WO2018186356A1

WO2018186356A1 - Organic electroluminescent element, illumination device, display device, and transition metal complex

Info

Publication number: WO2018186356A1
Application number: PCT/JP2018/014132
Authority: WO
Inventors: 西関　雅人; 山田　哲也; 康生宮田
Original assignee: コニカミノルタ株式会社
Priority date: 2017-04-04
Filing date: 2018-04-02
Publication date: 2018-10-11
Also published as: JPWO2018186356A1

Abstract

A problem to be solved by the present invention is to provide, as a blue phosphorescence element, an organic electroluminescent element that has a high light emission efficiency, a low driving voltage, and excellent durability while having sufficiently short wave emitted light. In addition, another problem to be solved by the present invention is to provide an illumination device and a display device equipped with the organic electroluminescent element. Furthermore, another problem to be solved by the present invention is to provide a phosphorescent light-emitting transition metal complex that enables the foregoing to be realized, an organic electroluminescent element material that contains the phosphorescent light-emitting metal complex, and an organic electroluminescent element material composition. This organic electroluminescent element contains a phosphorescent light-emitting transition metal complex in at least one of organic layers including a light-emitting layer. The organic electroluminescent element is characterized in that the transition metal complex includes a ligand in which a plurality of aromatic rings are directly bonded to a transition metal serving as a center metal, and the ligand satisfies two specific requirements.

Description

Organic electroluminescence element, lighting device, display device, and transition metal complex

The present invention relates to an organic electroluminescent element, an illumination device, a display device, a transition metal complex, an organic electroluminescent element material, and an organic electroluminescent element material composition, and more particularly, has a sufficiently short-wave emission as a blue phosphorescent element. However, the present invention relates to an organic electroluminescence element and the like having high luminous efficiency, low driving voltage, and excellent durability.

Conventionally, as a light-emitting electronic display device, there is an electroluminescence display (ELD). As a constituent element of ELD, an inorganic electroluminescence element and an organic electroluminescence element (hereinafter also referred to as an organic EL element) can be given. Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

On the other hand, an organic EL element has a configuration in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer to recombine excitons. It is an element that emits light by utilizing the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Therefore, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it is attracting attention from the viewpoints of space saving and portability.

Develop organic EL elements for practical use, for example, Princeton University A. Baldo et al. , Nature, 395, pages 151 to 154 (1998), an organic EL device using phosphorescence emission from an excited triplet has been reported. Since then, US Pat. No. 6,097,147 has been disclosed. , M.C. A. Baldo et al. , Nature, 403, 17, 750-753 (2000), and the like, research on materials that exhibit phosphorescence at room temperature has become active.

Organic EL elements that use phosphorescence emission can in principle achieve light emission efficiency about 4 times that of elements that use previous fluorescence emission. Research and development of electrodes and electrodes are conducted all over the world.

As a material constituting a light-emitting element, many compounds have been studied focusing on heavy metal complexes such as iridium complexes. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001) describe that these metal complexes are used in a light-emitting layer of an organic electroluminescence element (also referred to as an organic EL element).

As described above, the phosphorescence emission method is a method having a very high potential, but in an organic EL device using phosphorescence emission, a method for controlling the position of the emission center, in particular, recombination inside the emission layer, How to stably emit light and how to improve the light emitting property of the phosphorescent material itself is an important technical issue from the viewpoint of the efficiency and life of the device.

As luminescent materials for blue phosphorescence used in organic EL devices, iridium complexes having ligands such as phenylpyrazole, imidazophenanthridine, and phenylimidazole are known. It is very difficult to satisfy all of light emission and high durability at the same time.

It has been disclosed that a metal complex having phenylimidazole as a ligand is a light emitting material having a relatively short emission wavelength (see, for example, Patent Document 1 and Patent Document 2).

In the technologies described in these patent documents, in order to improve the luminescent property and the luminescent lifetime at the same time, we are considering expanding the π-conjugated system in the substituent to the imidazole ring. Thus, it has not been possible to obtain a dopant having a short wavelength of light emission, a high emission property, and a long emission life at the same time.

US Patent Application Publication No. 2011/0057559 US Patent Application Publication No. 2011/0204333

The present invention has been made in view of the above-described problems and situations, and the problem to be solved is that the light emission efficiency is high, the driving voltage is low, and the durability is high, while having a sufficiently short-wave emission as a blue phosphorescent element. It is to provide an excellent organic electroluminescence device. Moreover, it is providing the illuminating device and display apparatus with which it was comprised. Furthermore, it is providing the phosphorescence-emitting transition metal complex which can make it possible, the organic electroluminescent element material containing the said phosphorescent metal complex, and organic electroluminescent element material composition.

It was well known that the emission wavelength was shortened by introducing an electron-withdrawing substituent into the phenylimidazole skeleton of a metal complex having phenylimidazole as a ligand, but this emission wavelength was shortened. When a light-emitting device using a metal complex as a light-emitting dopant is produced, the light-emitting device is energized even though the light-emitting quantum efficiency (PLQE; light-emitting efficiency by photoexcitation) of the dopant alone measured in a solution state or a solid state is good. It has been found that the luminous efficiency (EQE; external extraction quantum efficiency) is not as high as expected.

As a result of detailed analysis of this problem, it was found that the energy level of the molecular orbital of the metal complex was greatly reduced by the electron-withdrawing group introduced for shortening the wave length, so that the adjacent hole transport layer The level difference between the highest occupied orbital (hereinafter also referred to as HOMO) of the host material in which the metal complex is dispersed in the hole transport material or the light emitting layer and the HOMO level of the metal complex is enlarged. As a result, it was found that the movement of holes from the hole transporting material and the host material was hindered, and as a result, the probability of exciton generation on the dopant was significantly reduced. In the present application, when the energy level is low, the level is deep, and when the energy level is high, the level is also shallow.

By introducing a specific hole-transporting group into the phenylimidazole skeleton of a metal complex having an electron-withdrawing group, using phenylimidazole as a ligand, without continuing a conjugated system, Without greatly changing the emission wavelength, the hole injection into the dopant is promoted, the emission efficiency is improved, and the lifetime deterioration due to the inflow of excess holes to the adjacent layer of the emission layer, which causes the emission lifetime to decrease, is improved. Various complexes were examined under the focus of improvement.

As a result of the study, the introduction of the specific hole-transporting substituent disclosed in the present invention promotes hole injection into the light-emitting dopant, and exciton generation due to charge recombination on the metal complex occurs. The light emission efficiency is improved by being promoted, and at the same time, the emission lifetime of the light emitting element can be extended by suppressing the inflow of excessive holes to the adjacent layer of the light emitting layer, which causes a decrease in the light emission lifetime. .

The present inventors examined the expansion of applicability of the technical idea of the present invention, and not only a metal complex having phenylimidazole as a ligand, but also a transition having a partial structure represented by the following general formula (2) It has been found that the same effects can be obtained in general metal complexes, and it has been found that the above-mentioned problems can be solved by an organic electroluminescence element containing a phosphorescent transition metal complex represented by the general formula (1).

Furthermore, the present inventors have examined the expansion of applicability of the technical idea of the present invention, and are directly bonded to the transition metal as well as the transition metal complex having the partial structure represented by the general formula (2). If the aromatic ring satisfies two specific requirements, the same effect can be obtained for all phosphorescent transition metal complexes consisting of a central metal and a plurality of aromatic ring ligands directly bonded to the central metal. I found out that

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. An organic electroluminescence device containing a phosphorescent transition metal complex in at least one organic layer including a light emitting layer,
The transition metal complex has a ligand in which a plurality of aromatic rings are directly bonded to a transition metal as a central metal, and satisfies the following requirements (1) and (2): Electroluminescence element.
(1) At least one of the plurality of aromatic rings directly bonded to the transition metal has an electron withdrawing group.
(2) At least one of the plurality of aromatic rings directly bonded to the transition metal is a positive chain containing a nitrogen atom and an aromatic ring which are conjugated with the aromatic ring and are connected by a single bond. It has a pore transporting partial structure.

2. When the transition metal complex is evaluated by molecular orbital calculation, any one of the binding orbitals from the highest occupied orbital (HOMO) to the fifth lower energy level (HOMO-5) is the binding orbital. The absolute value of the difference between the energy level of the highest occupied orbital and the binding orbital has an electron density distribution in which 80% or more of the upper electrons exist on the hole transporting partial structure 2. The organic electroluminescence device according to item 1, wherein the organic electroluminescence device is less than 0.7 eV.

3. The absolute value of the difference in emission maximum wavelength calculated by molecular orbital calculation for each of the transition metal complex and the transition metal complex having a structure obtained by removing the hole transporting partial structure from the transition metal complex is 10 nm or less. 3. The organic electroluminescence device according to item 1 or 2, characterized in that it exists.

4. The hole transporting partial structure containing a nitrogen atom and an aromatic ring each may be an unsubstituted or substituted diarylamino group, carbazol-9-yl group, phenoxazin-10-yl group, Item 4. The organic electroluminescence device according to any one of Items 1 to 3, which is selected from a phenothiazin-10-yl group, a dihydrophenazin-5-yl group, and a dihydroacridin-10-yl group. .

5. Any one of Items 1 to 4, wherein the electron-withdrawing group is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. The organic electroluminescent element according to claim 1.

6. 6. The organic electroluminescence device according to any one of items 1 to 5, wherein at least one of the plurality of aromatic rings directly bonded to the transition metal is an azole ring.

7. The organic electroluminescence according to any one of items 1 to 6, wherein at least one of the plurality of aromatic rings directly bonded to the transition metal is an imidazole ring or a triazole ring. element.

8. An organic luminescence device having at least one organic layer including a light emitting layer, wherein at least one of the organic layers contains a transition metal complex represented by the following general formula (1): The organic electroluminescent element according to any one of items 1 to 7.

General formula (1)
ML _A · L _B · (L _C ) n
[Wherein, ML _A represents a partial structure represented by the following general formula (2), and M represents a transition metal of group 8 to 10 in the periodic table of elements. L _A to L _C each represents a divalent ligand, and L _A to L _C may be the same or different, and may be bonded to each other. n represents 1 or 0. ]

[Where,
Ring B represents a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed with C═C.
Ring C represents a 5- or 6-membered aromatic heterocyclic ring formed with C═N.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents an integer of 0 to 2. 1 ≦ nb + nc ≦ 4. When there are a plurality of Rb and Rc, they may be the same or different from each other.
HTG represents a hole transporting partial structure including a nitrogen atom and an aromatic ring.
L represents an arylene group having 6 to 10 carbon atoms, and L is bonded to ring B or ring C, but conjugation with ring B or ring C is not continuous. n1 represents 1 or 2. n2 represents 1 or 2. When there are a plurality of L, they may be the same or different.
M represents a transition metal of group 8 to 10 in the periodic table. ]
9. Each of the hole transporting partial structures containing a nitrogen atom and an aromatic ring represented by HTG may be an unsubstituted or substituted diarylamino group, carbazol-9-yl group, phenoxazine- 9. The organic electroluminescence device according to item 8, which is selected from a 10-yl group, a phenothiazin-10-yl group, a dihydrophenazin-5-yl group and a dihydroacridin-10-yl group.

10. Item 8. The electron-withdrawing group represented by Rb and Rc is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. Or the organic electroluminescent element of Claim 9.

11. Item 11. The organic electroluminescence device according to any one of Items 8 to 10, wherein the aromatic heterocycle represented by the ring C represents an azole ring.

12. Item 12. The organic electroluminescent element according to any one of Items 8 to 11, wherein the aromatic heterocycle represented by the ring C represents an imidazole ring or a triazole ring.

13. 9. The organic electroluminescence device according to item 8, wherein the partial structure represented by the general formula (2) is represented by a partial structure represented by the following general formula (3).

[Where,
Ring A represents a divalent arylene group having 6 to 10 carbon atoms.
Ring B represents a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed with C═C.
Ring C represents a 5-membered aromatic heterocycle formed with N—C═N.
Ra represents a substitutable substituent. na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1.
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents any of 4, 5 and 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent. ]
14 9. The organic electroluminescent element according to item 8, wherein the partial structure represented by the general formula (2) is a partial structure represented by the following general formula (4).

[Where,
Y ₁ and Y ₂ represent a carbon atom or a nitrogen atom.
Ring C represents a 5-membered aromatic heterocycle formed with N—C═N.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing substituent that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ each represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1;
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ , Ar ₆ each represents an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent. ]
15. 9. The organic electroluminescent element according to item 8, wherein the partial structure represented by the general formula (2) is represented by a partial structure represented by the following general formula (5).

[Where,
One of X ₁ and X ₂ represents a carbon atom, and the other represents a nitrogen atom.
Y ₁ and Y ₂ represent a carbon atom or a nitrogen atom.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1.
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent. ]
16. 9. The organic electroluminescence device according to item 8, wherein the partial structure represented by the general formula (2) is represented by a partial structure represented by the following general formula (6).

[Where,
Y ₁ and Y ₂ represent a carbon atom or a nitrogen atom.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1.
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ , and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom, and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent. ]
17. Item 13 wherein the electron withdrawing group represented by Rb and Rc is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. The organic electroluminescent element according to any one of items 1 to 16.

18. 18. The organic electroluminescence element according to any one of items 1 to 17, wherein the transition metal is iridium.

19. In the light emitting layer, a fluorene derivative, a dibenzofuran derivative, a dibenzothiophene derivative, a carbazole derivative, or a compound in which at least one carbon atom of a hydrocarbon ring constituting these condensed ring compound derivatives is substituted with a nitrogen atom, and The organic electroluminescence device according to any one of items 1 to 18, wherein a combination thereof is contained as a host material.

20. 20. The organic electroluminescence device according to any one of items 1 to 19, wherein the organic layer containing the phosphorescent transition metal complex is a coating formation layer.

21. 21. A display device comprising the organic electroluminescence element according to any one of items 1 to 20.

22. An organic electroluminescence device according to any one of items 1 to 20 is provided.

23. A phosphorescent transition metal complex having a ligand in which a plurality of aromatic rings are directly bonded to a transition metal as a central metal, characterized by satisfying the following four requirements Complex.
(1) At least one of the plurality of aromatic rings directly bonded to the transition metal has an electron withdrawing group.
(2) At least one of the plurality of aromatic rings directly bonded to the transition metal is a positive chain containing a nitrogen atom and an aromatic ring which are conjugated with the aromatic ring and are connected by a single bond. It has a hole transporting partial structure.
(3) In the evaluation by molecular orbital calculation, one of the binding orbitals from the highest occupied orbital (HOMO) to the fifth lower energy level (HOMO-5) is an electron on the binding orbital. 80% or more has an electron density distribution existing on the hole transporting partial structure, and the absolute value of the difference between the energy level of the highest occupied orbital and the binding orbital is 0. (4) Difference in emission maximum wavelength calculated by molecular orbital calculation for each of the transition metal complex and the transition metal complex having a structure obtained by removing the hole transporting partial structure from the transition metal complex The absolute value of is 10 nm or less 24. An organic electroluminescent element material comprising the transition metal complex according to item 23.

