Amine compound having azabenzoxazole ring structure, and organic electroluminescent element using same

Abstract

The purpose of the present invention is to provide a compound which absorbs light having a wavelength of 400-410 nm from sunlight, does not affect a material inside an organic EL element, and has a high refractive index in a wavelength range of 450-750 nm, in order to prevent deterioration inside the element and considerably improve light extraction efficiency.　The present invention is an amine compound having a specific benzazole ring structure with a high refractive index. This organic EL element has at least a positive electrode, a hole transport layer, a light-emitting layer, an electron transport layer, a negative electrode, and a capping layer in this order, wherein the capping layer preferably contains an amine compound having a specific benzazole ring structure according to the present invention.

Description

Amine compound having an azabenzoxazole ring structure and organic electroluminescence device using the same

[0001] The present invention relates to a compound suitable for a self-luminous electronic element suitable for various display devices, particularly a compound suitable for an organic electroluminescence element (hereinafter abbreviated as organic EL element), and an organic EL element, electronic equipment, or electronic element using the compound.

[0002] Organic EL elements are self-luminous elements, and therefore are brighter and more visible than liquid crystal elements, and are capable of producing clearer displays, and therefore have been the subject of vigorous research.

[0003] In 1987, C. W. Tang et al. of Eastman Kodak Company made organic EL devices practical by developing a layered structure element in which various roles are assigned to each material. They layered a phosphor capable of transporting electrons and an organic material capable of transporting holes, and emitted light by injecting both charges into the phosphor layer, achieving 1000 cd / m at a voltage of 10 V or less. ２ Such high brightness is achieved (see, for example, Patent Documents 1 and 2).

[0004] To date, many improvements have been made to put organic EL elements into practical use, and the various roles of the laminated structure have been further subdivided to form electroluminescent elements in which 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 are provided in this order on a substrate, thereby achieving high efficiency and durability in light-emitting elements with a bottom-emission structure that emits light from the bottom (see, for example, Non-Patent Document 1).

[0005] In recent years, light-emitting devices with a top-emission structure that uses a metal with a high work function as the anode and emits light from the top have come into use. In a bottom-emission structure in which light is extracted from the bottom where the pixel circuit is located, the area of ​​the light-emitting section is limited, whereas a light-emitting device with a top-emission structure has the advantage that light is extracted from the top, so it is not blocked by the pixel circuit and the light-emitting section can be made larger. In light-emitting devices with a top-emission structure, a semi-transparent electrode such as LiF / Al / Ag (see, for example, Non-Patent Document 2), Ca / Mg (see, for example, Non-Patent Document 3), or LiF / MgAg is used as the cathode.

[0006] In such light-emitting devices, when light emitted from the light-emitting layer is incident on another film, light incident at an angle greater than a certain level is totally reflected at the interface between the light-emitting layer and the other film. As a result, only a portion of the emitted light can be utilized. In recent years, light-emitting devices have been proposed that provide a high-refractive-index "capping layer" on the outside of a semi-transparent electrode with a low refractive index in order to improve light extraction efficiency (see, for example, Non-Patent Documents 2 and 3).

[0007] The effect of the capping layer on the top-emission light-emitting device is as follows: ３ In a light-emitting device using this as the light-emitting material, the current efficiency was 38 cd / A when there was no capping layer, but by providing a 60 nm thick ZnSe layer as a capping layer, the current efficiency became 64 cd / A, an improvement of approximately 1.7 times. It has also been shown that the maximum points of the transmittance of the semi-transparent electrode and capping layer do not necessarily coincide with the maximum points of the efficiency, and that the maximum point of the light extraction efficiency is determined by the interference effect (see, for example, Non-Patent Document 3).

