Amine compounds having an azabenzoxazole ring structure and organic electroluminescent elements using the same

Abstract

The present application aims at preventing deterioration inside an organic EL element, greatly improving light extraction efficiency, and providing a compound that absorbs light of wavelengths of 400 nm to 410 nm of sunlight without affecting materials inside the element, and has a high refractive index in the range of wavelengths of 450 nm to 750 nm. The present application is an amine compound that has a high refractive index and a specific benzoxazole ring structure. In an organic EL element having, in at least this order, an anode electrode, a hole transporting layer, a light emitting layer, an electron transporting layer, a cathode electrode, and a cover layer, the cover layer preferably contains the amine compound of the present application that has a specific benzoxazole ring structure.

Description

Technical Field

[0001] This invention relates to compounds suitable for self-emissive electronic elements for various display devices, and more particularly to compounds suitable for organic electroluminescent elements (hereinafter referred to as organic EL elements), and organic EL elements, electronic devices or electronic components obtained using the compounds. Background Technology

[0002] Organic EL elements are self-emissive, therefore they are brighter, have better visibility, and can display vividly compared to liquid crystal elements, and therefore have been actively researched.

[0003] In 1987, CWTang et al. of Eastman Kodak developed a layered structure element that distributed various functions to various materials, thus making organic EL elements using organic materials practical. They achieved 1000 cd / m² light emission at voltages below 10V by layering an electron-transporting phosphor with an organic material that transports holes, and injecting the charges of both into the phosphor layer. 2 The above high brightness (see, for example, Patent Document 1 and Patent Document 2).

[0004] To date, various improvements have been made to make organic EL devices practical. By further subdividing the various functions of the stacked structure, an electroluminescent device is made by sequentially arranging an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode on a substrate. Thus, high efficiency and durability are achieved in a bottom-emitting structure light-emitting device that emits light from the bottom (see, for example, Non-Patent Literature 1).

[0005] In recent years, top-emitting light-emitting elements, which use a metal with a high work function as the anode and emit light from the top, have become increasingly common. In bottom-emitting structures where light is extracted from the bottom (where pixel circuitry is present), the area of ​​the light-emitting portion is limited. In contrast, top-emitting light-emitting elements have the advantage of allowing for a wider light-emitting portion because light is extracted from the top and not blocked by the pixel circuitry. In top-emitting light-emitting elements, the cathode uses semi-transparent electrodes such as LiF / Al / Ag (e.g., see Non-Patent Document 2), Ca / Mg (e.g., see Non-Patent Document 3), and LiF / MgAg.

[0006] In such light-emitting elements, when light emitted from the light-emitting layer is incident on other films, light incident at an angle greater than a certain angle will undergo total internal reflection at the interface between the light-emitting layer and other films. Therefore, only a portion of the emitted light can be utilized. In recent years, in order to improve the light extraction efficiency, light-emitting elements with a high-refractive-index "coating layer" disposed on the outside of a semi-transparent electrode with a low refractive index have been proposed (see, for example, Non-Patent Documents 2 and 3).

[0007] Regarding the effect of the capping layer in the light-emitting element of the top-emitting structure, in a light-emitting element using Ir(ppy)3 as the luminescent material, the current efficiency without the capping layer is 38 cd / A. In contrast, by setting a ZnSe layer with a film thickness of 60 nm as the capping layer, the current efficiency becomes 64 cd / A, showing an efficiency improvement of approximately 1.7 times. Furthermore, it is shown that the maximum transmittance of the semi-transparent electrode and the capping layer does not necessarily coincide with the maximum efficiency, and that the maximum light extraction efficiency is determined by the interference effect (see, for example, Non-Patent Literature 3).

[0008] Previously, the use of high-precision metal masks during the formation of capping layers has been proposed. However, this method presents several problems when used at high temperatures: the metal mask deforms due to heat, leading to reduced alignment accuracy. Consequently, ZnSe, with a melting point exceeding 1100°C (see, for example, Non-Patent Document 3), cannot be deposited at the correct location using a high-precision metal mask, potentially affecting the light-emitting element itself. Furthermore, even sputtering-based film deposition can impact the light-emitting element. Therefore, capping layers using inorganic materials are unsuitable.

[0009] In addition, as a capping layer for adjusting the refractive index, in the case of using tris(8-hydroxyquinoline) aluminum (hereinafter abbreviated as Alq3) (for example, refer to Non-Patent Document 2), Alq3 is known as an organic EL material that is used as a green light-emitting material or is commonly used as an electron transport material. It has weak absorption around 450 nm, which is used in blue light-emitting materials. Therefore, in the case of blue light-emitting elements, there are also problems of reduced color purity and reduced light extraction efficiency.

[0010] In addition, components made using conventional cover layers have the following problems: sunlight with wavelengths of 400nm to 410nm is transmitted, affecting the materials inside the component, reducing color purity and light extraction efficiency.

[0011] In order to improve the characteristics of organic EL devices, especially to absorb sunlight with wavelengths of 400nm to 410nm without affecting the internal materials of the device, and to significantly improve the light extraction efficiency, materials with high absorption coefficients, high refractive indices, and excellent film stability and durability are sought as the coating layer.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: US5792557 A

[0015] Patent Document 2: US5639914 A

[0016] Patent Document 3: International Publication No. 2014 / 009310

[0017] Patent Document 4: US2014 / 0225100A1

[0018] Non-patent literature

[0019] Non-patent literature 1: Proceedings of the 9th Lecture of the Chinese Society of Applied Physics, pp. 55-61 (2001)

[0020] Non-patent literature 2: Appl. Phys. Let., 78, 544 (2001)

[0021] Non-patent literature 3: Appl. Phys. Let., 82, 466 (2003)

[0022] Non-patent literature 4: SYNLETT., 7, 1172 (2009)

[0023] Non-patent literature 5: J.Org.Chcm.,60,7508(1995)

[0024] Non-patent literature 6: Synth. Commun., 11, 513 (1981)

[0025] Non-patent literature 7: Appl. Phys. Lett., 98, 083302 (2011) Summary of the Invention

[0026] The object of this invention is to provide a compound with a high refractive index in the wavelength range of 450 nm to 750 nm, which absorbs sunlight with wavelengths of 400 nm to 410 nm without affecting the internal materials of the element, in order to improve the element characteristics of organic EL elements. Furthermore, by using this compound as a constituent material of a capping layer, an organic EL element in which internal degradation is suppressed and light extraction efficiency is significantly improved is provided.

[0027] The physical properties of the material suitable for the capping layer of organic EL elements can be listed as follows: (1) high absorption coefficient; (2) high refractive index; (3) capable of vapor deposition; (4) stable thin film state; (5) high glass transition temperature. In addition, the physical properties of the organic EL element provided by the present invention can be listed as follows: (1) absorbs light with wavelengths of 400nm to 410nm; (2) high light extraction efficiency; (3) color purity does not decrease; (4) light is transmitted without changing over time; (5) long lifespan.

[0028] Therefore, in order to achieve the above-mentioned objectives, the inventors focused on the excellent film stability and durability of aryl amine-based materials, and selected amine compounds with high refractive index and specific benzo[a]azole ring structures at a concentration of 10 -5 The invention was completed by using a material with high absorbance in the wavelength range of 400 nm to 410 nm in the absorption spectrum at a mol / L concentration as a material to form a capping layer to fabricate organic EL elements and conducting in-depth evaluation of the characteristics of the elements.

[0029] That is, the present invention provides amine compounds having an azirconoxazole ring structure and organic EL elements using the same. Additionally, it provides electronic elements having an organic layer containing the aforementioned amine compound and electronic devices obtained using such electronic elements.

[0030] 1) An amine compound having an azabenzoxazole ring structure, represented by the following general formula (a-1).

