Organic compound and organic light-emitting device

Abstract

To provide an organic metal complex that emits red light with high color purity.SOLUTION: An organic metal complex is represented by the general formula (1) in the figure. In the formula (1), X1 to X3 each represent a nitrogen atom or the like; Y represents an aryl group or a heterocyclic group; L represents a bidentate ligand; M represents a metal atom such as Ir; m represents an integer from 1 to 3; n represents an integer from 0 to 2; and R1 to R5 each represent a hydrogen atom or the like.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an organic compound and an organic light-emitting device using the same.

Background Art

[0002] An organic light-emitting device (also referred to as an organic electroluminescence device (organic EL device)) is an electronic device having a pair of electrodes and an organic compound layer disposed between these electrodes. By injecting electrons and holes from these pair of electrodes, excitons of a light-emitting organic compound in the organic compound layer are generated, and when the excitons return to the ground state, the organic light-emitting device emits light.

[0003] Recent progress in organic light-emitting devices is remarkable, and examples include low driving voltage, various emission wavelengths, high-speed responsiveness, and the ability to make the light-emitting device thinner and lighter.

[0004] In addition, as the color reproduction range used for displays, standards such as sRGB and AdobeRGB are used, and materials for reproducing them have been demanded. Recently, BT-2020 has been cited as a standard for further expanding the color reproduction range.

[0005] Currently, as an attempt to improve the luminous efficiency of organic EL devices, the use of phosphorescent emission has been proposed. An organic EL device using phosphorescent emission is expected to have a luminous efficiency improvement of about four times higher than that of a fluorescent emission device in theory. Therefore, the creation of phosphorescent organic metal complexes has been actively carried out until now. This is because the creation of organic metal complexes with excellent emission characteristics is important in providing high-performance organic light-emitting devices.

[0006] As organic metal complexes created so far, Compound 1-a below is described in Patent Document 1, and Compound 2-a below is described in Patent Document 2.

[0007]

Chemical Formula

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] Although the organic light-emitting devices using the compounds described in Patent Documents 1 and 2 can emit light with high luminous efficiency and high color purity, further improvement is required to emit light with the red chromaticity coordinates required by BT-2020.

[0010] The present invention is made to solve the above problems, and an object thereof is to provide an organometallic complex that emits red light with high color purity.

Means for Solving the Problems

[0011] The organometallic complex according to one embodiment of the present invention is characterized by being represented by the following general formula (1).

[0012]

Chemical Formula

[0013] In formula (1), X 1 to X 3 are each independently selected from a carbon atom or a nitrogen atom, and at least one is a nitrogen atom. The carbon atom has a hydrogen atom or a substituent, and the substituent is selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

[0014] Y is a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. wherein the heterocyclic group is a pyridyl group, a pyrazyl group, a pyrimidyl group, a triazolyl group, an imidazolyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a carbazolyl group, an acridinyl group, a phenanthrolyl group, a furanyl group, a thiophenyl group, a dibenzofuranyl group, or a dibenzothiophenyl group The aryl group and the heterocyclic group represented by Y may have a substituent selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

[0015] L is a bidentate ligand. M is Iridium m represents an integer from 1 to 3, and n represents an integer from 0 to 2. However, m + n is 3.

[0016] R 1 to R 5 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

Advantages of the Invention

[0017] According to the present invention, an organometallic complex capable of emitting red light with high color purity by the basic skeleton itself can be provided.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0019] <Organometallic complex> The organometallic complex according to this embodiment will be described. The organometallic complex according to this embodiment is represented by the following general formula (1).

[0020]

Chemical formula

[0021] In formula (1), X 1 to X 3 are each independently selected from a carbon atom or a nitrogen atom, and at least one is a nitrogen atom. The carbon atom has a hydrogen atom or a substituent, and the substituent is selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

[0022] Y is a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. The aryl group and the heterocyclic group represented by Y may have substituents selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

[0023] L is a bidentate ligand. When there are a plurality of Ls, the plurality of Ls may be the same or different. M is a metal atom selected from Ir, Pt, Rh, Os, and Zn. m represents an integer from 1 to 3, and n represents an integer from 0 to 2. However, m + n = 3.

[0024] R 1 to R 5 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

[0025] X 1 to X 3 The substituents that the carbon atoms of may have and R 1 to R 5 Examples of the halogen atom represented by include, but are not limited to, fluorine, chlorine, bromine, iodine, etc.

[0026] X 1 to X 3 The substituents that the carbon atoms of may have and R 1 to R 5Examples of the alkyl group represented by [alkyl group] include alkyl groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. Specific examples include methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, tertiary butyl group, secondary butyl group, octyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, etc., but are not limited thereto.

[0027] X 1 to X 3 substituents that the carbon atoms of [substituents] may have and R 1 to R 5 Examples of the alkoxy group represented by [alkoxy group] include alkoxy groups having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms. Specific examples include methoxy group, ethoxy group, propoxy group, 2-ethyl-hexyloxy group, benzyloxy group, etc., but are not limited thereto.

[0028] X 1 to X 3 substituents that the carbon atoms of [substituents] may have and R 1 to R 5Examples of the amino group represented by include an amino group substituted with any of an alkyl group, an aryl group, and an amino group. The alkyl group, aryl group, and amino group may have a halogen atom as a substituent. The aryl group and amino group may have an alkyl group as a substituent. The amino group may have substituted alkyl groups bonded to each other to form a ring. Specifically, N-methylamino group, N-ethylamino group, N,N-dimethylamino group, N,N-diethylamino group, N-methyl-N-ethylamino group, N-benzylamino group, N-methyl-N-benzylamino group, N,N-dibenzylamino group, anilino group, N,N-diphenylamino group, N,N-dinaphthylamino group, N,N-difluorenylamino group, N-phenyl-N-tolylamino group, N,N-ditolylamino group, N-methyl-N-phenylamino group, N,N-dianisorylamino group, N-mesityl-N-phenylamino group, N,N-dimesitylamino group, N-phenyl-N-(4-tert-butylphenyl)amino group, N-phenyl-N-(4-trifluoromethylphenyl)amino group, N-piperidyl group, etc. can be mentioned, but it is not limited to these.

[0029] X 1 to X 3 The substituent that the carbon atom of may have and R 1 to R 5 Examples of the aryl group represented by include an aryl group having 6 to 18 carbon atoms. Specifically, phenyl group, naphthyl group, indenyl group, biphenyl group, terphenyl group, fluorenyl group, phenanthryl group, triphenylenyl group, etc. can be mentioned.

[0030] X 1 to X 3 The substituent that the carbon atom of may have and R 1 to R 5Examples of the heterocyclic group represented by include heterocyclic groups having 3 to 15 carbon atoms. The heterocyclic group may have nitrogen, sulfur, or oxygen as a heteroatom. Specifically, examples include a pyridyl group, a pyrazyl group, a pyrimidyl group, a triazolyl group, an imidazolyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a carbazolyl group, an acridinyl group, a phenanthrolyl group, a furanyl group, a thiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, etc., but are not limited thereto.

[0031] X 1 to X 3 The substituent that the carbon atom may have and R 1 to R 5 Examples of the aryloxy group represented by include a phenoxy group, a thienyloxy group, etc., but are not limited thereto.

[0032] X 1 to X 3 The substituent that the carbon atom may have and R 1 to R 5 Examples of the silyl group represented by include a trimethylsilyl group, a triphenylsilyl group, etc., but are not limited thereto.

[0033] The above alkyl group, alkoxy group, amino group, aryl group, heterocyclic group, aryloxy group may have a halogen atom as a substituent. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine, and it may be a fluorine atom.

[0034] The above amino group, aryl group, heterocyclic group, aryloxy group may have an alkyl group as a substituent. The alkyl group may have 1 to 10 carbon atoms. More specifically, it may be a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, or a tertiary butyl group.

[0035] The above alkyl group, alkoxy group, amino group, aryl group, heterocyclic group, aryloxy group may have an aryl group as a substituent. The aryl group may have 6 to 12 carbon atoms. More specifically, it may be a phenyl group, a biphenyl group, or a naphthyl group.

