阅读说明：本技术 空间电荷转移化合物、以及包括该化合物的有机发光二极管和有机发光显示装置 (Space charge transfer compound, and organic light emitting diode and organic light emitting display device including the same ) 是由 鲁效珍 尹炅辰 徐辅民 于 2019-05-31 设计创作，主要内容包括：本公开提供了由下式表示的空间电荷转移化合物,以及包括所述空间电荷转移化合物的OLED和有机发光显示装置。<Image he="367" wi="344" file="DDA0002080527650000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The present disclosure provides space charge transfer compounds represented by the following formula, and OLEDs and organic light emitting display devices including the same)

1. A space charge transfer compound represented by formula 1:

[ formula 1]

Wherein A is selected from formula 2 and D is selected from formula 3:

[ formula 2]

[ formula 3]

Wherein X₁、X₂And X₃Each independently is carbon or nitrogen, and X₁To X₃At least one of which is nitrogen,

Wherein R is₁And R₂Each independently selected from the group consisting of hydrogen, C1-C10 alkyl, and C6-C30 aryl, R₃And R₄Each independently selected from the group consisting of hydrogen, cyano and C1-C10 alkyl, and

Wherein R is₅And R₆Each independently selected from the group consisting of hydrogen and heteroaryl, and R₇And R₈each is hydrogen or R₇And R₈Bonded together to form fused rings.

2. The space charge transfer compound of claim 1, wherein a is selected from formula 4:

[ formula 4]

3. The space charge transfer compound of claim 1, wherein D is selected from formula 5:

[ formula 5]

4. The space charge transfer compound of claim 1, wherein the space charge transfer compound is one of the compounds of formula 6:

[ formula 6]

5. The space charge transfer compound of claim 1, wherein the difference between the singlet energy level of the space charge transfer compound and the triplet energy level of the space charge transfer compound is less than about 0.3 eV.

6. An organic light emitting diode comprising:

A first electrode;

A second electrode facing the first electrode; and

A first luminescent material layer between the first electrode and the second electrode, the first luminescent material layer comprising the space charge transfer compound of claim 1.

7. An organic light-emitting diode according to claim 6, wherein the first luminescent material layer further comprises a first host, and the space charge transfer compound functions as a dopant.

8. The organic light-emitting diode of claim 7, wherein a difference between an energy level of the HOMO of the first host and an energy level of the HOMO of the dopant or an energy level of the LUMO of the first host and an energy level of the LUMO of the dopant is less than about 0.5 eV.

9. An organic light-emitting diode according to claim 6, wherein the first luminescent material layer further comprises a host and a first dopant, and the space charge transfer compound functions as a second dopant, and

Wherein the singlet energy level of the second dopant is greater than the singlet energy level of the first dopant.

10. The organic light emitting diode of claim 9, wherein the triplet energy level of the second dopant is less than the triplet energy level of the host and greater than the triplet energy level of the first dopant.

11. The organic light emitting diode of claim 7, further comprising:

A second light emitting material layer including a second host and a first fluorescent dopant, and positioned between the first electrode and the first light emitting material layer.

12. The organic light emitting diode of claim 11, further comprising:

An electron blocking layer between the first electrode and the second light emitting material layer,

Wherein a material of the second body is the same as a material of the electron blocking layer.

13. The organic light emitting diode of claim 11, further comprising:

A third light emitting material layer including a third host and a second fluorescent dopant, and positioned between the second electrode and the first light emitting material layer.

14. The organic light emitting diode of claim 13, further comprising:

A hole blocking layer between the second electrode and the third light emitting material layer,

Wherein a material of the third body is the same as a material of the hole blocking layer.

15. the organic light-emitting diode of claim 13, wherein the singlet energy level of the space charge transfer compound is greater than each of the singlet energy level of the first fluorescent dopant and the singlet energy level of the second fluorescent dopant.

16. The organic light-emitting diode of claim 13, wherein the singlet and triplet energy levels of the first host are greater than the singlet and triplet energy levels of the space charge transfer compound, respectively, and

Wherein the singlet energy level of the second host is greater than the singlet energy level of the first fluorescent dopant and the singlet energy level of the third host is greater than the singlet energy level of the second fluorescent dopant.

17. The organic light-emitting diode of claim 11, wherein the singlet energy level of the space charge transfer compound is greater than the singlet energy level of the first fluorescent dopant.

18. The organic light emitting diode of claim 11, wherein the singlet and triplet energy levels of the first host are greater than the singlet and triplet energy levels of the space charge transfer compound, respectively, and

Wherein the singlet energy level of the second host is greater than the singlet energy level of the first fluorescent dopant.

19. An organic light-emitting diode according to claim 6, wherein the space charge transfer compound is one of the following compounds:

20. An organic light emitting display device comprising:

a substrate;

The organic light emitting diode of claim 6, disposed on the substrate; and

And an encapsulation film covering the organic light emitting diode.

Technical Field

The present invention relates to a light emitting material, and more particularly, to a space charge transfer compound having excellent light emitting efficiency, and an OLED and an organic light emitting display device including the same.

Background

The demand for large-sized display devices has led to the development of flat panel display devices as image display devices. Among flat panel display devices, OLEDs have been rapidly developed.

In the OLED, when electrons from a cathode serving as an electron injection electrode and holes from an anode serving as a hole injection electrode are injected into a light emitting material layer, the electrons and the holes are combined together and disappear, so that light is emitted from the OLED. A flexible substrate (e.g., a plastic substrate) can be used as a base substrate for an OLED having excellent driving voltage, power consumption, and color purity characteristics.

The OLED includes a first electrode as an anode on a substrate, a second electrode as a cathode facing the first electrode, and an organic light emitting layer therebetween.

In order to improve light emitting efficiency, the organic light emitting layer may include a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an Emitting Material Layer (EML), an electron transport layer (HTL), and an Electron Injection Layer (EIL) sequentially stacked on the first electrode.

Holes are transferred from the first electrode into the EML via the HIL and HTL, and electrons are transferred from the second electrode into the EML via the EIL and ETL.

the electrons and holes combine in the EML to generate excitons, which transition from an excited state to a ground state, thereby emitting light.