[0031]

[0032] In the aforementioned general formula (a-1), A, B, and C may be chosen to be the same as or different from each other, representing the group shown in the following general formula (b-1), a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group, wherein at least one of A, B, and C is the group shown in the following general formula (b-1).

[0033] L1, L2, and L3 may be chosen to be the same as or different from each other, representing a single bond, a substituted or unsubstituted divalent aromatic hydrocarbon group, a substituted or unsubstituted divalent aromatic heterocyclic group, or a substituted or unsubstituted divalent fused polycyclic aromatic group.

[0034]

[0035] In the formula, R can be chosen to be the same or different from each other, representing the site bonded to L1, L2 or L3 in the aforementioned general formula (a-1), hydrogen atom, deuterium atom, chlorine atom, cyano, nitro, trimethylsilyl, triphenylsilyl, optional linear or branched alkyl with 1 to 6 carbon atoms having a substituent, optional cycloalkyl with 5 to 10 carbon atoms having a substituent, optional linear or branched alkenyl with 2 to 6 carbon atoms having a substituent, optional linear or branched alkoxy with 1 to 6 carbon atoms having a substituent, optional cycloalkoxy with 5 to 10 carbon atoms having a substituent, substituted or unsubstituted aryloxy, substituted or unsubstituted aromatic hydrocarbon, substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted fused polycyclic aromatic group, and one R represents the site bonded to L1, L2 or L3 in the aforementioned general formula (a-1).

[0036] Y can be chosen to be the same or different from each other, representing carbon or nitrogen atoms substituted by R. Among them, at least one of Y is a nitrogen atom substituted by R.

[0037] 2) An amine compound having an azabenzoxazole ring structure according to 1) above, wherein, among A, B and C in the aforementioned general formula (a-1), the groups other than those shown in the aforementioned general formula (b-1) are substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted phenanthyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothiophene, substituted or unsubstituted indolyl, substituted or unsubstituted benzimidazolyl, substituted or unsubstituted imidazopyridyl, substituted or unsubstituted benzoxazole, substituted or unsubstituted benzothiazolyl, substituted or unsubstituted dibenzofuranyl, or substituted or unsubstituted dibenzothiaphene.

[0038] 3) An amine compound having an azabenzoxazole ring structure according to 2) above, wherein the group represented by the aforementioned general formula (b-1) is the group represented by the following general formula (b-2) or (b-3).

[0039]

[0040] The R in the aforementioned general formulas (b-2) and (b-3) is defined in the same way as R in the aforementioned general formula (b-1).

[0041] 4) An amine compound having an azabenzoxazole ring structure according to 3) above, wherein the group represented by the aforementioned general formula (b-2) is the group represented by the following general formula (b-4), and the group represented by the aforementioned general formula (b-3) is the group represented by the following general formula (b-5).

[0042]

[0043] The R in the aforementioned general formulas (b-4) and (b-5) is defined in the same way as R in the aforementioned general formula (b-1).

[0044] 5) An amine compound having an azabenzoxazole ring structure as described in 1) above, wherein L1, L2 and L3 in the aforementioned general formula (a-1) are single bonds, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, substituted or unsubstituted naphthylene, substituted or unsubstituted dibenzofuranylene, or substituted or unsubstituted dibenzothiopheneylene.

[0045] 6) An amine compound having an azabenzoxazole ring structure according to 4) above, wherein only one of A, B and C in the aforementioned general formula (a-1) is a group shown in the aforementioned general formula (b-4) or (b-5).

[0046] 7) An amine compound having an azabenzoxazole ring structure according to 4) above, wherein, among A, B and C in the aforementioned general formula (a-1), both are groups shown in the aforementioned general formula (b-4) or (b-5).

[0047] 8) An amine compound having an azabenzoxazole ring structure according to 4) above, wherein A, B and C in the aforementioned general formula (a-1) are all groups shown in the aforementioned general formula (b-4) or (b-5).

[0048] 9) An organic EL element having at least an anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode electrode, and a capping layer in sequence, wherein the capping layer contains an amine compound having an azirzooxazole ring structure as described in any one of 1) to 8).

[0049] 10) The organic EL element according to 9) above, wherein the extinction coefficient of the capping layer is 0.2 or higher in the wavelength range of 400 nm to 410 nm, and the concentration is 10 -5 The absorbance in the absorption spectrum of mol / L is above 0.2 in the wavelength range of 400 nm to 410 nm.

[0050] 11) The organic EL element according to 9) above, wherein the refractive index of the capping layer is 1.85 or higher in the wavelength range of 450 nm to 750 nm.

[0051] 12) The organic EL element according to 9) above, wherein the capping layer is a mixed layer formed of two or more compounds including the aforementioned amine compound having an azabenzoxazole ring structure, or a stack formed of layers each containing two or more compounds individually.

[0052] 13) An electronic component having a pair of electrodes and an organic layer sandwiched therebetween, wherein the organic layer contains an amine compound having an azabenzoxazole ring structure as described in any one of 1) to 8).

[0053] 14) An electronic device that uses the electronic components described in 13) above.

[0054] The "aromatic hydrocarbon group," "aromatic heterocyclic group," or "fused polycyclic aromatic group" represented by A, B, C, L1, L2, L3, and R in general formulas (a-1) and (b-1) are specifically listed as phenyl, biphenyl, terphenyl, naphthyl, anthraceneyl, phenanthrene, fluorenyl, spirodifluorenyl, indene, pyrene, perylene, and fluorene. Anthrayl, benzophenanthryl, pyridyl, pyrimidinyl, triazinyl, furanyl, pyrroleyl, thiopheneyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiopheneyl, indolyl, carbazoyl, imidazopyridyl, benzooxazolyl, benzothiazoyl, quinoxalinyl, benzoimidazoyl, pyrazolyl, dibenzofuranyl, dibenzothiopheneyl, naphridyl, phenanthrolyl, acridineyl, and carbazoyl, etc. In addition, groups selected from aryl groups with 6 to 30 carbon atoms or heteroaryl groups with 2 to 20 carbon atoms can be listed.

[0055] The R in general formula (b-1) represents "a straight-chain or branched alkyl group having 1 to 6 carbon atoms with a substituent", "a cycloalkyl group having 5 to 10 carbon atoms with a substituent", "a straight-chain or branched alkenyl group having 2 to 6 carbon atoms with a substituent", "a straight-chain or branched alkoxy group having 1 to 6 carbon atoms with a substituent", "a cycloalkoxy group having 5 to 10 carbon atoms with a substituent", or "a substituted or unsubstituted aryloxy group", and includes "a straight-chain or branched alkyl group having 1 to 6 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a straight-chain or branched alkyl group having 1 to 6 carbon atoms with a substituent ... "2-6 straight-chain or branched alkenyl groups", "1-6 straight-chain or branched alkoxy groups", "5-10 cycloalkoxy groups", or "aryloxy groups", specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, vinyl, allyl, isopropenyl, 2-butenyl, methyloxy, ethyloxy, n-propyloxy, cyclopentyloxy, cyclohexyloxy, 1-adamantyloxy, phenyloxy, tolyloxy, and biphenyloxy, etc.