[0036] The above alkyl group, alkoxy group, amino group, aryl group, heterocyclic group, aryloxy group may have a heterocyclic group as a substituent. The heterocyclic group may have 3 to 9 carbon atoms. The heterocyclic group may have nitrogen, sulfur, or oxygen as a heteroatom. More specifically, it may be a pyridyl group or a pyrrolyl group.

[0037] The above alkyl group, alkoxy group, amino group, aryl group, heterocyclic group, aryloxy group may have an amino group as a substituent. The amino group may have an alkyl group or an aryl group, and the alkyl groups may be bonded to each other to form a ring. Specifically, it may be a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, or a ditolylamino group.

[0038] The above alkyl group, alkoxy group, amino group, aryl group, heterocyclic group, aryloxy group may have an aralkyl group such as a benzyl group, an alkoxy group such as a methoxy group, an ethoxy group, or a propoxy group, an aryloxy group such as a phenoxy group, a cyano group, etc. as a substituent. The substituents are not limited to these.

[0039] Hereinafter, the specific structure of L in formula (1) will be described. The partial structure ML of the complex containing L is a structure containing a monodentate bidentate ligand (L).

[0040] Here, specific examples of the monodentate bidentate ligand include ligands having acetylacetone, phenylpyridine, picolinic acid, oxalate, salen, etc. as a basic skeleton, but are not limited thereto.

[0041] The organometallic complex according to one embodiment of the present invention is preferably an organometallic complex represented by the formula (1), wherein M is Ir, and the partial structure MLn is a structure represented by any one of the following general formulas (10) and (11).

[0042]

Chemical formula

[0043] In the general formulas (10) and (11), * represents a position bonded or coordinated to the iridium, that is, the metal M.

[0044] In the formulas (10) and (11), R 11 to R 21 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an aralkyl group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group.

[0045] In the organic compound according to this embodiment, by providing a group other than a hydrogen atom, that is, a halogen atom, an alkyl group, an alkoxy group, an amino group, an aryl group, a heterocyclic group, an aryloxy group, a silyl group, or a cyano group, on the basic skeleton, concentration quenching can be reduced. Further, by these substitutions, a compound having improved sublimability during sublimation and improved solvent solubility when used in coating can be obtained.

[0046] Next, a method for synthesizing the organometallic complex according to this embodiment will be described. The organometallic complex according to this embodiment is synthesized, for example, according to the following reaction scheme.

[0047]

Chemical formula

[0048] In the above synthesis scheme, the organometallic complex according to this embodiment is synthesized via the states shown in the following (a) to (h). (a) Pyridine derivative (E1) (b) Aldehyde derivative (E3) (c) Olefin derivative (E5) (d) Chlorophenanthroline derivative (E6) (e) Ligand derivative (E8) (f) Dichlorodimer derivative (E9) (g) Acetylacetone derivative (E11) (h) Tris complex (E12)

[0049] Also, in the above synthetic scheme, various exemplified compounds can be synthesized by changing E1, E7, and E10 respectively.

[0050] The present invention is not limited to the above synthetic scheme, and various synthetic reagents can be used.

[0051] The organometallic complex according to this embodiment has a nitrogen atom at the position of X 1 to X 3 in the general formula (1), so it becomes a stable compound that exhibits highly efficient red emission with high color purity. Hereinafter, an organometallic complex having a nitrogen atom at any one of X 1 to X 3 will be mainly described. However, a plurality of X 1 to X 3 may be nitrogen atoms. When a plurality of them are nitrogen atoms, it becomes an organometallic complex having properties combining their respective characteristics.

[0052] Hereinafter, while giving comparative compounds having a structure similar to the organometallic complex according to the present invention for comparison, the properties of the basic skeleton of the organometallic complex according to the present invention will be described. Specifically, 2-b which is the basic form of Comparative Compound 1-a and Comparative Compound 2-a shown below will be given as comparative compounds. Here, the basic form refers to a structure in which all substituents on the basic skeleton are hydrogen atoms.

[0053]

Chemical formula

[0054] Exemplary compound A1 has a basic skeleton represented by the general formula (1), and X 1 and X 3 are carbon atoms having a hydrogen atom as a substituent, X 2 is a nitrogen atom, Y is an unsubstituted phenyl group, L is acetylacetone, m is 2, and n is 1.

[0055]

Chemical formula

[0056] [1] Since X 1 to X 3 has a nitrogen atom at its position, the emission wavelength is long. In inventing the organometallic complex represented by the formula (1), the inventors focused on the basic skeleton of the ligand of the organometallic complex itself. Specifically, an attempt was made to obtain a compound in which the emission peak of the organometallic complex having only the basic skeleton of the ligand is in a wavelength region with high color purity. In the present embodiment, high color purity means that the maximum emission wavelength is in the band of 620 nm or more in a dilute solution. In CIE coordinates, the X coordinate is 0.68 or more and the Y coordinate is 0.33 or less. By using these materials with high color purity, a light-emitting device that satisfies the color purity of red emission in BT-2020 can be obtained.

[0057] Here, the inventors compared the measured maximum peak wavelengths of Comparative Compound 1-a and Exemplary Compound A1 of the present invention. The results are shown in Table 1. The measurement of the emission wavelength was performed by photoluminescence (PL) measurement of a diluted toluene solution at an excitation wavelength of 350 nm at room temperature using Hitachi F-4500.

[0058]

Table 1

[0059] From Table 1, although the emission color of Comparative Compound 1-a is red, it is not in the band of 620 nm or more, so it is not in the region with high color purity in this specification. On the other hand, Exemplary Compound A1 has a maximum emission wavelength of 620 nm or more, and thus exhibits a long-wavelength red emission color suitable for the red color of the display standards such as BT-2020.

[0060] The following will be described in detail. The inventors have found that by replacing the carbon atom of the benzoisoquinoline skeleton coordinated to the metal atom with a nitrogen atom in Comparative Compound 1-a, the emission wavelength becomes longer. That is, by replacing the carbon atom of the benzoisoquinoline skeleton with a nitrogen atom, the benzoisoquinoline skeleton part is replaced with a phenanthroline skeleton. By using the phenanthroline skeleton, the electron-withdrawing effect of the nitrogen atom can be obtained. Due to this electron-withdrawing effect, the organometallic complex having the phenanthroline skeleton according to the present invention has a lower LUMO (Lowest Unoccupied Molecular Orbital) than Comparative Compound 1-a having a benzoisoquinoline ligand. As a result, the band gap of the organometallic complex becomes smaller, so the emission wavelength becomes longer. In the organometallic complex according to the present invention, no matter which of the nitrogen atoms is provided at the position of X 1 to X 3 the same effect can be obtained. Therefore, the organometallic complex according to the present invention is a compound having a longer emission wavelength than Comparative Compound 1-a.

[0061] Table 1 shows the ratio of the emission efficiency of each compound when the emission efficiency of Comparative Compound 1-a is set to 1.0.

[0062] From the above, the organometallic complex according to the present invention can emit red light with high color purity. The red chromaticity coordinates will be described in detail in the examples.

[0063] [2] Since it has a nitrogen atom at the position of X 1 to X 3 the emission efficiency is high. Table 2 describes exemplary compound A1 and comparative compounds 2-b, 2-c, 2-d, and 2-e. From the comparison with these, the properties of the organometallic complex according to the present invention are explained. Table 2 shows the results of molecular orbital calculations of oscillator strength. Also, molecular orbital calculations were used to record the image diagrams of the center of conjugation and transitions.

[0064]

Table 2

[0065] When the electron transition of the exciton of the organometallic complex is of the MLCT type, the excited electron transitions from the metal atom side to the bidentate ligand side. At this time, by designing the molecule so that the center of gravity of the conjugated plane of the ligand is farther from the metal atom, the dipole moment at the time of excitation of the complex can be increased, and the oscillator strength can be improved. That is, the luminescence quantum yield becomes high, and the luminescence efficiency can be improved.