25. An organic electroluminescent element material composition comprising the transition metal complex according to item 23.

By the above means of the present invention, it is possible to provide an organic electroluminescence device having high emission efficiency, low driving voltage and excellent durability while having sufficiently short-wave light emission as a blue phosphorescent device. In addition, a lighting device and a display device including the same can be provided. Furthermore, the phosphorescent transition metal complex which can make it possible, the organic electroluminescent element material and organic electroluminescent element material composition containing the said phosphorescent metal complex can be provided.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

By introducing an electron-withdrawing group into the aromatic ring directly bonded to the central metal of the metal complex, the emission wavelength can be shortened. By introducing a hole transporting group, it is considered that the emission wavelength can be suppressed and the hole injection into the dopant can be promoted. For this reason, it is considered that the light emission efficiency can be improved, the life deterioration due to excessive inflow of holes into the adjacent layer of the light emitting layer, which causes the light emission life to be reduced, can be improved, and the driving voltage can be kept low.

Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of the display unit of the display device of FIG. 1 is a circuit diagram of a pixel of the display device of FIG. Schematic diagram of a passive matrix display device Schematic of lighting device Cross section of the lighting device

The organic electroluminescence device of the present invention is an organic electroluminescence device containing a phosphorescent transition metal complex in at least one organic layer including a light emitting layer, wherein the transition metal complex is a central metal. It has a ligand in which a plurality of aromatic rings are directly bonded to the transition metal, and satisfies the requirements (1) and (2). This feature is a technical feature common to or corresponding to the claimed invention.

As an embodiment of the present invention, from the viewpoint of manifesting the effect of the present invention, the transition metal complex has a lower energy level (HOMO-5) lower than the highest occupied orbital (HOMO) in the evaluation by molecular orbital calculation. ) Have an electron density distribution in which 80% or more of the electrons on the bonding orbital exist on the hole transporting partial structure, and the highest occupied space The absolute value of the difference between the energy level of the orbit and the binding orbit is preferably less than 0.7 eV.

In addition, the absolute value of the difference in emission maximum wavelength calculated by molecular orbital calculation for each of the transition metal complex and the transition metal complex having a structure obtained by removing the hole transporting partial structure from the transition metal complex is 10 nm. The following is preferable.

Further, in the present invention, the hole transporting partial structure containing a nitrogen atom and an aromatic ring may be an unsubstituted or substituted diarylamino group, carbazol-9-yl group, phenoxy group, respectively. It is preferably selected from a sadin-10-yl group, a phenothiazin-10-yl group, a dihydrophenazin-5-yl group and a dihydroacridin-10-yl group.

In addition, the electron withdrawing group is preferably selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group.

In addition, it is preferable that at least one of the plurality of aromatic rings directly bonded to the transition metal is an azole ring.

Furthermore, in the present invention, it is preferable that at least one of the plurality of aromatic rings directly bonded to the transition metal is an imidazole ring or a triazole ring.

An embodiment of the present invention is an organic luminescence device having at least one organic layer including a light emitting layer, from the viewpoint of manifesting the effects of the present invention, wherein at least one of the organic layers is represented by the general formula (1). It is preferable to contain the transition metal complex represented by these.

That is, among the transition metal complexes satisfying the requirements of the present invention, the phosphorescent transition metal complex having the partial structure represented by the general formula (2) is easy to synthesize the ligand constituting the transition metal complex. From the viewpoints of the properties and ease of synthesis of the transition metal complex.

In addition, each of the hole transporting partial structures containing a nitrogen atom and an aromatic ring represented by HTG may be an unsubstituted or substituted diarylamino group, carbazol-9-yl group, phenoxy group. It is preferably selected from a sadin-10-yl group, a phenothiazin-10-yl group, a dihydrophenazin-5-yl group and a dihydroacridin-10-yl group.

In the present invention, the electron withdrawing group represented by Rb and Rc is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. Is preferred.

In the phosphorescent transition metal complex having the partial structure represented by the general formula (2), ring C is a 5-membered nitrogen-containing heteroaromatic ring having 3 or less nitrogen atoms from the viewpoint of robustness of the compound. It is preferable. That is, ring C is preferably an azole ring. More preferably, it is an imidazole ring or a triazole ring.

In the phosphorescent transition metal complex having the partial structure represented by the general formula (2), from the viewpoint of fastness of the compound, the ring C is preferably an azole ring, and more specifically, The phosphorescent transition metal complex represented by the formula (2) is preferably a phosphorescent transition metal complex having a partial structure represented by the general formula (3).

Specifically, the phosphorescent transition metal complex represented by the general formula (1) is a phosphorescent transition metal complex having a partial structure represented by the general formula (3). preferable.

In the phosphorescent organometallic complex having the partial structure represented by the general formula (2) or the general formula (3), the ring B is a 6-membered aromatic from the viewpoint of luminescence and fastness of the compound. It is preferably a hydrocarbon ring or a nitrogen-containing heteroaromatic ring. That is, the phosphorescent transition metal complex having the partial structure represented by the general formula (2) or (3) is the phosphorescent transition metal complex having the partial structure represented by the general formula (4). A metal complex is preferred.

Specifically, the phosphorescent transition metal complex represented by the general formula (1) is a phosphorescent transition metal complex having a partial structure represented by the general formula (4). preferable.

More preferably, the phosphorescent transition metal complex having the partial structure represented by the general formula (4) is phosphorescent having the partial structure represented by either the general formula (5) or (6). A luminescent transition metal complex is preferred.

In the general formulas (3) to (6), the electron-withdrawing group represented by Rb and Rc is a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, or a fluorinated group. It is preferably selected from alkyl groups.

The transition metal is preferably iridium.

Further, in the light emitting layer, a fluorene derivative, a dibenzofuran derivative, a dibenzothiophene derivative, a carbazole derivative, or a compound in which at least one carbon atom of a hydrocarbon ring constituting these condensed ring compound derivatives is substituted with a nitrogen atom, And it is preferable to contain these combinations as a host material.

Furthermore, it is preferable that the organic layer containing the phosphorescent transition metal complex is a coating formation layer because a homogeneous film is easily obtained and pinholes are hardly generated.

The organic EL element of the present invention can be suitably included in a lighting device and a display device.

As an embodiment of the present invention, the transition metal complex of the present invention is a phosphorescent transition metal complex having a ligand in which a plurality of aromatic rings are directly bonded to a transition metal as a central metal, It is preferable to satisfy the four requirements (1) to (4).

Furthermore, the phosphorescent transition metal complex of the present invention can be preferably used as a material for an organic electroluminescence element.

Moreover, the composition containing the phosphorescent transition metal complex of the present invention can be preferably used as a material composition for an organic electroluminescence device.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<< Organic electroluminescence device of the present invention >>
The organic electroluminescence device of the present invention is an organic electroluminescence device containing a phosphorescent transition metal complex in at least one organic layer including a light emitting layer, wherein the transition metal complex is a central metal. It has a ligand in which a plurality of aromatic rings are directly bonded to a transition metal, and satisfies the following requirements (1) and (2).
(1) At least one of the plurality of aromatic rings directly bonded to the transition metal has an electron withdrawing group.
(2) At least one of the plurality of aromatic rings directly bonded to the transition metal is a positive chain containing a nitrogen atom and an aromatic ring which are conjugated with the aromatic ring and are connected by a single bond. It has a hole transporting partial structure.

That is, as a basic requirement of the present invention, in the phosphorescent transition metal complex, at least one of a plurality of aromatic rings directly bonded to the transition metal has an electron-withdrawing group, whereby the transition metal The triplet excitation energy of the complex is expanded, and the wavelength of phosphorescence emission accompanying triplet transition is shortened.

On the other hand, as the phosphorescence emission wavelength is shortened by introducing an electron-withdrawing group, the energy level of the highest occupied orbital (HOMO) of the transition metal complex is lowered, so that adjacent hole transport is performed. The difference in level between the HOMO level of the host material in which the transition metal complex is dispersed in the hole transport material of the layer and the light emitting layer and the HOMO level of the transition metal complex has expanded. As a result, the movement of holes from the hole transport material or the host material is inhibited, and as a result, the generation probability of excitons on the transition metal complex is significantly reduced, which may cause a decrease in luminous efficiency. It becomes a problem.

The essential requirement for promoting the movement of holes to the transition metal complex and restoring the light emission efficiency is that at least one of the plurality of aromatic rings directly bonded to the transition metal is the aromatic ring. And having a hole transporting partial structure containing a nitrogen atom and an aromatic ring connected by a single bond.

Conventionally, it has been attempted to introduce a hole transporting partial structure containing a nitrogen atom and an aromatic ring into a transition metal as a substituent, but in the present invention, it is introduced for shortening the wave length. In many cases, the effects of the electron withdrawing group are contradictory to each other, and a desired result cannot be obtained by simple combination.

In the present invention, when the hole transporting partial structure containing a nitrogen atom and an aromatic ring is bonded to at least one of the plurality of aromatic rings directly bonded to the transition metal, the aromatic In the state where the conjugation with the ring is broken, by connecting to the nitrogen atom by a single bond, we succeeded in minimizing the side effects caused by introducing a hole transporting partial structure.

The characteristics common to the transition metal complexes satisfying the constituent requirements of the present invention can be confirmed by molecular orbital calculation. The following common features were confirmed by detailed analysis of the electron orbital of the transition metal complex of the present invention by molecular orbital calculation. Here, the molecular orbital calculation method used was calculated by using Gaussian09, which is molecular orbital calculation software manufactured by Gaussian, USA, and performing structural optimization using B3LYP / LANL2DZ as a keyword.

When the molecular orbital calculation of the transition metal complex of the present invention is performed and the calculated molecular orbital is examined in detail, from the highest occupied orbital (HOMO) to the fifth lowest energy level (HOMO-5) of the transition metal complex. In any one of the bonding orbitals, there is an orbit having an electron density distribution in which 80% or more of the electrons on the bonding orbitals exist on the hole transporting partial structure, and Looking at the absolute value of the difference between the energy level of the highest occupied orbit (HOMO-x: x is one of 1 to 5), it can be confirmed that both are less than 0.7 eV. It was.

On the other hand, when a similar analysis is performed on other transition metal complexes that have a hole transporting partial structure but do not satisfy the constituent requirements of the present invention, they are also the highest occupied orbitals of the transition metal complexes. (HOMO) The electron density distribution in which at least 60% of the electrons on the bonding orbitals are present on the hole transporting partial structure in any one of the bonding orbitals of the lower energy level. Although there are orbits having the above, they were all 0.9 eV or more in terms of the absolute value of the difference between the energy level of the highest occupied orbit and the binding orbit.

That is, the absolute value of the difference between the energy level of the highest occupied orbital and the binding orbital among the binding orbitals of the lower energy level from the highest occupied orbital (HOMO) of the transition metal complex is 0. 80% or more of the electrons in the orbit of less than 0.7 eV are distributed in the hole transporting partial structure, which promotes the movement of holes to the transition metal complex of the present invention and restores the luminous efficiency. Conceivable.

In addition, 80% or more of the electrons of the orbital whose absolute value of the difference between the energy level of the highest occupied orbital (HOMO) and the binding orbital is less than 0.7 eV is distributed in the hole transporting partial structure. As a result, the binding orbital from the highest occupied orbital (HOMO) to the fifth lowest energy level (HOMO-5: HOMO as the first and the sixth binding orbital counting from there) It is thought that it was located in any one of the sex trajectories.

On the other hand, triplet excitation energy of the transition metal complex having the structure except for the hole transporting moiety triplet excitation energy (T ₁₎ from the said transition metal complex of a transition metal complex of the present invention (T ₁ ) Is calculated by molecular orbital calculation, and the triplet excitation energy (T ₁ ) is converted into the emission maximum wavelength (λmax) and compared, the absolute value of the difference between the emission maximum wavelengths is 10 nm or less. Thus, it was confirmed that the increase of the emission wavelength due to the introduction of the hole transporting partial structure was suppressed to be extremely small.

<< Constituent layers of organic EL elements >>
In the present invention, the organic layer refers to a layer containing an organic substance. Hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer constituting organic electroluminescence (hereinafter also referred to as organic EL) provided between the anode and the cathode The constituent layers of the organic EL device of the present invention will be described. In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode (vi) anode / hole transport layer / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (vii) anode / anode buffer Layer / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer / cathode When a plurality of light emitting layers are included, a non-light emitting intermediate layer may be provided between the light emitting layers. In addition, among the above layer structures, an organic compound layer including a light emitting layer excluding an anode and a cathode can be used as one light emitting unit, and a plurality of light emitting units can be stacked. The plurality of stacked light emitting units may have a non-light emitting intermediate layer between the light emitting units, and the intermediate layer may further include a charge generation layer.

The organic EL element of the present invention is preferably a white light emitting layer, and is preferably a lighting device using these. Each layer which comprises the organic EL element of this invention is demonstrated.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light when excitons generated by recombination of electrons and holes injected from the cathode or the electron transport layer or the anode or the hole transport layer are deactivated. The portion to be formed may be in the light emitting layer or at the interface between the light emitting layer and the adjacent layer.

The total thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the stability of the emission color against the driving current and preventing the application of a high voltage unnecessary during the light emission, and the film homogeneity. It is preferably adjusted in the range of 2 nm to 5 μm, more preferably adjusted in the range of 2 to 200 nm, particularly preferably in the range of 5 to 100 nm.

For the production of the light emitting layer, a light emitting dopant or a host material (hereinafter also referred to as a host compound) described later is used, for example, a vacuum deposition method, a wet method (also referred to as a wet process, for example, a spin coating method, a casting method, a die coating method, Blade coating method, roll coating method, ink jet method, printing method, spray coating method, curtain coating method, LB method (Langmuir-Blodgett method and the like can be mentioned)) and the like. can do. Preferably, the light emitting layer is a layer formed through a wet process. By forming the layer by a wet process, damage to the light emitting layer due to heat can be reduced as compared with the vacuum deposition method.

The light emitting layer of the organic EL device of the present invention contains a light emitting dopant and a host compound, and at least one light emitting dopant is a phosphorescent transition metal complex represented by the general formula (1). It is preferable that there is a phosphorescent transition metal complex having a partial structure represented by any one of the general formulas (2) to (6).