The external quantum efficiency of the luminescent material of EML can be represented by the following equation:

η_ext＝η_int×г×Φ×η_out-coupling

In the above formula, ("η)_int"is the internal quantum efficiency," г "is the charge balance factor," Φ "is the radiative quantum efficiency," η_out-couplingIs an outputThe coupling efficiency.

Generally, assuming a 1: 1 matched hole and electron, the charge balance factor has a value of "1". RadioQuantum efficiency "Φ" is a value related to the effective luminous efficiency of the light emitting material.

Internal quantum efficiency [. eta. ]_int"is the ratio of excitons that generate light to excitons that are generated by the combination of holes and electrons. In the fluorescent compound, the maximum value of the internal quantum efficiency was 0.25. When the hole and the electron combine to generate an exciton, the ratio of singlet exciton to triplet exciton is 1: 3. however, in the fluorescent compound, only singlet excitons, not triplet excitons, participate in light emission.

Output coupling efficiency [. eta. ]_out-coupling"is a ratio of light emitted from the display device to light emitted from the EML. When isotropic compounds are deposited by thermal evaporation to form thin films, the light emitting materials are randomly oriented. In this case, the output coupling efficiency of the display device may be assumed to be 0.2.

Accordingly, OLEDs including fluorescent compounds as the light emitting material have a maximum luminous efficiency of less than about 5%.

In order to overcome the disadvantage of the light emitting efficiency of fluorescent compounds, phosphorescent compounds for OLEDs, in which both singlet excitons and triplet excitons participate in light emission, have been developed.

A red phosphorescent compound and a green phosphorescent compound having relatively high efficiency were introduced and developed. However, no blue phosphorescent compound satisfies the requirements of luminous efficiency and reliability.

Disclosure of Invention

Accordingly, the disclosed embodiments relate to a space-charge transfer compound (space-through charge transfer compound) and an OLED and organic light emitting display device using the same, which substantially obviate one or more problems due to limitations and disadvantages of the related art.

It is an object of the embodiments of the present disclosure to provide a space charge transfer compound having high luminous efficiency.

It is another object of the disclosed embodiments to provide an OLED and an organic light emitting display device having improved light emitting efficiency.

Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purpose of embodiments of the invention, as embodied and broadly described herein, embodiments relate to a method of manufacturing a display deviceWherein a is selected from formula 2 and D is selected from formula 3: [ formula 2]][ formula 3]]Wherein X₁、X₂And X₃Each independently is carbon or nitrogen, and X₁To X₃At least one of which is nitrogen, wherein R₁and R₂Each independently selected from the group consisting of hydrogen, C1-C10 alkyl, and C6-C30 aryl, R₃And R₄each independently selected from the group consisting of hydrogen, cyano and C1-C10 alkyl, and wherein R₅And R₆Each independently selected from the group consisting of hydrogen and heteroaryl, R₇And R₈Each is hydrogen or R₇And R₈Bonded together to form fused rings.

Embodiments are also directed to an organic light emitting diode comprising: a first electrode; a second electrode facing the first electrode; and a first luminescent material layer between the first electrode and the second electrode, the first luminescent material layer including the space charge transfer compound.

Embodiments also relate to an organic light emitting display device including: a substrate; the organic light emitting diode on the substrate; and an encapsulation film covering the organic light emitting diode.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the disclosure.

fig. 1 is a view illustrating a light emitting mechanism of a space charge transfer compound according to the present disclosure.

Fig. 2A and 2B are views illustrating charge transfer in a space charge transfer compound according to the present disclosure.

Fig. 3A and 3B are views showing the HOMO distribution and LUMO distribution of the space charge transfer compound 1 according to the present disclosure.

Fig. 4A and 4B are views showing the HOMO distribution and LUMO distribution of comparative compound 1.

Fig. 5A and 5B are views showing the HOMO distribution and LUMO distribution of the space charge transfer compound 13 according to the present disclosure.

Fig. 6A and 6B are views showing the HOMO distribution and LUMO distribution of comparative compound 2.

Fig. 7 is a schematic cross-sectional view of an organic light emitting display device according to the present disclosure.

Fig. 8 is a schematic cross-sectional view of an Organic Light Emitting Diode (OLED) according to the present disclosure.

Fig. 9 is a schematic cross-sectional view of an Organic Light Emitting Diode (OLED) according to the present disclosure.

Fig. 10 is a schematic cross-sectional view of an Organic Light Emitting Diode (OLED) according to the present disclosure.

Detailed Description

Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings.

The space charge transfer compounds of the present disclosure have: a biphenyl nucleus (or bridge); an electron acceptor moiety bonded (linked) to one of the 2-position of the biphenyl nucleus and the 2' -position of the biphenyl nucleus; and an electron donor moiety bonded to the other of the 2-position of the biphenyl nucleus and the 2' -position of the biphenyl nucleus. The space charge transfer compound may be represented by formula 1 below.

[ formula 1]

In formula 1, a as an electron acceptor moiety is selected from formula 2.

[ formula 2]

In formula 2, X₁、X₂And X₃Each independently is carbon or nitrogen, and X₁To X₃At least one of which is nitrogen. Furthermore, R₁And R₂Each independently selected from the group consisting of hydrogen, C1-C10 alkyl, and C6-C30 aryl. For example, R₁and R₂Each may be phenyl. R₃And R₄Each independently selected from the group consisting of hydrogen, cyano, and C1-C10 alkyl.

For example, the electron acceptor moiety a may be selected from formula 3.

[ formula 3]

In formula 1, D as an electron donor moiety is selected from formula 4.

[ formula 4]

In the formula 4, the first and second organic solvents are,R₅And R₆Each independently selected from the group consisting of hydrogen and heteroaryl. For example, R₅And R₆Each may be a carbazolyl group. Furthermore, R₇And R₈Each is hydrogen or R₇And R₈Bonded together to form fused rings.

For example, the electron donor moiety D can be selected from formula 5.