[0066] The phenanthroline ligand according to the present invention has a nitrogen atom at a position far from the metal atom, that is, at the position of X 1 to X 3 . As shown in the center-of-conjugation and transition image diagrams described in Table 2, the center of conjugation of the phenanthroline ligand according to the present invention is farther from the metal atom than those of comparative compounds 2-b to 2-e. For this reason, the dipole moment increases, the oscillator strength can be improved, and the luminescence quantum yield becomes high.

[0067] On the other hand, in each of comparative compounds 2-b to 2-e, a nitrogen atom is provided at a position relatively close to the metal atom. As a result, the center of conjugation of the ligand of comparative compounds 2-b to 2-e is closer to the metal atom than that of the organometallic complex according to the present invention. Therefore, the dipole moment decreases, the oscillator strength decreases, and the luminescence quantum yield becomes low.

[0068] [3] Since it has a nitrogen atom at the position of X 1 to X 3 , the stability of the exciton is high As described above, the electron transfer of the exciton of the organometallic complex according to the present invention transfers from the metal atom side to the phenanthroline side. Since the nitrogen atom has a higher electronegativity than the carbon atom, the phenanthroline skeleton in which the carbon atom of the benzoisoquinoline skeleton is replaced by a nitrogen atom has a stronger polarization than the benzoisoquinoline skeleton, and thus a bias can occur in the π electron cloud. Such a bias of electrons makes it difficult for excitons to exist stably. That is, it is preferable that the bias of the π electron cloud caused by the nitrogen atom exists separately so as not to react with the exciton. More specifically, it is preferable that the arrow representing the transition shown in Table 2 and the nitrogen atom are separated. When the arrow representing the transition and the nitrogen atom are arranged overlappingly as in Comparative Compound 2-b, the proportion of the excitation energy used for intermolecular reactions etc. instead of luminescence increases in the excited state. That is, since the luminous efficiency decreases, a large current is required to obtain the same luminance, and as a result, the driving durability of the light-emitting element decreases.

[0069] Table 1 and Table 2 show the device durability results of Comparative Compound 2-b when the device durability of Exemplary Compound A1 shown in the examples is set to 1.0. Since the exemplary compound A1 according to the present invention introduces a nitrogen atom outside the transition dipole moment, it is less likely to be affected by the nitrogen atom in the transition. On the other hand, since Comparative Compounds 2-b to 2-e introduce a nitrogen atom inside the transition dipole moment, they are more likely to be affected by the nitrogen atom in the transition. Therefore, the exemplary compound A1 according to the present invention has higher stability in the excited state than Comparative Compounds 2-b to 2-e in that it is not affected by the transition dipole moment.

[0070] From the above, the organometallic complex of the present invention has high stability in the excited state. Thereby, when used as a light-emitting material of an organic light-emitting element, it is possible to have excellent device driving durability.

[0071] In addition, the calculated values of the oscillator strength of the molecular structure described in Table 2 were obtained using the following molecular orbital calculations.

[0072] The calculation method of the molecular orbital calculation method used the currently widely used density functional theory (DFT). The functional B3LYP and the basis function 6-31G* were used. Similar results can be obtained using the basis function 6-31G(d).The molecular orbital calculation method was performed using Gaussian09 (Gaussian09, Revision C.01, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford CT, 2010.).

[0073] [X 1 to X 3 Among them, X 2 [Characteristics of organometallic complexes where X is a nitrogen atom] In general formula (1), X 2 An organometallic complex having a nitrogen atom at the position of, that is, the organometallic complex represented by general formula (2) has longer-wavelength emission, higher efficiency, and higher excited-state stability among the organometallic complexes according to the present invention.

[0074]

Chemical formula

[0075] Among the organometallic complexes according to the present invention, the one having longer-wavelength emission will be explained. In general formula (2), R 1 to R 7 may be the same as the options for R 1 to R 5 .

[0076] In the ring structure having a nitrogen atom, the electron-withdrawing effect of the nitrogen atom is particularly large at the ortho and para positions. This is as can be seen from the following resonance structural formula. That is, the electron density at the ortho and para positions is lower than others. As a result, the electron density of the nitrogen atom coordinated to the metal atom decreases, and the LUMO of the organometallic complex becomes lower. Consequently, the band gap becomes narrower and the emission wavelength becomes longer. Therefore, the organometallic complex having a nitrogen atom at X2 has a long emission wavelength.

[0077]

Chemical formula

[0078] Also, as shown in Table 2, among the organometallic complexes according to the present invention, the organometallic complex having a nitrogen atom at X 2 has a higher oscillator strength and a higher quantum yield because the center of gravity of the conjugated plane of the ligand is present further away. A compound with a high quantum yield has a high emission efficiency. Therefore, among the organometallic complexes according to the present invention, the organometallic complex having a nitrogen atom at X 2 has a high emission efficiency.

[0079] Also, among the organometallic complexes according to the present invention, X2 The organometallic complex having a nitrogen atom has higher excited state stability. X 2 The organometallic complex having a nitrogen atom can take a quinoid structure when writing a resonance structural formula as shown above. As a result, the π-conjugated system is stabilized, so that the stability is high even in the excited state. As a result, when used in an organic light-emitting device, the device durability life becomes long.

[0080] Therefore, X 2 The organometallic complex having a nitrogen atom is an organometallic complex having high color purity, high efficiency, and long life.

[0081] [Features of the organometallic complex in which X 1 to X 3 Among them, X 1 or X 3 is a nitrogen atom] In the general formula (1), the organometallic complex having a nitrogen atom at the position of X 1 or X 3 , that is, the organometallic complexes represented by the general formulas (3) and (4) are compounds capable of reducing intermolecular interaction among the organometallic complexes according to the present invention.

[0082]

Chemical formula

[0083] In the general formula (3), the options for R 1 to R 5 , R 7 and R 8 may be the same as those for R 1 to R 5 .

[0084] In the general formula (4), the options for R 1 to R 6 , and R 8 may be the same as those for R 1 to R 5 .

[0085] The organometallic complexes represented by General Formulas (3) and (4) are compounds in which the positional relationship between the two nitrogen atoms in the phenanthroline skeleton of the ligand is asymmetric among the organometallic complexes according to the present invention. As a result, the intermolecular interaction is reduced. If the intermolecular interaction is reduced, the sublimability is enhanced.

[0086] The improvement in sublimability enables the purification of the material to a high purity by sublimation purification and the fabrication of an organic light-emitting device by vapor deposition. As a result, the impurities contained in the organic light-emitting device can be reduced, and it is possible to reduce the decrease in luminous efficiency and the decrease in driving durability caused by the impurities. Further, the reduction of concentration quenching is preferable in terms of improving the luminous efficiency of the organic light-emitting device.

[0087] Y in General Formula (1) represents a ring structure. The ring structure may be an aryl group, a heterocyclic group, or an alicyclic structure. More specifically, it may be a benzene ring, a naphthyl ring, a fluorene ring, a phenanthrene ring, a pyridine ring, a quinoline ring, a triazine ring, a dibenzofuran ring, a dibenzothiophene ring, a cyclohexane ring, or the like. Preferably, a benzene ring having substituents at the 3-position and 5-position is preferable. The 3,5-positions are defined with the position where it is bonded to the phenanthroline skeleton as the 1-position. The substituent is preferably an alkyl group, more preferably a methyl group. That is, 3,5-dimethylbenzene is preferable.

[0088] Specific examples of the organometallic complex according to the present invention are shown below. However, the present invention is not limited thereto.

[0089]

Chemical formula

[0090]

Chemical formula

[0091]

Chemical formula

[0092]

Chem.

[0093] Among the above-exemplified compounds, the compounds of Group A are organometallic complexes represented by the general formula (2), where X 2 is a nitrogen atom. The compounds of Group A are compounds that have longer-wavelength emission, higher efficiency, and higher excited-state stability among the organometallic complexes according to the present invention.