In addition, the light-emitting layer according to the present invention may be used in combination with compounds described in the following patent publications.

For example, International Publication No. 00/70655, JP 2002-280178, JP 2001-181616, JP 2002-280179, JP 2001-181617, JP 2002-280180, JP 2001-247859, JP 2002-299060, JP 2001-313178, JP 2002-302671, JP 2001-345183, JP 2002-324679, International publication No. 02/15645, JP 2002-332291 A, JP 2002-50484 A, JP 2002-332292 A, JP 2002-83684 A, JP 2002-540572 A, JP 2002-2002 A. No. 117978, Japanese Patent Laid-Open No. 2002-3385 No. 8, JP-A No. 2002-170684, JP-A No. 2002-352960, WO 01/93642, JP-A No. 2002-50483, JP-A No. 2002-1000047, JP-A No. 2002-173684 Gazette, JP-A-2002-359082, JP-A-2002-175484, JP-A-2002-363552, JP-A-2002-184582, JP-A-2003-7469, JP-T-2002-525808, JP 2003-7471, JP 2002-525833, JP 2003-31366, JP 2002-226495, JP 2002-234894, JP 2002-233506, JP JP 2002-241751 A, JP 2001-31977 A JP, JP 2001-319780, JP 2002-62824, JP 2002-1000047, JP 2002-203679, JP 2002-343572, JP 2002-203678. Etc.

(1) Luminescent dopant As the luminescent dopant, a fluorescent dopant (also referred to as a fluorescent compound) or a phosphorescent dopant (also referred to as a phosphorescent dopant, a phosphorescent compound, a phosphorescent compound, or the like) can be used.

As a result of intensive studies to achieve the above-described object of the present invention, the present inventors have used a phosphorescent transition metal complex represented by the general formula (1) as a phosphorescent dopant, It has been found that a high light emission luminance, a low drive voltage, and a long light emission life can be simultaneously achieved while having a short wavelength, and the present invention has been achieved. Moreover, it turned out that the organic electroluminescent element produced using the phosphorescence dopant of this invention is improved also at the point of temporal stability.

In the phosphorescent transition metal complex represented by the general formula (1) according to the present invention, M is preferably a group 8-10 transition metal in the periodic table.

By changing the combination of the ligands coordinated to the transition metal atom M or introducing a substituent into the ligand, the emission wavelength of the phosphorescent transition metal complex is adjusted to a desired region. Can be controlled.

(1.1) Phosphorescent dopant The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), Although the phosphorescence quantum yield is defined to be a compound of 0.01 or more at 25 ° C., the preferred phosphorescence quantum yield is 0.1 or more.

The phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

There are two types of emission of phosphorescent dopants in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent dopant. It is an energy transfer type to obtain light emission from a phosphorescent dopant. The other is a carrier trap type in which a phosphorescent dopant serves as a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. In any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.

As the phosphorescent dopant in the embodiment of the present invention, a phosphorescent transition metal complex represented by the general formula (1) described below is used.

(1.1.1) Phosphorescent transition metal complex represented by general formula (1) General formula (1)
ML _A · L _B · (L _C ) n
[Wherein, ML _A represents a partial structure represented by the following general formula (2), and M represents a transition metal of group 8 to 10 in the periodic table of elements. L _A to L _C each represents a divalent ligand, and L _A to L _C may be the same or different, and may be bonded to each other. n represents 1 or 0. ]

In general formula (2), ring B represents a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed with C═C.

Examples of the 6-membered aromatic hydrocarbon ring represented by ring B include a benzene ring. Examples of the 5-membered or 6-membered aromatic heterocycle represented by ring B include oxazole ring, pyridine ring, and pyridazine. Ring, pyrimidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, thiadiazole ring, and the like.

In the phosphorescent transition metal complex having the partial structure represented by the general formula (2), ring B is a 6-membered aromatic hydrocarbon ring or a nitrogen-containing compound from the viewpoint of luminescence and fastness of the compound. It is preferably a heteroaromatic ring, and more preferably, ring B is a benzene ring, a pyridine ring, or a pyrimidine ring.

Ring C represents a 5- or 6-membered aromatic heterocycle formed with C═N.
Examples of the 5-membered aromatic heterocycle represented by ring C include a triazole ring, an imidazole ring, and a tetrazole.
Examples of the 6-membered aromatic heterocycle represented by ring C include a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, and a triazine ring.

In the phosphorescent transition metal complex having the partial structure represented by the general formula (2), from the viewpoint of the emission wavelength of the compound, the ring C is preferably a pyridine ring or an azole ring, more preferably An azole ring, more preferably an imidazole ring or a triazole ring.

Rb and Rc represent electron-withdrawing substituents that can be substituted for ring B and ring C, respectively.
Examples of electron withdrawing groups include fluorine atoms, cyano groups, nitro groups, fluorinated alkyl groups such as trifluoromethyl groups, fluorinated aryl groups such as pentafluorophenyl groups, formyl groups, alkylcarbonyl groups, arylcarbonyl Group, carbamoyl group, pentafluorosulfanyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, alkylsulfamoyl group, arylsulfamoyl group, phospheno group, phosphine oxide group, and the like.

In the present invention, the electron withdrawing group is preferably selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group.

Nb represents an integer from 0 to 3, and nc represents an integer from 0 to 2. 1 ≦ nb + nc ≦ 4. When there are a plurality of Rb and Rc, they may be the same or different from each other.

HTG represents a hole transporting partial structure containing a nitrogen atom and an aromatic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, a furan ring, a thiophene ring, a benzofuran ring, and a benzothiophene ring. HTG is preferably a structure composed of nitrogen atoms substituted by two aromatic rings, and the two aromatic rings may be bonded to each other to form a cyclic structure. The connecting part of the two aromatic rings may be directly bonded by a single bond or bonded via an atom selected from an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom. May be. Further, the aromatic ring may be substituted, and examples of the substituent include a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 4 carbon atoms. preferable.

Specifically, diarylamino group, arylheteroarylamino group, bis (heteroarylamino) group, carbazol-9-yl group, phenoxazin-10-yl group, phenothiazin-10-yl group, 5,10-dihydro Examples include phenazin-5-yl group and 9,10-dihydroacridin-10-yl group. These groups may be further substituted.

The following structure can be given as an example of HTG.

In the formula, * represents a binding site with ring B or ring C, which is a ligand part of the transition metal complex, or with linking group L.

L represents an arylene group having 6 to 10 carbon atoms, and L is bonded to ring B or ring C, but conjugation with ring B or ring C is not continuous. In order that conjugation does not continue at the bonding part of L and ring B or ring C, the bonding part of L and ring B or ring C is a single bond, and further, L and ring B or ring sandwich this single bond. The dihedral angle formed by C may be 30 ° or more. Specifically, a substituent may be introduced on two o-position atoms adjacent to the bonding portion between L and ring B or ring C. The dihedral angle becomes larger as the number of substituents to be introduced increases or becomes bulky. As the substituent, an alkyl group or an alkoxy group is preferable, and an alkyl group is more preferable.

Examples of the arylene having 6 to 10 carbon atoms include a phenylene group and a naphthalene group which may be unsubstituted or substituted. As the substituent, a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 4 carbon atoms is preferable. n1 represents 1 or 2. n2 represents 1 or 2. When there are a plurality of L, they may be the same or different.

As preferred examples of the linking group L, linking groups LG-1 to LG-12 are shown below. In the formula, * represents a bonding site with a hole transporting partial structure. # Represents a binding site with the ligand portion of the transition metal complex.

In the formula, * represents a bonding site with the hole transporting partial structure HTG. # Represents a binding site with ring B or ring C which is a ligand part of the transition metal complex.

M represents a transition metal of group 8 to 10 in the periodic table. Examples of the group 8-10 transition metal include iridium, rhodium, osmium, ruthenium, palladium, platinum, and the like. Iridium, palladium, and platinum are preferable, and iridium is most preferable.

In the general formula (1), L _B and L _C represent a monoanionic bidentate ligand coordinated to M. Specific examples of monoanionic bidentate ligands represented by L _B and L _C include ligands of the following formulas.

In said formula, X represents the atom chosen from a nitrogen atom, an oxygen atom, and a sulfur atom. X _A and X _B represent a carbon atom or a nitrogen atom. _A plurality of X _A and X _B present in each ligand may be the same or different from each other.
R ′, R ″ and R ″ ′ each represent a hydrogen atom or a substituent. Examples of the substituent represented by R ′, R ″ and R ″ ′ include, for example, an alkyl group, an alkenyl group, an alkynyl group, Aromatic hydrocarbon ring group, cycloalkoxy group, cycloalkylthio group, non-aromatic heterocyclic group, aromatic hydrocarbon group, aromatic heterocyclic group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkoxycarbonyl group , Aryloxycarbonyl group, sulfamoyl group, acyl group, acyloxy group, amide group, carbamoyl group, ureido group, sulfinyl group, alkylsulfonyl group, arylsulfonyl group or heteroarylsulfonyl group, amino group, halogen atom, fluorinated hydrocarbon Group, cyano group, nitro group, hydroxy group, mercapto group, silyl group, phosphono group, etc. It is.

(1.1.2) A phosphorescent transition metal complex having a partial structure represented by the general formula (3) According to a preferred embodiment of the phosphorescent transition metal complex represented by the general formula (1) One is a phosphorescent transition metal complex in which the partial structure represented by the general formula (2) is a partial structure represented by the following general formula (3).

In general formula (3),
Ring A represents a divalent arylene group having 6 to 10 carbon atoms.
Ring B represents a 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed with C═C.
Ring C represents a 5-membered aromatic heterocycle formed with N—C═N.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc represent electron-withdrawing substituents that can be substituted for ring B and ring C, respectively.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1;
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ each represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r represent 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent.

Examples of the substituent represented by Ra and R ₁ and R ₂ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group). Group, tridecyl group, tetradecyl group, pentadecyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg ethynyl group, propargyl group etc.), non-aromatic hydrocarbon ring group (eg cyclo Alkyl groups (eg, cyclopentyl group, cyclohexyl group, etc.), cycloalkoxy groups (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), cycloalkylthio groups (eg, cyclopentylthio group, cyclohexylthio group, etc.), tetrahydronaphthalene ring, 9 , 10-Dihydroanthracene ring, biphenyle A monovalent group derived from a ring, etc.), a non-aromatic heterocyclic group (for example, epoxy ring, aziridine ring, thiirane ring, oxetane ring, azetidine ring, thietane ring, tetrahydrofuran ring, dioxolane ring, pyrrolidine ring, pyrazolidine ring , Imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring, ε-caprolactone ring, ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran ring 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring, tetrahydrothiopyran ring, thiomorpholine ring, thiomorpholine-1,1-dioxide ring, pyranose ring, diazabicyclo [2,2,2] -octane Ring, phenoxazine , Monovalent group derived from phenothiazine ring, oxanthrene ring, thioxanthene ring, phenoxathiin ring, etc.), aromatic hydrocarbon group (for example, benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene) Ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene Ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, monovalent group derived from anthraanthrene ring, etc.), aromatic heterocyclic group (for example, silole ring, furan ring, thiophene ring, oxazole) Ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine Ring, triazine ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, Consists of carbazole ring, azacarbazole ring (represents any one or more of carbon atoms constituting carbazole ring replaced by nitrogen atom), dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring Rings in which any one or more carbon atoms are replaced by nitrogen atoms, benzodifuran rings, benzodithiophene rings, acridine rings, benzoquinoline rings, phenazine rings, phenanthridine rings, phenanthroline rings, cyclazine rings, quinines Phosphorus ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, A monovalent group derived from an anthradifuran ring, an anthrathiophene ring, an anthradithiophene ring, a thianthrene ring, a phenoxathiin ring, a dibenzocarbazole ring, an indolocarbazole ring, a dithienobenzene ring, etc.), an alkoxy group (for example, , Methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group) , Ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (for example, methyloxycarbonyl group, ethyloxycarbonyl group, Butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, Dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group Group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2- Ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group) , Phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group) Group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, Methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl Group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylurea) Group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group) 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2 -Ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl group, naphthi) Rusulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthyl) Amino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl) Group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), phosphono group and the like.

(1.1.3) A phosphorescent transition metal complex having a partial structure represented by the general formula (4) More preferred embodiment of the phosphorescent transition metal complex represented by the general formula (1) One of them is a phosphorescent transition metal complex in which the partial structure represented by the general formula (2) is a partial structure represented by the following general formula (4).

In general formula (4),
Y ₁ and Y ₂ represent a carbon atom or a nitrogen atom.
Ring C represents a 5-membered aromatic heterocycle formed with N—C═N.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc represent electron-withdrawing substituents that can be substituted for ring B and ring C, respectively.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1;
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ each represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, there is no corresponding Lx, and adjacent Ar rings are not connected to each other. x represents any of 4, 5 and 6.
p, q and r represent 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent.

(1.1.4) Phosphorescent transition metal complex having a partial structure represented by general formula (5) Further preferred embodiment of phosphorescent transition metal complex represented by general formula (1) One of them is a phosphorescent transition metal complex in which the partial structure represented by the general formula (2) is a partial structure represented by the following general formula (5).

In general formula (5),
One of X1 and X2 represents a carbon atom and the other represents a nitrogen atom.
Y ₁ and Y ₂ represent a carbon atom or a nitrogen atom.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc represent electron-withdrawing substituents that can be substituted for ring B and ring C, respectively.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1;
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ each represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ , and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom, and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r represent 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R _{1 and} R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent.

(1.1.5) Further preferred embodiment of phosphorescent transition metal complex having partial structure represented by general formula (6): phosphorescent transition metal complex represented by general formula (1) The other is a phosphorescent transition metal complex in which the partial structure represented by the general formula (2) is a partial structure represented by the following general formula (6).

In general formula (6),
Y ₁ and Y ₂ represent a carbon atom or a nitrogen atom.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc represent electron-withdrawing substituents that can be substituted for ring B and ring C, respectively.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L ₁ , L ₂ and L ₃ represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1;
Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ and Ar ₆ each represent an aromatic group having 6 to 10 carbon atoms.
L ₄ , L ₅ and L ₆ are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r represent 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R ₁ and R ₂ each represent a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ represents a substituent.

The blue phosphorescent transition metal complex according to the present invention will be further described.

(1.1.6) Examples of Molecular Orbital Calculations of Transition Metal Complexes Hereinafter, specific examples of molecular calculations of transition metal complexes represented by the general formula (1) will be described, but the present invention is not limited thereto.