[ formula 5]

In space charge transfer compounds, an electron donor moiety and an electron acceptor moiety are bonded (bound or linked) in the molecule such that the overlap between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) is reduced. As a result, a charge transfer complex is generated, and the light emission efficiency of the space charge transfer compound is improved. That is, in the space charge transfer compound, triplet excitons are used for light emission, so that the light emission efficiency is improved.

In other words, since the space charge transfer compound of the present disclosure includes both the electron donor moiety and the electron acceptor moiety, charges are easily transferred in the molecule, and the light emitting efficiency is improved.

In the space charge transfer compounds of the present disclosure, since the electron donor moiety and the electron acceptor moiety are bonded to the 2-and 2' -positions of the biphenyl nucleus, respectively, the gap or distance between the electron donor moiety and the electron acceptor moiety is reduced or minimized. Accordingly, charge transfer is directly generated via a space between the electron donor moiety and the electron acceptor moiety, so that the conjugation length in the space charge transfer compound becomes shorter than that in another compound in which charge transfer is generated through a bonding orbit. As a result, the red shift problem in light emission can be prevented, and the space charge transfer compound of the present disclosure can provide deep blue light emission.

Referring to fig. 1, which is a view illustrating a light emitting mechanism of a space charge transfer compound according to the present disclosure in which both triplet excitons and singlet excitons participate in light emission such that light emitting efficiency is improved.

that is, the triplet excitons are field or thermally activated, and the triplet excitons and singlet excitons are transferred to the intermediate state "I₁"and converted to ground state" S₀"to emit light. In other words, singlet "S₁"and triplet" T₁"transition to intermediate state" I₁”(S₁->I₁<-T₁) And in an intermediate state "I₁"the singlet excitons and triplet excitons participate in light emission, so that emission efficiency is improved. The compound having the above-described light emission mechanism may be referred to as a Field Activated Delayed Fluorescence (FADF) compound or a Thermally Activated Delayed Fluorescence (TADF) compound.

In the fluorescent compounds of the prior art, since HOMO and LUMO are dispersed throughout the molecule, the interconversion of HOMO and LUMO is not possible. (law of selection)

however, in FADF compounds, the interaction between HOMO and LUMO is small because the overlap between HOMO and LUMO in the molecule is relatively small. Thus, the change in spin state of one electron does not affect the other electrons and a new charge transfer band is generated that does not comply with the selection rules.

In addition, since the electron donor moiety and the electron acceptor moiety are spatially separated from each other in the molecule, a dipole moment is generated in a polarization state. In the polarization state dipole moment, the interaction between HOMO and LUMO is further reduced, making the light emission mechanism not compliant with the selection rule. Thus, in FADF or TADF compounds, a triplet ` T ` can be generated₁"and singlet" S₁"to intermediate state" I₁"such that the triplet excitons can participate in light emission.

When the OLED is driven, it produces from 25% singlet "S₁"excitons and 75% triplet" T₁"exciton to intermediate state" I₁"inter-system transition (inter-system crossing), and in an intermediate state" I₁"the singlet excitons and the triplet excitons of" turn to the ground state to emit light. As a result, FADF compounds have a theoretical quantum efficiency of 100%.

For example, the space charge transfer compound in formula 1 may be one of the compounds in formula 6.

[ formula 6]

The space charge transfer compound of the present disclosure has a wide energy band gap, so that the light emitting efficiency of an OLED using the compound is improved.

The HOMO and LUMO distributions of compound 1 in formula 6 are shown in fig. 3A and 3B, and the HOMO and LUMO distributions of comparative compound 1 of formula 7 are shown in fig. 4A and 4B. The HOMO distribution and LUMO distribution of compound 13 in formula 6 are shown in fig. 5A and 5B, and the HOMO distribution and LUMO distribution of comparative compound 2 of formula 8 are shown in fig. 6A and 6B. The energy levels of the HOMO, LUMO and energy band gap (Eg) of compounds 1 and 13 and comparative compounds 1 and 2 are listed in Table 1.

[ formula 7]

[ formula 8]

TABLE 1

	HOMO	LUMO	Eg
				Compound 1	5.22	1.74	3.48
Comparative Compound 1	5.33	1.98	3.35
				Compound 13	5.52	1.92	3.6
Comparative Compound 2	5.60	2.14	3.46

As shown in fig. 3A to 6B and table 1, HOMO and LUMO are easily separated and the energy band gap is increased in the space charge transfer compound of the present disclosure, compared to the comparative compound. Therefore, in the space charge transfer compound of the present disclosure, the triplet excitons participate in light emission, so that the light emission efficiency is improved and deep blue light emission is provided.

Synthesis of

1. Synthesis of Compound 1

(1) Compound B

[ reaction formula 1-1]

In N₂In a gas purge system, compound a and butyllithium (BuLi, 1.5 equivalents) were added to diethyl ether and the mixture was stirred at a temperature of-78 ℃. After reacting the mixture for 2 hours, trimethyl borate (1.2 eq.) was added and the mixture was stirred at a temperature of-78 ℃ for 30 minutes. The mixture was reacted at room temperature for 14 hours. Deionized water (30ml) containing HCl was added and the organic solvent was removed. The residue was filtered to give compound B as a white solid.

(2) Compound D

[ reaction formulae 1-2]

In N₂In a gas purge system, compound B, compound C (0.6 equiv.), Pd (0) (0.1 equiv.), and potassium carbonate (4.0 equiv.) were added to toluene, and the mixture was stirred in an oil bath at a temperature of 80 ℃ for 34 hours. Water was added to the mixture and extraction was performed. Column chromatography was performed using a developing solvent of hexane and dichloromethane (7: 1) to obtain compound D as a white solid.

(3) Compound E

[ reaction formulae 1 to 3]

In N₂In a gas purging system, carbazole, compound C (0.5 equivalent), CuI (0.1 equivalent), diaminocyclohexane (3.5 equivalents), and potassium phosphate (4.0 equivalents) were added to 1, 4-dioxane, and the mixture was stirred in an oil bath at a temperature of 90 ℃ for 12 hours. Water was added to the mixture and extraction was performed. Column chromatography was performed using a developing solvent of hexane and dichloromethane (9: 1) to obtain compound E as a white solid.