[0056] The "substituents" in A, B, C, L1, L2, L3, and R of general formulas (a-1) and (b-1), namely "substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", "substituted fused polycyclic aromatic group", "alkyl group with 1 to 6 carbon atoms of optional substituent", "cycloalkyl group with 5 to 10 carbon atoms of optional substituent", "alkenyl group with 2 to 6 carbon atoms of optional substituent", "alkoxy group with 1 to 6 carbon atoms of optional substituent", "cycloalkoxy group with 5 to 10 carbon atoms of optional substituent", or "substituted aryloxy group", specifically, can include deuterium, cyano, nitro; halogen atoms such as fluorine, chlorine, bromine, and iodine; silyl groups such as trimethylsilyl and triphenylsilyl; and methyl, ethyl, and propyl groups with 1 to 6 carbon atoms. Straight-chain or branched alkyl groups; straight-chain or branched alkoxy groups with 1 to 6 carbon atoms, such as methyloxy, ethyloxy, and propyloxy; alkenyl groups such as vinyl and allyl; aryloxy groups such as phenyloxy and tolyloxy; arylalkoxy groups such as benzyloxy and phenethyloxy; aromatic hydrocarbon groups or fused polycyclic aromatic hydrocarbon groups such as phenyl, biphenyl, terphenyl, naphthyl, anthracene, phenanthryl, fluorenyl, spirodifluorenyl, indene, pyrene, perylene, fluoranyl, and benzophenanthryl. Groups include pyridyl, thiophene, furanyl, pyrroleyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiophene, indolyl, carbazoyl, imidazopyridyl, benzooxazolyl, benzothiazoyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiophene, carbazoyl, etc.; and aryl groups having 6 to 30 carbon atoms or heteroaryl groups having 2 to 20 carbon atoms, etc., which may optionally be further substituted with the substituents exemplified above. Furthermore, these substituents may optionally form a ring with the substituted benzene ring or with multiple substituents substituted on the same benzene ring, optionally by means of single bonds, substituted or unsubstituted methylene groups, oxygen atoms, or sulfur atoms.

[0057] In the amine compounds of the present invention having an azabenzoxazole ring structure, it is preferred from the viewpoint of absorption coefficient and refractive index that L1, L2 and L3 in the aforementioned general formula (a-1) are single bonds, substituted or unsubstituted phenylene, or substituted or unsubstituted naphthyl groups. More preferably, they are single bonds, unsubstituted phenylene, or unsubstituted naphthyl groups.

[0058] In the amine compounds of the present invention having an azabenzoxazole ring structure, it is preferred from the viewpoint of absorption coefficient and refractive index that one of the Rs in the aforementioned general formulas (b-4) and (b-5) is a site bonded to L1, L2 or L3 in the aforementioned general formula (a-1) and the other two are hydrogen atoms.

[0059] From the viewpoint of stability when forming thin films, the glass transition temperature of the amine compound having the azabenzoxazole ring structure of the present invention is preferably 100°C or higher.

[0060] In the organic EL element of the present invention, the thickness of the aforementioned cover layer is preferably in the range of 30 nm to 120 nm from the viewpoint of light extraction efficiency, and more preferably in the range of 40 nm to 80 nm.

[0061] In the organic EL element of the present invention, the extinction coefficient of the aforementioned capping layer is 0.2 or higher in the wavelength range of 400 nm to 410 nm, and the concentration is 10. -5 From the viewpoint of suppressing internal degradation of the element, it is preferable that the absorbance in the absorption spectrum of the mol / L element is 0.2 or more in the wavelength range of 400 nm to 410 nm. The extinction coefficient is more preferably 0.5 or more, and the absorbance is more preferably 0.3 or more.

[0062] In the organic EL element of the present invention, it is preferred from the viewpoint of light extraction efficiency that the refractive index of the aforementioned capping layer is 1.85 or more in the wavelength range of 450 nm to 750 nm. More preferably, it is 1.90 or more.

[0063] In the organic EL element of the present invention, the aforementioned capping layer can be fabricated by forming a mixed layer of two or more different compounds or a stack of layers each containing these compounds individually. At least one of the compounds is an amine compound with an azirconoxazole ring structure as described in the present invention.

[0064] The amine compounds of the aforementioned general formula (a-1) of this invention, which have an azabenzoxazole ring structure, are characterized by: (1) high absorption coefficient, (2) high refractive index in the wavelength range of 450 nm to 750 nm, (3) ability to be vapor-deposited, (4) stable thin film state, and (5) high heat resistance. The aforementioned compounds of this invention, by being disposed on the outside of the transparent or semi-transparent electrode of the organic EL element and used as a covering layer with a higher refractive index than the semi-transparent electrode, can significantly improve light extraction efficiency and obtain organic EL elements in which material degradation inside the element is suppressed. Attached Figure Description

[0065] Figure 1 The diagram shows the structure of compounds (1) to (12) as examples of compounds of the present invention.

[0066] Figure 2 The diagram shows the structure of compounds (13) to (27) as examples of compounds of the present invention.

[0067] Figure 3The diagram shows the structure of compounds (28) to (42) as examples of compounds of the present invention.

[0068] Figure 4 The diagram shows the structure of compounds (43) to (54) as examples of compounds of the present invention.

[0069] Figure 5 The diagram shows the structure of compounds (55) to (66) as examples of compounds of the present invention.

[0070] Figure 6 The diagram shows the structure of compounds (67) to (81) as examples of compounds of the present invention.

[0071] Figure 7 The diagram shows the structure of compounds (82) to (96) as examples of compounds of the present invention.

[0072] Figure 8 The diagram shows the structure of compounds (97) to (111) as examples of compounds of the present invention.

[0073] Figure 9 The diagram shows the structure of compounds (112) to (126) as examples of compounds of the present invention.

[0074] Figure 10 The diagram shows the structure of compounds (127) to (138) as examples of compounds of the present invention.

[0075] Figure 11 The diagram shows the structure of compounds (139) to (153) as examples of compounds of the present invention.

[0076] Figure 12 The diagram shows the structure of compounds (154) to (165) as examples of compounds of the present invention.

[0077] Figure 13 The diagram shows the structure of compounds (166) to (173) as examples of compounds of the present invention.

[0078] Figure 14 This diagram illustrates the configuration of organic EL elements in embodiments and comparative examples of the present invention. Detailed Implementation

[0079] The amine compounds with an azabenzoxazole ring structure shown in the aforementioned general formula (a-1) of the present invention are novel compounds. The azabenzoxazole derivatives that form the main skeleton of these compounds can be synthesized by their own known methods as follows (see, for example, Non-Patent Document 4). Furthermore, by using the synthesized haloazabenzoxazole derivatives and aryl amines, a coupling reaction is performed using a copper catalyst, palladium catalyst, or the like, thereby synthesizing the amine compounds with an azabenzoxazole ring structure shown in the aforementioned general formula (a-1) of the present invention. In addition, by preparing the haloazabenzoxazole derivatives into borate ester derivatives and then performing a coupling reaction with haloaryl amines, the amine compounds with an azabenzoxazole ring structure shown in the aforementioned general formula (a-1) of the present invention can be synthesized in the same way (see, for example, Non-Patent Documents 5 and 6).

[0080]

[0081] Specific examples of preferred compounds among the amine compounds of the aforementioned general formula (a-1) having an azabenzoxazole ring structure suitable for use in the organic EL element of the present invention are shown below. Figures 1 to 13 However, it is not limited to these compounds.

[0082] The purification of amine compounds with an azabenzoxazole ring structure as shown in the aforementioned general formula (a-1) is not particularly limited and can be carried out using known methods for purifying organic compounds, such as column chromatography-based purification, adsorption purification based on silica gel, activated carbon, activated clay, etc., solvent-based recrystallization purification, crystallization purification, and sublimation purification. The compounds can be identified by NMR analysis. As physical properties, the melting point, glass transition temperature (Tg), and refractive index are preferably measured. The melting point serves as an indicator of vapor deposition properties, the glass transition temperature (Tg) serves as an indicator of the stability of the thin film state, and the refractive index serves as an indicator related to the improvement of light extraction efficiency.

[0083] Melting point and glass transition temperature (Tg) can be determined using powder and a high-sensitivity differential scanning calorimeter (Bruker AXS KK, DSC3100SA).