Here, the molecular orbital calculation method to be used was calculated by using Gaussian09, a molecular orbital calculation software manufactured by Gaussian, USA, and performing structure optimization using B3LYP / LANL2DZ as a keyword.

(1.1.6.1) Calculation Example-1
In the compound of Calculation Example 1-a, an electron cloud is distributed in the central metal and the aromatic ring portion directly connected to the central metal in any molecular orbital of HOMO to HOMO-5.

On the other hand, the compound of Calculation Example 1-b, which is a compound obtained by substituting the compound of Calculation Example 1-a with a diphenylamino group as a hole transporting partial structure, is HOMO-3 (fourth binding orbital counting from HOMO). The calculation results show that molecular orbitals corresponding to) are distributed on the hole transport site (HTG). The absolute value of the level difference between this orbital energy level and HOMO (hereinafter also simply referred to as level difference) was 0.23 eV. In addition, the triplet excitation energy calculated by calculation of this compound is 435 nm, the difference from that of the compound of calculation example 1-a for comparison is 4 nm, and it is estimated from the calculation results that the wavelength change is small. .

Furthermore, as a result of synthesizing the compounds of Calculation Example 1-a and Calculation Example 1-b and measuring the emission wavelength at room temperature, the compound of Calculation Example 1-a was 465 nm and the compound of Calculation Example 1-b was 465 nm, respectively. It was confirmed that the wavelength change was smaller than the calculation result.

Similarly, the compound of Calculation Example 1-c, which is a compound obtained by substituting the compound of Calculation Example 1-a with a carbazol-9-yl group as a hole transporting partial structure, is also represented by HOMO-3 (fourth counting from HOMO). It was shown from the calculation results that molecular orbitals corresponding to (binding orbitals) are distributed on the hole transport site (HTG). The level difference between this orbital level and HOMO was 0.45 eV. In addition, the triplet excitation energy calculated by calculation of this compound is 435 nm, the difference from that of the compound of calculation example 1-a for comparison is 4 nm, and it is estimated from the calculation results that the wavelength change is small. . The results of the molecular calculations are summarized in Table I below.

Moreover, what showed the molecular orbital calculated by calculation, and what was imaged are shown.
In Calculation Example 1-b and Calculation Example 1-c, it can be seen that the orbits of HOMO-3 are distributed over one hole transporting site.

In the following molecular orbitals, the calculation results show that electrons exist inside the region partitioned by solid lines on each atom. In each region, the dot notation and the hatched notation indicate that the phases of the molecular orbitals are different from each other.

(1.1.6.2) Calculation Example-2
In the compound of Calculation Example 2-a, an electron cloud is distributed over the central metal and the aromatic ring portion directly connected to the central metal in any molecular orbital of HOMO to HOMO-5.

On the other hand, the compound of Calculation Example 2-b, which is a compound obtained by substituting the compound of Calculation Example 2-a with a diphenylamino group as a hole transporting partial structure, is HOMO-3 (fourth binding orbital counting from HOMO). The calculation results show that molecular orbitals corresponding to) are distributed on the hole transport site (HTG). The level difference between this orbital level and HOMO was 0.52 eV. Further, the triplet excitation energy calculated by calculation of this compound is 434 nm, and the difference from that of the compound of calculation example 2-a for comparison is 1 nm, and it is estimated from the calculation results that the wavelength change is small. .

Similarly, the compound of Calculation Example 2-c, which is a compound obtained by substituting the compound of Calculation Example 2-a with a carbazol-9-yl group as a hole transporting partial structure, is also represented by HOMO-3 (fourth counting from HOMO). It was shown from the calculation results that molecular orbitals corresponding to (binding orbitals) are distributed on the hole transport site (HTG). The level difference between this orbital level and HOMO was 0.63 eV. Further, the triplet excitation energy calculated by calculation of this compound is 435 nm, the difference from that of the compound of Comparative Example 2-a is 2 nm, and it is estimated from the calculation results that the wavelength change is small. . The results of molecular calculations are summarized in Table II below.

Further, the molecular orbitals calculated by calculation were the same as those in Calculation Example 1.
The result of Calculation Example 2 shows only an imaged image.

In Calculation Example 2-b and Calculation Example 2-c, it was found that the orbit of HOMO-3 was distributed on one hole transporting site.

(1.1.6.3) Calculation Example-3
The result of Calculation Example 3 was the same as that of Calculation Example 1 and Calculation Example 2. From the calculation results, it can be seen from the calculation results that the molecular orbitals corresponding to HOMO-3 (fourth binding orbital counting from HOMO) are distributed on the hole-transporting site (HTG) in any compound having a hole-transporting substituent introduced. Indicated. The results of molecular calculations are summarized in Table III below.

Further, the molecular orbitals calculated by calculation were the same as those in Calculation Example 1.
Only the figure which also imaged the result of the calculation example 3 is shown. In calculation example 3-b and calculation example 3-c, it was found that the orbit of HOMO-3 was distributed on one hole transporting site.

(1.1.6.4) Calculation Example-4
The result of Calculation Example 4 was the same as that of Calculation Example 1, Calculation Example 2, and Calculation Example 3. From the calculation results, it can be seen from the calculation results that the molecular orbitals corresponding to HOMO-3 (fourth binding orbital counting from HOMO) are distributed on the hole-transporting site (HTG) in any compound having a hole-transporting substituent introduced. Indicated. The results of the molecular calculations are summarized in Table IV below.

Further, the molecular orbitals calculated by calculation were the same as those in Calculation Example 1.
Only the result of calculation example 4 is also shown in an image. Also in Calculation Example 4-b and Calculation Example 4-c, it was found that the orbit of HOMO-3 was distributed on one hole transporting site.

(1.1.6.5) Calculation example-5
In the compound of Calculation Example 5-a, an electron cloud is distributed in the central metal and the aromatic ring portion directly connected to the central metal in any molecular orbital of HOMO to HOMO-5.

On the other hand, the compound of Calculation Example 5-b, which is a compound obtained by substituting the compound of Calculation Example 5-a with a diphenylamino group as a hole transporting partial structure, has a strong electron-withdrawing substituent effect, and thus the energy level of the entire complex. The calculation results showed that molecular orbitals corresponding to HOMO (the highest level binding orbitals) were distributed on the hole transport sites (HTG) due to the lowering of the position. From the calculation, molecular orbitals corresponding to HOMO-1 (second bonding orbit counted from HOMO) and HOMO-2 (third bonding orbit counted from HOMO) are also present on the hole transport site (HTG). Distribution was shown from the calculation results. The calculation results show that the orbit showing the electron distribution corresponding to HOMO in a normal transition metal complex (for example, the compound of Calculation Example 5-a) is HOMO-3. The orbital level difference between the calculated HOMO and the normal HOMO-3 orbit was 0.31 eV. In addition, the triplet excitation energy calculated by calculation of this compound is 427 nm, the difference from that of the compound of calculation example 5-a for comparison is −1 nm, and it is estimated from the calculation results that the wavelength change is small. The

Similarly, the compound of Calculation Example 5-c, which is a compound obtained by substituting the compound of Calculation Example 5-a with a carbazol-9-yl group as a hole transporting partial structure, is also a complex due to the strong electron-withdrawing substituent. The calculation results show that molecular orbitals corresponding to HOMO (bonding orbitals with the highest energy level) are distributed on the hole transport site (HTG) by lowering the overall level. From the calculation, molecular orbitals corresponding to HOMO-1 (second bonding orbit counted from HOMO) and HOMO-2 (third bonding orbit counted from HOMO) are also present on the hole transport site (HTG). Distribution was shown from the calculation results. The calculation results show that the orbit showing the electron distribution corresponding to HOMO in a normal transition metal complex (for example, the compound of Calculation Example 5-a) is HOMO-3. The level difference between the calculated HOMO and the normal HOMO orbital of HOMO-3 was 0.18 eV. Further, the triplet excitation energy calculated by calculation of this compound is 428 nm, the difference from that of the compound of Comparative Example 5-a is 0 nm, and it is estimated from the calculation results that the wavelength change is small. . The results of the molecular calculations are summarized in Table V below.

In addition, a diagram illustrating a molecular orbital calculated by calculation and an imaged diagram are shown.
In Calculation Example 5-b and Calculation Example 5-c, it can be seen that the orbitals of HOMO, HOMO-1, and HOMO-2 are distributed on different hole transporting sites. It was also found that the orbit of HOMO-3 shows an electron distribution corresponding to normal HOMO.

(1.1.6.6) Calculation Example-Comparison 1
As a comparison with Calculation Example 5, Calculation Example 5-a is a compound obtained by substituting an aromatic ring that is not hole-transporting to the compound of Calculation Example 5-a. From the calculation results, it was shown that the electron clouds were distributed in the central metal and the aromatic ring portion directly connected to the central metal in any of the molecular orbitals of No. 5. The result of molecular orbital calculated by calculation shows only an imaged figure.

(1.1.6.7) Calculation Example-Comparison 2
As a comparison with calculation examples 1 to 5, molecular orbital calculation was performed for a transition metal having no electron-withdrawing group as a substituent on the aromatic ring of the ligand.

Calculation Example-Comparative 2-a compound has an electron cloud distributed in the central metal and the aromatic ring part directly connected to the central metal in any molecular orbital of HOMO to HOMO-5.

On the other hand, the compound of Calculation Example-Comparison 2-b, which is a compound in which the compound of Comparative Example 2-a is substituted with a diphenylamino group as a hole transporting partial structure, is HOMO-3 (fourth counting from HOMO). The calculation results show that molecular orbitals corresponding to the bonding orbitals of (HTG) are distributed on the hole transport site (HTG). The level difference between this orbital level and HOMO is 0.92 eV. It can be seen that the level difference is large compared to the transition metal complex of the present invention.

Similarly, the compound of Calculation Example-Comparison 2-c, which is a compound obtained by substituting the compound of Calculation Example-Comparative 2-a with a carbazol-9-yl group as a hole transporting partial structure, is also represented by HOMO-3 (from HOMO). The calculation results show that molecular orbitals corresponding to the fourth bonding orbital are distributed on the hole transport site (HTG), and the level difference between this orbital level and HOMO is 1 It can be seen that the level difference is larger than that of the transition metal complex of the present invention.

The results of molecular calculations are summarized in Table VI below.

The results of molecular orbitals calculated by calculation are only images.

From the above calculation examples, it can be seen that the characteristics common to the transition metal complexes of the present invention can be verified by molecular orbital calculation.

That is, the phosphorescent transition metal complex has a ligand in which a plurality of aromatic rings are directly bonded to the transition metal as the central metal, and (1) the ligand is bonded directly to the transition metal. At least one of the plurality of aromatic rings has an electron-withdrawing group, and (2) at least one of the plurality of aromatic rings directly bonded to the transition metal is bonded to the aromatic ring. When having a hole transporting partial structure containing a nitrogen atom and an aromatic ring connected to each other by a single bond, the transition metal complex has the highest occupied orbital in the evaluation by molecular orbital calculation. One of the bonding orbitals from (HOMO) to the fifth lower energy level (HOMO-5) is such that 80% or more of the electrons on the bonding orbital are on the hole transporting partial structure. Has an existing electron density distribution, and The absolute value of the difference between the energy level of the occupied molecular orbital and the bonding orbital is less than 0.7eV, it was found to be confirmed as a common characteristic.

At the same time, the absolute value of the difference in emission maximum wavelength calculated by the molecular orbital calculation for each of the transition metal complex and the transition metal complex having a structure obtained by removing the hole transporting partial structure from the transition metal complex, It was found that the thickness was 10 nm or less as a common characteristic.

(1.1.7) Specific Examples of Blue Phosphorescent Transition Metal Complex Specific examples of the transition metal complex represented by the general formula (1) are described below, but the present invention is not limited thereto. .

Of the aromatic rings directly bonded to the metal complex, the upper part of the exemplary compounds having the structures represented by the following general formulas (DP-A) to (DP-Y) is represented by the general formula (2) and the general formula Ring C described in formula (3), and the lower part represents ring B.

R ₁ and R ₂ are synonymous with R ₁ and R ₂ described in the general formulas (3) to (6), and each represents a hydrogen atom or a substituent, and at least one of R ₁ and R ₂ is Represents a substituent.

Q ₁₀₁ , Q ₁₀₂ , Q ₁₀₃ , Q ₂₀₁ , Q ₂₀₂ , Q ₂₀₃ , Q ₃₀₁ , Q ₃₀₂ , Q ₄₀₁ , Q ₄₀₂ , Q ₄₀₃ and Q ₄₀₄ each independently represent a hydrogen atom or a substituent, and are substituted The groups include Ra ₁ , Ra ₂ , Ra ₃ , Rb ₁ , Rb ₂ , Rb ₃ , Rc ₁ , Rc ₂ , Rd ₁ , Rd ₂ , Rd ₃ and the general formulas (3) to (6). The substituent described in Rd ₄ and the hole transporting partial structure according to the present invention are included.

At least one of ring B or ring C has an electron withdrawing group. At least one of ring B or ring C is bonded to any one of the hole transporting partial structures HTG-1 to HTG-15. At this time, they may be bonded via any one of the linking groups LG-1 to LG-12.

In the compound examples, the hole transporting partial structures HTG-1 to HTG-15 and the linking groups LG-1 to LG-12 have the structures described above.

The ligands AL-1 to AL-24 in the above compound examples have the following structures.

In the formula, * represents a binding site with a transition metal.

These metal complexes are described in, for example, Organic Letter, vol. 16, 2579-2581 (2001), Inorganic Chemistry, Vol. 30, No. 8, pp. 1685-1687 (1991), J. Am. Am. Chem. Soc. , 123, 4304 (2001), Inorganic Chemistry, Vol. 40, No. 7, pages 1704-1711 (2001), Inorganic Chemistry, Vol. 41, No. 12, pages 3055-3066 (2002) , New Journal of Chemistry. 26, 1171 (2002), Organic Letter, vol8, No. 3, pp. 415 to 418 (2006), and further by applying methods such as references described in these documents.

Below, the synthesis example of a typical compound is shown.
Synthesis of complex DP-A1 Synthesis of Intermediate C-1 According to the following reaction scheme, 3-bromobenzoic acid and 1.5 equivalents of thionyl chloride were mixed and reacted at reflux temperature for 3 hours, and then excess thionyl chloride was concentrated under reduced pressure. To give 3-brominated benzoic acid chloride. Subsequently, 1.2 equivalents of 2-chloroethylamine hydrochloric acid and 3.0 equivalents of triethylamine were stirred in methylene chloride at room temperature for 1 hour, and the above-mentioned 3-brominated benzoic acid chloride was added. Reaction was performed for a while to obtain Intermediate A-1. The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 72%. In the reaction scheme, RT represents room temperature and y represents the isolated yield.