(4) Compound F

[ reaction formulae 1 to 4]

In N₂In the gas purging system, the gas is purged,Compound E and BuLi (1.5 equiv.) are added to diethyl ether and the mixture is stirred at a temperature of-78 ℃. After reacting the mixture for 2 hours, trimethyl borate (1.2 eq.) was added and the mixture was stirred at a temperature of-78 ℃ for 30 minutes. The mixture was reacted at room temperature for 24 hours. Deionized water (30ml) containing HCl was added and the organic solvent was removed. The residue was filtered to give compound F as a white solid.

(5) Compound 1

[ reaction formulae 1 to 5]

In N₂in a gas purge system, compound F, compound D (1.3 equiv.), Pd (0) (0.1 equiv.) and potassium carbonate (4.0 equiv.) were added to toluene and the mixture was stirred in an oil bath at a temperature of 80 ℃ for 48 hours. Water was added to the mixture and extraction was performed. Column chromatography using a developing solvent of hexane and dichloromethane (9.5: 0.5) gave compound 1 as a white solid.

2. Synthesis of Compound 13

(1) Compound H

[ reaction formula 2-1]

In N₂In a gas purge system, compound G and CuCN (1.5 equivalents) were added to Dimethylformamide (DMF) and the mixture was stirred at a temperature of 150 ℃ for 48 hours. The mixture was slowly added to ice water at 0 ℃ and stirred for 30 minutes. An aqueous ammonia solution was added and extraction was performed. The solvent was removed and the resultant was adsorbed on silica. Column chromatography was performed using a developing solvent of dichloromethane and hexane (1: 1) to obtain a solid compound H.

(2) Compound I

[ reaction formula 2-2]

In N₂In a gas purging system, compound H, carbazole (0.5 equivalent), CuI (0.1 equivalent), diaminocyclohexane (3.5 equivalents), and potassium phosphate (4.0 equivalents) were added to 1, 4-dioxane, and the mixture was stirred in an oil bath at a temperature of 90 ℃ for 24 hours. Water was added to the mixture and extraction was performed. Column chromatography was performed using a developing solvent of hexane and ethyl acetate (7: 1) to obtain compound I as a white solid.

(3) Compound 13

[ reaction formulae 2 to 3]

In N₂In a gas purge system, compound B, compound I (1.3 equiv), Pd (0) (0.1 equiv) and potassium carbonate (4.0 equiv) were added to toluene and the mixture was stirred in an oil bath at a temperature of 80 ℃ for 50 hours. Water was added to the mixture and extraction was performed. Column chromatography using a developing solvent of hexane and ethyl acetate (6: 1) gave compound 13 as a white solid.

3. Synthesis of Compound 8

(1) Compound K

[ reaction formula 3-1]

In N₂In a gas purge system, compound J and butyllithium (BuLi, 1.5 equivalents) were added to diethyl ether and the mixture was stirred at a temperature of-78 ℃. After the mixture was reacted for 1 hour, trimethyl borate (1.2 eq.) was added and the mixture was stirred at a temperature of-78 ℃ for 30 minutes. The mixture was reacted at room temperature for 12 hours. Deionized water (30ml) containing HCl was added and the organic solvent was removed. The residue was filtered to give compound K as a white solid.

(2) Compound M

[ reaction formula 3-2]

In N₂In a gas purging system, compound K, compound L (0.5 equivalent), CuI (0.1 equivalent), diaminocyclohexane (3.5 equivalents), and potassium phosphate (4.0 equivalents) were added to 1, 4-dioxane, and the mixture was stirred in an oil bath at a temperature of 60 ℃ for 24 hours. Water was added to the mixture and extraction was performed. Column chromatography was performed using a developing solvent of hexane and dichloromethane (9: 1) to obtain compound M as a white solid.

(3) Compound O

[ reaction formula 3-3]

In N₂In a gas purge system, compound M, compound N (0.6 eq), Pd (0) (0.1 eq) and potassium carbonate (4.0 eq) were added to toluene and the mixture was stirred in an oil bath at a temperature of 80 ℃ for 12 hours. Water was added to the mixture and extraction was performed. The solvent was evaporated to give compound O as a yellow solid.

(4) compound Q

[ reaction formulae 3 to 4]

In N₂In a gas purging system, the compound P, bicarbazole (0.45 equivalent), CuI (0.1 equivalent), diaminocyclohexane (3.5 equivalents), and potassium phosphate (4.0 equivalents) were added to 1, 4-dioxane, and the mixture was stirred in an oil bath at a temperature of 60 ℃ for 14 hours. Water was added to the mixture and extraction was performed. Column chromatography was performed using a developing solvent of hexane and dichloromethane (10: 1) to obtain compound Q as a white solid.

(5) Compound 8

[ reaction formulae 3 to 5]

in N₂In a gas purging system, will combineCompound Q, Compound O (1.3 equiv.), Pd (0) (0.1 equiv.), and potassium carbonate (4.0 equiv.) were added to toluene, and the mixture was stirred in an oil bath at a temperature of 100 ℃ for 24 hours. Water was added to the mixture and extraction was performed. Column chromatography using a developing solvent of hexane and dichloromethane (5: 1) gave compound 8 as a white solid.

4. Synthesis of Compound 19

(1) Compound T

[ reaction formula 4-1]

In N₂In a gas purge system, compound R, compound S (1.0 equivalent), Pd (0) (0.1 equivalent), and potassium carbonate (4.0 equivalents) were added to toluene, and the mixture was stirred in an oil bath at a temperature of 80 ℃ for 18 hours. Water was added to the mixture and extraction was performed. Column chromatography was performed using a developing solvent of hexane and dichloromethane (9: 1) to obtain compound T as a white solid.

(2) Compound U

[ reaction formula 4-2]

In N₂In a gas purging system, the compound T, carbazole (0.5 equivalent), CuI (0.1 equivalent), diaminocyclohexane (3.5 equivalents), and potassium phosphate (4.0 equivalents) were added to 1, 4-dioxane, and the mixture was stirred in an oil bath at a temperature of 80 ℃ for 12 hours. Water was added to the mixture and extraction was performed. Column chromatography using a developing solvent of hexane and dichloromethane (9: 1) gave compound U as a white solid.

