active matrix light-emitting device. An active matrix light-emitting device will be described with reference to fig. 4.

The active matrix light-emitting device shown in fig. 4A and 4B includes a pixel portion 302, a circuit portion 303, a circuit portion 304A, and a circuit portion 304B.

The circuit portion 303, the circuit portion 304a, and the circuit portion 304b can be used as a scanning line driver circuit (gate driver) or a signal line driver circuit (source driver). Alternatively, a gate driver or a source driver which is externally provided may be electrically connected to the pixel portion 302.

A lead 307 is provided over the first substrate 301. The lead wire 307 is electrically connected to an FPC308 as an external input terminal. The FPC308 transmits a signal (for example, a video signal, a clock signal, a start signal, a reset signal, or the like) or a potential from the outside to the circuit portion 303, the circuit portion 304a, and the circuit portion 304 b. In addition, the FPC308 may be mounted with a Printed Wiring Board (PWB). The structure shown in fig. 4A and 4B can be referred to as a light-emitting module including a light-emitting device (or a light-emitting device) and an FPC.

The pixel portion 302 includes a plurality of pixels including an organic EL device 317, a transistor 311, and a transistor 312. The transistor 312 is electrically connected to a first electrode 313 included in the organic EL device 317. The transistor 311 is used as a switching transistor. The transistor 312 is used as a transistor for current control. Note that the number of transistors included in each pixel is not particularly limited, and can be appropriately set as needed.

The circuit portion 303 includes a plurality of transistors such as a transistor 309 and a transistor 310. The circuit portion 303 may be formed of a circuit including a transistor having a single polarity (either of N-type and P-type), or may be formed of a CMOS circuit including an N-type transistor and a P-type transistor. Further, a configuration having a driving circuit outside may be employed.

The transistor structure included in the light-emitting device of this embodiment mode is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. In addition, a top gate type or a bottom gate type transistor structure may be employed. Alternatively, a gate electrode may be provided above and below the semiconductor layer in which the channel is formed.

The crystallinity of a semiconductor material used for a transistor is also not particularly limited, and an amorphous semiconductor or a semiconductor having crystallinity (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 semiconductor having crystallinity is used, deterioration in characteristics of the transistor can be suppressed, and therefore, the semiconductor is preferable.

A metal oxide (oxide semiconductor) is preferably used for the semiconductor layer of the transistor. In addition, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon, single crystal silicon, and the like).

For example, the semiconductor layer preferably contains indium, M (M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium), and zinc. In particular, M is preferably one or more selected from the group consisting of aluminum, gallium, yttrium, and tin.

In particular, as the semiconductor layer, an oxide (IGZO) containing indium (In), gallium (Ga), and zinc (Zn) is preferably used.

When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In the sputtering target for forming the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. The atomic ratio of the metal elements In the sputtering target includes In: M: Zn 1:1:1, In: M: Zn 1:1:1.2, In: M: Zn 2:1:3, In: M: Zn 3:1:2, In: M: Zn 4:2:3, In: M: Zn 4:2:4.1, In: M: Zn 5:1:6, In: M: Zn 5:1:7, In: M: Zn 5:1:8, In: M: Zn 6:1:6, and In: M: Zn 5:2: 5.

The transistors included in the circuit portion 303, the circuit portion 304a, and the circuit portion 304b and the transistors included in the pixel portion 302 may have the same structure or different structures. The plurality of transistors included in the circuit portion 303, the circuit portion 304a, and the circuit portion 304b may have the same configuration or two or more different configurations. Similarly, the plurality of transistors included in the pixel portion 302 may have the same structure or two or more different structures.

An end portion of the first electrode 313 is covered with an insulating layer 314. As the insulating layer 314, an organic compound such as a negative photosensitive resin or a positive photosensitive resin (acrylic resin) or an inorganic compound such as silicon oxide, silicon oxynitride, or silicon nitride can be used. The upper or lower end of the insulating layer 314 preferably has a curved surface with curvature. This makes it possible to provide a film formed over the insulating layer 314 with good coverage.

An EL layer 315 is provided over the first electrode 313, and a second electrode 316 is provided over the EL layer 315. The EL layer 315 includes a light-emitting layer, a hole-injecting layer, a hole-transporting layer, an electron-injecting layer, a charge-generating layer, and the like.

The plurality of transistors and the plurality of organic EL devices 317 are sealed by the first substrate 301, the second substrate 306, and the sealant 305. The space 318 surrounded by the first substrate 301, the second substrate 306, and the sealant 305 may also be filled with an inert gas (nitrogen, argon, or the like) or an organic substance (including the sealant 305).

An epoxy-based resin or glass frit may be used as the sealant 305. As the sealing agent 305, a material which does not transmit moisture or oxygen as much as possible is preferably used. In the case where glass frit is used as a sealant, a glass substrate is preferably used for the first substrate 301 and the second substrate 306 in view of adhesiveness.

This embodiment mode can be combined with other embodiment modes as appropriate.

(embodiment mode 3)

In this embodiment, an electronic device in which a light-emitting device according to one embodiment of the present invention can be used will be described with reference to fig. 5.

Fig. 5A shows a biometric system for finger veins, which includes a housing 911, a light source 912, a detection stage 913, and the like. By placing a finger on the test table 913, the vein shape can be photographed. A light source 912 that emits near-infrared light is provided above the inspection stage 913, and an imaging device 914 is provided below the inspection stage 913. The detection stage 913 is made of a material that transmits near infrared light, and can capture near infrared light irradiated from the light source 912 and transmitted through the finger by the imaging device 914. Further, an optical system may be provided between the inspection stage 913 and the imaging device 914. The above-described configuration of the apparatus can also be used for a biometric system targeting a palm vein.

A light-emitting device of one embodiment of the present invention can be used for the light source 912. The light emitting device according to one embodiment of the present invention can be provided in a curved shape, and can irradiate light to an object with high uniformity. In particular, a light-emitting device that emits near-infrared light having the strongest peak intensity in wavelengths of 760nm or more and 900nm or less is preferable. The vein position can be detected by receiving light transmitted through a finger, a palm, or the like and imaging the light. This effect is used as a biological recognition. In addition, by combining with the global shutter method, even if the object moves, it is possible to perform detection with high accuracy.

The light source 912 may include a plurality of light-emitting portions such as the light-emitting portions 915, 916, and 917 shown in fig. 5B. The light emitting sections 915, 916, 917 may each emit light having a different wavelength. The light emitting sections 915, 916, and 917 may emit light at different timings. Therefore, different images can be continuously captured by changing the wavelength or angle of the illumination light, and a plurality of images can be used for recognition to achieve high security.

Fig. 5C shows a biometric system for a palm vein, which includes a housing 921, an operation button 922, a detection unit 923, a light source 924 that emits near-infrared light, and the like. By brushing the hand on the detection unit 923, the shape of the palm vein can be detected. In addition, a password or the like may be input using the operation buttons. A light source 924 is disposed around the detector 923 to irradiate the object (palm) with light. Then, the light reflected by the object enters the detection unit 923. A light-emitting device according to one embodiment of the present invention can be used for the light source 924. The imaging device 925 is disposed directly below the detection unit 923, and can capture an image of an object (a whole palm). Further, an optical system may be provided between the detection unit 923 and the imaging device 925. The above-described machine structure can also be used for a biometric recognition system targeting a finger vein.

Fig. 5D is a nondestructive inspection apparatus including a frame body 931, an operation panel 932, a transport mechanism 933, a display 934, an inspection unit 935, a light source 938 that emits near-infrared light, and the like. A light-emitting device of one embodiment of the present invention can be used for the light source 938. The detection member 936 is conveyed by the conveying mechanism 933 right under the detection unit 935. Near-infrared light is irradiated from the light source 938 to the detection member 936, and the transmitted light is captured by the imaging device 937 provided in the detection unit 935. The captured image is displayed on the display 934. Then, the inspected member 936 is conveyed to the outlet of the frame 931, and defective products are sorted and recovered. By performing imaging using near-infrared light, defective elements such as defects and foreign matter in the member to be detected can be detected at high speed without loss.