[0084] The refractive index and extinction coefficient can be measured by fabricating an 80 nm thin film on a silicon substrate and using a spectrophotometer (FILMETRICS F10-RT-UV).

[0085] Regarding absorbance, the concentration was adjusted to 10 using toluene solvent. -5 The solution was obtained at a concentration of mol / L. Furthermore, regarding the absorbance coefficient, the concentration was adjusted to 5.0 × 10⁻⁶ using toluene solution. -6 mol / L, 1.0×10 -5mol / L, 1.5×10 - 5 mol / L and 2.0×10 -5 Solutions of these four concentrations (mol / L) were obtained and measured using a UV-Vis-NIR spectrophotometer (V-650, manufactured by Nippon Spectrophotometer Co., Ltd.).

[0086] As structures for the organic EL element of the present invention, for example, in the case of a top-emitting structure light-emitting element, examples include: an element that sequentially comprises an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a capping layer on a glass substrate; and an element having a hole injection layer between the anode and the hole transport layer; an element having an electron blocking layer between the hole transport layer and the light-emitting layer; an element having a hole blocking layer between the light-emitting layer and the electron transport layer; and an element having an electron injection layer between the electron transport layer and the cathode. In these multilayer structures, one organic layer can perform the functions of several layers. For example, it can be configured to function as both a hole injection layer and a hole transport layer, both a hole transport layer and an electron blocking layer, both a hole blocking layer and an electron transport layer, and both an electron transport layer and an electron injection layer. In addition, it can be configured by stacking two or more organic layers with the same function, and it can also be configured by stacking two hole transport layers, two light-emitting layers, two electron transport layers, and two capping layers.

[0087] The total film thickness of all layers in the organic EL element is preferably around 200 nm to 750 nm, more preferably around 350 nm to 600 nm. Furthermore, the thickness of the capping layer is preferably, for example, 30 nm to 120 nm, more preferably 40 nm to 80 nm. In this case, good light extraction efficiency can be obtained. It should be noted that the thickness of the capping layer can be appropriately varied depending on the type of light-emitting material used in the light-emitting element, the thickness of the organic EL element excluding the capping layer, etc.

[0088] As the anode of the organic EL element of the present invention, an electrode material with a high work function, such as ITO or gold, is used.

[0089] As the hole injection layer for the organic EL element of the present invention, arylamine compounds having three or more triphenylamine structures in their molecules and having structures obtained by linking them via single bonds or divalent groups without heteroatoms can be used, such as star-shaped triphenylamine derivatives, various triphenylamine tetramers, and other materials. Alternatively, porphyrin compounds represented by copper phthalocyanine, acceptor heterocyclic compounds such as hexacyanoazabenzophenanthrene, and coating-type polymeric materials can also be used. These materials can be used individually as films, or mixed with other materials to form films in monolayer form, or in stacked structures of individually formed layers, mixed layers, or a combination of individually formed layers and mixed layers. These materials can be used for thin film formation not only by vapor deposition but also by known methods such as spin coating and inkjet printing.

[0090] As the hole transport layer of the organic EL element of the present invention, benzidine derivatives such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (hereinafter referred to as TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (hereinafter referred to as NPD), and N,N,N',N'-tetraphenylbenzidine can be used; 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter referred to as TAPC) and the like can also be used. Particularly preferred are arylamine compounds having two triphenylamine structures in the molecule and having a structure obtained by linking them by single bonds or divalent groups without heteroatoms, such as N,N,N',N'-tetraphenylbenzidine. Furthermore, arylamine compounds having three or more triphenylamine structures in the molecule and having a structure obtained by linking them by single bonds or divalent groups without heteroatoms, such as various triphenylamine trimers and tetramers, are also preferred. These materials can be used individually as films, or mixed with other materials to form films in a monolayer form. They can also be used to create stacked structures of individually formed layers, stacked structures of mixed layers, or stacked structures of individually formed layers and mixed layers. Furthermore, coating-type polymers such as poly(3,4-ethylenedioxythiophene) (hereinafter referred to as PEDOT) and poly(styrene sulfonate) (hereinafter referred to as PSS) can be used as hole injection / delivery layers. These materials can be used for film formation not only by vapor deposition but also by known methods such as spin coating and inkjet printing.

[0091] In addition, in the hole injection layer or hole transport layer, substances obtained by further P-doping the materials commonly used in the layer with antimony hexachloride tribromophenylamine, axial alkene derivatives (for example, see Patent Document 3), etc., can be used; polymeric compounds whose partial structure has the structure of benzidine derivatives such as TPD, etc.

[0092] As the electron blocking layer of the organic EL element of the present invention, carbazole derivatives such as 4,4',4”-tris(N-carbazole)triphenylamine (hereinafter referred to as TCTA), 9,9-bis[4-(carbazole-9-yl)phenyl]fluorene, 1,3-bis(carbazole-9-yl)phenyl (hereinafter referred to as mCP), and 2,2-bis(4-carbazole-9-yl-phenyl)adamantane (hereinafter referred to as Ad-Cz) can be used; 9-[4-(carbazole-9-yl)phenyl]-9-[4-(triphenylsilyl)] Compounds with electron-blocking properties, such as those represented by [phenyl]-9H-fluorene, which have triphenylsilyl and triarylamine structures, can be used as monolayers or mixed with other materials. They can also be fabricated into stacked structures of individually formed layers, mixed layers, or a combination of individually formed and mixed layers. Besides vapor deposition, these materials can also be used to form thin films using known methods such as spin coating and inkjet printing.

[0093] As the light-emitting layer of the organic EL element of the present invention, metal complexes of hydroxyquinoline derivatives, primarily Alq3, various other metal complexes, anthracene derivatives, bis(styrene)benzene derivatives, pyrene derivatives, oxazole derivatives, poly(p-phenylene)ethylene derivatives, etc., can be used. Furthermore, the light-emitting layer can be composed of a host material and a dopant material. As the host material, anthracene derivatives are preferred. In addition, based on the aforementioned light-emitting materials, heterocyclic compounds with a partial structure having an indole ring as a fused ring, heterocyclic compounds with a partial structure having a carbazole ring as a fused ring, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, polydialkylfluorene derivatives, etc., can be used. Furthermore, as dopant materials, quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, aminostyrene derivatives, etc., can be used. They can be used as single-layer films, or mixed with other materials to form films. They can also be made into stacked structures of single-layer films, stacked structures of mixed-layer films, or stacked structures of single-layer films and mixed-layer films.

[0094] In addition, phosphorescent materials can also be used as luminescent materials. Phosphorescent materials can include metal complexes such as iridium and platinum, green phosphorescent materials such as Ir(ppy)3, blue phosphorescent materials such as Firpic and Fir6, and red phosphorescent materials such as Btp2Ir(acac). As the host material, for hole injection / transport, carbazole derivatives such as 4,4'-bis(N-carbazolyl)biphenyl (hereinafter referred to as CBP), TCTA, and mCP can be used. For electron transport, p-bis(triphenylsilyl)benzene (hereinafter referred to as UGH2) and 2,2',2”-(1,3,5-phenylene)tris(1-phenyl-1H-benzimidazole) (hereinafter referred to as TPBI) can be used, enabling the fabrication of high-performance organic EL devices.

[0095] To avoid concentration quenching, the phosphorescent luminescent material is preferably doped in the host material at a rate of 1 to 30% by weight relative to the total luminescent layer by co-evaporation.

[0096] Alternatively, materials that emit delayed fluorescence, such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN CDCB derivatives, can also be used as luminescent materials (see, for example, Non-Patent Literature 7). In addition to vapor deposition, these materials can also be formed into thin films using known methods such as spin coating and inkjet printing.