(3) Compound 19

[ reaction formula 4-3]

In N₂In the gas purge system, compound U, compound B (1.4 equivalents), and P were introducedd (0) (0.15 equiv.) and potassium carbonate (4.0 equiv.) were added to toluene and the mixture was stirred in an oil bath at a temperature of 100 ℃ for 24 hours. Water was added to the mixture and extraction was performed. Column chromatography using a developing solvent of hexane and dichloromethane (8: 1) gave compound 19 as a white solid.

In the space charge transfer compound of the present disclosure, 25% of singlet excitons and 75% of triplet excitons are converted into an intermediate state by an external force, i.e., a field generated when the OLED is driven. (intersystem crossing.) the excitons in the intermediate state are shifted to the ground state, so that the light emission efficiency is improved. That is, in the fluorescent compound, since both singlet excitons and triplet excitons participate in light emission, the light emission efficiency is improved.

OLED

An ITO layer was deposited on the substrate and washed to form an anode (3mm x3 mm). The substrate is loaded into a vacuum chamber at about 10 deg.f^-6To 10^-7A hole injection layer, a hole transport layer, a light emitting material layer, an electron transport layer, an electron injection layer, and a cathode (Al) were sequentially formed on the anode at a base pressure of Torr. The light emitting material layer was formed using a host composed of the material in formula 9 and a dopant (30 wt%).

[ formula 9]

(1) Example 1(Ex1)

Compound 1 in formula 6 is used as a dopant in the light emitting material layer.

(2) Example 2(Ex2)

The compound 13 in formula 6 is used as a dopant in the light emitting material layer.

(3) Example 3(Ex3)

the compound 8 in formula 6 is used as a dopant in the light emitting material layer.

(4) Example 4(Ex4)

The compound 19 in formula 6 is used as a dopant in the light emitting material layer.

(5) Comparative example 1(Ref1)

The compound in formula 7 is used as a dopant in the light emitting material layer.

(6) comparative example 2(Ref2)

The compound in formula 8 is used as a dopant in the light emitting material layer.

The characteristics of the OLEDs in examples 1 to 4 and comparative examples 1 and 2, i.e., PL maximum value (PL)_maxNm), extinction time of the luminescent exciton (Tau, μ s), voltage (V), current efficiency (cd/a), power efficiency (lm/W), external quantum efficiency (EQE,%), color coordinate index (cie (x), cie (y)), lifetime (T95, hr), and are listed in table 2. The lifetime is the time to change the brightness from the initial brightness (300nit) to 95%.

TABLE 2

As shown in table 2, the OLED including the space charge transfer compound of the present disclosure has high luminous efficiency and long life and provides deep blue emission, as compared to the OLEDs of comparative examples 1 and 2.

for example, compound 1 and compound 13 of formula 6 and comparative compound 1 of formula 7 and comparative compound 2 of formula 8 differ in the bonding position of the electron donor moiety, and the distance between the electron acceptor moiety and the electron donor moiety of compound 1 and compound 13 decreases. Accordingly, charge transfer properties via the space between the electron donor moiety and the electron acceptor moiety are improved, so that the space charge transfer compound of the present disclosure has advantages of high luminous efficiency, long life, and deep blue light emission.

in addition, since the extinction time of the luminescent exciton is several microseconds, the space charge transfer compound of the present disclosure has a delayed fluorescence characteristic. Typical fluorescent materials have an extinction time of a few nanoseconds.

Fig. 7 is a schematic cross-sectional view of an organic light emitting display device according to the present disclosure.

As shown in fig. 7, the OLED device 100 includes a substrate 110, a TFT Tr, and an organic light emitting diode D connected to the TFT Tr.

The substrate 110 may be a glass substrate or a plastic substrate. For example, the substrate 110 may be a polyimide substrate.

The buffer layer 120 is formed on the substrate, and the TFT Tr is formed on the buffer layer 120. The buffer layer 120 may be omitted.

The semiconductor layer 122 is formed on the buffer layer 120. The semiconductor layer 122 may include an oxide semiconductor material or polysilicon.

When the semiconductor layer 122 includes an oxide semiconductor material, a light-shielding pattern (not shown) may be formed under the semiconductor layer 122. Light to the semiconductor layer 122 is shielded or blocked by the light blocking pattern so that thermal degradation of the semiconductor layer 122 can be prevented. On the other hand, when the semiconductor layer 122 includes polysilicon, impurities may be doped to both sides of the semiconductor layer 122.

A gate insulating layer 124 is formed on the semiconductor layer 122. The gate insulating layer 124 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 130 formed of a conductive material (e.g., metal) is formed on the gate insulating layer 124 to correspond to the center of the semiconductor layer 122.

In fig. 7, a gate insulating layer 124 is formed on the entire surface of the substrate 110. Alternatively, the gate insulating layer 124 may be patterned to have the same shape as the gate electrode 130.

An interlayer insulating layer 132 formed of an insulating material is formed on the gate electrode 130. The interlayer insulating layer 132 may be formed of an inorganic insulating material, such as silicon oxide or silicon nitride, or an organic insulating material, such as benzocyclobutene or photo-acryl.

The interlayer insulating layer 132 includes a first contact hole 134 and a second contact hole 136 exposing both sides of the semiconductor layer 122. The first and second contact holes 134 and 136 are positioned at both sides of the gate 130 to be spaced apart from the gate 130.

The first contact hole 134 and the second contact hole 136 are formed through the gate insulating layer 124. Alternatively, when the gate insulating layer 124 is patterned to have the same shape as the gate electrode 130, the first and second contact holes 134 and 136 are formed only through the interlayer insulating layer 132.

A source electrode 140 and a drain electrode 142 formed of a conductive material (e.g., metal) are formed on the interlayer insulating layer 132.

the source and drain electrodes 140 and 142 are spaced apart from each other with respect to the gate electrode 130 and contact both sides of the semiconductor layer 122 via the first and second contact holes 134 and 136, respectively.