Next, 1 equivalent of the intermediate A-1 and 1.5 equivalents of phosphorus pentachloride were reacted in xylene under heating and refluxing for 3 hours. After cooling the reaction solution to room temperature, 1.5 equivalents of 4-iodo-2,6-dimethylaniline was added, and the mixture was heated again and reacted at reflux temperature for 10 hours to obtain Intermediate B-1. The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 80%.

Then, this intermediate B-1 was dissolved in 20 times the amount of methylene chloride: acetonitrile mixed solvent (1: 1), and while stirring this solution, 2.0 equivalents of potassium permanganate and the same weight Of K-10 clay, finely crushed in a mortar, was added little by little. After completion of the addition, the mixture was reacted at room temperature for 4 hours to obtain Intermediate C-1. The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 65%.

2. Synthesis of Intermediate D-1 According to the following reaction scheme, 1 equivalent of Intermediate C-1 and 1.5 equivalents of bis-tolylamine, 2 mol% tetrakis (triphenylphosphine) palladium (0), 1. 8 equivalents of sodium-tert-butoxide were reacted in a toluene-water mixed solvent at reflux temperature for 10 hours to obtain Intermediate D-1. The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 85%.

3. Synthesis of Ligand L-1 According to the following reaction scheme, 1 equivalent of Intermediate D-1 and 2.5 equivalents of N-brominated succinimide were added in 10 volumes of dimethylformamide at 50 ° C. The reaction was performed for a while to obtain an intermediate E-1. The reaction solution was diluted with water and ethyl acetate, washed with water three times, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained crude product of Intermediate E-1 was dissolved in 10 times the amount of dehydrated tetrahydrofuran (THF), and cooled to −78 ° C. in a nitrogen atmosphere. A 1.1 equivalent amount of n-butyllithium in hexane was added dropwise thereto, and the reaction was further continued for 3 hours under cooling. Then, under cooling, excess water was added to stop the reaction. After the temperature was raised to room temperature, the reaction solution was washed with saturated saline. Thereafter, it was dried over magnesium sulfate and concentrated under reduced pressure to obtain ligand L-1. The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 68%.

・ Synthesis of Intermediate F-1

Under a nitrogen atmosphere, 1.20 g (2.0 mmol; 4.0 equivalent) of ligand L-1 and 0.18 g (0.50 mmol; 1.0 equivalent) of iridium acetate were suspended in 30 ml of ethylene glycol. . Heating was started as it was, and the reaction was carried out at 160 ° C. for 5 hours under a nitrogen atmosphere. The reaction solution was cooled, 30 ml of methanol was added, and the precipitated crystals were collected by filtration. The obtained crystals were further washed with methanol and dried to obtain 620 mg of a crude product. This crude product was purified by sika gel column chromatography (hexane-tetrahydrofuran = 10: 1 to 4: 1) and GPC (gel permeation chromatography) to obtain 540 mg (yield 54%) of intermediate F-1. .
・ Synthesis of complex DP-A1

540 mg (0.27 mmol) of intermediate F-1 and 0.95 g (8.1 mmol; 10.0 equivalents) of zinc cyanide and 0.59 g (9 mmol; 11.0 equivalents) of zinc powder under a nitrogen atmosphere Bis (dibenzylideneacetone) palladium (0) 0.16 g (0.28 mmol, 1.0 eq), tri (tert-butyl) phosphine 0.27 g (1.35 mmol, 5.0 eq) in dimethylacetamide Suspended in 20 ml. Heating was started as it was, and a reaction was performed at 150 ° C. for 30 hours in a nitrogen atmosphere. The reaction mixture was diluted with water and ethyl acetate, washed with water three times, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained crude product was purified by column gel chromatography (hexane-tetrahydrofuran = 10: 1 to 4: 1) and GPC (gel permeation chromatography) to obtain 158 mg (yield 35%) of complex DP-A1. It was.

It was confirmed by MASS and 1H-NMR that the purified compound was the target product.

The PL emission maximum wavelength in the solution of Exemplified Compound DP-A1 measured using Hitachi F-4500 is
450 nm (T = 77 K in 2-methyltetrahydrofuran), 456 nm (room temperature in methylene chloride)
Met.
Synthesis of complex DP-A162 Synthesis of Intermediate A-2 According to the following reaction scheme, 1 equivalent of 4-bromo-2,6-diisopropylaniline and 1.5 equivalents of bis- (4-isopropylphenyl) amine, 2 mol% of tetrakis ( Triphenylphosphine) palladium (0) and 1.8 equivalents of sodium-tert-butoxide were reacted in a toluene-water mixed solvent at reflux temperature for 10 hours to obtain Intermediate A-2. The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 85%.

2. Synthesis of Ligands L-2 and L-3 According to the following reaction scheme, Intermediate A-2 was reacted with 1.1 equivalents of n-butyllithium in ether under a nitrogen atmosphere. Next, 1.05 equivalent of an ether solution of 3-bromobenzonitrile was added dropwise thereto, and the mixture was further reacted at room temperature for 3 hours. Water was added to the reaction solution to stop the reaction, followed by washing with water three times. The extract was dried over magnesium sulfate and concentrated under reduced pressure. The resulting crude product was purified by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) to give intermediate B-2. The isolation yield was 72%.

Then, 1 equivalent of intermediate B-2 and 2.2 equivalents of 3-bromo-1,1,1-trifluoropropan-2-one, 2.0 equivalents of sodium bicarbonate are dissolved in isopropyl alcohol, The reaction was carried out for 3 hours under heating to reflux. The reaction solution was concentrated to obtain a crude product of Intermediate C-2.

The isolation yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 70%.

Next, this intermediate C-2 was dissolved in 20 times the amount of toluene, 0.5 equivalent of p-toluenesulfonic acid was added, and the mixture was reacted for 8 hours with heating under reflux. The reaction solution was neutralized with sodium hydroxide, washed with water three times, and concentrated to obtain a crude product of ligand L-2.

The isolated yield after purification by silica gel chromatography (hexane: ethyl acetate = 10: 1 to 2: 1) was 65%.

Ligand L-3 is synthesized from 3-bromobenzonitrile and 2,6-diisopropylaniline via intermediates D-2 and E-2 by the same reaction as intermediates B-2 and C-2 did. The isolation yield of intermediate D-2 was 80%, the isolation yield of intermediate E-2 was 76%, and the isolation yield of ligand L-3 was 70%.

3. Synthesis of intermediate F-2

Under a nitrogen atmosphere, 0.70 g (1.0 mmol; 2.0 eq) of ligand L-2, 0.45 g (1.0 mmol; 2.0 eq) of ligand L-3 and iridium acetate 18 g (0.50 mmol; 1.0 equivalent) was suspended in 30 ml of ethylene glycol. Heating was started as it was, and the reaction was carried out at 160 ° C. for 5 hours under a nitrogen atmosphere. The reaction solution was cooled, 30 ml of methanol was added, and the precipitated crystals were collected by filtration. The obtained crystals were further washed with methanol and dried to obtain 720 mg of a crude product. This crude product was purified by sika gel column chromatography (hexane-tetrahydrofuran = 10: 1 to 4: 1) and GPC (gel permeation chromatography) to obtain 480 mg (yield 42%) of intermediate F-2. .
・ Synthesis of complex DP-A162

480 mg (0.20 mmol) of intermediate F-2 and 0.70 g (6.0 mmol; 30.0 equivalents) of zinc cyanide and 0.43 g (6.6 mmol; 33.0) of zinc powder under a nitrogen atmosphere Equivalent)), 0.115 g (0.20 mmol, 1.0 equivalent) of bis (dibenzylideneacetone) palladium (0), 0.202 g (1.0 mmol, 5.0 equivalent) of tri (tert-butyl) phosphine. Suspended in 20 ml of dimethylacetamide. Heating was started as it was, and a reaction was performed at 150 ° C. for 30 hours in a nitrogen atmosphere. The reaction mixture was diluted with water and ethyl acetate, washed with water three times, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained crude product was purified by column gel chromatography (hexane-tetrahydrofuran = 10: 1 to 4: 1) and GPC (gel permeation chromatography) to obtain 192 mg (yield 45%) of complex DP-A162. It was.

It was confirmed by MASS and ¹ H-NMR that the purified compound was the target product.

The maximum PL emission wavelength in a solution of Exemplified Compound DP-A162 measured using Hitachi F-4500 was 448 nm (T = 77K in 2-methyltetrahydrofuran) and 454 nm (room temperature in methylene chloride).

Other compounds of the present invention can also be synthesized with good yield by using appropriate raw materials and reactions as in the above synthesis examples.

(1.2) Fluorescent dopants Fluorescent dopants (also referred to as fluorescent compounds) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamines. And dyes having a high fluorescence quantum yield such as laser dyes and the like, and dyes based on dyes, pyrylium dyes, perylene dyes, stilbene dyes, polythiophene dyes, rare earth complex phosphors, and the like.

(1.3) Combined use with conventionally known light-emitting dopants The light-emitting dopant according to the present invention may be used in combination with a plurality of types of compounds, a combination of phosphorescent dopants having different structures, a phosphorescent dopant and A combination of fluorescent dopants may also be used. Known phosphorescent dopants and fluorescent dopants can be used.

(2) Host material In the present invention, the host material (also referred to as a host compound) is a compound contained in the light emitting layer, the mass ratio in the layer is 20% or more, and at room temperature (25 ° C.). A phosphorescence quantum yield of phosphorescence is defined as a compound having a value of less than 0.1. The phosphorescence quantum yield is preferably less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

The host compound that can be used in the present invention is not particularly limited, and compounds conventionally used in organic EL elements can be used. Typically, a carbazole derivative, a triarylamine derivative, an aromatic derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, an oligoarylene compound or the like having a basic skeleton, or a carboline derivative or a diazacarbazole derivative (here And the diazacarbazole derivative represents one in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom.

As the known host compound that can be used in the present invention, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being longer, and has a high Tg (glass transition temperature) is preferable.

In the present invention, conventionally known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of the metal complex of this invention used as the said phosphorescence dopant, and / or a conventionally well-known compound, and, thereby, arbitrary luminescent colors can be obtained. The host compound used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound (polymerizable host compound) having a polymerizable group such as a vinyl group or an epoxy group. Of course, one or a plurality of such compounds may be used.

Specific examples of known host compounds include compounds described in the following documents. JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-260861, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

Next, an injection layer, a blocking layer, an electron transport layer, and the like that are preferably used as the constituent layers of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. May be.

An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Representative phthalocyanine buffer layer, oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polymer buffer layer using conductive polymer such as polyaniline (emeraldine) or polythiophene, tris (2-phenylpyridine) ) Orthometalated complex layers represented by iridium complexes and the like.
Similarly, azatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as the hole injection material.

The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, as described in JP-A Nos. 11-204258 and 11-204359 and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on November 30, 1998)”. There is a hole blocking layer.

The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking.

Moreover, the structure of the electron transport layer described later can be used as a hole blocking layer according to the present invention, if necessary.

The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

The hole blocking layer contains the carbazole derivative, carboline derivative, or diazacarbazole derivative (shown in which any one of the carbon atoms constituting the carboline ring of the carboline derivative is replaced by a nitrogen atom). It is preferable to contain.

In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the anode. Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.

The ionization potential is defined by the energy required to discharge electrons in the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be determined by the following method, for example.

(1) The second decimal place of the value (eV unit converted value) calculated by structural optimization using B3LYP / 6-31G * as a keyword using Gaussian 09, a molecular orbital calculation software manufactured by Gaussian, USA The ionization potential can be obtained as a value rounded off. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

(2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopy can be suitably used.

On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved.

Moreover, the structure of the hole transport layer described later can be used as an electron blocking layer as necessary. The thickness of the hole blocking layer and the electron transporting layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has any of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. Further, azatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.

The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino -(2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and also two described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material. In addition, cyclometalated complexes and orthometalated complexes such as copper phthalocyanine and tris (2-phenylpyridine) iridium complex can also be used as the hole transport material.

Also, JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.

The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. The thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. This hole transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use a hole transport layer having a high p property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer was injected from the cathode. Any material can be used as long as it has a function of transferring electrons to the light-emitting layer, and any material known in the art can be selected and used alone or in combination. For example, a nitro-substituted fluorene derivative , Diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like.

Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

Also, metal complexes of 8-quinolinol derivatives, such as tris (8-quinolinol) aluminum (Alq ₃ ), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.

In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material for the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.

The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. The thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use an electron transport layer having a high n property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be produced.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO.

Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern of a desired shape may be formed by a photolithography method, or when pattern accuracy is not so required (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.

Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.

The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

Further, after producing the above metal on the cathode with a thickness of 1 to 20 nm, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic, polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and further, oxygen measured by a method according to JIS K 7126-1987. A high barrier film having a permeability of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less and a water vapor permeability of 1 × 10 ⁻⁵ g / (m ² · 24 h) or less is preferable. .

The material for forming the barrier film may be any material that has a function of suppressing the intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.

The external extraction quantum efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more.

Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

Also, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.

Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned.

Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less, and a method according to JIS K 7129-1992. It is preferable that the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is 1 × 10 ⁻³ g / (m ² · 24 h) or less.

For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

In addition, since an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable. A desiccant may be dispersed in the adhesive.

Application of the adhesive to the sealing portion may be performed using a commercially available dispenser or may be printed like screen printing.

In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, and the like used for the sealing can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light and the light, and the light is guided through the transparent electrode or the light emitting layer.

As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from the substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).

In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

When a medium with a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. .

Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

Also, the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low-refractive index layer is reduced when the thickness of the low-refractive index medium is about the wavelength of light and the electromagnetic wave exuded by evanescent enters the substrate.

The method of introducing a diffraction grating into an interface that causes total reflection or in any medium is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. Of these, light that cannot go out due to total reflection between layers, etc. is diffracted by introducing a diffraction grating into any layer or medium (inside a transparent substrate or transparent electrode). I want to take it out.

It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much.

However, by making the refractive index distribution a two-dimensional distribution, the light traveling in all directions is diffracted, and the light extraction efficiency is increased.

As described above, the position where the diffraction grating is introduced may be in any one of the layers or in the medium (in the transparent substrate or the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

《Condensing sheet》
The organic EL device of the present invention is processed on the light extraction side of the substrate, for example, so as to provide a microlens array-like structure, or in combination with a so-called condensing sheet, for example, with respect to a specific direction, for example, the device light emitting surface. By condensing in the front direction, the luminance in a specific direction can be increased.