[0094] Among Group A, A8 to A40 are compounds having a substituent at the ortho position of the nitrogen atom not coordinated to the metal. As described above, the introduction of a nitrogen atom polarizes the π electrons in the ligand, increasing the electron density on the introduced nitrogen atom. Therefore, intermolecular packing is likely to occur. By introducing a substituent at the ortho position of the nitrogen atom not coordinated to the metal, intermolecular packing can be reduced and sublimability can be improved. In addition, in the synthesis of organometallic complexes, when coordinating a metal atom and a ligand, the presence of multiple coordinatable nitrogen atoms may hinder coordination to the target position. Therefore, by introducing a substituent at the ortho position of the nitrogen atom not coordinated to the metal, coordination to the metal atom can be reduced and coordination to the target position can be promoted. From the above, among Group A, A8 to A40 are more preferable in terms of reducing intermolecular packing and promoting metal coordination at the target position.

[0095] The substituents substituting at the ortho position of the nitrogen atom are each selected from a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an aralkyl group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. The substituent provided at the ortho position of the nitrogen atom may be a halogen atom or an alkyl group, the halogen atom may be a fluorine atom, and the alkyl group may be an alkyl group having 1 to 4 carbon atoms.

[0096] Among the Group A, A1 to A25, A37, and A38 are organometallic complexes having a ligand represented by the general formula (11) as an auxiliary ligand. Among the organometallic complexes according to the present invention, these organometallic complexes are preferable because they have a small molecular weight and can sublime at a lower temperature.

[0097] Among the Group A, A26 to A31 are organometallic complexes having a ligand represented by the general formula (10) as an auxiliary ligand. Among the organometallic complexes according to the present invention, these organometallic complexes are preferable because they have a relatively small molecular weight and high thermal stability.

[0098] Among the Group A, A35 and A36 are compounds composed only of the phenanthroline ligand according to the present invention. Among the organometallic complexes according to the present invention, these compounds are preferable because they have even higher thermal stability.

[0099] Among the above-exemplified compounds, the compounds of Group B and Group C are organometallic complexes represented by the general formulas (4) and (3), where X 1 or X 3 is a nitrogen atom. The compounds of Group B and Group C are compounds that can suppress intermolecular interaction and have high sublimability among the organometallic complexes according to the present invention.

[0100] Among Group B and Group C, B5 to B20 and C5 to C20 are compounds having a substituent at the ortho position of the nitrogen atom not coordinated to the metal. As described above, they are more preferable in terms of reducing intermolecular packing and promoting metal coordination at the target position.

[0101] The substituents substituting at the ortho position of the nitrogen atom are each selected from a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an aralkyl group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. The substituent provided at the ortho position of the nitrogen atom may be a halogen atom or an alkyl group, the halogen atom may be a fluorine atom, and the alkyl group may be an alkyl group having 1 to 4 carbon atoms.

[0102] Among the Group B and Group C, B1 to B16, B20, C1 to C16 and C20 are organometallic complexes having a ligand represented by the general formula (11) as an auxiliary ligand. Among the organometallic complexes according to the present invention, these compounds are preferable because they have a small molecular weight and can sublime at a lower temperature.

[0103] Among the Group B and Group C, B17 and C17 are organometallic complexes having a ligand represented by the general formula (10) as an auxiliary ligand. Among the organometallic complexes according to the present invention, these organometallic complexes are preferable because they have a relatively small molecular weight and high thermal stability.

[0104] Among the Group B and Group C, B18, B19, C18 and C19 are organometallic complexes composed only of the phenanthroline ligand according to the present invention. Among the organometallic complexes according to the present invention, these organometallic complexes are preferable because they have even higher thermal stability.

[0105] The organometallic complex according to the present invention is a compound that exhibits light emission suitable for red light emission. Therefore, by using the organometallic complex according to the present invention as a constituent material of an organic light-emitting device, an organic light-emitting device having good light-emitting characteristics and excellent durability characteristics can be obtained.

[0106] ≪Organic Light-Emitting Device≫ Next, the organic light-emitting device of the present embodiment will be described. The organic light-emitting device of the present embodiment includes at least a first electrode, a second electrode, and an organic compound layer disposed between these electrodes. One of the first electrode and the second electrode is an anode and the other is a cathode. In the organic light-emitting device of the present embodiment, the organic compound layer may be a single layer or a laminate composed of a plurality of layers as long as it has a light-emitting layer. Here, when the organic compound layer is a laminate composed of a plurality of layers, the organic compound layer may have, in addition to the light-emitting layer, a hole injection layer, a hole transport layer, an electron blocking layer, a hole-exciton blocking layer, an electron transport layer, an electron injection layer, and the like. The light-emitting layer may be a single layer or a laminate composed of a plurality of layers.

[0107] In the organic light-emitting device of the present embodiment, at least one layer of the organic compound layer contains the organometallic complex according to the present embodiment. Specifically, the organic compound according to the present embodiment is included in any one of the above-described light-emitting layer, hole injection layer, hole transport layer, electron blocking layer, hole / exciton blocking layer, electron transport layer, electron injection layer, and the like. The organic compound according to the present embodiment is preferably included in the light-emitting layer.

[0108] In the organic light-emitting device of the present embodiment, when the organic compound according to the present embodiment is included in the light-emitting layer, the light-emitting layer may be a layer composed only of the organic compound according to the present embodiment, or may be a layer composed of the organometallic complex according to the present embodiment and another compound. Here, when the light-emitting layer is a layer composed of the organometallic complex according to the present embodiment and another compound, the organic compound according to the present embodiment may be used as a host of the light-emitting layer, or may be used as a guest. Further, it may be used as an assist material that can be included in the light-emitting layer. Here, the host is a compound having the largest mass ratio among the compounds constituting the light-emitting layer. The guest is a compound having a mass ratio smaller than that of the host among the compounds constituting the light-emitting layer and is a compound responsible for main emission. The assist material is a compound having a mass ratio smaller than that of the host among the compounds constituting the light-emitting layer and assisting the emission of the guest. Incidentally, the assist material is also called a second host. The host material can also be called the first compound, and the assist material can be called the second compound.

[0109] When the organic compound according to the present embodiment is used as a guest of the light-emitting layer, the concentration of the guest is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, based on the entire light-emitting layer.

[0110] The inventors have conducted various studies and found that when the organic compound according to this embodiment is used as a host or a guest in the light-emitting layer, particularly as a guest in the light-emitting layer, an element with high-efficiency and high-brightness light output and extremely high durability can be obtained. This light-emitting layer may be a single layer or a multi-layer, and it is also possible to mix colors with the red light emission, which is the light emission color of this embodiment, by including a light-emitting material having another light emission color. The multi-layer means a state in which a light-emitting layer and another light-emitting layer are laminated. In this case, the light emission color of the organic light-emitting element is not limited to red. More specifically, it may be white or an intermediate color. In the case of white, another light-emitting layer emits a color other than red, that is, blue or green. Also, the film-forming method is film formation by evaporation or coating film formation. Details of this will be described in detail in the examples described later.

[0111] The organometallic complex according to this embodiment can be used as a constituent material of an organic compound layer other than the light-emitting layer constituting the organic light-emitting element according to this embodiment. Specifically, it may be used as a constituent material of an electron transport layer, an electron injection layer, a hole transport layer, a hole injection layer, a hole blocking layer, etc. In this case, the light emission color of the organic light-emitting element is not limited to red. More specifically, it may be white light emission or an intermediate color.

[0112] Here, in addition to the organic compound according to this embodiment, conventionally known low-molecular and high-molecular hole-injecting compounds or hole-transporting compounds, host compounds, light-emitting compounds, electron-injecting compounds or electron-transporting compounds, etc. can be used together as needed. Examples of these compounds are given below.

[0113] As the hole injection and transport material, a material with a high hole mobility is preferred so as to facilitate the injection of holes from the anode and transport the injected holes to the light-emitting layer. Further, in order to suppress deterioration of the film quality such as crystallization in the organic light-emitting device, a material with a high glass transition temperature is preferred. Examples of low molecular weight and high molecular weight materials having hole injection and transport performance include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. Furthermore, the above hole injection and transport materials are also preferably used for the electron blocking layer. Specific examples of the compounds used as the hole injection and transport materials are shown below, but are of course not limited thereto.