Fig. 5E shows a mobile phone including a housing 981, a display portion 982, operation buttons 983, an external connection interface 984, a speaker 985, a microphone 986, a first camera 987, a second camera 988, and the like. The mobile phone includes a touch sensor in the display portion 982. The housing 981 and the display portion 982 have flexibility. Various operations such as making a call or inputting characters can be performed by touching the display portion 982 with a finger, a stylus, or the like. A visible light image may be acquired by the first camera 987 and an infrared light image (near infrared light image) may be acquired by the second camera 988. A mobile phone or a display portion 982 shown in fig. 5E may include a light-emitting device according to one embodiment of the present invention.

This embodiment mode can be combined with other embodiment modes as appropriate.

[ example 1]

In this embodiment, a structure, a manufacturing method, and characteristics of a light-emitting device 1 according to one embodiment of the present invention will be described with reference to fig. 6 and 8 to 13.

The light-emitting device 1 manufactured in the present embodiment includes an intermediate layer 816, a light-emitting unit 802a, a light-emitting unit 802b, an electrode 801, and an electrode 803, and has a function of emitting light (refer to fig. 6).

The intermediate layer 816 has a region sandwiched between the light-emitting cells 802a and 802b, and the intermediate layer 816 has a function of supplying electrons to one of the light-emitting cells 802a and 802b and supplying holes to the other of the light-emitting cells 802a and 802 b.

The light emitting cell 802a has a region sandwiched between the electrode 801 and the interlayer 816, and the light emitting cell 802a includes a light emitting layer 813 a. In addition, the light emitting layer 813a contains a first light emitting material. Bis {4, 6-dimethyl-2- [3- (3, 5-dimethylphenyl) -2-benzo [ g ]]Quinoxaline-kappa N]Phenyl- κ C } (2,2,6, 6-tetramethyl-3, 5-heptanedione- κ)²O, O') iridium (III) (abbreviation: [ Ir (dmdpbq)₂(dpm)]) (structural formula (100)) is used for the first light-emitting material. [ Ir (dmdpbq)2(dpm) will be explained in reference examples]Example of synthesis of (1).

The light-emitting unit 802b has a region sandwiched between the intermediate layer 816 and the electrode 803, and the light-emitting unit 802b includes a light-emitting layer 813 b. In addition, the light-emitting layer 813b also contains a first light-emitting material. The distance D1 is between the light emitting layer 813b and the light emitting layer 813 a. The distance D1 is 5nm or more and 65nm or less. In the light-emitting device 1, the distance D1 was (15+0.1+5+10) nm — 30.1nm (see table 1).

The maximum of the spectrum of the light emitted by the fabricated light-emitting device 1 is located at the wavelength of 802nm (refer to fig. 13). (6.3X 10)^-3) X 802nm is 5.05nm, and (81.3X 10)^-3) X 802nm is 65.2 nm. Therefore, the distance D1(═ 30.1nm) is included in the range of 5.05nm or more and 65.2nm or less.

The electrode 801 has a higher reflectance at a wavelength of 802nm than the electrode 803. The electrode 803 has a higher transmittance at a wavelength of 802nm than the electrode 801, and transmits a part of light and reflects another part of light.

Electrode 803 has a distance D2 from electrode 801. The value obtained by multiplying the distance D2 by 1.8 is included in the range of 0.3 times or more and 0.6 times or less the wavelength 802 nm. The light-emitting device 1 includes a reflective first film, and a conductive film having light-transmitting properties is interposed between the reflective first film and the light-emitting layer 813 a. Specifically, an alloy (Ag — Pd — Cu) (APC)) film of silver (Ag), palladium (Pd), and copper (Cu) is included, and the APC film and the light-emitting layer 813a sandwich 10nm of ITSO. In this structure, the distance D2 is (10+20+20+15+15+0.1+5+10+15+20+45+1) nm — 176.1 nm. Therefore, the value obtained by multiplying the distance D2(═ 176.1nm) by 1.8 is (1.8 × 176.1 ═ 316.98nm, and this value is included in the range of (0.3 × 802 ═)240.6nm or more and (0.6 × 802 ═)481.2nm or less.

In addition, the first luminescent material exhibits its emission spectrum in solution at a wavelength PL1 which is at its maximum, with a difference of 100nm or less between the wavelength EL1 and the second wavelength PL 1.

For the first light-emitting material [ Ir (dmdpbq)₂(dpm)]The emission spectrum was exhibited in a dichloromethane solution with the maximum wavelength being 807nm (see FIG. 28). Therefore, there is a difference of 5nm between the maximum wavelength 802nm in the spectrum of the light emitted by the light emitting device 1 and the maximum wavelength 807nm of the emission spectrum of the first light emitting material observed in the solution.

Table 1 shows a specific structure of the light emitting device 1. In addition, the chemical formula of the material used in this example is shown below.

[ Table 1]

*2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)₂(dpm)](0.7:0.3:0.1 15nm)

[ chemical formula 1]

< production of light-emitting device 1 >)

As shown in fig. 6, the light emitting device 1 shown in the present embodiment has the following structure: a first electrode 801 is formed over the substrate 800, a light-emitting unit 802a (a hole injection layer 811a, a hole transport layer 812a, a light-emitting layer 813a, an electron transport layer 814a, and an electron injection layer 815a), an intermediate layer 816, and a light-emitting unit 802b (a hole transport layer 812b, a light-emitting layer 813b, an electron transport layer 814b, and an electron injection layer 815b) are sequentially stacked over the first electrode 801, and a second electrode 803 is stacked over the light-emitting unit 802 b.

First, a first electrode 801 is formed over a substrate 800. The electrode area is 4mm²(2 mm. times.2 mm). A glass substrate is used as the substrate 800. The first electrode 801 is formed by the following method: first, an alloy film (Ag — Pd — Cu (apc) film) of silver (Ag), palladium (Pd), and copper (Cu) was formed in a thickness of 100nm by a sputtering method, and then an ITSO film was formed in a thickness of 10nm by a sputtering method. Note that in this embodiment, the first electrode 801 is used as an anode.

Here, as the pretreatment, the surface of the substrate was washed with water, baked at 200 ℃ for 1 hour, and then subjected to UV ozone treatment for 370 seconds. Thereafter, the substrate is introduced into the interior thereof and depressurized to 10^-4In a vacuum deposition apparatus of about Pa, vacuum baking was performed at a temperature of 170 ℃ for 30 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

Next, a hole injection layer 811a is formed over the first electrode 801. Is decompressed to 10 degrees in the vacuum evaporation device^-4After Pa, 1,3, 5-tris (dibenzothiophen-4-yl) benzene (abbreviated as DBT3P-II) and molybdenum oxide were co-evaporated at a ratio of DBT3P-II to 2:1 (weight ratio) and a thickness of 20nm to form a hole injection layer 811 a.

Next, a hole transporting layer 812a is formed on the hole injecting layer 811 a. The hole transport layer 812a was formed by co-evaporation using N- (1, 1' -biphenyl-4-yl) -N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] -9, 9-dimethyl-9H-fluoren-2-amine (PCBBiF for short) to a thickness of 20 nm.

Next, a light-emitting layer 813a is formed over the hole-transporting layer 812 a. 2- [ 3' - (dibenzothiophen-4-yl) biphenyl-3-yl as host material]Dibenzo [ f, h ]]Quinoxaline (abbreviated as 2mDBTBPDBq-II), PCBBiF as an auxiliary material and bis {4, 6-dimethyl-2- [3- (3, 5-dimethylphenyl) -2-benzo [ g ] as a guest material (phosphorescent material)]Quinoxaline-kappa N]Phenyl- κ C } (2,2,6, 6-tetramethyl-3, 5-heptanedione- κ)²O, O') iridium (III) (abbreviation: [ Ir (dmdpbq)₂(dpm)]) (structural formula (100)) 2mDBTBPDBq-II PCBBiF [ Ir (dmdpbq) ]₂(dpm)]Co-evaporation was performed in a ratio of 0.7:0.3: 0.1. Here, the thickness thereof was set to 15 nm.

Next, an electron transporting layer 814a is formed over the light emitting layer 813 a. The electron transport layer 814a was formed by sequentially evaporating 2, 9-bis (naphthalene-2-yl) -4, 7-diphenyl-1, 10-phenanthroline (NBphen for short) to a thickness of 15 nm.

Next, an electron injection layer 815a is formed on the electron transport layer 814 a. The electron injection layer 815a was formed by depositing lithium oxide (Li) to a thickness of 0.1nm by vapor deposition₂O) is formed.