As an example of a microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

As the condensing sheet, it is possible to use, for example, a sheet that has been put to practical use in an LED backlight of a liquid crystal display device. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

Further, in order to control the light emission angle from the light emitting element, a light diffusion plate / film may be used in combination with the light collecting sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

First, an anode is produced by forming a thin film made of a desired electrode material, for example, an anode material on a suitable substrate by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably 10 to 200 nm.

Next, organic compound thin films such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are organic EL element materials, are formed thereon.

As a method for forming each of these layers, there are a vapor deposition method, a wet process (spin coating method, casting method, ink jet method, printing method) and the like as described above, but it is easy to obtain a homogeneous film and it is difficult to generate pinholes. In view of the above, film formation by a coating method such as a spin coating method, an ink jet method, or a printing method is preferable in the present invention. In particular, the organic layer containing the phosphorescent transition metal complex according to the present invention is preferably formed through a wet process for the above reason.

Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

After forming these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm. By providing, a desired organic EL element can be obtained.

It is also possible to reverse the production order and produce the cathode, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, It can use effectively for the use as a backlight of a liquid crystal display device, and an illumination light source especially.

In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like during film formation, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total of CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.

Further, when the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is measured when the 2 ° viewing angle front luminance is measured by the above method. It means that it is in the region of x = 0.33 ± 0.07 and y = 0.33 ± 0.1.

<Display device>
The display device of the present invention will be described. The display device of the present invention has the organic EL element.

The display device of the present invention may be single color or multicolor, but here, the multicolor display device will be described.

In the case of a multicolor display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by a vapor deposition method, a cast method, a spin coat method, an inkjet method, a printing method, or the like.

In the case of patterning only the light emitting layer, the method is not limited, but is preferably a vapor deposition method, an inkjet method, or a printing method. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

It is also possible to reverse the production order to produce the cathode, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, and the anode in this order.

When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

The multicolor display device can be used as a display device, a display, and various light sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

Display devices and displays include televisions, personal computers, mobile devices, AV devices, teletext displays, information displays in automobiles, and the like. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

Light emitting sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. However, it is not limited to this.

Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an example of a display device composed of organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like. The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside, and the pixels for each scanning line respond to the image data signal by the scanning signal. The image information is sequentially emitted to scan the image and display the image information on the display unit A.

FIG. 2 is a schematic diagram of the display unit A.

The display unit A has a wiring unit including a plurality of scanning lines 5 and data lines 6 and a plurality of pixels 3 on the substrate. The main members of the display unit A will be described below. FIG. 2 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

The scanning line 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are illustrated). Not)

When the scanning signal is applied from the scanning line 5, the pixel 3 receives the image data signal from the data line 6 and emits light according to the received image data.

A full color display can be achieved by appropriately arranging pixels in the red region, the green region, and the blue region on the same substrate.

Next, the light emission process of the pixel will be described.

FIG. 3 is a circuit diagram of the pixel.

The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 via the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10. The power supply line 7 connects the organic EL element 10 to the potential of the image data signal applied to the gate. Current is supplied.

When the scanning signal moves to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 13 holds the charged potential of the image data signal even when the driving of the switching transistor 11 is turned off, the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL elements 10 of the plurality of pixels, and the organic EL elements 10 of the plurality of pixels 3 emit light. It is carried out. Such a light emitting method is called an active matrix method.

Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or by turning on / off a predetermined light emission amount by a binary image data signal. Good. The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which an organic EL element emits light according to a data signal only when a scanning signal is scanned.

FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixel 3 connected to the applied scanning line 5 emits light according to the image data signal.

In the passive matrix method, there is no active element in the pixel 3, and the manufacturing cost can be reduced.

《Lighting device》
The lighting device of the present invention will be described. The illuminating device of this invention has the said organic EL element.

The organic EL element of the present invention may be used as a kind of lamp such as an illumination or exposure light source, a projection device that projects an image, or a display device that directly recognizes a still image or a moving image ( It may be used as a display.

The drive method when used as a display device for moving image reproduction may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, it is possible to produce a full-color display device by using two or more organic EL elements of the present invention having different emission colors.

Further, the organic EL material of the present invention can be applied to an organic EL element that emits substantially white light as a lighting device. A plurality of light emitting colors are simultaneously emitted by a plurality of light emitting materials to obtain white light emission by color mixing. The combination of a plurality of emission colors may include three emission maximum wavelengths of the three primary colors of blue, green, and blue, or two using the relationship of complementary colors such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.

In addition, a combination of light emitting materials for obtaining a plurality of emission colors is a combination of a plurality of phosphorescent or fluorescent materials, a light emitting material that emits fluorescence or phosphorescence, and light from the light emitting material as excitation light. Any of those combined with a dye material that emits light may be used, but in the white organic EL device according to the present invention, only a combination of a plurality of light-emitting dopants may be mixed.

A mask is provided only at the time of forming a light emitting layer, a hole transport layer, an electron transport layer, etc., and it is only necessary to arrange them separately by coating with the mask. Since other layers are common, patterning of the mask or the like is not necessary. In addition, for example, an electrode film can be formed by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like, and productivity is also improved. According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are luminescent white.

There is no restriction | limiting in particular as a luminescent material used for a light emitting layer, For example, if it is a backlight in a liquid crystal display element, the metal complex which concerns on this invention so that it may suit the wavelength range corresponding to CF (color filter) characteristic, Any one of known luminescent materials may be selected and combined to whiten.

As described above, the white light emitting organic EL element according to the present invention is used as a kind of lamp such as household illumination, interior lighting, and exposure light source as various light emitting light sources and lighting devices in addition to the display device and display. It is also useful for display devices such as backlights for liquid crystal display devices.

Others such as backlights for watches, signboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

<< One Embodiment of Lighting Device of the Present Invention >>
One aspect of the lighting device of the present invention that includes the organic EL element of the present invention will be described.

The non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a 300 μm thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX The track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS. A device can be formed.

FIG. 5 shows a schematic diagram of the lighting device. As shown in FIG. 5, the organic EL element 101 is covered with a glass cover 102.

The sealing operation with the glass cover 102 is preferably performed in a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) without bringing the organic EL element 101 into contact with the atmosphere.

FIG. 6 shows a cross-sectional view of the lighting device. As shown in FIG. 6, the lighting device mainly includes a cathode 105, an organic EL layer 106, and a glass substrate 107 with a transparent electrode, and these members are covered with a glass cover 102.

The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

<Transition metal complex>
The transition metal complex of the present invention can be preferably used as a material for an organic electroluminescence element in the above-described organic electroluminescence element. In addition, the composition containing the phosphorescent transition metal complex of the present invention can be preferably used as a material composition for an organic electroluminescence device.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

The structure of the compound used in the examples is shown below.

[Example 1]
<Vapor deposition type blue light emitting organic EL element>
<< Production of Blue Light-Emitting Organic EL Element 1-1 >>
After patterning on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm × 100 mm × 1.1 mm glass substrate was formed as a positive electrode on a 100 mm × 100 mm × 1.1 mm glass substrate, this transparent ITO electrode was provided. The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of the hole injection material 1 is put into a molybdenum resistance heating boat, and 200 mg of the hole transport material 1 is put into another molybdenum resistance heating boat, 200 mg of the host compound (OC-11) is put into another resistance heating boat made of molybdenum, 100 mg of the luminescent dopant (Comparative Compound 1) is put into another resistance heating boat made of molybdenum, and the electron transport material 1 is put into another resistance heating boat made of molybdenum. And 200 mg of the electron transport material 2 was placed in another molybdenum resistance heating boat and attached to a vacuum deposition apparatus.

The vacuum chamber was then depressurized to 4 × 10 ⁻⁴ Pa, heated by energizing the heating boat containing the hole injection material 1 and deposited on a transparent support substrate at a deposition rate of 0.1 nm / second. A 20 nm hole injection layer was provided.

Furthermore, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing the hole transport material 1 was heated by heating, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / second. A 20 nm hole transport layer was provided.

Further, the hole transport layer was heated by energizing the heating boat containing the host compound (OC-11) and the light-emitting dopant (Comparative Compound 1) at a deposition rate of 0.2 nm / second and 0.035 nm / second, respectively. A 40 nm-thick luminescent layer was provided by co-evaporation. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Further, the heating boat containing the electron transport material 1 was energized and heated, and was deposited on the light emitting layer at a deposition rate of 0.1 nm / second to provide a 10 nm thick hole blocking layer.

In addition, the heating boat containing the electron transport material 2 is further energized and heated, and deposited on the hole blocking layer at a deposition rate of 0.1 nm / second to further form an electron transport layer having a thickness of 20 nm. Was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Subsequently, lithium fluoride 0.5 nm and aluminum 110 nm were vapor-deposited to form a cathode, and an organic EL element 1-1 was produced. In the table below, the organic EL element is abbreviated as EL, for example, the organic EL element 1-1 is denoted as EL1-1.

<< Preparation of organic EL elements 1-2 to 1-75 >>
In the production of the organic EL device 1-1, except that only the hole injection material, the hole transport material, the host compound, and the light emitting dopant (abbreviated as dopant in the following table) were replaced with the compounds shown in Tables VII to IX. Organic EL elements 1-2 to 1-75 were produced in the same manner as the organic EL element 1-1.

<< Evaluation of organic EL elements >>
When evaluating the obtained organic EL elements 1-1 to 1-75, the non-light-emitting surface of each organic EL element after production was covered with a glass case, and a glass substrate having a thickness of 300 μm was used as a sealing substrate. In addition, an epoxy-based photo-curing adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing material around the periphery, and this is placed on the cathode so as to be in close contact with the transparent support substrate and irradiated with UV light from the glass substrate side. Then, it was cured and sealed, and an illumination device as shown in FIGS. 5 and 6 was formed and evaluated.

FIG. 5 shows a schematic diagram of the lighting device. The organic EL element 101 is covered with a glass cover 102 (in addition, the sealing operation with the glass cover 102 is a glove box (purity of 99.999% or more in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere). In a high-purity nitrogen gas atmosphere).

FIG. 6 shows a cross-sectional view of the lighting device. Inside the lighting device, a glass substrate 107 with a transparent electrode as an anode, an organic EL layer 106 and a cathode 105 are laminated in this order. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

(1) External extraction quantum efficiency Current that gives each organic EL element room temperature (25 ° C.), initial luminance 2000 cd / m ² , and 4000 cd / m ² (shown as luminance A and luminance B in the following tables, respectively). The external extraction quantum efficiency (η) was calculated as an evaluation measure of the light emission efficiency by driving at a constant current and measuring the drive current [mA] immediately after the start of lighting. Here, CS-1000 (manufactured by Konica Minolta Co., Ltd.) was used for measurement of light emission luminance.

The external extraction quantum yields are all expressed as relative values with the organic EL element 1-1 at an initial luminance of 2000 cd / m ² as a reference (100).

(2) RT driving voltage the organic EL device (25 ° C.), the initial luminance 2000 cd / ^{m 2,} and 4000 cd / ^{m 2} at a current giving by constant current driving, measuring the lighting start immediately after the drive current [mA] Thus, the driving voltage was measured. Here, CS-1000 (manufactured by Konica Minolta Co., Ltd.) was used for measurement of light emission luminance.

All of the drive voltages are shown as relative values with the organic EL element 1-1 at an initial luminance of 2000 cd / m ² as a reference (100).

Drive voltage = {(drive voltage of each element / drive voltage of the organic EL element 1-1 (initial luminance 2000 cd / m ² ))} × 100
A smaller value indicates a lower drive voltage for comparison.

(3) Driving voltage increase rate When driving at a constant current of 10 mA / cm ² , the initial voltage and the voltage after 200 hours were measured. The increase in voltage after 200 hours with respect to the initial voltage was displayed as a percentage and used as the drive voltage increase rate.

Drive voltage increase rate (%) = {[(Drive voltage after driving 200 hours for each organic EL element / V) − (Initial drive voltage for each organic EL element / V)] / (Initial drive voltage for each organic EL element) / V)} × 100
(4) Half light emission lifetime (25 ° C)
The half-light emission lifetime was evaluated according to the measurement method shown below.

Each organic EL element is driven at a constant current in a high-temperature bath at 25 ° C. and 70 ° C. with a current that gives an initial luminance of 2000 cd / m ² , and a time to become 1/2 (1000 cd / m ² ) of the initial luminance is obtained. This was taken as a measure of half-life.

The half-light emission lifetime was expressed as a relative value set with the reference (100) as the half-light emission lifetime of the organic EL device 1-1 obtained at 25 ° C.

(5) Initial degradation Initial degradation was evaluated according to the measurement method shown below.

At the time of measuring the half light emission lifetime at 25 ° C., the time required for the emission luminance of each organic EL element to reach 90% (1800 cd / m ² ) of the initial luminance was measured, and this was used as a measure of initial deterioration.

The initial deterioration was expressed as a relative value set with the reference (100) as the half-light emission lifetime of the organic EL element 1-1.

The initial deterioration was calculated based on the following formula.

Initial degradation = {(90% arrival time of luminance of organic EL element 1-1 (hr)) / (90% arrival time of each organic EL element (hr))} × 100
That is, the smaller the initial deterioration value is, the smaller the initial deterioration is.

<Measurement of emission chromaticity>
About each organic EL element, the luminescent color was observed and it confirmed visually that all showed blue. Further, a 2-degree viewing angle front luminance at 1000 cd / m ² was measured with a spectral radiance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.), and the chromaticity in the CIE chromaticity coordinates (CIE 1931 color system) ( x, y) was determined.

The above evaluation results are shown in Tables VII to IX. In the table below, the initial luminance is 2000 cd / m.
² was shown as luminance A, and initial 4000 cd / m ² was shown as luminance B.

From Tables VII to IX, the organic EL elements 1-7 to 1-75 of the present invention have higher external extraction quantum efficiency and initial luminance than the comparative organic EL elements 1-1 to 1-6. It can be seen that there is little deterioration, and accordingly, it has a long life at both room temperature and high temperature.

It can also be seen that the drive voltage rise is also suppressed.

From these results, it is useful to use the phosphorescent transition metal complex according to the present invention as a blue light-emitting dopant in at least improving luminous efficiency, reducing driving voltage, and improving luminous lifetime. Recognize.

[Example 2]
<Wet process type blue light emitting element>
<< Preparation of Blue Light-Emitting Organic EL Element 2-1 >>
After patterning on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm × 100 mm × 1.1 mm glass substrate was formed as a positive electrode on a 100 mm × 100 mm × 1.1 mm glass substrate, this transparent ITO electrode was provided. The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

On this transparent support substrate, a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) to 70% with pure water at 3000 rpm for 30 seconds. After the film formation by spin coating, the film was dried at 200 ° C. for 1 hour to provide a first hole transport layer having a thickness of 30 nm.