[0114] [Chemical formula]

[0115] As the light-emitting material mainly related to the light-emitting function, in addition to the organometallic complex represented by the general formula (1), condensed ring compounds (for example, fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylene vinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives can be mentioned.

[0116] Specific examples of the compounds used as the light-emitting material are shown below, but are of course not limited thereto.

[0117] [Chemical formula]

[0118] As the light-emitting layer host or light-emitting assist material contained in the light-emitting layer, in addition to aromatic hydrocarbon compounds or their derivatives, there are also carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, and organoberyllium complexes.

[0119] Specific examples of the compounds used as the light-emitting layer host or light-emitting assist material contained in the light-emitting layer are shown below, but of course, they are not limited to these.

[0120]

Chemical formula

[0121] As the electron transport material, it can be arbitrarily selected from those capable of transporting the electrons injected from the cathode to the light-emitting layer, and is selected in consideration of the balance with the hole mobility of the hole transport material. Materials having electron transport performance include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, and condensed ring compounds (such as fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.). Furthermore, the above electron transport materials are also preferably used in the hole blocking layer. Specific examples of the compounds used as the electron transport material are shown below, but of course, they are not limited to these.

[0122]

Chemical formula

[0123] Hereinafter, the constituent members other than the organic compound layer that constitute the organic light-emitting device of the present embodiment will be described. The organic light-emitting device may be provided by forming a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, etc. may be provided on the second electrode. When providing a color filter, a planarization layer may be provided between the protective layer. The planarization layer can be composed of an acrylic resin or the like.

[0124] As the substrate, quartz, glass, silicon, resin, metal, etc. may be used. Further, a switching element such as a transistor and wiring may be provided on the substrate, and an insulating layer may be provided thereon. As the insulating layer, the material is not limited as long as a contact hole can be formed to ensure conduction between the anode and the wiring and insulation from unconnected wiring can be ensured. For example, resins such as polyimide, silicon oxide, silicon nitride, etc. can be used.

[0125] As the constituent material of the anode, it is preferable to use a material with as large a work function as possible. For example, simple metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, etc., mixtures containing these, alloys combined with these, metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide, etc. can be used. Also, conductive polymers such as polyaniline, polypyrrole, polythiophene, etc. can be used. These electrode materials may be used alone or in combination of two or more. Also, the anode may be composed of a single layer or multiple layers. When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys thereof, laminated ones, etc. can be used. Also, when used as a transparent electrode, oxide transparent conductive layers such as indium tin oxide (ITO), indium zinc oxide, etc. can be used, but it is not limited thereto. For the formation of the anode, photolithography technology can be used.

[0126] On one hand, as the constituent material of the cathode, those with a small work function are preferable. For example, alkali metals such as lithium, alkaline earth metals such as calcium, simple metals such as aluminum, titanium, manganese, silver, lead, chromium, or mixtures containing these can be mentioned. Alternatively, alloys formed by combining these simple metals can also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, zinc-silver, etc. can be used. The use of metal oxides such as indium tin oxide (ITO) is also possible. These electrode materials may be used alone or in combination of two or more kinds. Also, the cathode may have a single-layer structure or a multi-layer structure. Among them, it is preferable to use silver, and in order to suppress the aggregation of silver, it is more preferable to use a silver alloy. As long as the aggregation of silver can be suppressed, the ratio of the alloy does not matter. For example, it may be 1:1.

[0127] The cathode may be used as a top emission element using an oxide conductive layer such as ITO, or as a bottom emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. As the method for forming the cathode, although not particularly limited, it is more preferable to use direct current and alternating current sputtering methods, etc., because the film coverage is good and the resistance is easily reduced.

[0128] A protective layer may be provided after the formation of the cathode. For example, by adhering glass provided with a moisture absorbent on the cathode, the intrusion of water, etc. into the organic compound layer can be suppressed, and the occurrence of display defects can be suppressed. Also, as another embodiment, a passivation film such as silicon nitride may be provided on the cathode to suppress the intrusion of water, etc. into the organic compound layer. For example, after the formation of the cathode, it can be transported to another chamber without breaking the vacuum, and a silicon nitride film with a thickness of 2 μm can be formed by CVD method to be used as a protective layer. A protective layer using atomic layer deposition method (ALD method) may be provided after the film formation by CVD method.

[0129] In addition, a color filter may be provided for each pixel. For example, a color filter adapted to the pixel size may be provided on a separate substrate and bonded to the substrate provided with the organic light-emitting element, or a color filter may be patterned using photolithography technology on a protective layer such as silicon oxide.

[0130] The organic compound layers (hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) constituting the organic light-emitting element according to this embodiment are formed by the following method. That is, for the formation of the organic compound layer, dry processes such as vacuum evaporation, ionized evaporation, sputtering, and plasma can be used. Instead of the dry process, a wet process of dissolving in an appropriate solvent and forming a layer by a known coating method (for example, spin coating, dipping, casting method, LB method, inkjet method, etc.) can also be used. Here, when a layer is formed by a vacuum evaporation method or a solution coating method, crystallization and the like hardly occur and the stability over time is excellent. When forming a film by a coating method, a film can also be formed in combination with an appropriate binder resin. Examples of the binder resin include, but are not limited to, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicon resin, urea resin, etc. The binder resin may be used alone as a homopolymer or copolymer, or two or more kinds may be mixed and used. Furthermore, if necessary, additives such as known plasticizers, antioxidants, and ultraviolet absorbers may be used in combination.

[0131] <Device using an organic light-emitting element> The organic light-emitting element according to this embodiment can be used as a component of a display device or a lighting device. In addition, there are applications such as an exposure light source of an electrophotographic image forming device, a backlight of a liquid crystal display device, and a light-emitting device having a color filter as a white light source.

[0132] The display device may be an image information processing device having an image input unit that inputs image information from an area CCD, a linear CCD, a memory card, etc., an information processing unit that processes the input information, and a display unit that displays the input image. Further, the display unit included in an imaging device or an inkjet printer may have a touch panel function. The driving method of this touch panel function may be an infrared method, a capacitance method, a resistive film method, or an electromagnetic induction method, and is not particularly limited. Further, the display device may be used for the display unit of a multifunction printer.

[0133] By using the device using the organic light-emitting element according to this embodiment, a good image quality and a stable display even for long-time display can be achieved.

[0134] <Display device> The display device according to this embodiment has a plurality of pixels, and at least one of these pixels has the organic light-emitting element of this embodiment. And this pixel has the organic light-emitting element according to this embodiment and an active element. The display device may be used as the display unit of an image display device having an input unit for inputting image information and a display unit for outputting an image.

[0135] FIG. 1 is a cross-sectional schematic view showing an example of the display device according to this embodiment.

[0136] FIG. 1(a) is a cross-sectional schematic view of an example of a pixel constituting the display device according to this embodiment. The pixel has a sub-pixel 10. The sub-pixel is divided into 10R, 10G, and 10B by its light emission. The emission color may be distinguished by the wavelength emitted from the light-emitting layer, or the light emitted from the sub-pixel may be selectively transmitted or color-converted by a color filter or the like. Each sub-pixel has a reflective electrode 2 which is a first electrode on an interlayer insulating layer 1, an insulating layer 3 covering the end of the reflective electrode 2, an organic compound layer 4 covering the first electrode and the insulating layer, a transparent electrode 5, a protective layer 6, and a color filter 7.

[0137] The interlayer insulating layer 1 may have transistors and capacitor elements arranged below or inside thereof. The transistor and the first electrode may be electrically connected via a contact hole or the like (not shown).

[0138] The insulating layer 3 is also called a bank and a pixel isolation film. It covers the end of the first electrode and is arranged surrounding the first electrode. The portion where the insulating layer is not arranged is in contact with the organic compound layer 4 and serves as a light-emitting region.