Next, an intermediate layer 816 is formed on the electron injection layer 815 a. DBT3P-II and molybdenum oxide were co-evaporated at a thickness of 5nm with DBT3P-II: 2:1 (weight ratio) to form the intermediate layer 816.

Next, a hole transport layer 812b is formed on the intermediate layer 816. The hole transport layer 812b was formed by evaporation using PCBBiF so as to have a thickness of 10 nm.

Next, a light-emitting layer 813b is formed over the hole-transporting layer 812 b. 2mDBTBPDBq-II was used as a host material, PCBBiF was used as an auxiliary material, and [ Ir (dmdpbq) was used as a guest material₂(dpm)]The weight ratio of the two components is 2mDBTBPDBq-II to PCBBiF: [ Ir (dmdpbq) ]₂(dpm)]Co-evaporation was performed at a ratio of 0.7:0.3: 0.1. Here, the thickness thereof was set to 15 nm.

Next, an electron transporting layer 814b is formed over the light emitting layer 813 b. The electron transport layer 814b was formed by sequentially evaporating 2mDBTBPDBq-II and NBphen to a thickness of 20nm and 45nm, respectively.

Next, an electron injection layer 815b is formed on the electron transport layer 814 b. The electron injection layer 815b is formed by evaporating lithium fluoride (LiF) to have a thickness of 1 nm.

Next, a second electrode 803 is formed over the electron injection layer 815 b. Silver (Ag) and magnesium (Mg) were co-evaporated so that Ag: Mg was 10:1 (volume ratio) and the thickness was 30nm, to form the second electrode 803. In the present embodiment, the second electrode 803 is used as a cathode.

Next, a buffer layer 804 is formed over the second electrode 803. The buffer layer 804 was formed by evaporating DBT3P-II to a thickness of 100 nm.

The light-emitting device 1 is formed on the substrate 800 by the above-described procedure. In the vapor deposition process of the above-described manufacturing method, vapor deposition is performed by a resistance heating method.

In addition, the light emitting device manufactured as described above is sealed with another substrate (not shown). When sealing is performed using another substrate (not shown), another substrate (not shown) to which an adhesive agent that is cured by ultraviolet light is applied is fixed to the substrate 800 in a glove box in a nitrogen atmosphere, and the substrates are bonded to each other so that the adhesive agent adheres to the periphery of the light-emitting device formed over the substrate 800. At 6J/cm when sealing²The adhesive was cured by irradiation with 365nm ultraviolet light, and heat treatment was performed at 80 ℃ for 1 hour, thereby stabilizing the adhesive.

In addition, the light emitting device 1 employs a microcavity resonator structure. The light-emitting element 1 was fabricated such that the optical distance between the pair of reflective electrodes (APC film and Ag: Mg film) was about 1/2 wavelengths from the maximum peak wavelength of light emission of the guest material.

< operating characteristics of light emitting device 1 >)

The operating characteristics of the light emitting device 1 were measured. Note that the measurement was performed at room temperature (atmosphere maintained at 25 ℃).

Fig. 8 shows the current density-radiance characteristics of the light-emitting device 1. Fig. 9 shows the voltage-current density characteristics of the light emitting device 1. Fig. 10 shows the current density-radiant flux characteristics of the light emitting device 1. Fig. 11 shows the voltage-emittance characteristics of the light-emitting device 1. Fig. 12 shows the current density-external quantum efficiency characteristics of the light-emitting device 1. Note that assuming that the light distribution characteristics of the light emitting device are of the lambert type, the radiance, radiant flux, and external quantum efficiency are calculated using the radiant luminance.

Table 2 shows 8.9W/sr/m²The main initial characteristic values of the nearby light emitting devices 1.

[ Table 2]

As shown in fig. 8 to 12 and table 2, it is understood that the light-emitting device 1 exhibits excellent characteristics. For example, the light-emitting device 1 emits light with a higher radiance than the light-emitting devices 2 and 3 described later under the same current density. In addition, for example, the light-emitting device 1 has higher external quantum efficiency than the light-emitting devices 2 and 3 under the same current density condition. In addition, for example, the driving voltage of the light emitting device 1 is lower than that of the light emitting device 3 under the condition of the same current density.

In addition, FIG. 13 shows the current at 10mA/cm²The current density of (a) causes an emission spectrum when a current flows through the light emitting device 1. The measurement of the emission spectrum was performed using a near infrared spectroscopic radiance meter (SR-NIR, manufactured by Topukang Co., Ltd.). As shown in FIG. 13, the light-emitting device 3 exhibited an emission spectrum having a maximum peak at around 802nm, which was derived from [ Ir (dmdpbq) ] included in the light-emitting layer 813a and the light-emitting layer 831b₂(dpm)]。

In addition, the emission spectrum is narrowed due to the adoption of the microcavity resonator structure, and the half-width thereof is shown as 35 nm. The light-emitting device 1 efficiently emits light of 760nm or more and 900nm or less, and therefore can be said to have a high effect as a light source for a sensor or the like.

(reference example 1)

In this reference example, the structure, the manufacturing method, and the characteristics of the manufactured light-emitting device 2 are described using fig. 7A and fig. 14 to 19.

The light-emitting device 2 manufactured in the present reference example includes a light-emitting unit 802, an electrode 801, and an electrode 803, and has a function of emitting light (refer to fig. 7). Note that the light emitting device 2 is different from the light emitting device 1 in that: the number of the light emitting units is one.

The light-emitting unit 802 has a region sandwiched between the electrode 801 and the electrode 803, and the light-emitting unit 802 includes a light-emitting layer 813. In addition, the light emitting layer 813 contains a first light emitting material. Will [ Ir (dmdpbq)₂(dpm)]For the first luminescent material.

The maximum of the spectrum of the light emitted by the fabricated light-emitting device 2 was located at the wavelength 798nm (refer to fig. 19).

Table 3 shows a specific structure of the light emitting device 2.

[ Table 3]

*2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)₂(dpm)](0.7:0.3:0.1 40nm)

< production of light-emitting device 2 >)

As shown in fig. 7A, the light emitting device 2 shown in the present embodiment has the following structure: a first electrode 801 is formed over the substrate 800, a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked over the first electrode 801, and a second electrode 803 is stacked over the electron injection layer 815.

First, a first electrode 801 is formed over a substrate 800. The electrode area is 4mm²(2 mm. times.2 mm). A glass substrate is used as the substrate 800. In addition, the first electrode 801 is formed by the following method: first, an alloy film (Ag — Pd — Cu (apc) film) of silver (Ag), palladium (Pd), and copper (Cu) was formed in a thickness of 100nm by a sputtering method, and then an ITSO film was formed in a thickness of 10nm by a sputtering method. Note that in this embodiment, the first electrode 801 is used as an anode.

Here, as the pretreatment, the surface of the substrate was washed with water, baked at 200 ℃ for 1 hour, and then subjected to UV ozone treatment for 370 seconds. Thereafter, the substrate is introduced into the interior thereof and depressurized to 10^-4In a vacuum deposition apparatus of about Pa, vacuum baking was performed at a temperature of 170 ℃ for 30 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

Next, a hole injection layer 811 is formed over the first electrode 801. Is decompressed to 10 degrees in the vacuum evaporation device^-4After Pa, DBT3P-II and molybdenum oxide were co-evaporated at a thickness of 25nm so that DBT3P-II and molybdenum oxide were 2:1 (weight ratio), to form a hole injection layer 811.

Next, a hole transport layer 812 is formed on the hole injection layer 811. The hole transport layer 812 was formed by evaporation using PCBBiF so as to have a thickness of 20 nm.

Next, a light-emitting layer 813 is formed over the hole-transporting layer 812. 2mDBTBPDBq-II was used as a host material, PCBBiF was used as an auxiliary material, and [ Ir (dmdpbq) was used as a guest material₂(dpm)]The weight ratio of the two components is 2mDBTBPDBq-II to PCBBiF: [ Ir (dmdpbq) ]₂(dpm)]Co-evaporation was performed at a ratio of 0.7:0.3: 0.1. Here, the thickness thereof was set to 40 nm.

Next, an electron transporting layer 814 is formed over the light emitting layer 813. The electron transport layer 814 was formed by sequentially evaporating 2mDBTBPDBq-II and NBphen to a thickness of 20nm and 75nm, respectively.