[0097] As the hole-blocking layer of the organic EL element of the present invention, compounds with hole-blocking properties such as phenanthrene derivatives such as copper bath (hereinafter referred to as BCP), metal complexes of hydroxyquinoline derivatives such as aluminum(III)bis(2-methyl-8-hydroxyquinoline)-4-phenylphenol salt (hereinafter referred to as BAlq), various rare earth complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, and benzo[a]azole derivatives can be used. These materials can also serve as electron transport layer materials. They can be formed into films alone, or mixed with other materials and formed into films in the form of monolayers, or they can be formed into stacked structures of individually formed layers, stacked structures of mixed formed layers, or stacked structures of individually formed layers and mixed formed layers. In addition to vapor deposition, these materials can also be formed into thin films using known methods such as spin coating and inkjet printing.

[0098] As the electron transport layer of the organic EL element of this invention, metal complexes of hydroxyquinoline derivatives, primarily Alq3 and Balq, various other metal complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, pyridine derivatives, benzimidazole derivatives, benzoxazole derivatives, thiadiazole derivatives, anthracene derivatives, carbodiimide derivatives, quinoxaline derivatives, pyridoindole derivatives, phenanthroline derivatives, and silicone derivatives can be used. These materials can be used individually as films, or mixed with other materials to form films in a monolayer form. They can also be used to create stacked structures of individually formed layers, stacked structures of mixed layers, or stacked structures of individually formed layers and mixed layers. Besides vapor deposition, these materials can also be used to form thin films using known methods such as spin coating and inkjet printing.

[0099] As the electron injection layer of the organic EL element of the present invention, alkali metal salts such as lithium fluoride and cesium fluoride; alkaline earth metal salts such as magnesium fluoride; metal complexes of hydroxyquinoline derivatives such as lithium hydroxyquinoline; metal oxides such as aluminum oxide; or metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs) can be used. By preferentially selecting the electron transport layer and the cathode, these can be omitted.

[0100] Furthermore, in the electron injection layer or electron transport layer, a material obtained by further N-doping a metal such as cesium with a material commonly used in that layer can be used.

[0101] As the cathode of the organic EL element of the present invention, electrode materials with low work function such as aluminum, alloys with even lower work function such as magnesium-silver alloys, magnesium-calcium alloys, magnesium-indium alloys, aluminum-magnesium alloys, ITO, IZO, etc. are used as electrode materials.

[0102] As the capping layer for the organic EL element of the present invention, an amine compound having an azabenzoazole ring structure as shown in the aforementioned general formula (a-1) is used. These compounds can be formed individually, or mixed with other materials to form a single layer, or they can be fabricated into a stacked structure of individually formed layers, a stacked structure of mixed layers, or a stacked structure of individually formed layers and mixed layers. These materials can be used for thin film formation not only by vapor deposition, but also by known methods such as spin coating and inkjet printing.

[0103] It should be noted that the above description refers to organic EL elements with a top-emitting structure, but the present invention is not limited thereto, and can also be applied to organic EL elements with a bottom-emitting structure, and organic EL elements with a dual-emitting structure that emits light from both the top and bottom. In these cases, the electrodes existing along the direction from which light is extracted from the light-emitting element need to be transparent or semi-transparent.

[0104] The refractive index of the material constituting the capping layer is preferably greater than that of the adjacent electrode. That is, the capping layer is used to improve the light extraction efficiency in the organic EL element; however, a high reflectivity at the interface between the capping layer and the material contacting the capping layer results in significant light interference, thus this effect is effective. Therefore, the refractive index of the material constituting the capping layer is preferably greater than that of the adjacent electrode; a refractive index of 1.70 or higher is acceptable, more preferably 1.80 or higher, and particularly preferably 1.85 or higher.

[0105] Example

[0106] Hereinafter, specific descriptions will be made of embodiments of the present invention using examples, but the present invention is not limited to the following examples as long as it does not depart from its spirit.

[0107] [Example 1]

[0108] <Bis(4-naphth-1-yl-phenyl)4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-amine: Synthesis of compound (123)>

[0109] 5.0 g of bis(4-naphth-1-yl-phenyl)-4-bromophenyl-amine, 3.1 g of 2-{4-(4,4,5,5-tetramethyl[1,3,2]dioxaborane-2-yl)-phenyl}-7-azabenzoxazole, 0.5 g of tetra(triphenylphosphine)palladium(0), and 1.8 g of potassium carbonate were added to a nitrogen-purified reaction vessel and refluxed with a toluene / EtOH / H2O mixture and stirred overnight. After natural cooling, methanol / H2O was added to the system, the mixture was filtered, and the solid was collected to obtain a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixture to obtain 4.0 g of yellow powder of compound (123) (yield 66.7%).

[0110]

[0111] The structure of the obtained yellow powder was identified using NMR.

[0112] use 1 H-NMR (CDCl3) detected the following 33 hydrogen signals.

[0113] δ(ppm)=8.36(3H),8.06(3H),7.92(2H),7.86(2H),7.81(2H),7.66(2H),7.57-7.45(12H),7.41-7.33(7H).

[0114] [Example 2]

[0115] <<4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphth-1-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine: Synthesis of compound (124)>

[0116] 5.0 g of 4-bromophenyl-(4-naphth-1-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine, 3.1 g of 2-{4-(4,4,5,5-tetramethyl[1,3,2]dioxaborane-2-yl)-phenyl}-7-azabenzoxazole, 0.5 g of tetra(triphenylphosphine)palladium(0), and 1.8 g of potassium carbonate were added to a nitrogen-purified reaction vessel and refluxed with stirring overnight in a toluene / EtOH / H2O mixed solvent. After natural cooling, methanol / H2O was added to the system, and the mixture was filtered to obtain the crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 4.4 g of yellow powder of compound (124) (yield 73.3%) of 4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphth-1-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine: compound (124).

[0117]

[0118] The structure of the obtained yellow powder was identified using NMR.

[0119] use 1 H-NMR (CDCl3) detected the following 33 hydrogen signals.

[0120] δ(ppm)=8.35(3H),8.06(3H),7.91(3H),7.86(2H),7.80(2H),7.77(1H),7.71(2H),7.64(2H),7.56-7.43(8H),7.38-7.31(7H).

[0121] [Example 3]

[0122] <<4-(7-azabenzoxazol-2-yl)-phenyl-(4-naphth-1-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine: Synthesis of compound (25)>

[0123] (4-naphth-1-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine: 7.0 g, 4-bromo-(7-azabenzoxazol-2-yl)-benzene: 5.0 g, palladium(II) acetate: 0.1 g, tri-tert-butylphosphine: 0.2 g, sodium tert-butoxide: 2.4 g were added to a nitrogen-purified reaction vessel and stirred under reflux for 5 hours in toluene solvent. After natural cooling, methanol was added to the system for dispersion and washing, and the solid was filtered and removed to obtain the crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 7.1 g of yellow powder of compound (25) 4-(7-azabenzoxazol-2-yl)-phenyl-(4-naphth-1-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine (yield 69.5%).

[0124]

[0125] The structure of the obtained yellow powder was identified using NMR.

[0126] use 1 H-NMR (CDCl3) detected the following 29 hydrogen signals.

[0127] δ(ppm)=8.30(1H),8.19(2H),8.00(1H),8.05-8.01(2H),7.95-7.87(5H),7.79-7.74(3H),7.57-7.47(8H),7.40-7.30(7H).