[0139] The organic compound layer 4 has a hole injection layer 41, a hole transport layer 42, a first light-emitting layer 43, a second light-emitting layer 44, and an electron transport layer 45.

[0140] The second electrode 5 may be a transparent electrode, a reflective electrode, or a semi-transmissive electrode.

[0141] The protective layer 6 reduces the penetration of moisture into the organic compound layer. Although the protective layer is shown as a single layer, it may be a plurality of layers. Each layer may have an inorganic compound layer and an organic compound layer.

[0142] The color filter 7 is divided into 7R, 7G, and 7B according to its color. The color filter may be formed on a planarization film (not shown). Also, it may have a resin protective layer (not shown) on the color filter. Further, the color filter may be formed on the protective layer 6. Or it may be bonded after being provided on a counter substrate such as a glass substrate.

[0143] FIG. 1(b) is a schematic cross-sectional view showing an example of a display device having an organic light-emitting element and a transistor connected to this organic light-emitting element. The organic light-emitting element 26 has an anode 21, an organic compound layer 22, and a cathode 23. The transistor is an example of an active element. The transistor may be a thin-film transistor (TFT).

[0144] The display device 100 in Fig. 1(b) includes a substrate 11 made of glass, silicon, etc., and an insulating layer 12 is provided on top of it. On the insulating layer, active elements 18 such as TFTs are arranged, and a gate electrode 13, a gate insulating film 14, and a semiconductor layer 15 of the active element are arranged. The TFT 18 is also composed of a semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is provided on top of the TFT 18. The anode 21 constituting the organic light-emitting element is connected to the source electrode 17 through a contact hole 20 provided in the insulating film.

[0145] Note that the electrical connection method between the electrodes (anode, cathode) included in the organic light-emitting element 26 and the electrodes (source electrode, drain electrode) included in the TFT is not limited to the mode shown in Fig. 1(b). That is, any one of the anode or the cathode and any one of the TFT source electrode or drain electrode may be electrically connected. TFT refers to a thin-film transistor.

[0146] In the display device 100 of Fig. 1(b), the organic compound layer is illustrated as if it were a single layer, but the organic compound layer 22 may be a plurality of layers. On the cathode 23, a first protective layer 24 and a second protective layer 25 for reducing the deterioration of the organic light-emitting element are provided.

[0147] In the display device 100 of Fig. 1(b), a transistor is used as the switching element, but other switching elements may be used instead.

[0148] Also, the transistor used in the display device 100 of Fig. 1(b) is not limited to a transistor using a single-crystalline silicon wafer, and may also be a thin-film transistor having an active layer on the insulating surface of the substrate. Examples of the active layer include non-single-crystalline silicon such as single-crystalline silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystalline oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide. Note that the thin-film transistor is also called a TFT element.

[0149] The transistor included in the display device 100 in FIG. 1(b) may be formed within a substrate such as an Si substrate. Here, being formed within the substrate means fabricating the transistor by processing the substrate itself such as an Si substrate. That is, having a transistor within the substrate can also be regarded as the substrate and the transistor being integrally formed.

[0150] The organic light-emitting element according to the present embodiment has its emission luminance controlled by a TFT which is an example of a switching element, and an image can be displayed by the respective emission luminances by providing the organic light-emitting elements in a plurality of planes. Note that the switching element according to the present embodiment is not limited to a TFT, and may be a transistor formed of low-temperature polysilicon or an active matrix driver formed on a substrate such as an Si substrate. Being on the substrate can also mean within the substrate. Whether to provide a transistor within the substrate or use a TFT is selected according to the size of the display portion. For example, if the size is about 0.5 inches, it is preferable to provide the organic light-emitting element on the Si substrate.

[0151] The display device may include a plurality of light-emitting elements. The light-emitting element may include a drive circuit. The drive circuit may be an active matrix type that independently controls the light emission of the first light-emitting element and the second light-emitting element. The active matrix type circuit may be voltage programming or current programming. The drive circuit has a pixel circuit for each pixel. The pixel circuit may include a light-emitting element, a transistor that controls the emission luminance of the light-emitting element, a transistor that controls the light emission timing, a capacitor that holds the gate voltage of the transistor that controls the emission luminance, and a transistor for connecting to GND without passing through the light-emitting element.

[0152] The light-emitting elements constituting the light-emitting device may be 10 μm apart from each other, 7 μm apart from each other, or 5 μm or less apart from each other.

[0153] FIG. 2(a) is a schematic diagram of an image forming apparatus 36 according to an embodiment of the present invention. The image forming apparatus includes a photoreceptor, an exposure light source, a developing unit, a charging unit, a transferrer, a conveyance roller, and a fixing unit.

[0154] Light 29 is irradiated from the exposure light source 28, and an electrostatic latent image is formed on the surface of the photoreceptor 27. This exposure light source has the organic light-emitting element according to the present invention. The developing unit 31 has toner or the like. The charging unit 30 charges the photoreceptor. The transferrer 32 transfers the developed image onto the recording medium 34. The conveying unit 33 conveys the recording medium 34. The recording medium 34 is, for example, paper. The fixing unit 35 fixes the image formed on the recording medium.

[0155] FIGS. 2(b) and 2(c) are schematic views showing a state in which a plurality of light-emitting portions 38 are arranged on a long substrate in the exposure light source 28. 37 is a direction parallel to the axis of the photoreceptor and represents the column direction in which the organic light-emitting elements are arranged. This column direction is the same as the direction of the axis around which the photoreceptor 27 rotates. This direction can also be called the major axis direction of the photoreceptor.

[0156] FIG. 2(b) shows a form in which the light-emitting portions are arranged along the major axis direction of the photoreceptor. FIG. 2(c) shows a form different from (b), in which the light-emitting portions are alternately arranged in the column direction in each of the first column and the second column. The first column and the second column are arranged at different positions in the row direction.

[0157] In the first column, a plurality of light-emitting portions are arranged at intervals. The second column has light-emitting portions at positions corresponding to the intervals between the light-emitting portions in the first column. That is, also in the row direction, a plurality of light-emitting portions are arranged at intervals.

[0158] The arrangement in FIG. 2(c) can also be described as, for example, a state of being arranged in a grid pattern, a state of being arranged in a staggered grid, or a checkered pattern.

[0159] FIG. 3 is a schematic diagram showing an example of the display device according to the present embodiment. The display device 1000 may include a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are connected to flexible printed circuits FPC 1002 and 1004. An organic light-emitting element according to the present embodiment may be used for the display panel 1005. Transistors are printed on the circuit board 1007. The battery 1008 may not be provided if the display device is not a portable device, or even if it is a portable device, it does not need to be provided at this position.

[0160] FIG. 4 is a schematic diagram showing an example of the display device according to the present embodiment. FIG. 4(a) shows a display device such as a TV monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. An organic light-emitting element according to the present embodiment may be used for the display unit 1302. The display device 1300 also has a base 1303 that supports the frame 1301 and the display unit 1302. The base 1303 is not limited to the form shown in FIG. 4(a). The lower side of the frame 1301 may also serve as the base. The frame 1301 and the display unit 1302 may be bent. The radius of curvature may be 5000 mm or more and 6000 mm or less. The display device 1310 in FIG. 4(b) is configured to be foldable and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may have an organic light-emitting element according to the present embodiment. The first display unit 1311 and the second display unit 1312 may be a single seamless display device. The first display unit 1311 and the second display unit 1312 can be separated at the bending point. The first display unit 1311 and the second display unit 1312 may display different images, or may display one image together.

[0161] <Photoelectric conversion device> The display device according to this embodiment may be used in a display unit of a photoelectric conversion device such as an imaging device having an optical unit with a plurality of lenses and an imaging element that receives light that has passed through the optical unit. The photoelectric conversion device may have a display unit that displays information acquired by the imaging element. Further, the display unit may be a display unit exposed to the outside of the photoelectric conversion device or a display unit disposed within a viewfinder. The photoelectric conversion device may be a digital camera or a digital video camera.