Next, an electron injection layer 815 is formed on the electron transport layer 814. The electron injection layer 815 is formed by evaporating lithium fluoride (LiF) to a thickness of 1 nm.

Next, a second electrode 803 is formed over the electron injection layer 815. Silver (Ag) and magnesium (Mg) were co-evaporated so that Ag: Mg was 10:1 (volume ratio) and the thickness was 30nm, to form the second electrode 803. In the present embodiment, the second electrode 803 is used as a cathode.

Next, a buffer layer 804 is formed over the second electrode 803. The buffer layer 804 was formed by evaporating DBT3P-II to a thickness of 100 nm.

The light emitting device 2 is formed on the substrate 800 through the above-described processes. In the vapor deposition process of the above-described manufacturing method, vapor deposition is performed by a resistance heating method.

In addition, the light emitting device 2 is sealed with another substrate (not shown). The sealing method is the same as that of the light emitting device 1, and reference can be made to example 1.

< operating characteristics of light emitting device 2 >)

The operating characteristics of the light emitting device 2 were measured. Note that the measurement was performed at room temperature (atmosphere maintained at 25 ℃).

Fig. 14 shows the current density-radiance characteristics of the light-emitting device 2. Fig. 15 shows the voltage-current density characteristics of the light emitting device 2. Fig. 16 shows the current density-radiant flux characteristics of the light-emitting device 2. Fig. 17 shows the voltage-emittance characteristics of the light-emitting device 2. Fig. 18 shows the current density-external quantum efficiency characteristics of the light-emitting device 2. Note that assuming that the light distribution characteristics of the light emitting device are of the lambert type, the radiance, radiant flux, and external quantum efficiency are calculated using the radiant luminance.

Table 4 shows 4.9W/sr/m²The main initial characteristic values of the nearby light emitting devices 2.

[ Table 4]

In addition, FIG. 19 shows the current at 10mA/cm²The current density of (a) makes the emission spectrum when a current flows through the light emitting device 2. The measurement of the emission spectrum was performed using a near infrared spectroscopic radiance meter (SR-NIR, manufactured by Topukang Co., Ltd.).

(reference example 2)

In this reference example, the structure, the manufacturing method, and the characteristics of the manufactured light-emitting device 3 are described using fig. 7B and fig. 20 to 25.

The light-emitting device 3 manufactured in the present reference example includes an intermediate layer 816, a light-emitting unit 802a, a light-emitting unit 802B, an electrode 801, and an electrode 803, and has a function of emitting light (refer to fig. 7B). The light emitting device 3 is different from the light emitting device 1 in that: the distance between the light emitting layer 813b and the light emitting layer 813a is longer than that of the light emitting device 1. In addition, the light emitting device 3 is different from the light emitting device 1 in that: the distance between the electrode 801 and the electrode 803 is longer than that of the light emitting device 1.

The intermediate layer 816 has a region sandwiched between the light-emitting cells 802a and 802b, and the intermediate layer 816 has a function of supplying electrons to one of the light-emitting cells 802a and 802b and supplying holes to the other of the light-emitting cells 802a and 802 b.

The light emitting cell 802a has a region sandwiched between the electrode 801 and the interlayer 816, and the light emitting cell 802a includes a light emitting layer 813 a. In addition, the light emitting layer 813a contains a first light emitting material.

The light-emitting unit 802b has a region sandwiched between the intermediate layer 816 and the electrode 803, and the light-emitting unit 802b includes a light-emitting layer 813 b. In addition, the light-emitting layer 813b also contains a first light-emitting material. The distance D1 is between the light emitting layer 813b and the light emitting layer 813 a. In the light-emitting device 3, the distance D1 was (20+90+0.1+2+10+60) nm 182.1nm (see table 5).

The maximum of the spectrum of the light emitted by the fabricated light-emitting device 2 was located at the wavelength 799nm (refer to fig. 25).

The electrode 801 has a higher reflectance at the wavelength EL1 than the electrode 803. The electrode 803 has a higher transmittance at the wavelength EL1 than the electrode 801, and transmits a part of light and reflects another part of light.

Table 5 shows a specific structure of the light emitting device 3 used in the present reference example. In addition, chemical formulas of materials used in the present reference example are shown below.

[ Table 5]

*2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)₂(dpm)](0.7:0.3:0.1 40nm)

[ chemical formula 2]

< production of light-emitting device 3 >)

As shown in fig. 7B, the light emitting device 3 shown in the present embodiment has the following structure: a first electrode 801 is formed over the substrate 800, a light-emitting unit 802a (a hole injection layer 811a, a hole transport layer 812a, a light-emitting layer 813a, an electron transport layer 814a, and an electron injection layer 815a), an intermediate layer 816, and a light-emitting unit 802b (a hole injection layer 811b, a hole transport layer 812b, a light-emitting layer 813b, an electron transport layer 814b, and an electron injection layer 815b) are sequentially stacked over the first electrode 801, and a second electrode 803 is stacked over the light-emitting unit 802 b.

First, a first electrode 801 is formed over a substrate 800. The electrode area is 4mm²(2 mm. times.2 mm). A glass substrate is used as the substrate 800. In addition, the first electrode 801 is formed by the following method: first, an alloy film (Ag-Pd-Cu (APC)) of silver (Ag), palladium (Pd) and copper (Cu) was formed in a thickness of 100nm by a sputtering method, and then the sputtering method was used to form a filmAn ITSO film was formed to a thickness of 10 nm. Note that in this embodiment, the first electrode 801 is used as an anode.

Here, as the pretreatment, the surface of the substrate was washed with water, baked at 200 ℃ for 1 hour, and then subjected to UV ozone treatment for 370 seconds. Thereafter, the substrate is introduced into the interior thereof and depressurized to 10^-4In a vacuum deposition apparatus of about Pa, vacuum baking was performed at a temperature of 170 ℃ for 30 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

Next, a hole injection layer 811a is formed over the first electrode 801. Is decompressed to 10 degrees in the vacuum evaporation device^-4After Pa, DBT3P-II and molybdenum oxide were co-evaporated at a thickness of 10nm so that DBT3P-II and molybdenum oxide were 2:1 (weight ratio), to form a hole injection layer 811 a.

Next, a hole transporting layer 812a is formed on the hole injecting layer 811 a. The hole transport layer 812a was formed by co-evaporation using PCBBiF so as to have a thickness of 30 nm.

Next, a light-emitting layer 813a is formed over the hole-transporting layer 812 a. 2mDBTBPDBq-II was used as a host material, PCBBiF was used as an auxiliary material, and an organometallic complex [ Ir (dmdpbq) ] was used as a guest material (phosphorescent material)₂(dpm)]The weight ratio of the two components is 2mDBTBPDBq-II to PCBBiF: [ Ir (dmdpbq) ]₂(dpm)]Co-evaporation was performed at a ratio of 0.7:0.3: 0.1. Here, the thickness thereof was set to 40 nm.

Next, an electron transporting layer 814a is formed over the light emitting layer 813 a. The electron transport layer 814a was formed by sequentially evaporating 2mDBTBPDBq-II and NBphen to a thickness of 20nm and 90nm, respectively.

Next, an electron injection layer 815a is formed on the electron transport layer 814 a. The electron injection layer 815a was formed by depositing lithium oxide (Li) to a thickness of 0.1nm by vapor deposition₂O) is formed.

Next, an intermediate layer 816 is formed on the electron injection layer 815 a. The intermediate layer 816 was formed by vapor deposition using copper phthalocyanine (CuPc) to a thickness of 2 nm.

Next, a hole injection layer 811b is formed on the intermediate layer 816. DBT3P-II and molybdenum oxide were co-evaporated at a ratio of DBT3P-II to molybdenum oxide of 2:1 (weight ratio) and a thickness of 10nm to form a hole injection layer 811 b.

Next, a hole transporting layer 812b is formed on the hole injecting layer 811 b. The hole transport layer 812b was formed by evaporation using PCBBiF so as to have a thickness of 60 nm.

Next, a light-emitting layer 813b is formed over the hole-transporting layer 812 b. 2mDBTBPDBq-II was used as a host material, PCBBiF was used as an auxiliary material, and an organometallic complex [ Ir (dmdpbq) ] according to one embodiment of the present invention was used as a guest material (phosphorescent material)₂(dpm)]The weight ratio of the two components is 2mDBTBPDBq-II to PCBBiF: [ Ir (dmdpbq) ]₂(dpm)]Co-evaporation was performed at a ratio of 0.7:0.3: 0.1. Here, the thickness thereof was set to 40 nm.