This substrate was transferred to a nitrogen atmosphere, and a solution obtained by dissolving 50 mg of the hole transport material 3 in 10 ml of toluene was formed on the first hole transport layer by spin coating at 1000 rpm for 30 seconds. . Furthermore, after irradiating with ultraviolet light for 180 seconds to perform photopolymerization / crosslinking, vacuum drying was performed at 60 ° C. for 1 hour to obtain a second hole transport layer.

On this second hole transport layer, using a solution in which 100 mg of the host compound (host material 1) and 15 mg of the luminescent dopant (comparative compound 1) are dissolved in 10 ml of butyl acetate, under the condition of 600 rpm for 30 seconds, A thin film was formed by spin coating. Furthermore, it vacuum-dried at 60 degreeC for 1 hour, and was set as the light emitting layer about 70 nm thick.

Next, a thin film was formed on the light emitting layer by spin coating using a solution obtained by dissolving 50 mg of the electron transport material 3 in 10 ml of hexafluoroisopropanol (HFIP) at 1000 rpm for 30 seconds. Furthermore, it vacuum-dried at 60 degreeC for 1 hour, and was set as the electron carrying layer about 30 nm thick.

Subsequently, this substrate was fixed to a substrate holder of a vacuum deposition apparatus, and after the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, 0.4 nm of potassium fluoride was deposited as a cathode buffer layer, and further 110 nm of aluminum was deposited. Thus, a cathode was formed to produce an organic EL element 2-1.

<< Preparation of organic EL elements 2-2 to 2-75 >>
In the production of the organic EL element 2-1, the organic EL elements 2-2 to 2-75 were prepared in the same manner as the organic EL element 2-1, except that only the host compound and the light-emitting dopant were replaced with the compounds shown in Tables X to XII. Produced.

<< Evaluation of organic EL elements >>
With respect to the obtained organic EL devices 2-1 to 2-75, the device performance was evaluated by the same method and standard as in Example 1.

In this example, in each evaluation of (1) external extraction quantum efficiency, (2) driving voltage, (4) half-light emission lifetime, and (5) initial deterioration, Example 1 was made with reference to the organic EL element 2-1. The relative value was obtained in the same manner as described above.

Evaluation results are shown in Tables X to XII.

From Tables X to XII, the organic EL elements 2-7 to 2-75 of the present invention have higher external extraction quantum efficiency and initial luminance degradation than the comparative organic EL elements 2-1 to 2-6. Accordingly, it can be seen that the life is long at both room temperature and high temperature.

Furthermore, it can be seen that the organic EL elements 2-7 to 2-75 of the present invention also suppress the increase in driving voltage.

From these results, even when the light emitting layer is formed by a wet process using a spin coating method, the phosphorescent property according to the present invention is used as a blue light emitting dopant in order to improve the light emission efficiency, reduce the driving voltage, and improve the light emission life. It can be seen that it is useful to use a transition metal complex of

Example 3
<Vapor deposition type white light emitting element-1>
<< Production of White Light-Emitting Organic EL Element 3-1 >>
After patterning on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm × 100 mm × 1.1 mm glass substrate was formed as a positive electrode on a 100 mm × 100 mm × 1.1 mm glass substrate, this transparent ITO electrode was provided. The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of the hole injection material 1 is put into a molybdenum resistance heating boat, and 200 mg of the hole transport material 1 is put into another molybdenum resistance heating boat, In another molybdenum resistance heating boat, 200 mg of the host compound (OC-11) is added. In another molybdenum resistance heating boat, 100 mg of the luminescent dopant (Comparative Compound 1) is added. In another molybdenum resistance heating boat, the luminescent dopant (D -6) was put in 100 mg, 200 mg of the electron transport material 1 was put in another resistance heating boat made of molybdenum, and 200 mg of the electron transport material 2 was put in another resistance heating boat made of molybdenum, and attached to a vacuum deposition apparatus.

Further, the heating boat containing the host compound (OC-11), the luminescent dopant (Comparative Compound 1) and the luminescent dopant (D-6) was energized and heated, and the deposition rate was 0.2 nm / second and 0.022 nm, respectively. A light emitting layer having a thickness of 40 nm was provided by co-evaporation on the hole transport layer at a rate of 0.0010 nm / sec. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Subsequently, lithium fluoride 0.5 nm and aluminum 110 nm were vapor-deposited to form a cathode, and an organic EL element 3-1 was produced.

<< Production of organic EL elements 3-2 to 3-75 >>
In the production of the organic EL device 3-1, the organic EL device 3 was prepared except that only the comparative compound 1 was replaced with the compounds shown in Tables XIII to XV among the hole injection material, the hole transport material, the host compound, and the light emitting dopant. In the same manner as in Example 1, organic EL devices 3-2 to 3-75 were produced.

<< Evaluation of organic EL elements >>
With respect to the obtained organic EL devices 3-1 to 3-75, the performance of the devices was evaluated by the same method and standard as in Example 1.

In this example, in each evaluation of (1) external extraction quantum efficiency, (2) driving voltage, (4) half-light emission lifetime, and (5) initial deterioration, Example 1 was made with reference to the organic EL element 3-1. The relative value was obtained in the same manner as described above.

Evaluation results are shown in Tables XIII to XV.

The organic EL device according to the present invention was measured with a spectral radiance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.), and as a result of measuring the 2-degree viewing angle front luminance at 1000 cd / m ² , CIE chromaticity coordinates ( It was confirmed that the chromaticity in the CIE 1931 color system was in the region of x = 0.33 ± 0.07 and y = 0.33 ± 0.1 and emitted white light.

From Tables XIII to XV, the organic EL devices 3-7 to 3-75 of the present invention have higher external extraction quantum efficiency and initial luminance degradation than the comparative organic EL devices 3-1 to 3-6. Accordingly, it can be seen that the life is long at both room temperature and high temperature.

Furthermore, it can be seen that the organic EL elements 3-7 to 3-75 of the present invention also suppress the increase in driving voltage.

From these results, even in the case where a single light emitting layer is formed with two kinds of light emitting dopants to emit white light, the invention relates to the present invention as a light emitting dopant in order to improve light emission efficiency, drive voltage, and light emission life. It can be seen that it is useful to use a phosphorescent transition metal complex.

Example 4
<Vapor deposition type white light emitting element-2>
<< Preparation of white light emitting element 4-1 >>
After patterning on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm × 100 mm × 1.1 mm glass substrate was formed as a positive electrode on a 100 mm × 100 mm × 1.1 mm glass substrate, this transparent ITO electrode was provided. The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of the hole injection material 1 is put into a molybdenum resistance heating boat, and 200 mg of the hole transport material 1 is put into another molybdenum resistance heating boat, In another molybdenum resistance heating boat, 200 mg of the host compound (OC-11) is added. In another molybdenum resistance heating boat, 100 mg of the luminescent dopant (Comparative Compound 1) is added. In another molybdenum resistance heating boat, the luminescent dopant (D -3) 100 mg, 100 mg of luminescent dopant (D-6) in another molybdenum resistance heating boat, 200 mg of electron transport material 1 in another molybdenum resistance heating boat, and another molybdenum resistance heating boat 200 mg of the electron transport material 2 was put in and attached to a vacuum deposition apparatus.

Further, the hole transport layer was heated by energizing the heating boat containing the host compound (OC-11) and the light-emitting dopant (Comparative Compound 1) at a deposition rate of 0.2 nm / second and 0.035 nm / second, respectively. A blue light emitting layer having a thickness of 20 nm was provided by co-evaporation. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Further, the heating boat containing the host compound (OC-11), the luminescent dopant (D-3), and the luminescent dopant (D-6) was energized and heated, and the deposition rates were 0.2 nm / second and 0.010 nm, respectively. A yellow light emitting layer having a thickness of 20 nm was provided by co-evaporation on the hole transport layer at a rate of 0.0010 nm / sec. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Subsequently, lithium fluoride 0.5 nm and aluminum 110 nm were vapor-deposited to form a cathode, and an organic EL element 4-1 was produced.

<< Production of organic EL elements 4-2 to 4-75 >>
In the production of the organic EL element 4-1, the organic EL element 4 was replaced except that only the comparative compound 1 was replaced with the compounds shown in Tables XVI to XVIII among the hole injection material, the hole transport material, the host compound, and the light emitting dopant. In the same manner as in Example 1, organic EL elements 4-2 to 4-75 were produced.

<< Evaluation of organic EL elements >>
With respect to the obtained organic EL elements 4-1 to 4-75, the performance of the elements was evaluated by the same method and standard as in Example 1.

In this example, in each evaluation of (1) external extraction quantum efficiency, (2) drive voltage, (4) half-light emission lifetime, and (5) initial deterioration, Example 1 was made with reference to the organic EL element 4-1. The relative value was obtained in the same manner as described above.

Evaluation results are shown in Tables XVI to XVIII.

The organic EL device according to the present invention was measured with a spectral radiance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.), and as a result of measuring the 2 ° viewing angle front luminance at 1000 cd / m ² , CIE chromaticity coordinates ( It was confirmed that the chromaticity in the CIE 1931 color system was in the region of x = 0.33 ± 0.07 and y = 0.33 ± 0.1 and emitted white light.

From Tables XVI to XVIII, the organic EL elements 4-7 to 4-75 of the present invention have higher external extraction quantum efficiency and initial luminance degradation than the comparative organic EL elements 4-1 to 4-6. Accordingly, it can be seen that the life is long at both room temperature and high temperature.

Furthermore, it can be seen that the organic EL elements 4-7 to 4-75 of the present invention also suppress the increase in driving voltage.

From these results, even when two layers of light emitting layers are formed with the same host compound and three types of light emitting dopants to emit white light, it is necessary to improve the light emission efficiency, drive voltage, and light emission life. It can be seen that it is useful to use the phosphorescent transition metal complex according to the present invention as a dopant.

Example 5
<Vapor deposition type white light emitting element-3>
<< Preparation of white light emitting element 5-1 >>
After patterning on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm × 100 mm × 1.1 mm glass substrate was formed as a positive electrode on a 100 mm × 100 mm × 1.1 mm glass substrate, this transparent ITO electrode was provided. The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of the hole injection material 1 is put into a molybdenum resistance heating boat, and 200 mg of the hole transport material 1 is put into another molybdenum resistance heating boat, 200 mg of host compound 1 (OC-11) is put into another resistance heating boat made of molybdenum, 200 mg of host compound 2 (OC-6) is put into another resistance heating boat made of molybdenum, and the luminescent dopant is put into another resistance heating boat made of molybdenum. 100 mg of (Comparative Compound 1) was added, 100 mg of the luminescent dopant (D-3) was put in another molybdenum resistance heating boat, and 100 mg of the luminescent dopant (D-6) was put in another molybdenum resistance heating boat. 200 mg of electron transport material 1 is put in a resistance heating boat, and another molybdenum resistance heating boat The electron transport material 2 placed 200mg Doo, mounted in a vacuum deposition apparatus.

Further, the heating boat containing the host compound (OC-6), the luminescent dopant (D-3) and the luminescent dopant (D-6) was energized and heated, and the deposition rates were 0.2 nm / second and 0.010 nm, respectively. A yellow light emitting layer having a thickness of 20 nm was provided by co-evaporation on the hole transport layer at a rate of 0.0010 nm / sec. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Subsequently, lithium fluoride 0.5 nm and aluminum 110 nm were vapor-deposited to form a cathode, and an organic EL element 5-1 was produced.

<< Production of organic EL elements 5-2 to 5-75 >>
In the production of the organic EL device 5-1, only the comparative compound 1 among the hole injection material, the hole transport material, the host compound 1 (OC-11), the host compound 2 (OC-6), and the light emitting dopant is shown in Table XIX. Organic EL elements 5-2 to 5-75 were produced in the same manner as the organic EL element 5-1, except that the compounds shown in FIGS.

<< Evaluation of organic EL elements >>
With respect to the obtained organic EL devices 5-1 to 5-75, the performance of the devices was evaluated by the same method and standard as in Example 1.

In this example, in each evaluation of (1) external extraction quantum efficiency, (2) driving voltage, (4) half light emission lifetime, and (5) initial deterioration, Example 1 was made with reference to the organic EL element 5-1. The relative value was obtained in the same manner as described above.

Evaluation results are shown in Tables XIX to XXI.

From Tables XIX to XXI, the organic EL elements 5-7 to 5-75 of the present invention have higher external extraction quantum efficiency and initial luminance degradation than the comparative organic EL elements 5-1 to 5-6. Accordingly, it can be seen that the life is long at both room temperature and high temperature.

Furthermore, it can be seen that the organic EL elements 5-7 to 5-75 of the present invention also suppress the increase in driving voltage.

From these results, even when two light emitting layers are formed with two different host compounds and three light emitting dopants to emit white light, the light emission efficiency is improved, the driving voltage is reduced, and the light emission life is improved. Then, it turns out that it is useful to use the phosphorescence-emitting transition metal complex based on this invention as a light emission dopant.

Example 6
<Wet process type white light emitting element-1>
<< Production of White Light-Emitting Organic EL Element 6-1 >>
After patterning a substrate (NA Techno-Glass NA-45) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode, this ITO transparent electrode was provided. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

The substrate was transferred to a nitrogen atmosphere, and a solution of 50 mg of the hole transport material 3 dissolved in 10 ml of toluene was formed on the first hole transport layer by spin coating at 1000 rpm for 30 seconds. After irradiating with ultraviolet light for 180 seconds to carry out photopolymerization / crosslinking, vacuum drying was performed at 60 ° C. for 1 hour to form a second hole transport layer.

On this second hole transport layer, 100 mg of the host compound (OC-11), 14 mg of the luminescent dopant (Comparative Compound 1), 1 mg of the luminescent dopant (D-13) and 0.5 mg of the luminescent dopant (D-6) ) Was dissolved in 10 ml of toluene using a spin coating method at 1000 rpm for 30 seconds to form a light emitting layer. Furthermore, it vacuum-dried at 60 degreeC for 1 hour, and was set as the light emitting layer about 70 nm thick.

Subsequently, this substrate was fixed to a substrate holder of a vacuum deposition apparatus, and after the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, 0.4 nm of potassium fluoride was deposited as a cathode buffer layer, and further 110 nm of aluminum was deposited. Thus, a cathode was formed, and an organic EL element 6-1 was produced.

In addition, the substrate temperature at the time of vapor deposition was room temperature.