[0128] [Example 4]

[0129] <Synthesis of bis(4-naphth-2-yl-phenyl)-4-(7-azabenzoxazol-2-yl)-phenyl-amine: Compound (44)>

[0130] 5.0 g of bis(4-naphthyl-2-yl-phenyl)-amine, 3.6 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.4 g of tris(diphenylmethyleneacetone)dipalladium(0), 0.4 g of tri-tert-butylphosphine, and 1.7 g of sodium tert-butoxide were added to a nitrogen-purified reaction vessel and refluxed and stirred overnight in xylene solvent. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and removal of the solid to obtain the crude product. The crude product was purified by recrystallization using monochlorobenzene solvent to obtain 3.2 g of yellow powder of compound (44) bis(4-naphthyl-2-yl-phenyl)-4-(7-azabenzoxazol-2-yl)-phenyl-amine (yield 43.8%).

[0131]

[0132] The structure of the obtained yellow powder was identified using NMR.

[0133] use 1 H-NMR (CDCl3) detected the following 29 hydrogen signals.

[0134] δ(ppm)=8.30(1H),8.17(2H),8.07(2H),8.02(1H),7.95-7.87(6H),7.78(2H),7.73(4H),7.54-7.47(4H),7.37-7.27(7H).

[0135] [Example 5]

[0136] <Synthesis of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-naphth-1-yl-phenyl)-amine: Compound (140)>

[0137] 1.9 g of 4-(naphthyl-1-yl)-phenylamine, 5.2 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.2 g of tris(diphenylmethyleneacetone)dipalladium(0), 0.2 g of tri-tert-butylphosphine, and 1.9 g of sodium tert-butoxide were added to a nitrogen-purified reaction vessel and stirred under reflux in toluene for 8 hours. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and removal of the solid to obtain the crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 3.8 g of yellow powder of compound (140) bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-naphthyl-1-yl)-phenylamine (yield 72.1%).

[0138]

[0139] The structure of the obtained yellow powder was identified using NMR.

[0140] use 1 H-NMR (CDCl3) detected the signals of the following 25 hydrogen atoms.

[0141] δ(ppm)=8.33(2H),8.25(4H),8.06-8.01(3H),7.95-7.88(2H),7.58-7.49(6H),7.39-7.34(8H).

[0142] [Example 6]

[0143] <Synthesis of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-carbazole-9-yl-phenyl)-amine compound (144)>

[0144] 2.3 g of 4-(carbazole-9-yl)-phenyl-amine, 5.1 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.2 g of tris(diphenylmethyleneacetone)dipalladium(0), 0.2 g of tri-tert-butylphosphine, and 2.0 g of sodium tert-butoxide were added to a nitrogen-purified reaction vessel and stirred under reflux for 6 hours in toluene. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and removal of the solid to obtain the crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 3.9 g of yellow powder of compound (144) bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-carbazole-9-yl-phenyl)-amine (yield 67.7%).

[0145]

[0146] The structure of the obtained yellow powder was identified using NMR.

[0147] use 1 H-NMR (CDCl3) detected the signals of the following 26 hydrogen atoms.

[0148] δ(ppm)=8.34(2H),8.27(4H),8.17(2H),8.06(2H),7.60(2H),7.52(2H),7.46(4H),7.40-7.30(8H).

[0149] [Example 7]

[0150] <Synthesis of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-[1,1']binaphthyl-4-yl-amine: Synthesis of compound (146)>

[0151] 5.0 g of [1,1']binaphthyl-4-ylamine, 11.2 g of 4-bromo-(7-azabenzoxazol-2-yl)benzene, 0.5 g of tris(diphenylmethyleneacetone)dipalladium(0), 0.6 g of tri-tert-butylphosphine, and 5.4 g of sodium tert-butoxide were added to a nitrogen-purified reaction vessel and refluxed and stirred overnight in toluene. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and removal of the solid to obtain the crude product. The crude product was purified by crystallization using a tetrahydrofuran / acetone mixed solvent to obtain 8.2 g of yellow powder of compound (146) bis(4-(7-azabenzoxazol-2-yl)-phenyl)-[1,1']binaphthyl-4-ylamine (yield 67.2%).

[0152]

[0153] The structure of the obtained yellow powder was identified using NMR.

[0154] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0155] δ(ppm)=8.32(2H),8.22(4H),8.05-7.98(5H),7.64(1H),7.60-7.31(15H).

[0156] [Example 8]

[0157] <<4-(7-azabenzoxazol-2-yl)-phenyl-(4'-(naphth-1-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: Synthesis of compound (166)>

[0158] 10.0 g of (4'-(naphthyl-1-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine, 6.2 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.4 g of tris(diphenylmethyleneacetone)dipalladium(O), 0.2 g of tri-tert-butylphosphine, and 3.0 g of sodium tert-butoxide were added to a nitrogen-purified reaction vessel and stirred under reflux in toluene overnight. After natural cooling, the filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent to obtain 8.6 g of yellow powder of compound (166) (yield 61.0%).

[0159]

[0160] The structure of the obtained yellow powder was identified using NMR.

[0161] use 1 H-NMR (CDCl3) detected the following 31 hydrogen signals.

[0162] δ(ppm)=8.32(1H),8.18(2H),8.03(1H),7.99(1H),7.93(1H),7.89(1H),7.85(2H) ,7.75(2H),7.69(2H),7.61-7.58(3H),7.56-7.44(5H),7.35-7.22(9H),7.00(1H).

[0163] [Example 9]

[0164] <<4-(7-azabenzoxazol-2-yl)-phenyl-(4'-(dibenzothiophene-4-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: Synthesis of compound (167)>

[0165] (4'-(dibenzothiophene-4-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: 12.0 g, 4-bromo-(7-azabenzoxazol-2-yl)-benzene: 6.7 g, tris(diphenylmethyleneacetone)dipalladium(O): 0.6 g, tri-tert-butylphosphine: 0.5 g, sodium tert-butoxide: 3.2 g were added to a nitrogen-purified reaction vessel and refluxed with toluene solvent overnight. After natural cooling, the filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent to obtain 9.5 g of yellow powder of compound (167) (yield 58.0%).

[0166]

[0167] The structure of the obtained yellow powder was identified using NMR.

[0168] use 1 H-NMR (CDCl3) detected the following 31 hydrogen signals.

[0169] δ(ppm)=8.31(1H),8.22-8.16(4H),8.02(1H),7.85(5H),7.77(2H),7.68(2H),7.60-7.47(6H),7.34-7.22(9H),6.99(1H).

[0170] [Example 10]

[0171] <<4-(7-azabenzoxazol-2-yl)-phenyl-(4-(dibenzothiophene-4-yl)-phenyl)-(4'-(benzofuran-2-yl)-biphenyl-4-yl)-amine: Synthesis of compound (168)>

[0172] (4-(dibenzothiophene-4-yl)-phenyl)-(4'-(benzofuran-2-yl)-biphenyl-4-yl)-amine: 7.0 g, 4-bromo-(7-azabenzoxazol-2-yl)-benzene: 4.4 g, tris(diphenylmethyleneacetone)dipalladium(O): 0.4 g, tri-tert-butylphosphine: 0.3 g, sodium tert-butoxide: 1.9 g were added to a nitrogen-purified reaction vessel and refluxed with toluene and stirred overnight. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and removal of the solid to obtain the crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 8.5 g of yellow powder of compound (168) (yield 89.8%).

[0173]

[0174] The structure of the obtained yellow powder was identified using NMR.

[0175] use 1 H-NMR (CDCl3) detected the following 31 hydrogen signals.

[0176] δ(ppm)=8.31(1H),8.21-8.16(4H),8.03(1H),7.96(2H),7.86(1H),7.76-7 .71(4H),7.67(2H),7.61-7.52(4H),7.48(2H),7.38-7.23(9H),7.08(1H).