Next, an electron transporting layer 814b is formed over the light emitting layer 813 b. The electron transport layer 814b was formed by sequentially evaporating 2mDBTBPDBq-II and NBphen to a thickness of 20nm and 65nm, respectively.

Next, an electron injection layer 815b is formed on the electron transport layer 814 b. The electron injection layer 815b is formed by evaporating lithium fluoride (LiF) to have a thickness of 1 nm.

Next, a second electrode 803 is formed over the electron injection layer 815 b. Silver (Ag) and magnesium (Mg) were co-evaporated so that Ag: Mg was 10:1 (volume ratio) and the thickness was 20nm, to form the second electrode 803. In the present embodiment, the second electrode 803 is used as a cathode.

Next, a buffer layer 804 is formed over the second electrode 803. The buffer layer 804 was formed by evaporating DBT3P-II to a thickness of 110 nm.

The light-emitting device 3 is formed on the substrate 800 by the above-described procedure. In the vapor deposition process of the above-described manufacturing method, vapor deposition is performed by a resistance heating method.

In addition, the light-emitting device 3 is sealed with another substrate (not shown). The sealing method is the same as that of the light emitting device 1, and reference can be made to example 1.

In addition, the light emitting device 3 employs a microcavity resonator structure. The light-emitting device 3 was fabricated in such a manner that the optical distance between the pair of reflective electrodes (APC film and Ag: Mg film) was about 1 wavelength with respect to the maximum peak wavelength of light emission of the guest material.

< operating characteristics of light emitting device 3 >)

The operating characteristics of the light emitting device 3 were measured. Note that the measurement was performed at room temperature (atmosphere maintained at 25 ℃).

Fig. 20 shows the current density-radiance characteristics of the light-emitting device 3. Fig. 21 shows the voltage-current density characteristics of the light emitting device 3. Fig. 22 shows the current density-radiant flux characteristics of the light-emitting device 3. Fig. 23 shows the voltage-emittance characteristics of the light-emitting device 3. Fig. 24 shows the current density-external quantum efficiency characteristics of the light-emitting device 3. Note that assuming that the light distribution characteristics of the light emitting device are of the lambert type, the radiance, radiant flux, and external quantum efficiency are calculated using the radiant luminance.

Table 6 shows 6.8W/sr/m²The main initial characteristic values of the nearby light emitting devices 3.

[ Table 6]

In addition, FIG. 25 shows the current at 10mA/cm²The current density of (a) makes the emission spectrum when a current flows through the light emitting device 3. The measurement of the emission spectrum was performed using a near infrared spectroscopic radiance meter (SR-NIR, manufactured by Topukang Co., Ltd.).

[ example 2]

In this embodiment, the structures of the light emitting devices 11 to 20, calculation using calculated values, and calculation results according to one embodiment of the present invention will be described with reference to fig. 26 and 27.

Fig. 26 is a diagram illustrating the structures of a light-emitting device according to an embodiment of the present invention and a device according to a reference example.

Fig. 27 is a diagram illustrating calculation results of a light-emitting device according to an embodiment of the present invention and a device according to a reference example. Specifically, a diagram showing how the external quantum efficiency changes depending on the distance D1 between two light-emitting layers will be described.

< structural example of light emitting device >

A light-emitting device according to one embodiment of the present invention includes an intermediate layer 104, a light-emitting unit 103a, a light-emitting unit 103b, an electrode 101, and an electrode 102, and has a function of emitting light (see fig. 26).

The intermediate layer 104 has a function of supplying electrons to one of the light emitting unit 103a and the light emitting unit 103b and supplying holes to the other of the light emitting unit 103a and the light emitting unit 103 b.

< light-emitting layer 113a >)

The light emitting unit 103a has a region sandwiched between the electrode 101 and the intermediate layer 104. The light emitting unit 103a includes a light emitting layer 113a, and the light emitting layer 113a contains a first light emitting material. In this embodiment, the thickness of the light-emitting layer 113a was set to 10nm, and [ ir (dmdpbq)2(dpm) ] was used for the first light-emitting material.

< light-emitting layer 113b >)

The light emitting unit 103b has a region sandwiched between the intermediate layer 104 and the electrode 102. The light emitting unit 103b includes a light emitting layer 113b, and the light emitting layer 113b contains a second light emitting material. In this embodiment, the thickness of the light-emitting layer 113b is set to 10nm, and the same material as the first light-emitting material is used for the second light-emitting material.

A light-emitting device of one mode of the present invention emits light exhibiting a spectrum whose maximum is located at a wavelength EL 1. In the present embodiment, light exhibiting a spectrum whose maximum is located in the vicinity of 800nm is emitted.

< electrode 101 >)

The electrode 101 has a higher reflectance at the wavelength EL1 than the electrode 102. In the present embodiment, silver having a thickness of 100nm is used for the electrode 101.

< < electrode 102 >)

The electrode 102 has a higher transmittance at the wavelength EL1 than the electrode 101. The electrode 102 transmits a part of light at the wavelength EL1 and reflects another part of light. In the present embodiment, silver having a thickness of about 30nm is used for the electrode 102. In addition, a light-emitting device according to one embodiment of the present invention includes a protective layer 105 having a thickness of about 100 nm. The protective layer 105 is in contact with the electrode 102.

In addition, there is a distance D2 between electrode 102 and electrode 101. The value obtained by multiplying the distance D2 by 1.8 is included in the range of 0.3 times or more and 0.6 times or less of the wavelength EL 1. In the present embodiment, the distance D2 is a distance in the range of 134nm to 266 nm.

The light-emitting layer 113b is spaced apart from the light-emitting layer 113a by a distance D1. In the present embodiment, the distance D1 is a distance in the range of 10nm to 90 nm.

Specifically, 10nm is used as the distance D1 of the light emitting device 12, 20nm is used as the distance D1 of the light emitting device 13, 30nm is used as the distance D1 of the light emitting device 14, 40nm is used as the distance D1 of the light emitting device 15, 50nm is used as the distance D1 of the light emitting device 16, 60nm is used as the distance D1 of the light emitting device 17, 70nm is used as the distance D1 of the light emitting device 18, 80nm is used as the distance D1 of the light emitting device 19, and 90nm is used as the distance D1 of the light emitting device 20.

Further, the light-emitting layer 113a is spaced apart from the electrode 101 by a distance D33. Further, the light-emitting layer 113b is spaced apart from the electrode 102 by a distance D34.

The distance D33, the distance D34, the thickness of the electrode 102, and the thickness of the protective layer 105 at each distance D1 were optimized by a computer. This compares the magnitude of the efficiency of light extraction from the light-emitting device at the respective distances D1.

< calculation method >)

In this example, a calculation was performed using an organic device simulator (manufactured by chemical simulation of film optics simulator: setfos; CYBERNET SYSTEMS co., ltd.).

In this calculation, the thickness, refractive index n, extinction coefficient k, measured value of the emission spectrum (photoluminescence (PL) spectrum) of the light-emitting material, and the emission position of each layer constituting the light-emitting device are input, and multiplied by Purcell factor, and the emission intensity and peak waveform in the front direction in consideration of the radioactive decay rate modulation of excitons are calculated.

The refractive index n of each layer is assumed to be 1.8 and the extinction coefficient k is assumed to be 0. As the value of silver (Ag) used for the reflective electrode and the semi-reflective electrode, the values described in pages 355-356 of Handbook of Optical Constants of Solids Volume 1 are referred to.

In the measurement of the emission spectrum of the light-emitting material, a near-infrared spectral radiance meter (SR-NIR, manufactured by topotecan) was used as a detector, an ultraviolet light-emitting LED (NSCU 033B manufactured by japan chemical industries co., ltd.) was used as excitation light, UV U360 (manufactured by armont optics ltd.) was used as a band-pass filter, and SCF-50S-42L (manufactured by sigma optical co., ltd.) was used as a high-pass filter.