[0008] Conventionally, the use of a high-resolution metal mask has been proposed for forming a capping layer, but there is a problem in that the metal mask distorts due to heat when used under high-temperature conditions, resulting in reduced alignment accuracy. Therefore, ZnSe, which has a high melting point of 1100°C or higher (see, for example, Non-Patent Document 3), cannot be deposited in an accurate position using a high-resolution metal mask, and this may affect the light-emitting element itself. Furthermore, even when formed by sputtering, the light-emitting element is affected, so capping layers made of inorganic constituent materials are not suitable for use.

[0009] In addition, tris(8-hydroxyquinoline)aluminum (hereinafter referred to as Alq) is used as a capping layer for adjusting the refractive index. ３ When Alq is used (for example, see Non-Patent Document 2), ３ is known as an organic EL material that is generally used as a green light-emitting material or an electron transport material, and has weak absorption in the vicinity of 450 nm that is used as a blue light-emitting material, so in the case of blue light-emitting devices, there have been problems of reduced color purity and reduced light extraction efficiency.

[0010] Furthermore, elements fabricated with conventional capping layers allow sunlight with wavelengths of 400 nm to 410 nm to pass through, affecting materials inside the element and resulting in problems such as a decrease in color purity and light extraction efficiency.

[0011] In order to improve the device characteristics of organic EL devices, particularly those that can absorb sunlight with wavelengths of 400 nm to 410 nm without affecting the materials inside the device and that can significantly improve the light extraction efficiency, there is a demand for a material for the capping layer that has a high absorption coefficient, a high refractive index, and excellent thin film stability and durability.

[0012] US5792557 AUS5639914 A International Publication No. 2014 / 009310 US2014 / 0225100 A1

[0013] Proceedings of the 9th Seminar of the Japan Society of Applied Physics, pages 55-61 (2001) Appl. Phys. Let. , 78, 544 (2001) Appl. Phys. Let. , 82, 466 (2003) SYNLET. , 7, 1172 (2009) J. Org. Chcm. , 60, 7508 (1995) Synth. Commun. , 11, 513 (1981) Appl. Phys. Lett. , 98, 083302 (2011)

[0014] The object of the present invention is to provide a compound that absorbs sunlight having a wavelength of 400 nm to 410 nm without affecting materials inside the device, and has a high refractive index in the wavelength range of 450 nm to 750 nm, thereby improving the device characteristics of the organic EL device. Furthermore, the object of the present invention is to provide an organic EL device in which deterioration inside the device is suppressed and light extraction efficiency is significantly improved by using the compound as a constituent material of a capping layer.

[0015] The physical properties of the capping layer material suitable for organic EL devices include (1) a high absorption coefficient, (2) a high refractive index, (3) the ability to be vapor-deposited, (4) a stable thin film state, and (5) a high glass transition temperature. The physical properties of the organic EL device provided by the present invention include (1) absorption of light with a wavelength of 400 nm to 410 nm, (2) high light extraction efficiency, (3) no decrease in color purity, (4) light transmission without change over time, and (5) a long life.

[0016] Therefore, in order to achieve the above object, the present inventors have focused on the fact that arylamine-based materials have excellent thin film stability and durability, and have developed a method for producing a thin film of 100% arylamine-based materials from an amine compound having a specific benzoazole ring structure with a high refractive index. －５ Materials with high absorbance in the wavelength range of 400 nm to 410 nm in the absorption spectrum of 100 mol / L were selected, and organic EL devices were fabricated using the materials as materials for the capping layer. As a result of extensive evaluation of the device characteristics, the present invention was completed.

[0017] That is, the present invention provides the following amine compound having an azabenzoxazole ring structure and an organic EL device using the same. Also provided are an electronic device having an organic layer containing the amine compound and an electronic apparatus using the electronic device.

[0018] 1) Amine compounds having an azabenzoxazole ring structure represented by the following general formula (a-1):

[0019]

[0020] In the general formula (a-1), A, B, and C may be the same or different from one another and represent a group represented by 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, provided that at least one of A, B, and C is a group represented by the following general formula (b-1): １ , L ２ and L ３ may be the same or different and each represent 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.