[0177] [Example 11]

[0178] <<4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphth-2-yl-phenyl)-(4-phenanthrene-9-yl-phenyl)-amine: Synthesis of compound (172)>

[0179] (4-naphth-2-yl-phenyl)-(4-phenanthrene-9-yl-phenyl)amine: 6.0 g, 2-(4'-chloro-biphenyl-4-yl)-7-azabenzoxazole: 4.3 g, tris(diphenylmethyleneacetone)dipalladium(0): 0.4 g, tri-tert-butylphosphine: 0.3 g, sodium tert-butoxide: 1.8 g were added to a nitrogen-purified reaction vessel and refluxed with toluene solvent overnight. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and solid removal to obtain the crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 5.1 g (yield 54.0%) of yellow powder of compound (172) 4'-(7-azabenzoxazole-2-yl)-biphenyl-4-yl-(4-naphth-2-yl-phenyl)-(4-phenanthrene-9-yl-phenyl)-amine.

[0180]

[0181] The structure of the obtained yellow powder was identified using NMR.

[0182] use 1 H-NMR (CDCl3) detected the following 35 hydrogen signals.

[0183] δ(ppm)=8.80(1H),8.74(1H),8.38-8.36(3H),8.09-8.07(3H),7.94-7.86(4H),7.82-7.59(12H),7.53-7.46(4H),7.39-7.35(7H).

[0184] [Example 12]

[0185] <<4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-dibenzofuran-3-yl-phenyl)-(4-naphth-2-yl-phenyl)-amine: Synthesis of compound (173)>

[0186] (4-Dibenzofuran-3-yl-phenyl)-(4-naphth-2-yl-phenyl)amine: 6.0 g, 2-(4'-chloro-biphenyl-4-yl)-7-azabenzoxazole: 4.4 g, tris(diphenylmethyleneacetone)dipalladium(O): 0.4 g, tri-tert-butylphosphine: 0.3 g, sodium tert-butoxide: 1.9 g were added to a nitrogen-purified reaction vessel and refluxed with stirring overnight in xylene solvent. After natural cooling, methanol was added to the system for dispersion and washing, followed by filtration and removal of the solid to obtain the crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent to obtain 2.5 g of yellow powder of compound (173) (yield 26.3%).

[0187]

[0188] The structure of the obtained yellow powder was identified using NMR.

[0189] use 1 H-NMR (CDCl3) detected the following 33 hydrogen signals.

[0190] δ(ppm)=8.37-8.35(3H), 8.09-8.06(2H), 8.01-7.86(5H), 7.81-7.76(4H), 7.71-7.58(8H), 7.53-7.45(3H), 7.38-7.31(8H).

[0191] [Example 13]

[0192] For the compounds obtained in the foregoing examples, the melting point and glass transition temperature were determined using a high-sensitivity differential scanning calorimeter (Bruker AXSK.K., DSC3100SA). The results are summarized in Table 1.

[0193] [Table 1]

[0194] Melting point Glass transition temperature Compound (123) - 123.1℃ Compound (124) - 120.4℃ Compound (25) 112.6℃ 108.8℃ Compound (44) 249.0℃ 105.1℃ Compound (140) 251.1℃ 124.8℃ Compound (144) 291.6℃ 144.0℃ Compound (146) 318.2℃ 159.1℃ Compound (166) - 125.4℃ Compound (167) - 138.6℃ Compound (168) - 136.7℃ Compound (172) - 138.0℃ Compound (173) - 125.9℃

[0195] Based on the foregoing results, the compounds obtained in the examples have glass transition temperatures above 100°C, indicating that the thin film is in a stable state.

[0196] [Example 14]

[0197] Using the compounds obtained in the foregoing examples, an 80 nm thick vapor-deposited film was fabricated on a silicon substrate. The refractive index n and extinction coefficient k at wavelengths of 400 nm and 410 nm were measured using a spectrophotometer (FILMETRICS F10-RT-UV). For comparison, measurements were also performed on the comparative compounds (2-1) and Alq3 with the following structural formulas (see, for example, Patent Document 4). The measurement results are summarized in Table 2.

[0198]

[0199] [Table 2]

[0200]

[0201] As shown in Table 2, the refractive indices of compound (2-1) and Alq3 at a wavelength of 450 nm are 1.88–1.93, while the refractive indices of the compounds of the present invention are 2.29–2.52. Furthermore, the refractive indices of compound (2-1) and Alq3 at a wavelength of 750 nm are 1.73–1.78, while the refractive indices of the compounds of the present invention are 1.89–1.95. This indicates that by using the compounds of the present invention, an improvement in the light extraction efficiency of organic EL devices can be expected.

[0202] The extinction coefficients of compounds (2-1) and Alq3 at wavelengths of 400 nm to 410 nm are 0.06 to 0.16, while the extinction coefficient of the compound of the present invention is 0.53 to 1.08. This indicates that by fully absorbing sunlight at wavelengths of 400 nm to 410 nm and using it as a cover layer, it is possible to suppress the influence on the materials inside the component.

[0203] [Example 15]

[0204] Using the compound of the present invention, a concentration of 10 was prepared. -5 A mol / L toluene solution was prepared, and the absorbance at wavelengths of 400 nm and 410 nm was measured using a UV-Vis-NIR spectrophotometer (Nippon Spectrophotometer, V-650). Additionally, a solution with a concentration of 5 × 10⁻⁶ mol / L was prepared. -6 mol / L, 1×10 -5 mol / L, 1.5×10 -5 mol / L and 2.0×10 -5Toluene solutions of four different concentrations (mol / L) were measured using a UV-Vis-NIR spectrophotometer (V-650, manufactured by Nippon Spectrophotometer Co., Ltd.), and the absorbance coefficients were calculated based on the resulting standard curves. For comparison, absorbance was also measured and absorbance coefficients were calculated for the comparative compounds (2-1) and Alq3 with the same structural formula. The results are summarized in Table 3.

[0205] [Table 3]

[0206]

[0207] As shown in Table 3, regarding the absorbance at wavelengths of 400 nm to 410 nm, the absorbance of comparative compounds (2-1) and Alq3 at wavelengths of 400 nm to 410 nm is 0.02 to 0.07, while the absorbance of the compound of the present invention is as high as 0.36 to 1.35. This indicates that the compound of the present invention can sufficiently absorb sunlight at wavelengths of 400 nm to 410 nm. Furthermore, regarding the absorption coefficient, the compound of the present invention has a value of 70,000 or higher, which is a larger value compared to the absorption coefficient of the comparative compounds. That is, it indicates that the compound of the present invention absorbs light more sufficiently than the comparative compounds under the same concentration conditions.

[0208] [Example 16]

[0209] Organic EL elements were fabricated using the compound (123) obtained in Example 1, and their characteristics were measured at room temperature in the atmosphere.

[0210] Organic EL components such as Figure 14 As shown, the material is fabricated by pre-forming a reflective ITO electrode, which serves as a transparent anode 2, on a glass substrate 1, and then sequentially depositing a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, an electron transport layer 6, an electron injection layer 7, a cathode 8, and a capping layer 9 on the resulting object.

[0211] Specifically, a glass substrate 1, obtained by sequentially depositing a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film, is ultrasonically cleaned in isopropanol for 20 minutes and then dried on a heating plate heated to 250°C for 10 minutes. Afterward, it undergoes a 2-minute UV ozone treatment, and the ITO-coated glass substrate is placed in a vacuum evaporation machine, with the pressure reduced to below 0.001 Pa. Next, with a transparent anode 2 covering the substrate, a binary evaporation process is performed on an electron acceptor (Acceptor-1) and a compound (3-1) of the following structural formula at a evaporation rate ratio of Acceptor-1:compound (3-1) = 3:97 to form a hole injection layer 3 with a film thickness of 10 nm.