In the measurement of the emission spectrum of infrared light, a thin film obtained by co-evaporation using a vacuum evaporation method was formed on a quartz substrate using 2 mDBTBDBBq-II, PCBBiF and bis {4, 6-dimethyl-2- [3- (3, 5-dimethylphenyl) -2-benzo [ g ] quinoxalinyl- κ N ] phenyl- κ C } (2,2,6, 6-tetramethyl-3, 5-heptanedione- κ 2O, O') iridium (III) (abbreviated as: [ Ir (dmdpbq)2(dpm) ]) in a weight ratio of 0.7:0.3:0.1 and a thickness of 50 nm.

Fig. 29 shows an emission spectrum used for the calculation. In fig. 29, the horizontal axis represents wavelength (unit: nm) and the vertical axis represents normalized intensity (arbitrary unit: a.u.) based on energy.

The light emitting position is assumed to be the center of the light emitting layer.

The luminescence quantum yield, exciton generation probability, and recombination probability were assumed to be 100%. That is, the external quantum efficiency (lambertian assumption) obtained by calculation represents the light extraction efficiency calculated from the front emission intensity assumed lambertian radiation.

In the calculation, the thickness close to the value of the target optical distance is input, and the thicknesses of the hole transport layer, the electron transport layer, the semi-reflective electrode, and the protective layer when the external quantum efficiency (lambertian assumption) is maximum are calculated.

The thickness of the intermediate layer was also calculated for devices having an optical distance between electrodes in the vicinity of λ.

< results >

Table 7, table 8, and fig. 27 show the calculation results. The light-emitting device of one embodiment of the present invention emits light with higher efficiency than the light-emitting device 21 of reference example 3 described later in the case where the distance D1 is 5nm or more and 65nm or less.

[ Table 7]

	Device 12	Device 13	Device 14	Device 15	Device 16
						Protective layer 105	106nm	106nm	105nm	105nm	105nm
Electrode 102	31nm	31nm	31nm	31nm	31nm
						Distance D34	84nm	79nm	74nm	69nm	64nm
Distance D1	10nm	20nm	30nm	40nm	50nm
						Distance D33	79nm	74nm	69nm	64nm	60nm
Maximum EL1	793nm	794nm	794nm	795nm	795nm
						External quantum efficiency	1.38	1.35	1.3	1.24	1.17

[ Table 8]

	Device 17	Device 18	Device 19	Device 20	Device 21
						Protective layer 105	102nm	104nm	104nm	101nm	113nm
Electrode 102	32nm	32nm	32nm	32nm	25nm
						Distance D34	58nm	33nm	47nm	42nm	92nm
Distance D1	60nm	70nm	80nm	90nm	193nm
						Distance D33	55nm	51nm	47nm	43nm	90nm
Maximum EL1	796nm	796nm	797nm	798nm	797nm
						External quantum efficiency	1.09	1.01	0.91	0.80	1.03

(reference example 3)

A value obtained by multiplying the distance D2(395nm ═ 90+10+193+10+92) by 1.8 in the light-emitting device 21 of the reference example is 0.89 times the maximum wavelength 797nm in the spectrum of the emitted light, and this value is not included in the range of 0.3 times or more and 0.6 times or less the maximum wavelength, which is different from the light-emitting device of one embodiment of the present invention.

(Synthesis example 1)

In this example, a method for synthesizing an organometallic complex according to an embodiment of the present invention will be described. In this example, a description will be given of bis {4, 6-dimethyl-2- [3- (3, 5-dimethylphenyl) -2-benzo [ g ] represented by the structural formula (100) of embodiment 1]Quinoxalinyl-kappa N]Phenyl- κ C } (2,2,6, 6-tetramethyl-3, 5-heptanedione- κ)²O, O') iridium (III) (abbreviation: [ Ir (dmdpbq)₂(dpm)]) The method of (1).

[ chemical formula 3]

< step 1: synthesis of 2, 3-bis (3, 5-dimethylphenyl) -2-benzo [ g ] quinoxaline (abbreviation: Hdmdpbq) >

First, an organic compound Hdmdpbq according to one embodiment of the present invention represented by structural formula (200) is synthesized in step 1. 3.20g of 3, 3', 5, 5' -tetramethylbenzil, 1.97g of 2, 3-diaminonaphthalene and 60mL of ethanol were placed in a three-necked flask equipped with a reflux tube, the air in the flask was replaced with nitrogen gas, and then the mixture was stirred at 90 ℃ for 7 hours. After a predetermined time, the solvent was distilled off. Then, the reaction mixture was purified by silica gel column chromatography using toluene as a developing solvent to obtain the objective compound (yellow solid, yield 3.73g, yield 79%). The synthesis scheme of step 1 is shown below in (a-1).

[ chemical formula 4]

The following shows the use of nuclear magnetic resonance method (¹H-NMR) results of analyzing the yellow solid obtained by the above step 1. From this, it was found that Hdmdpbq represented by the structural formula (200) was obtained in this example.

Of the resulting material¹The H NMR data are as follows:

¹H-NMR.δ(CD₂Cl₂)：2.28(s,12H),7.01(s,2H),7.16(s,4H),7.56-7.58(m,2H),8.11-8.13(m,2H),8.74(s,2H).

<step 2: di-mu-chloro-tetrakis {4, 6-dimethyl-2- [3- (3, 5-dimethylphenyl) -2-benzo [ g ]]Quinoxalinyl-kappa N]Phenyl-. kappa.C } diiridium (III) (abbreviation: [ Ir (dmdpbq))₂Cl]₂) Synthesis of (2)>

Then, in step 2, a binuclear complex [ Ir (dmdpbq) ] of one embodiment of the present invention represented by the structural formula (210) was synthesized₂Cl]₂. Then, 15mL of 2-ethoxyethanol and 5mL ofWater, 1.81g of Hdmdpbq obtained in step 1 and 0.66g of iridium chloride hydrate (IrCl)₃·H₂O) (manufactured by japan koku metal corporation) was placed in an eggplant type flask equipped with a reflux tube, and the air in the flask was replaced with argon gas. Then, the reaction was induced by irradiating microwave (2.45GHz, 100W) for 2 hours. After a predetermined period of time had elapsed, the obtained residue was suction-filtered with methanol and washed, whereby the objective compound (black solid, yield 1.76g, yield 81%) was obtained. The synthesis scheme of step 2 is shown below in (a-2).

[ chemical formula 5]

<And step 3: [ Ir (dmdpbq)₂(dpm)]Synthesis of (2)>

Then, an organometallic complex [ Ir (dmdpbq) ] represented by the structural formula (100) according to one embodiment of the present invention was synthesized in step 3₂(dpm)].20 mL of 2-ethoxyethanol, 1.75g of [ Ir (dmdpbq) ] obtained by the step 2₂Cl]₂0.50g of di-tert-valerylmethane (abbreviated as Hdpm) and 0.95g of sodium carbonate were put in an eggplant-shaped flask equipped with a reflux tube, and the atmosphere in the flask was replaced with argon gas. Then, the microwave (2.45GHz, 100W) was irradiated for 3 hours. The obtained residue was subjected to suction filtration using methanol, and then washed with water and methanol. The obtained solid was purified by silica gel column chromatography using methylene chloride as a developing solvent, and then recrystallized using a mixed solvent of methylene chloride and methanol, thereby obtaining the objective compound (dark green solid, yield 0.42g, yield 21%). The resulting dark green solid, 0.41g, was purified by sublimation using a gradient sublimation process. In sublimation purification, a dark green solid was heated at 300 ℃ under a pressure of 2.7Pa and an argon gas flow rate of 10.5 mL/min. After this sublimation purification, a dark green solid was obtained in 78% yield. The synthesis scheme of step 3 is shown below in (a-3).

[ chemical formula 6]

The nuclear magnetic resonance hydrogen spectrometry of the dark green solid obtained in step 3 is shown below (¹H-NMR). As a result, in this example, [ Ir (dmdpbq) represented by the structural formula (100) was obtained₂(dpm)]。

Of the resulting material¹The H NMR data are as follows:

¹H-NMR.δ(CD₂Cl₂)：0.75(s,18H),0.97(s,6H),2.01(s,6H),2.52(s,12H),4.86(s,1H),6.39(s,2H),7.15(s,2H),7.31(s,2H),7.44-7.51(m,4H),7.80(d,2H),7.86(s,4H),8.04(d,2H),8.42(s,2H),8.58(s,2H).

next, measure [ Ir (dmdpbq) ]₂(dpm)]Ultraviolet-visible absorption spectrum (hereinafter, simply referred to as absorption spectrum) and emission spectrum in a methylene chloride solution.