The semiconductor layer 122, the gate electrode 130, the source electrode 140, and the drain electrode 142 constitute a TFT Tr. The TFT Tr serves as a driving element.

In the TFT Tr, the gate electrode 130, the source electrode 140, and the drain electrode 142 are positioned over the semiconductor layer 122. That is, the TFT Tr has a coplanar structure.

Alternatively, in the TFT Tr, the gate electrode may be positioned below the semiconductor layer, and the source and drain electrodes may be positioned above the semiconductor layer, so that the TFT Tr may have an inverted staggered structure. In this case, the semiconductor layer may include amorphous silicon.

Although not shown, gate lines and data lines cross each other to define pixel regions, and switching TFTs are formed to be connected to the gate lines and the data lines. The switching TFT is connected to a TFT Tr as a driving element.

In addition, a power line that may be formed in parallel with and spaced apart from one of the gate line and the data line, and a storage capacitor for maintaining a voltage of the gate electrode of the TFT Tr in one frame may be further formed.

A passivation layer 150 including a drain contact hole 152 exposing the drain electrode 142 of the TFT Tr is formed to cover the TFT Tr.

First electrodes 160 connected to the drain electrodes 142 of the TFTs Tr via the drain contact holes 152 are respectively formed in each pixel region. The first electrode 160 may be an anode and may be formed of a conductive material having a relatively high work function. For example, the first electrode 160 may be formed of a transparent conductive material such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO).

When the OLED device 100 operates in a top emission type, a reflective electrode or a reflective layer may be formed under the first electrode 160. For example, the reflective electrode or the reflective layer may be formed of an aluminum-palladium-copper (APC) alloy.

A bank layer 166 is formed on the passivation layer 150 to cover an edge of the first electrode 160. That is, the bank layer 166 is positioned at the boundary of the pixel region and exposes the center of the first electrode 160 in the pixel region.

an organic light emitting layer 162 is formed on the first electrode 160. The organic light emitting layer 162 includes a space charge transfer compound of formula 1. The space charge transfer compound may be used as a dopant, and the organic light emitting layer 162 may further include a host. For example, the dopant may have about 1 wt% to 30 wt% with respect to the host. The organic light emitting layer 162 provides blue light.

The organic light emitting layer 162 may have a single-layer structure of a light emitting material layer including a light emitting material. In order to improve the light emitting efficiency of the OLED device, the organic light emitting layer 162 may have a multi-layer structure.

The second electrode 164 is formed over the substrate 110 where the organic light emitting layer 162 is formed. The second electrode 164 covers the entire surface of the display region, and may be formed of a conductive material having a relatively low work function to serve as a cathode. For example, the second electrode 164 may be formed of aluminum (Al), magnesium (Mg), or Al — Mg alloy.

The first electrode 160, the organic light emitting layer 162, and the second electrode 164 constitute an organic light emitting diode D.

An encapsulation film 170 is formed on the second electrode 164 to prevent moisture from penetrating into the organic light emitting diode D. The encapsulation film 170 includes a first inorganic insulating layer 172, an organic insulating layer 174, and a second inorganic insulating layer 176, which are sequentially stacked, but is not limited thereto.

A polarizing plate (not shown) for reducing reflection of ambient light may be disposed above the top emission type organic light emitting diode D. For example, the polarizing plate may be a circular polarizing plate.

In addition, a cover window (not shown) may be attached to the encapsulation film 170 or the polarizing plate. In this case, the substrate 110 and the cover window have flexible characteristics, so that a flexible OLED device may be provided.

Fig. 8 is a schematic cross-sectional view of an Organic Light Emitting Diode (OLED) according to the present disclosure.

As shown in fig. 8, the organic light emitting diode D includes a first electrode 160 and a second electrode 164 facing each other with an organic light emitting layer 162 therebetween. The organic emission layer 162 includes an Emission Material Layer (EML)240 between the first electrode 160 and the second electrode 164, a Hole Transport Layer (HTL)220 between the first electrode 160 and the EML 240, and an Electron Transport Layer (ETL)260 between the second electrode 164 and the EML 240.

In addition, the organic light emitting layer 162 may further include a Hole Injection Layer (HIL)210 between the first electrode 160 and the HTL 220 and an Electron Injection Layer (EIL)270 between the second electrode 164 and the ETL 260.

In addition, the organic light emitting layer 162 may further include an Electron Blocking Layer (EBL)230 between the HTL 220 and the EML 240 and a Hole Blocking Layer (HBL)250 between the EML 240 and the ETL 260.

The EML 240 includes a space charge transfer compound of formula 1 as a dopant, and may further include a host.

HOMO "of host_Host"HOMO of energy level and dopant_Dopant"difference between energy levels or LUMO of host" LUMO_Host"energy level and LUMO of dopant" LUMO_Dopant"is less than about 0.5 eV. In this case, the charge transfer efficiency from the host to the dopant can be improved.

The triplet level of the dopant is less than the triplet level of the host, and the difference between the singlet level of the dopant and the triplet level of the dopant is less than 0.3 eV. (Δ E)_STLess than or equal to 0.3 eV. ) With difference "Δ E_STThe smaller the "the higher the luminous efficiency. Further, even if the difference "Δ E" between the singlet level of the dopant and the triplet level of the dopant_ST"about a relatively large 0.3eV, singlet excitons and triplet excitons are also capable of being converted to intermediate states.

For example, the main body satisfying the above conditions may be selected from the materials in formula 10. (bis [2- (diphenylphosphino) phenyl ] ether oxide (DPEPO), 2, 8-bis (diphenylphosphoryl) dibenzothiophene (PPT), 2, 8-bis (9H-carbazol-9-yl) dibenzothiophene (DCzDBT), m-bis (carbazol-9-yl) biphenyl (m-CBP), diphenyl-4-triphenylsilylphenyl-phosphine oxide (TPSO1), 9- (9-phenyl-9H-carbazol-6-yl) -9H-carbazole (CCP) in that order).