[0162] FIG. 5 is a schematic diagram showing an example of the imaging device according to this embodiment. The imaging device 1100 may include a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may include the display device according to this embodiment. In that case, the display device may display not only the image to be captured but also environmental information, imaging instructions, and the like. The environmental information may include the intensity of external light, the direction of external light, the speed at which the subject moves, the possibility that the subject is blocked by an obstacle, and the like. Since the timing suitable for imaging is a very short time, it is better to display the information earlier. Therefore, it is preferable to use the display device using the organic light-emitting element of the present invention. This is because the organic light-emitting element has a high response speed. The display device using the organic light-emitting element can be more suitably used than a liquid crystal display device in a device that requires a high display speed. The imaging device 1100 has an optical unit (not shown). The optical unit has a plurality of lenses and forms an image on an imaging element housed in the housing 1104. The plurality of lenses can adjust the focus by adjusting their relative positions. This operation can also be performed automatically.

[0163] <Electronic device> The display device according to this embodiment may also be used in a display unit of an electronic device such as a mobile terminal. In that case, it may have both a display function and an operation function. Examples of the mobile terminal include mobile phones such as smartphones, tablets, and head-mounted displays.

[0164] FIG. 6 is a schematic diagram showing an example of a mobile device according to the present embodiment. The mobile device 1200 includes a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may include a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a reaction unit of a touch panel method. The operation unit may be a biometric recognition unit that recognizes a fingerprint and performs unlocking or the like. A mobile device having a communication unit can also be called a communication device.

[0165] <Illumination device> FIG. 7 is a schematic diagram showing an example of an illumination device according to the present embodiment. The illumination device 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical filter 1404, and a light diffusing unit 1405. The light source 1402 may include an organic light emitting element according to the present embodiment. The optical filter 1404 may be a filter that improves the color rendering property of the light source 1402. The light diffusing unit 1405 can effectively diffuse the light of the light source 1402, such as lighting up, and deliver the light to a wide range. If necessary, a cover may be provided on the outermost part.

[0166] The illumination device is, for example, a device that illuminates a room. The illumination device may emit any color from white, day white, or other blue to red. It may have a dimming circuit for dimming them. The illumination device may include the organic light emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit that converts an AC voltage into a DC voltage. The illumination device may have an inverter circuit. Also, white means a color temperature of 4200K and day white means a color temperature of 5000K. The illumination device may have a color filter. Further, the illumination device according to the present embodiment may have a heat radiating unit. The heat radiating unit releases the heat inside the device to the outside of the device, and examples thereof include a metal having a high specific heat and liquid silicone.

[0167] <Moving body> The mobile body according to this embodiment may be an automobile, a ship, an aircraft, a drone, or the like. The mobile body may have a body and a lighting device provided on the body. The lighting device may emit light to notify the position of the body. The lighting device has an organic light-emitting element according to this embodiment.

[0168] FIG. 8 is a schematic diagram showing an example of the mobile body according to this embodiment, and is a diagram showing an automobile having a tail lamp which is an example of a vehicle lighting device. The automobile 1500 as the body may have a tail lamp 1501 and may be configured to turn on the tail lamp 1501 when a brake operation or the like is performed. The tail lamp 1501 may have an organic light-emitting element according to this embodiment. The tail lamp 1501 may have a protective member for protecting the organic light-emitting element. The protective member has a certain degree of strength and may be made of any material as long as it is transparent, but is preferably made of polycarbonate or the like. A phthalic acid derivative, an acrylonitrile derivative, or the like may be mixed into the polycarbonate. The automobile 1500 may have a vehicle body 1503 and a window 1502 attached thereto. The window 1502 may be a transparent display as long as it is not a window for checking the front and rear of the automobile 1500. The transparent display may have an organic light-emitting element according to this embodiment. In this case, the constituent materials such as the electrodes of the organic light-emitting element are made of transparent members.

Example

[0169] Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited thereto.

[0170] [Example 1 (Synthesis of Exemplary Compound A2)]

[0171]

Chemical formula

[0172] After degassing the solvent of 2-ethoxyethanol (4 ml), 0.16 g (0.45 mmol) of iridium(III) chloride hydrate was added and stirred at room temperature for 30 minutes. Then, 0.26 g (0.94 mmol) of D8 was added, and the mixture was heated to 120 °C and stirred for 6 hours. After cooling, water was added, and the mixture was filtered and washed with water. By drying this, 0.27 g (yield 90%) of a red solid D9 was obtained.

[0173] [Chemical formula]

[0174] After degassing the solvent of 2-ethoxyethanol (5 ml), 0.20 g (0.13 mmol) of D9 and 52 mg (0.52 mmol) of acetylacetone were added and stirred at room temperature for 30 minutes. Then, 0.14 g (1.3 mmol) of sodium carbonate was added, and the mixture was heated to 100 °C and stirred for 6 hours. After cooling, methanol was added, and the mixture was filtered and washed with methanol. By drying this, 0.16 g (yield 72%) of a dark red solid A8 was obtained.

[0175] The emission spectrum of a toluene solution of exemplary compound A8 at 1 × 10 -5 mol / L was measured by photoluminescence at an excitation wavelength of 350 nm using Hitachi F-4500, and a spectrum with a maximum intensity at 615 nm was obtained.

[0176] In addition, the mass spectrometry of exemplary compound A2 was performed using MALDI-TOF-MS (Autoflex LRF manufactured by Bruker). [MALDI-TOF-MS] Measured value: m / z = 858 Calculated value: C 52 H 26 = 858

[0177] [Chemical formula]

[0178] 100 mg (0.117 mmol) of A8 and 333 mg (1.17 mmol) of D8 were heated to 230 °C and stirred for 3 hours. After cooling to 100 °C, 2 mL of toluene was added and stirred until it reached room temperature. Then heptane was added and filtration was performed. The filtrate was purified by silica gel column chromatography (mobile phase; ethyl acetate) to obtain 13.0 mg (yield 11%) of a dark red solid A35.

[0179] The emission spectrum of a toluene solution of the exemplified compound A35 at 1×10 -5 mol / L was measured by photoluminescence at an excitation wavelength of 350 nm using Hitachi F-4500, and a spectrum with a maximum intensity at 610 nm was obtained.

[0180] In addition, the exemplified compound A35 was subjected to mass spectrometry using MALDI-TOF-MS (Autoflex LRF manufactured by Bruker). [MALDI-TOF-MS] Measured value: m / z = 1042 Calculated value: C 52 H 26 = 1042

[0181] [Examples 2 to 20 (Synthesis of Exemplified Compounds)] Table 3 shows the exemplified compounds shown in Examples 2 to 20. The exemplified compounds were synthesized in the same manner as in Example 1, except that the raw materials D1, D7, and D10 in Example 1 were changed to raw material 1, raw material 2, and raw material 3. Also shown are the measured values of m / z of the mass spectrometry results measured in the same manner as in Example 1.

[0182]

Table 3-1

[0183]

Table 3-2

[0184]

Table 3-3

[0185] [Table 3-4]

[0186] [Example 21] An organic light-emitting device having a bottom emission structure in which an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode were sequentially formed on a substrate was fabricated.

[0187] First, ITO was deposited on a glass substrate, and an ITO electrode (anode) was formed by performing a desired patterning process. At this time, the film thickness of the ITO electrode was set to 100 nm. The substrate on which the ITO electrode was thus formed was used as an ITO substrate in the following steps. Next, vacuum evaporation by resistance heating was performed in a vacuum chamber of 1.33×10 -4 Pa, and the organic compound layers and electrode layers shown in Table 4 were continuously deposited on the above ITO substrate. At this time, the electrode area of the opposing electrode (metal electrode layer, cathode) was made to be 3 mm 2 .