In the measurement of the absorption spectrum, a methylene chloride solution (0.010mmol/L) was placed in a quartz dish using an ultraviolet-visible spectrophotometer (model V550, manufactured by Nippon Denshoku Co., Ltd.) and the measurement was performed at room temperature. In the measurement of emission spectrum, a methylene chloride deoxygenated solution (0.010mmol/L) was placed in a quartz dish under a nitrogen atmosphere using a fluorescence photometer (FS 920, manufactured by Hamamatsu photonics K.K.), sealed, and measured at room temperature.

Fig. 7 shows the measurement results of the obtained absorption spectrum and emission spectrum. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. In addition, the thin solid line in fig. 28 shows the absorption spectrum, and the thick solid line shows the emission spectrum. The absorption spectrum shown in FIG. 28 represents the result obtained by subtracting the absorption spectrum measured with dichloromethane alone placed in a quartz dish from the absorption spectrum measured with dichloromethane solution (0.010mmol/L) placed in a quartz dish.

As shown in FIG. 28, an organometallic complex [ Ir (dmdpbq) ] according to one embodiment of the present invention₂(dpm)]An emission peak was exhibited at 807nm, and near infrared light was observed from the dichloromethane solution.

This embodiment can be combined with any of the other embodiments described in this specification as appropriate.

[ example 3]

In this embodiment, a structure, a manufacturing method, and characteristics of a light-emitting device 4 according to one embodiment of the present invention will be described with reference to fig. 6 and fig. 30 to 35.

The light-emitting device 4 is different from the light-emitting device 1 described using table 1 in that: hole injection layer 811a, hole transport layer 812a, intermediate layer 816, hole transport layer 812b, and electron transport layer 814 b. Here, the difference will be described in detail, and the above description will be applied to a portion where the same structure as the above structure can be used. In the light-emitting device 4, the distance D1 was 25.1nm (see table 9) to (15+0.1+5+5) nm.

The maximum of the spectrum of the light emitted by the fabricated light-emitting device 4 is located at the wavelength 803nm (refer to fig. 35). (6.3X 10)^-3) X 803nm is 5.06nm, and (81.3X 10)^-3) X803 nm is 65.6 nm. Therefore, the distance D1(═ 25.1nm) is included in the range of 5.06nm or more and 65.6nm or less.

The light-emitting device 4 includes a reflective first film which sandwiches a conductive film having light-transmitting properties with the light-emitting layer 813 a. Specifically, an alloy (Ag — Pd — Cu) (APC)) film of silver (Ag), palladium (Pd), and copper (Cu) is included, and the APC film and the light-emitting layer 813a sandwich 10nm of ITSO. In this structure, the distance D2 is (10+10+32.5+15+15+0.1+5+5+15+20+52.5+1) nm (181.1 nm). Therefore, the value obtained by multiplying the distance D2 (181.1 nm) by 1.8 is 325.98nm (1.8 × 181.1), and is included in the range of 240.9nm or more (0.3 × 803) and 481.8nm or less (0.6 × 803).

Table 9 shows a specific structure of the light-emitting device 4.

[ Table 9]

*2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)₂(dpm)](0.7:0.3:0.1 15nm)

< production of light-emitting device 4 >)

Is decompressed to 10 degrees in the vacuum evaporation device^-4After Pa, PCBBiF and NDP-9 (analysis workshop)Manufactured by kayaku corporation, material serial No.: 1S20170124) was co-evaporated to form a hole injection layer 811a having a thickness of 10nm and PCBBiF: NDP-9 (weight ratio) was 1: 0.1.

The hole transport layer 812a was formed by evaporation using PCBBiF so as to have a thickness of 32.5 nm.

PCBBiF and NDP-9 were co-evaporated at a weight ratio of 1:0.1 (PCBBiF/NDP-9) and a thickness of 5nm to form an intermediate layer 816.

The hole transport layer 812b was formed by evaporation using PCBBiF to a thickness of 5 nm.

The electron transport layer 814b was formed by sequentially evaporating 2mDBTBPDBq-II and NBphen to a thickness of 20nm and 52.5nm, respectively.

< operating characteristics of light-emitting device 4 >)

The operating characteristics of the light-emitting device 4 are measured. Note that the measurement was performed at room temperature (atmosphere maintained at 25 ℃).

Fig. 30 shows the current density-radiance characteristics of the light-emitting device 4. Fig. 31 shows the voltage-current density characteristics of the light-emitting device 4. Fig. 32 shows the current density-radiant flux characteristics of the light-emitting device 4. Fig. 33 shows the voltage-emittance characteristics of the light-emitting device 4. Fig. 34 shows the current density-external quantum efficiency characteristics of the light-emitting device 4. Note that assuming that the light distribution characteristics of the light emitting device are of the lambert type, the radiance, radiant flux, and external quantum efficiency are calculated using the radiant luminance.

Table 10 shows 8.1W/sr/m²The main initial characteristic values of the nearby light-emitting devices 4.

[ Table 10]

As shown in fig. 30 to 34 and table 10, it is understood that the light-emitting device 4 exhibits favorable characteristics. For example, the light-emitting device 4 emits light with a higher radiance than the light-emitting devices 2 and 3 described above under the same current density. In addition, for example, the light-emitting device 4 has higher external quantum efficiency than the light-emitting devices 2 and 3 under the same current density condition. In addition, for example, the driving voltage of the light emitting device 4 is larger than that of the light emitting device 3 under the same current density condition.

In addition, FIG. 35 shows the current at 10mA/cm²The current density of (a) makes the emission spectrum when a current flows through the light emitting device 4. The measurement of the emission spectrum was performed using a near infrared spectroscopic radiance meter (SR-NIR, manufactured by Topukang Co., Ltd.). As shown in FIG. 35, the light-emitting device 4 exhibited an emission spectrum having a maximum peak at around 803nm, which was derived from [ Ir (dmdpbq) ] included in the light-emitting layer 813a and the light-emitting layer 831b₂(dpm)]。

In addition, the emission spectrum is narrowed due to the adoption of the microcavity resonator structure, and the half-width thereof is shown as 35 nm. The light-emitting device 4 efficiently emits light of 760nm or more and 900nm or less, and therefore can be said to have a high effect as a light source for a sensor or the like.

< viewing angle characteristics of light emitting device 3 >)

Next, the viewing angle characteristics of the EL spectrum of the light-emitting device 4 were investigated.

First, the EL spectrum in the front direction and the EL spectrum in the oblique direction of the light-emitting device 4 are measured. Specifically, the emission spectrum was measured at 17 ° with the direction perpendicular to the light emitting surface of the light emitting device 4 set to 0 °, every 10 ° from-80 ° to 80 °. The measurement was carried out using a multichannel spectrometer (PMA-12 manufactured by Hamamatsu photonics K.K.). From the above measurement results, the EL spectrum and the photon intensity ratio of the light emitting device 4 at each angle were obtained.

Fig. 36 shows EL spectra of 0 ° to 60 ° of the light-emitting device 4.

Fig. 37 shows photon intensities at various angles of the light emitting device 4 with the front photon intensity as a standard.

As shown in fig. 36 and 37, the light-emitting device 4 has a large viewing angle dependency and emits light strongly in the front direction. This is because the use of the microcavity resonator structure enhances the light emission in the front direction and reduces the light emission in the oblique direction. As described above, the viewing angle characteristic of the light emission intensity in the front direction is suitable for the light source of the sensor such as the vein sensor.

For example, in the present specification and the like, when it is explicitly described that "X is connected to Y", cases disclosed in the present specification and the like include: the case where X and Y are electrically connected; the case where X and Y are functionally linked; and X is directly linked to Y. Therefore, the connection relationship is not limited to a predetermined connection relationship such as the connection relationship shown in the drawings or the description, and a connection relationship other than the connection relationship shown in the drawings or the description is also disclosed in the drawings or the description.

Here, X and Y are objects (for example, devices, elements, circuits, wirings, electrodes, terminals, conductive films, layers, and the like).