[0212] On the hole injection layer 3, a compound (3-1) with the following structural formula is formed as a hole transport layer 4 with a film thickness of 140 nm.

[0213] On the hole transport layer 4, compound (3-2) with the following structural formula and compound (3-3) with the following structural formula are subjected to binary evaporation at a evaporation rate ratio of (3-2):(3-3)=5:95 to form a light-emitting layer 5 with a film thickness of 20nm.

[0214] On the light-emitting layer 5, compound (3-4) and compound (3-5) of the following structural formula are subjected to binary vapor deposition at a vapor deposition rate ratio of (3-4):(3-5)=50:50 to form an electron transport layer 6 with a film thickness of 30nm.

[0215] On the electron transport layer 6, lithium fluoride is formed as an electron injection layer 7 with a film thickness of 1 nm.

[0216] On the electron injection layer 7, a magnesium-silver alloy is formed as a cathode 8 with a film thickness of 12 nm.

[0217] Finally, the compound (123) of Example 1 was formed as a capping layer 9 with a film thickness of 60 nm.

[0218]

[0219] [Example 17]

[0220] In Example 16, instead of the compound (123) of Example 1, the compound (124) of Example 2 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0221] [Example 18]

[0222] In Example 16, instead of the compound (123) of Example 1, the compound (25) of Example 3 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0223] [Example 19]

[0224] In Example 16, instead of the compound (123) of Example 1, the compound (44) of Example 4 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0225] [Example 20]

[0226] In Example 16, instead of the compound (123) of Example 1, the compound (140) of Example 5 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0227] [Example 21]

[0228] In Example 16, instead of the compound (123) of Example 1, the compound (144) of Example 6 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0229] [Example 22]

[0230] In Example 16, instead of the compound (123) of Example 1, the compound (146) of Example 7 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0231] [Example 23]

[0232] In Example 16, instead of the compound (123) of Example 1, the compound (166) of Example 8 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0233] [Example 24]

[0234] In Example 16, instead of the compound (123) of Example 1, the compound (167) of Example 9 was formed with a film thickness of 60 nm as the capping layer 9. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0235] [Example 25]

[0236] In Example 16, instead of the compound (123) of Example 1, the compound (168) of Example 10 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere. The results of the measurement of the luminescence characteristics obtained by applying a DC voltage to the fabricated organic EL element are summarized in Table 4.

[0237] [Example 26]

[0238] In Example 16, instead of the compound (123) of Example 1, the compound (172) of Example 11 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0239] [Example 27]

[0240] In Example 16, instead of the compound (123) of Example 1, the compound (173) of Example 12 was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, the organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere.

[0241] [Comparative Example 1]

[0242] For comparison, in Example 16, Alq3 was formed as the capping layer 9 instead of the compound (123) of Example 1, with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in atmospheric conditions.

[0243] [Comparative Example 2]

[0244] For comparison, in Example 16, instead of compound (123) of Example 1, the comparative compound (2-1) of the above-described structure was formed as the capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in atmospheric conditions.

[0245] Using the organic EL elements prepared in Examples 16-27 and Comparative Examples 1 and 2, voltage, brightness, luminous efficiency, power efficiency, and element lifetime were measured, and the results are summarized in Table 4. Voltage, brightness, luminous efficiency, and power efficiency were measured at 10 mA / cm². 2 The constant current drive was used for measurement. Additionally, the component lifetime was determined by performing a 10 mA / cm² test. 2The constant current drive was measured in terms of the time it took for the initial brightness to decay to 95% of the initial brightness when the initial brightness was set to 100%.

[0246] [Table 4]

[0247]

[0248] As shown in Table 4, for a current density of 10 mA / cm² 2 The driving voltage of the components in Comparative Examples 1 and 2 is approximately the same as that of the components in Examples 16-27. However, the components in Examples 16-27 show significant improvements in brightness, luminous efficiency, power efficiency, and lifetime compared to the components in Comparative Examples 1 and 2. This indicates that by including a material with a high refractive index suitable for the organic EL element of the present invention in the capping layer, the light extraction efficiency can be significantly improved.

[0249] Industrial availability

[0250] The amine compound with an azabenzozazole ring structure shown in the general formula (a-1) of this invention has a high absorption coefficient, a high refractive index, can significantly improve light extraction efficiency, and exhibits film stability. Therefore, it is excellent as a compound suitable for organic EL elements. By using this compound to fabricate organic EL elements, high efficiency can be obtained, and sunlight can be absorbed without affecting the internal materials of the element, thus improving durability and lightfastness. In addition, by using this compound, which does not absorb in the blue, green, and red wavelength regions, it is particularly suitable for applications where excellent purity, vividness, and brightness are desired. It can be applied in, for example, household appliances and lighting applications.

[0251] Explanation of reference numerals in the attached figures

[0252] 1. Glass substrate

[0253] 2. Transparent anode

[0254] 3. Hole injection layer

[0255] 4 Hole transport layer

[0256] 5. Light-emitting layer

[0257] 6. Electron transport layer

[0258] 7 Electron Injection Layer

[0259] 8 Cathode

[0260] 9. Covering layer

Claims

1. An amine compound having an azabenzoxazole ring structure, represented by the following general formula (a-1), In formula (a-1), A, B, and C may be chosen to be the same as or different from each other, representing the groups shown in the following general formula (b-4), unsubstituted phenyl, unsubstituted biphenyl, unsubstituted naphthyl, unsubstituted phenanthryl, unsubstituted carbazolyl, unsubstituted benzofuranyl, unsubstituted benzothiophene, unsubstituted indolyl, unsubstituted benzimidazolyl, unsubstituted imidazopyridyl, unsubstituted benzooxazolyl, unsubstituted benzothiazolyl, unsubstituted dibenzofuranyl, or unsubstituted dibenzothiophene, wherein, At least one of A, B and C is a group represented by the following general formula (b-4); L1, L2, and L3 can be chosen to be the same as or different from each other, representing a single bond, an unsubstituted phenylene, an unsubstituted biphenylene, or an unsubstituted naphthylene; In formula (b-4), R can be chosen to be the same or different from each other, representing the site of bonding with L1, L2 or L3 in the general formula (a-1), a hydrogen atom, a deuterium atom, a chlorine atom, a cyano group or a nitro group, and one R represents the site of bonding with L1, L2 or L3 in the general formula (a-1).

2. The amine compound having an azabenzoxazole ring structure according to claim 1, wherein, Of A, B, and C in the general formula (a-1), only one is a group represented by the general formula (b-4).

3. The amine compound having an azabenzoxazole ring structure according to claim 1, wherein, Of A, B, and C in the general formula (a-1), both are groups represented by the general formula (b-4).

4. The amine compound having an azabenzoxazole ring structure according to claim 1, wherein, In the general formula (a-1), A, B, and C are all groups represented by the general formula (b-4).

5. An organic EL element, comprising at least an anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode electrode, and a capping layer in sequence, wherein, The coating layer contains an amine compound having a azirzooxazole ring structure as described in any one of claims 1 to 4.

6. The organic EL element according to claim 5, wherein, The extinction coefficient of the capping layer is above 0.2 in the wavelength range of 400nm to 410nm, and the concentration is 10. -5 The absorbance in the absorption spectrum of mol / L is above 0.2 in the wavelength range of 400nm to 410nm.

7. The organic EL element according to claim 5, wherein, The refractive index of the coating layer is above 1.85 in the wavelength range of 450nm to 750nm.

8. The organic EL element according to claim 5, wherein, The capping layer is a mixed layer formed of two or more compounds, including the amine compound having the azabenzoxazole ring structure, or a stack formed of layers each containing two or more compounds individually.

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