[ formula 10]

On the other hand, the space charge transfer compound of the present disclosure may serve as a host in the EML 240, and the EML 240 may further include a dopant to emit blue light. In this case, the dopant has about 1 to 30 wt% with respect to the host. Since development of a blue host having excellent performance is not sufficient, the space charge transfer compound of the present disclosure may be used as a host to increase the degree of freedom of the host. In this case, the triplet energy level of the dopant may be less than the triplet energy level of the host of the space charge transfer compound of the present disclosure.

The EML 240 may include a first dopant, a host, and a second dopant of the space charge transfer compound of the present disclosure. The sum of the first dopant and the second dopant may be about 1 wt% to 30 wt% to emit blue light. The second dopant may be a fluorescent material (compound). In this case, the luminous efficiency and color purity can be further improved.

The singlet energy level of the first dopant (space charge transfer compound) is greater than the singlet energy level of the second dopant. The first dopant has a triplet energy less than the triplet energy level of the host and greater than the triplet energy level of the second dopant.

In this case, the triplet energy level of the first dopant (i.e., the space charge transfer compound of the present disclosure) may be less than the triplet energy level of the host and greater than the triplet energy level of the second dopant. Further, a difference between the singlet energy level of the first dopant and the triplet energy level of the first dopant is less than 0.3 eV. (Δ E)_STLess than or equal to 0.3eV) with a difference of: "Delta E_STThe smaller the "the higher the luminous efficiency. In the space charge transfer compound of the present disclosure, even if the difference "Δ E" between the singlet energy level of the dopant and the triplet energy level of the dopant_ST"about a relatively large 0.3eV, singlet exciton" S₁"and triplet exciton" T₁"can also be converted into an intermediate state" I₁”。

As described above, in the space charge transfer compound of the present disclosure, since the electron donor moiety and the electron acceptor moiety are bonded to the biphenyl nucleus in one molecule, the overlap between the HOMO and the LUMO is reduced, and thus the space charge transfer compound of the present disclosure acts as a charge transfer complex, so that the light emission efficiency of the compound is improved. That is, in the space charge transfer compound of the present disclosure, the triplet excitons participate in light emission, so that the light emission efficiency of the compound is improved.

Since the electron donor moiety and the electron acceptor moiety are bonded to the 2-and 2' -positions of the biphenyl nucleus, respectively, the gap or distance between the electron donor moiety and the electron acceptor moiety is reduced or minimized. Accordingly, charge transfer is directly generated via a space between the electron donor moiety and the electron acceptor moiety, so that the conjugation length in the space charge transfer compound becomes shorter than that in another compound in which charge transfer is generated through a bonding orbit. As a result, the red shift problem in light emission can be prevented, and the space charge transfer compound of the present disclosure can provide deep blue light emission.

As a result, the OLED and organic light emitting display device including the space charge transfer compound have high light emitting efficiency and life span and provide high quality images.

fig. 9 is a schematic cross-sectional view of an Organic Light Emitting Diode (OLED) according to the present disclosure.

As shown in fig. 9, the organic light emitting diode D includes a first electrode 160 and a second electrode 164 facing each other with an organic light emitting layer 162 therebetween. The organic emission layer 162 includes an EML 340, an HTL 320, and an ETL 360, wherein the EML 340 includes a first layer 342 and a second layer 344 and is positioned between the first electrode 160 and the second electrode 164, the HTL 320 is positioned between the first electrode 160 and the EML 340, and the ETL 360 is positioned between the second electrode 164 and the EML 340.

In addition, the organic light emitting layer 162 may further include an HIL 310 between the first electrode 160 and the HTL 320 and an EIL 370 between the second electrode 164 and the ETL 360.

In addition, the organic light emitting layer 162 may further include an EBL 330 between the HTL 320 and the EML 340 and an HBL 350 between the EML 340 and the ETL 360.

In the EML 340, one of the first layer 342 and the second layer 344 includes a space charge transfer compound of the present disclosure as a dopant, and the other of the first layer 342 and the second layer 344 includes a fluorescent material as a dopant. The singlet energy level of the space charge transfer compound is greater than the singlet energy level of the fluorescent material.

an organic light emitting diode will be explained in which the first layer 342 includes a space charge transfer compound and the second layer 344 includes a fluorescent dopant.

In the organic light emitting diode D, the singlet state energy level and the triplet state energy level of the space charge transfer compound are transferred into the fluorescent material, so that light emission is generated from the fluorescent material. Accordingly, the quantum efficiency of the organic light emitting diode D increases, and the full width at half maximum (FWHM) of the organic light emitting diode D becomes narrow.

Space charge transfer compounds with delayed fluorescence properties have high quantum efficiency. However, since light emitted from the space charge transfer compound has a wide FWHM, light from the space charge transfer compound has poor color purity. On the other hand, the fluorescent material has a narrow FWHM and a high color purity. However, since the triplet level of the fluorescent material does not participate in light emission, the fluorescent material has low quantum efficiency.

since the EML 340 of the organic light emitting diode D in the present disclosure includes the first layer 342 and the second layer 344, wherein the first layer 342 includes a space charge transfer compound as a dopant and the second layer 344 includes a fluorescent material as a dopant, the organic light emitting diode D has advantages in both light emitting efficiency and color purity.

The triplet level of the space charge transfer compound is converted into the singlet level of the space charge transfer compound by an inter-system crossover (RISC) effect, and the singlet level of the space charge transfer compound is converted into the singlet level of the fluorescent material. That is, the difference between the triplet level of the space charge transfer compound and the singlet level of the space charge transfer compound is less than 0.3eV, so that the triplet level of the space charge transfer compound is converted into the singlet level of the space charge transfer compound by the RISC effect.

As a result, the space charge transfer compound has an energy transfer function, and the first layer 342 including the space charge transfer compound does not participate in light emission. Luminescence is generated in the second layer 344 comprising a fluorescent material.