Examples of the case where X and Y are directly connected include a case where an element capable of electrically connecting X and Y (for example, a switch, a transistor, a capacitor, an inductor, a resistor, a diode, a display element, a light-emitting element, a load, and the like) is not connected between X and Y, and a case where X and Y are not connected through an element capable of electrically connecting X and Y (for example, a switch, a transistor, a capacitor, an inductor, a resistor, a diode, a display element, a light-emitting element, a load, and the like).

As an example of the case where X and Y are electrically connected, one or more elements (for example, a switch, a transistor, a capacitor, an inductor, a resistor, a diode, a display element, a light-emitting element, a load, or the like) capable of electrically connecting X and Y may be connected between X and Y. In addition, the switch has a function of controlling on/off. In other words, the switch has a function of controlling whether or not to allow a current to flow by being in a conductive state (on state) or a non-conductive state (off state). Alternatively, the switch has a function of selecting and switching a current path. In addition, the case where X and Y are electrically connected includes the case where X and Y are directly connected.

As an example of the case where X and Y are functionally connected, one or more circuits (for example, a logic circuit (an inverter, a NAND circuit, a NOR circuit, or the like), a signal conversion circuit (a DA conversion circuit, an AD conversion circuit, a gamma correction circuit, or the like), a potential level conversion circuit (a power supply circuit (a voltage boosting circuit, a voltage dropping circuit, or the like), a level conversion circuit that changes a potential level of a signal, or the like), a voltage source, a current source, a switching circuit, an amplification circuit (a circuit that can increase a signal amplitude, an amount of current, or the like, an operational amplifier, a differential amplification circuit, a source follower circuit, a buffer circuit, or the like), a signal generation circuit, a storage circuit, a control circuit, or the like) that can functionally connect X and Y may be connected between X and Y. Note that, for example, even if other circuits are interposed between X and Y, when a signal output from X is transmitted to Y, it can be said that X and Y are functionally connected. The case where X and Y are functionally connected includes the case where X and Y are directly connected and the case where X and Y are electrically connected.

In addition, when it is explicitly described that "X is electrically connected to Y", cases disclosed in this specification and the like include: a case where X and Y are electrically connected (in other words, a case where X and Y are connected with another element or another circuit interposed therebetween); a case where X and Y are functionally connected (in other words, a case where X and Y are functionally connected with another circuit interposed therebetween); and X and Y are directly connected (in other words, X and Y are connected without interposing another element or another circuit). In other words, when explicitly described as "electrically connected", it means that the same contents as those explicitly described as "connected" only are included in the contents disclosed in this specification and the like.

Note that, for example, a case where a source (or a first terminal or the like) of a transistor is electrically connected to X through Z1 (or not through Z1), a drain (or a second terminal or the like) of the transistor is electrically connected to Y through Z2 (or not through Z2), and where the source (or the first terminal or the like) of the transistor is directly connected to a part of Z1, another part of Z1 is directly connected to X, a drain (or the second terminal or the like) of the transistor is directly connected to a part of Z2, and another part of Z2 is directly connected to Y can be expressed as follows.

For example, "X, Y, the source (or the first terminal, etc.) of the transistor, and the drain (or the second terminal, etc.) of the transistor are electrically connected to each other, and X, the source (or the first terminal, etc.) of the transistor, the drain (or the second terminal, etc.) of the transistor, and Y are electrically connected in this order". Alternatively, the expression "a source (or a first terminal or the like) of a transistor is electrically connected to X, a drain (or a second terminal or the like) of the transistor is electrically connected to Y, and X, the source (or the first terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor, and Y are sequentially electrically connected" may be used. Alternatively, it can be said that "X is electrically connected to Y via a source (or a first terminal or the like) and a drain (or a second terminal or the like) of the transistor, and X, the source (or the first terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor, and Y are provided to be connected to each other in this order". By defining the order of connection in the circuit configuration by using the same expression method as in this example, the technical range can be determined by distinguishing between the source (or the first terminal or the like) and the drain (or the second terminal or the like) of the transistor.

In addition, as another expression method, for example, the "source (or a first terminal or the like) of the transistor is electrically connected to X at least through a first connection path which does not have a second connection path between the source (or the first terminal or the like) of the transistor and the drain (or the second terminal or the like) of the transistor", the first connection path is a path passing through Z1, the drain (or the second terminal or the like) of the transistor is electrically connected to Y at least through a third connection path which does not have the second connection path, and the third connection path is a path passing through Z2 "may be expressed. Alternatively, the word "the source (or the first terminal or the like) of the transistor is electrically connected to X at least through Z1 on a first connection path having no second connection path having a connection path passing through the transistor, the drain (or the second terminal or the like) of the transistor is electrically connected to Y at least on a third connection path having no second connection path through Z2". Alternatively, the term "the source (or the first terminal or the like) of the transistor is electrically connected to X through Z1 via at least a first electrical path, the first electrical path does not have a second electrical path, the second electrical path is an electrical path from the source (or the first terminal or the like) of the transistor to the drain (or the second terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor is electrically connected to Y through Z2 via at least a third electrical path, the third electrical path does not have a fourth electrical path, and the fourth electrical path is an electrical path from the drain (or the second terminal or the like) of the transistor to the source (or the first terminal or the like) of the transistor". By defining a connection path in a circuit configuration by using the same expression method as those of these examples, the source (or first terminal or the like) and the drain (or second terminal or the like) of the transistor can be distinguished to determine the technical range.

Note that this expression method is an example, and is not limited to the above expression method. Here, X, Y, Z1 and Z2 are objects (e.g., devices, elements, circuits, wirings, electrodes, terminals, conductive films, layers, and the like).

In addition, even if independent components are electrically connected to each other in the circuit diagram, one component may have functions of a plurality of components. For example, when a part of the wiring is used as an electrode, one conductive film functions as both the wiring and the electrode. Therefore, the term "electrically connected" in the present specification also includes a case where one conductive film has a function of a plurality of components.

[ description of symbols ]

11: light emitting device, 12: light emitting device, 13: light emitting device, 14: light emitting device, 15: light emitting device, 16: light emitting device, 17: light emitting device, 18: light emitting device, 19: light emitting device, 20: light emitting device, 101: electrode, 102: electrode, 103 a: light-emitting unit, 103 b: light-emitting unit, 104: intermediate layer, 105: protective layer, 111 a: hole injection layer, 112: hole transport layer, 112 a: hole transport layer, 112 b: hole transport layer, 113 a: light-emitting layer, 113 b: light-emitting layer, 114 a: electron transport layer, 114 b: electron transport layer, 115 a: electron injection layer, 115 b: electron injection layer, 301: substrate, 302: pixel portion, 303: circuit unit, 304 a: circuit unit, 304 b: circuit unit, 305: sealant, 306: substrate, 307: wiring, 308: FPC, 309: transistor, 310: transistor, 311: transistor, 312: transistor, 313: electrode, 314: insulating layer, 315: EL layer, 316: electrode, 317: organic EL device, 318: space, 400: molecular weight, 401: electrode, 402: EL layer, 403: electrode, 405: insulating layer, 406: conductive layer, 407: adhesive layer, 416: conductive layer, 420: substrate, 422: adhesive layer, 423: barrier layer, 424: insulating layer, 450: organic EL device, 490 a: substrate, 490 b: substrate, 490 c: barrier layer, 800: substrate, 801: electrode, 802: light-emitting unit, 802 a: light-emitting unit, 802 b: light-emitting unit, 803: an electrode, 804: buffer layer, 811: hole injection layer, 811 a: hole injection layer, 811 b: hole injection layer, 812: hole transport layer, 812 a: hole transport layer, 812 b: hole transport layer, 813: light-emitting layer, 813 a: light-emitting layer, 813 b: light-emitting layer, 814: electron transport layer, 814 a: electron transport layer, 814 b: electron transport layer, 815: electron injection layer, 815 a: electron injection layer, 815 b: electron injection layer, 816: intermediate layer, 831 b: light-emitting layer, 911: frame body, 912: light source, 913: detection station, 914: image pickup apparatus, 915: light emitting section, 916: light-emitting section, 917: light emitting unit 921: frame, 922: operation buttons, 923: detection unit, 924: light source, 925: imaging device, 931: frame, 932: operation panel, 933: transport mechanism, 934: display, 935: detection unit, 936: detected member, 937: imaging device, 938: light source, 981: frame body, 982: display unit, 983: operation buttons, 984: external connection interface, 985: speaker, 986: microphone, 987: camera, 988: camera head