<< Preparation of organic EL elements 6-2 to 6-75 >>
In the production of the organic EL device 6-1, the organic EL device 6 was prepared in the same manner as the organic EL device 6-1, except that only the comparative compound 1 of the host compound and the light-emitting dopant was replaced with the compounds shown in Tables XXII to XXIV. -2 to 6-75 were produced.

<< Evaluation of organic EL elements >>
With respect to the obtained organic EL elements 6-1 to 6-75, the performance of the element was evaluated by the same method and standard as in Example 1.

In this example, in each evaluation of (1) external extraction quantum efficiency, (2) driving voltage, (4) half-light emission lifetime, and (5) initial deterioration, Example 1 was performed with reference to the organic EL element 6-1. The relative value was obtained in the same manner as described above.

Evaluation results are shown in Tables XXII to XXIV.

From Tables XXII to XXIV, compared with the comparative organic EL elements 6-1 to 6-6, the organic EL elements 6-7 to 6-75 of the present invention have high external extraction quantum efficiency and initial luminance degradation. Accordingly, it can be seen that the life is long at both room temperature and high temperature.

From these results, even when a light emitting layer is formed by a wet process using a spin coating method using three kinds of light emitting dopants to emit white light, in order to improve light emission efficiency, drive voltage, and light emission life, It can be seen that it is useful to use the phosphorescent transition metal complex according to the present invention as a dopant.

Example 7
<Wet process type white light emitting element-2>
<< Production of White Light-Emitting Organic EL Element 7-1 >>
After patterning a substrate (NA Techno-Glass NA-45) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode, this ITO transparent electrode was provided. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

On this second hole transport layer, 100 mg of host compound (host material 1), 14 mg of dopant (Comparative Compound 1), 1 mg of dopant (D-33), and 0.5 mg of dopant (Ir-14) are added. Using a solution dissolved in 10 ml of butyl acetate, a film was formed by a spin coating method at 1000 rpm for 30 seconds to form a light emitting layer. Ultraviolet light was irradiated for 15 seconds to cause photopolymerization / crosslinking, and further vacuum drying at 60 ° C. for 1 hour to obtain a light emitting layer having a thickness of about 70 nm.

Next, a thin film was formed on this light emitting layer by spin coating under a condition of 1000 rpm and 30 seconds using a solution of 50 mg of electron transport material 4 dissolved in 10 ml of methanol. After irradiating with ultraviolet light for 60 seconds to perform photopolymerization / crosslinking, it was further vacuum-dried at 60 ° C. for 1 hour to obtain an electron transport layer having a thickness of about 30 nm.

Subsequently, this substrate was fixed to a substrate holder of a vacuum deposition apparatus, and after the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, 0.4 nm of potassium fluoride was deposited as a cathode buffer layer, and further 110 nm of aluminum was deposited. Thus, a cathode was formed, and an organic EL element 7-1 was produced.

<< Preparation of organic EL elements 7-2 to 7-75 >>
In the production of the organic EL element 7-1, the organic EL element 7- was prepared in the same manner as the organic EL element 7-1 except that only the comparative compound 1 of the host compound and dopant was replaced with the compounds shown in Tables XXV to XXVII. 2-7-75 were prepared.

<< Evaluation of organic EL elements >>
With respect to the obtained organic EL devices 7-1 to 7-75, the device performance was evaluated by the same method and standard as in Example 1.

In this example, in each evaluation of (1) external extraction quantum efficiency, (2) drive voltage, (4) half-light emission lifetime, and (5) initial deterioration, Example 1 was made with reference to the organic EL element 7-1. The relative value was obtained in the same manner as described above.

Evaluation results are shown in Tables XXV to XXVII.

From Tables XXV to XXVII, the organic EL elements 7-7 to 7-75 of the present invention have higher external extraction quantum efficiency and initial luminance degradation than the comparative organic EL elements 7-1 to 7-6. Accordingly, it can be seen that the life is long at both room temperature and high temperature.

Furthermore, it can be seen that the organic EL elements 7-7 to 7-75 of the present invention also suppress the increase in driving voltage.

From these results, even in a white light-emitting element manufactured by forming a light-emitting layer using a spin coating method using three kinds of dopants and curing it by a photoreaction, the light emission efficiency is improved, the driving voltage is reduced, and the light emission lifetime is improved. It can be seen that it is useful to use the phosphorescent transition metal complex according to the present invention as a light-emitting dopant for improvement.

The organic electroluminescence element of the present invention has a sufficiently short wave emission as a blue phosphorescent element, has high emission efficiency, low driving voltage, and excellent durability, and is used as a display device, display, and various light emission sources. Can be used.

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate 108 with a transparent electrode Nitrogen gas 109 Water capturing Agent A Display unit B Control unit

Claims

An organic electroluminescence device containing a phosphorescent transition metal complex in at least one organic layer including a light emitting layer,
The transition metal complex has a ligand in which a plurality of aromatic rings are directly bonded to a transition metal as a central metal, and satisfies the following requirements (1) and (2): Electroluminescence element.
(1) At least one of the plurality of aromatic rings directly bonded to the transition metal has an electron withdrawing group.
(2) At least one of the plurality of aromatic rings directly bonded to the transition metal is a positive chain containing a nitrogen atom and an aromatic ring which are conjugated with the aromatic ring and are connected by a single bond. It has a pore transporting partial structure.
When the transition metal complex is evaluated by molecular orbital calculation, any one of the binding orbitals from the highest occupied orbital (HOMO) to the fifth lower energy level (HOMO-5) is the binding orbital. The absolute value of the difference between the energy level of the highest occupied orbital and the binding orbital has an electron density distribution in which 80% or more of the upper electrons exist on the hole transporting partial structure Is less than 0.7 eV, The organic electroluminescent element of Claim 1 characterized by the above-mentioned.
The absolute value of the difference in emission maximum wavelength calculated by molecular orbital calculation for each of the transition metal complex and the transition metal complex having a structure obtained by removing the hole transporting partial structure from the transition metal complex is 10 nm or less. The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is provided.
The hole transporting partial structure containing a nitrogen atom and an aromatic ring each may be an unsubstituted or substituted diarylamino group, carbazol-9-yl group, phenoxazin-10-yl group, The organic electroluminescence device according to any one of claims 1 to 3, wherein the organic electroluminescence device is selected from a phenothiazin-10-yl group, a dihydrophenazin-5-yl group, and a dihydroacridin-10-yl group. .
The electron withdrawing group is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. The organic electroluminescent element according to claim 1.
The organic electroluminescence device according to any one of claims 1 to 5, wherein at least one of the plurality of aromatic rings directly bonded to the transition metal is an azole ring.
The organic electroluminescence according to any one of claims 1 to 6, wherein at least one of the plurality of aromatic rings directly bonded to the transition metal is an imidazole ring or a triazole ring. element.
An organic luminescence device having at least one organic layer including a light emitting layer, wherein at least one of the organic layers contains a transition metal complex represented by the following general formula (1). The organic electroluminescent element according to any one of claims 1 to 7.
General formula (1)
ML A · L B · (L C ) n
[Wherein, ML A represents a partial structure represented by the following general formula (2), and M represents a transition metal of group 8 to 10 in the periodic table of elements. L A to L C each represents a divalent ligand, and L A to L C may be the same or different, and may be bonded to each other. n represents 1 or 0. ]

[Where,
Ring B represents a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed with C═C.
Ring C represents a 5- or 6-membered aromatic heterocyclic ring formed with C═N.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents an integer of 0 to 2. 1 ≦ nb + nc ≦ 4. When there are a plurality of Rb and Rc, they may be the same or different from each other.
HTG represents a hole transporting partial structure including a nitrogen atom and an aromatic ring.
L represents an arylene group having 6 to 10 carbon atoms, and L is bonded to ring B or ring C, but conjugation with ring B or ring C is not continuous. n1 represents 1 or 2. n2 represents 1 or 2. When there are a plurality of L, they may be the same or different.
M represents a transition metal of group 8 to 10 in the periodic table. ]
Each of the hole transporting partial structures containing a nitrogen atom and an aromatic ring represented by HTG may be an unsubstituted or substituted diarylamino group, carbazol-9-yl group, phenoxazine- 9. The organic electroluminescence device according to claim 8, wherein the organic electroluminescence device is selected from a 10-yl group, a phenothiazin-10-yl group, a dihydrophenazin-5-yl group and a dihydroacridin-10-yl group.
9. The electron withdrawing group represented by Rb and Rc is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. Or the organic electroluminescent element of Claim 9.
The organic electroluminescence device according to any one of claims 8 to 10, wherein the aromatic heterocycle represented by the ring C represents an azole ring.
The organic electroluminescence device according to any one of claims 8 to 11, wherein the aromatic heterocycle represented by the ring C represents an imidazole ring or a triazole ring.
The organic electroluminescent device according to claim 8, wherein the partial structure represented by the general formula (2) is represented by a partial structure represented by the following general formula (3).

[Where,
Ring A represents a divalent arylene group having 6 to 10 carbon atoms.
Ring B represents a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed with C═C.
Ring C represents a 5-membered aromatic heterocycle formed with N—C═N.
Ra represents a substitutable substituent. na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L 1 , L 2 and L 3 represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1.
Ar 1 , Ar 2 , Ar 3 , Ar 4 , Ar 5 and Ar 6 represent an aromatic group having 6 to 10 carbon atoms.
L 4 , L 5 and L 6 are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents any of 4, 5 and 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R 1 and R 2 each represent a hydrogen atom or a substituent, and at least one of R 1 and R 2 represents a substituent. ]
The organic electroluminescence device according to claim 8, wherein the partial structure represented by the general formula (2) is a partial structure represented by the following general formula (4).

[Where,
Y 1 and Y 2 represent a carbon atom or a nitrogen atom.
Ring C represents a 5-membered aromatic heterocycle formed with N—C═N.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing substituent that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L 1 , L 2 and L 3 each represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1;
Ar 1 , Ar 2 , Ar 3 , Ar 4 , Ar 5 , Ar 6 each represents an aromatic group having 6 to 10 carbon atoms.
L 4 , L 5 and L 6 are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R 1 and R 2 each represent a hydrogen atom or a substituent, and at least one of R 1 and R 2 represents a substituent. ]
The organic electroluminescence device according to claim 8, wherein the partial structure represented by the general formula (2) is represented by a partial structure represented by the following general formula (5).

[Where,
One of X 1 and X 2 represents a carbon atom, and the other represents a nitrogen atom.
Y 1 and Y 2 represent a carbon atom or a nitrogen atom.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L 1 , L 2 and L 3 represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1.
Ar 1 , Ar 2 , Ar 3 , Ar 4 , Ar 5 and Ar 6 represent an aromatic group having 6 to 10 carbon atoms.
L 4 , L 5 and L 6 are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R 1 and R 2 each represent a hydrogen atom or a substituent, and at least one of R 1 and R 2 represents a substituent. ]
The organic electroluminescence device according to claim 8, wherein the partial structure represented by the general formula (2) is represented by a partial structure represented by the following general formula (6).

[Where,
Y 1 and Y 2 represent a carbon atom or a nitrogen atom.
Ra represents a substitutable substituent, and na represents an integer of 0 to 3.
Rb and Rc each represents an electron-withdrawing group that can be substituted for ring B and ring C.
nb represents an integer of 0 to 3, and nc represents 0 or 1. 1 ≦ nb + nc ≦ 4.
When there are a plurality of Ra, Rb and Rc, they may be the same or different from each other.
Rd and Re each represent a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms.
nd and ne represent 0 or 1.
L 1 , L 2 and L 3 represent a divalent arylene group having 6 to 10 carbon atoms. k represents 0 or 1.
Ar 1 , Ar 2 , Ar 3 , Ar 4 , Ar 5 and Ar 6 represent an aromatic group having 6 to 10 carbon atoms.
L 4 , L 5 , and L 6 are selected from a single bond, an optionally substituted carbon atom, an optionally substituted nitrogen atom, an oxygen atom, and a sulfur atom, and connect adjacent aromatic rings.
m, n, and o represent 0 or 1, and when it is 0, the corresponding Lx does not exist, and adjacent aromatic rings are not connected to each other. x represents 4, 5, or 6.
p, q and r each represents 0 or 1; 1 ≦ p + q + r ≦ 2.
M represents a transition metal of group 8 to 10 in the periodic table.
R 1 and R 2 each represent a hydrogen atom or a substituent, and at least one of R 1 and R 2 represents a substituent. ]
The electron-withdrawing group represented by Rb and Rc is selected from a fluorine atom, a cyano group, a carbonyl group, a sulfonyl group, a pentafluorosulfanyl group, an oxycarbonyl group, and a fluorinated alkyl group. The organic electroluminescent element according to claim 1.
The organic electroluminescence device according to any one of claims 1 to 17, wherein the transition metal is iridium.
In the light emitting layer, a fluorene derivative, a dibenzofuran derivative, a dibenzothiophene derivative, a carbazole derivative, or a compound in which at least one carbon atom of a hydrocarbon ring constituting these condensed ring compound derivatives is substituted with a nitrogen atom, and The organic electroluminescence device according to any one of claims 1 to 18, wherein a combination thereof is contained as a host material.
The organic electroluminescent device according to any one of claims 1 to 19, wherein the organic layer containing the phosphorescent transition metal complex is a coating formation layer.
A display device comprising the organic electroluminescence element according to any one of claims 1 to 20.
An illuminating device comprising the organic electroluminescent element according to any one of claims 1 to 20.
A phosphorescent transition metal complex having a ligand in which a plurality of aromatic rings are directly bonded to a transition metal as a central metal, characterized by satisfying the following four requirements Complex.
(1) At least one of the plurality of aromatic rings directly bonded to the transition metal has an electron withdrawing group.
(2) At least one of the plurality of aromatic rings directly bonded to the transition metal is a positive chain containing a nitrogen atom and an aromatic ring which are conjugated with the aromatic ring and are connected by a single bond. It has a hole transporting partial structure.
(3) In the evaluation by molecular orbital calculation, one of the binding orbitals from the highest occupied orbital (HOMO) to the fifth lower energy level (HOMO-5) is an electron on the binding orbital. 80% or more has an electron density distribution existing on the hole transporting partial structure, and the absolute value of the difference between the energy level of the highest occupied orbital and the binding orbital is 0. (4) Difference in emission maximum wavelength calculated by molecular orbital calculation for each of the transition metal complex and the transition metal complex having a structure obtained by removing the hole transporting partial structure from the transition metal complex The absolute value of is 10 nm or less
An organic electroluminescence element material comprising the transition metal complex according to claim 23.
An organic electroluminescent element material composition comprising the transition metal complex according to claim 23.