The triplet level of the space charge transport compound is converted to the singlet level of the space charge transport compound by the RISC effect. In addition, since the singlet energy level of the space charge transfer compound is higher than that of the fluorescent material, the singlet energy level of the space charge transfer compound is converted into that of the fluorescent material. As a result, the fluorescent material emits light using the singlet level and the triplet level, so that the quantum efficiency (light emitting efficiency) of the organic light emitting diode D is improved.

In other words, the organic light emitting diode D and the OLED device 100 (of fig. 7) including the organic light emitting diode D have advantages in both light emitting efficiency and color purity.

The first and second layers 342, 344 can also include first and second bodies, respectively. The weight percentages of the first host and the second host may be greater than the weight percentages of the space charge transfer compound and the fluorescent material, respectively. In addition, the weight percentage of the space charge transfer compound in the first layer 342 may be greater than the weight percentage of the fluorescent material in the second layer 344. As a result, energy transfer from the space charge transfer compound into the second layer 344 is sufficiently generated.

The singlet energy level of the first host is greater than the singlet energy level of the space charge transfer compound (first dopant) and the triplet energy level of the first host is greater than the triplet energy level of the space charge transfer compound. Further, the singlet energy level of the second host is greater than the singlet energy level of the fluorescent material (second dopant).

When this condition is not satisfied, quenching occurs at the first and second dopants or energy transfer from the host to the dopants does not occur, and thus the quantum efficiency of the organic light emitting diode D is reduced.

For example, the second host included in the second layer 344 having a fluorescent material may be the same material as the HBL 350. In this case, the second layer 344 may have a hole blocking function with a light emitting function. That is, the second layer 344 may function as a buffer layer for blocking holes. When the HBL 350 is omitted, the second layer 344 functions as a light emitting layer and a hole blocking layer.

When the first layer 342 includes a fluorescent dopant and the second layer 344 includes a space charge transfer compound, the first body of the first layer 342 may be the same as the material of the EBL 330. In this case, the first layer 342 may have an electron blocking function with a light emitting function. That is, the first layer 342 may function as a buffer layer for blocking electrons. When the EBL 330 is omitted, the first layer 342 functions as a light emitting layer and an electron blocking layer.

Fig. 10 is a schematic cross-sectional view of an Organic Light Emitting Diode (OLED) according to the present disclosure.

As shown in fig. 10, the organic light emitting diode D includes a first electrode 160 and a second electrode 164 facing each other with an organic light emitting layer 162 therebetween. The organic emission layer 162 includes an EML 440, an HTL420, and an ETL 460, wherein the EML 440 includes a first layer 442, a second layer 444, and a third layer 446 and is positioned between the first electrode 160 and the second electrode 164, the HTL420 is positioned between the first electrode 160 and the EML 440, and the ETL 460 is positioned between the second electrode 164 and the EML 440.

In addition, the organic light emitting layer 162 may further include an HIL 410 between the first electrode 160 and the HTL420 and an EIL 470 between the second electrode 164 and the ETL 460.

In addition, the organic light emitting layer 162 may further include an EBL 430 between the HTL420 and the EML 440 and an HBL 450 between the EML 440 and the ETL 460.

In the EML 440, the first layer 442 is located between the second layer 444 and the third layer 446. That is, the second layer 444 is located between the EBL 430 and the first layer 442, and the third layer 446 is located between the first layer 442 and the HBL 450.

The first layer 442 (e.g., a first emitting material layer) may include a space charge transfer compound of the present disclosure as a dopant, and each of the second layer 344 (e.g., a second emitting material layer) and the third layer 446 (e.g., a third emitting material layer) may include a fluorescent material as a dopant. The fluorescent materials in the second and third layers 444, 446 may be the same or different. The space charge transfer compound has a singlet energy level greater than that of the fluorescent material.

In the organic light emitting diode D, the singlet energy level and the triplet energy level of the space charge transfer compound in the first layer 442 are transferred into the fluorescent material in the second layer 444 and/or the third layer 446, so that light emission is generated by the fluorescent material. As a result, the quantum efficiency of the OLED D increases, and the FWHM of the OLED narrows.

The first to third layers 442, 444 and 446 may further include first to third bodies, respectively. The first body to the third body are the same material or different materials. For example, each of the first body to the third body may be selected from the materials of formula 10.

In each of the first to third layers 442, 444, and 446, the first to third hosts may have a weight percentage greater than the space charge transfer compound and the fluorescent material, respectively. Further, the weight percentage of the space charge transfer compound (i.e., the first dopant) in the first layer 442 may be greater than the weight percentage of each of the fluorescent material (i.e., the second dopant) in the second layer 444 and the fluorescent material (i.e., the third dopant) in the third layer 446.

The singlet energy level of the first host is greater than the singlet energy level of the space charge transfer compound and the triplet energy level of the first host is greater than the triplet energy level of the space charge transfer compound. Further, the singlet energy level of the second host is greater than that of the fluorescent material in the second layer 444, and the singlet energy level of the third host is greater than that of the fluorescent material in the third layer 446.

For example, the second body in second layer 444 may be the same material as EBL 430. In this case, the second layer 444 may have an electron blocking function with a light emitting function. That is, the second layer 444 may function as a buffer layer for blocking electrons. When the EBL 430 is omitted, the second layer 444 functions as a light emitting layer and an electron blocking layer.

The third body in the third layer 446 may be the same material as the HBL 450. In this case, the third layer 446 may have a hole blocking function with a light emitting function. That is, the third layer 446 may function as a buffer layer for blocking holes. When the HBL 450 is omitted, the third layer 446 functions as a light-emitting layer and a hole-blocking layer.

The second body in the second layer 444 may be the same material as the EBL 430 and the third body in the third layer 446 may be the same material as the HBL 450. In this case, the second layer 444 may have an electron blocking function with a light emitting function, and the third layer 446 may have a hole blocking function with a light emitting function. That is, the second layer 444 may function as a buffer layer for blocking electrons, and the third layer 446 may function as a buffer layer for blocking holes. When the EBL 430 and the HBL 450 are omitted, the second layer 444 functions as a light-emitting layer and an electron blocking layer, and the third layer 446 functions as a light-emitting layer and a hole blocking layer.

It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the embodiments of the invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.