[0188] [Table 4]

[0189] Regarding the obtained device, the characteristics of the device were measured and evaluated. The maximum emission wavelength of the light-emitting device was 617 nm, the maximum external quantum efficiency (E.Q.E.) was 22%, and red light emission with chromaticity of (X, Y) = (0.69, 0.32) was obtained. Furthermore, a continuous drive test was performed at a current density of 100 mA / cm 2 , and the time when the luminance degradation rate reached 5% was measured. When the time when the luminance degradation rate of Comparative Example 1 reached 5% was set to 1.0, the luminance degradation rate ratio of this example was 1.0.

[0190] In this example, specifically, the current-voltage characteristics were measured with a microammeter 4140B manufactured by Hewlett-Packard Company, and the emission luminance was measured with a BM7 manufactured by Topcon Corporation.

[0191] [Examples 22 to 31, Comparative Example 1] In Examples 22 to 31, an organic light-emitting device was fabricated in the same manner as in Example 21, except that the compounds shown in Table 5 were appropriately changed. The characteristics of the obtained device were measured and evaluated in the same manner as in Example 21. The measurement results are shown in Table 6.

[0192]

Table 5

[0193] As described above, the chromaticity coordinates of Comparative Example 1 were (0.65, 0.34), and the red light-emitting device according to the present invention showed a chromaticity closer to the color reproduction range of BT2020. This is due to the fact that the organometallic complex according to the present invention emits red light at a longer wavelength.

[0194] Also, the maximum external quantum efficiency (E.Q.E.) of Comparative Example 2 was 15%, and the red light-emitting device according to the present invention had a higher luminous efficiency. This is due to the fact that the organometallic complex according to the present invention has a higher oscillator strength. Furthermore, the luminance degradation rate ratio of Comparative Example 2 was 0.6, and the red light-emitting device according to the present invention had a longer lifespan. This is due to the fact that the introduction position of the nitrogen atom in the organometallic complex according to the present invention is far from the metal atom, resulting in high exciton stability.

Explanation of Reference Numerals

[0195] 1 Interlayer Insulating Layer 2 Reflective Electrode 3 Insulating Layer 4 Organic Compound Layer 5 Transparent Electrode 6 Protective Layer 7 Color Filter 10 Sub-Pixel 11 Substrate 12 Insulating Layer 13 Gate Electrode 14 Gate Insulating Film 15 Semiconductor Layer 16 Drain Electrode 17 Source Electrode 18 Thin film transistor 19 Insulating film 20 Contact hole 21 Lower electrode 22 Organic compound layer 23 Upper electrode 24 Second protective layer 25 First protective layer 26 Organic light-emitting element 27 Photoconductor 28 Exposure light source 29 Light 30 Charging section 31 Developing section 32 Transfer section 33 Conveying section 34 Recording medium 35 Fixing section 36 Image forming apparatus 37 First direction parallel to the axis of the photoconductor 38 Light-emitting section 100 Display device 1000 Display device 1001 Upper cover 1002 Flexible printed circuit 1003 Touch panel 1004 Flexible printed circuit 1005 Display panel 1006 Frame 1007 Circuit board 1008 Battery 1009 Lower cover 1100 Imaging device 1101 Viewfinder 1102 Rear display 1103 Operation section 1104 Housing 1200 Electronic device 1201 Display section 1202 Operation section 1203 Housing 1300 Display device 1301 Frame 1302 Display section 1303 Base 1310 Display device 1311 First display unit 1312 Second display unit 1313 Housing 1314 Bending point 1400 Lighting device 1401 Housing 1402 Light source 1403 Circuit board 1404 Optical film 1405 Light diffusing part 1500 Automobile 1501 Tail lamp 1502 Window 1503 Vehicle body

Claims

1. An organometallic complex represented by the following general formula (1): 【Chemistry 1】 In formula (1), X １ ~X ３ are each independently selected from a carbon atom or a nitrogen atom, and at least one is a nitrogen atom. The carbon atom has a hydrogen atom or a substituent, and the substituent is selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group. The X １ ~X ３ The above-mentioned substituent is located at the ortho position relative to the nitrogen atom represented by the formula: Y is a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group, and the heterocyclic group is a pyridyl group, a pyrazyl group, a pyrimidyl group, a triazyl group, an imidazolyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a carbazolyl group, an acridinyl group, a phenanthrolyl group, a furanyl group, a thiophenyl group, a dibenzofuranyl group, or a dibenzothiophenyl group. The aryl group and the heterocyclic group represented by Y may have a substituent selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group. L is a bidentate ligand. M is iridium. m is an integer of 1 to 3, and n is an integer of 0 to 2, provided that m+n is 3. R １ ~R ５ are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

2. The organometallic complex according to claim 1, characterized in that it is represented by the following general formula (2): 【Chemistry 2】 R １ ~R ７ are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

3. The R ６ and R ７ 3. The organometallic complex according to claim 2, wherein is a substituted or unsubstituted alkyl group.

4. The R ６ and R ７ 3. The organometallic complex according to claim 2, wherein is an alkyl group having 1 to 4 carbon atoms.

5. The R ６ and R ７ 3. The organometallic complex according to claim 2, wherein is a methyl group.

6. The organometallic complex according to claim 1, characterized in that it is represented by the following general formula (3): 【Chemistry 3】 R １ ~R ５ , R ７ and R ８ are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

7. The organometallic complex according to claim 1, which is represented by the following general formula (4): 【Chemistry 4】 R １ ~R ６ , and R ８ are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a silyl group, and a cyano group.

8. 8. The organometallic complex according to claim 1, wherein m is 2, n is 1, and L is a structure represented by general formula (10) or (11). 【Chemistry 5】 In formulae (10) and (11), * represents the position at which the metal is bonded or coordinated. In formulae (10) and (11), R 11 to R 21 each independently represent a hydrogen atom, a halogen atom, a substituent, Substituted or unsubstituted alkyl groups, alkoxy groups, aralkyl groups, substituted amino groups, substituted or unsubstituted or an unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group, Be found out.

9. 9. The organometallic complex according to claim 1, wherein Y is a benzene ring having substituents at the 3- and 5-positions.

10. The X １ ~X ３ 2. The organometallic complex according to claim 1, characterized in that it has substituents at all ortho positions relative to the nitrogen atom represented by the formula:

11. 11. The organometallic complex according to claim 10, wherein the substituent at the ortho position to the nitrogen atom is selected from a halogen atom and an alkyl group.

12. 12. The organometallic complex of claim 1, wherein the organometallic complex has three different ligands.

13. 13. An organic light-emitting element comprising: a first electrode; a second electrode; and an organic compound layer disposed between the first electrode and the second electrode, the organic compound layer comprising a layer containing the organometallic complex according to claim 1.

14. The organic light-emitting element according to claim 13, wherein the layer containing the organometallic complex is a light-emitting layer.

15. The organic light-emitting device according to claim 14, which emits red light.

16. 16. The organic light-emitting element according to claim 14, further comprising another light-emitting layer disposed in a stacked state with the light-emitting layer, the another light-emitting layer emitting light of a color different from the color of light emitted by the light-emitting layer.

17. The organic light-emitting device according to claim 16, which emits white light.

18. 18. A display device comprising a plurality of pixels, each of the pixels comprising the organic light-emitting element according to claim 13 and an active element connected to the organic light-emitting element.

19. An input unit for inputting image information and a display unit for outputting an image, An image display device, wherein the display unit comprises the display device according to claim 18.

20. The imaging device includes an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit.

20. A photoelectric conversion device, wherein the display section displays information captured by the imaging element, and the display section has the display device according to claim 18.

21. The device has a housing, a communication unit that communicates with the outside, and a display unit, 20. An electronic device, wherein the display unit is a display device according to claim 18.

22. A lighting device having a light source and a light diffusion unit or an optical filter, 18. A lighting device, comprising the light source comprising the organic light-emitting element according to claim 13.

23. The drone has a body and a lighting device provided on the body, 18. A moving object, comprising: a lighting device comprising the organic light-emitting element according to claim 13.

24. A photoconductor and an exposure light source that irradiates the photoconductor with light, 18. An image forming apparatus, comprising: said exposure light source comprising the organic light emitting element according to claim 13.

Images