[0021]

[0022] In the formula, R may be the same or different from each other, and L in the general formula (a-1) １ , L ２ or L ３a hydrogen atom, a deuterium atom, a chlorine atom, a cyano group, a nitro group, a trimethylsilyl group, a triphenylsilyl group, a linear or branched alkyl group of 1 to 6 carbon atoms which may have a substituent, a cycloalkyl group of 5 to 10 carbon atoms which may have a substituent, a linear or branched alkenyl group of 2 to 6 carbon atoms which may have a substituent, a linear or branched alkyloxy group of 1 to 6 carbon atoms which may have a substituent, a cycloalkyloxy group of 5 to 10 carbon atoms which may have a substituent, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group; １ , L ２ or L ３ Each Y may be the same or different and represents a carbon atom or a nitrogen atom substituted with R, provided that at least one Y is a nitrogen atom substituted with R.

[0023] 2) The amine compound having an azabenzoxazole ring structure according to 1) above, wherein among A, B, and C in general formula (a-1), groups other than the group represented by general formula (b-1) are a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthrenyl group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted benzofuranyl group, a substituted or unsubstituted benzothiophenyl group, a substituted or unsubstituted indolyl group, a substituted or unsubstituted benzimidazolyl group, a substituted or unsubstituted imidazopyridyl group, a substituted or unsubstituted benzoxazolyl group, a substituted or unsubstituted benzothiazolyl group, a substituted or unsubstituted dibenzofuranyl group, or a substituted or unsubstituted dibenzothiophenyl group.

[0024] 3) The amine compound having an azabenzoxazole ring structure according to 2) above, wherein the group represented by general formula (b-1) is a group represented by the following general formula (b-2) or (b-3):

[0025]

[0026]

[0027] R in the general formula (b-2) and the general formula (b-3) has the same definition as R in the general formula (b-1).

[0028] 4) The amine compound having an azabenzoxazole ring structure according to 3) above, wherein the group represented by general formula (b-2) is a group represented by the following general formula (b-4), and the group represented by general formula (b-3) is a group represented by the following general formula (b-5):

[0029]

[0030]

[0031] R in the general formula (b-4) and the general formula (b-5) has the same definition as R in the general formula (b-1).

[0032] 5) L in the general formula (a-1) １ , L ２ and L ３ is a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted biphenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted dibenzofuranylene group, or a substituted or unsubstituted dibenzothiophenylene group.

[0033] 6) The amine compound having an azabenzoxazole ring structure according to 4) above, wherein only one of A, B, and C in general formula (a-1) is a group represented by general formula (b-4) or (b-5).

[0034] 7) The amine compound having an azabenzoxazole ring structure according to 4) above, wherein two of A, B, and C in general formula (a-1) are groups represented by general formula (b-4) or (b-5).

[0035] 8) The amine compound having an azabenzoxazole ring structure according to 4) above, wherein all of A, B, and C in general formula (a-1) are groups represented by general formula (b-4) or (b-5).

[0036] 9) An organic EL device 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 this order, wherein the capping layer contains the amine compound having an azabenzoxazole ring structure described in any one of 1) to 8) above.

[0037] 10) The extinction coefficient of the capping layer is 0.2 or more in the wavelength range of 400 nm to 410 nm, and the density is 10 －５ 9) The organic EL device according to 9) above, wherein the absorbance in the absorption spectrum at mol / L is 0.2 or more in the wavelength range of 400 nm to 410 nm.

[0038] 11) The organic EL device according to 9) above, wherein the refractive index of the capping layer is 1.85 or more in the wavelength range of 450 nm to 750 nm.

[0039] 12) The organic EL element according to 9) above, wherein the capping layer is a mixed layer made of two or more compounds including the amine compound having an azabenzoxazole ring structure, or a laminated layer made of layers each containing these two or more compounds singly.

[0040] 13) An electronic device having a pair of electrodes and an organic layer sandwiched between them, wherein the organic layer contains the amine compound having an azabenzoxazole ring structure described in any one of 1) to 8) above.

[0041] 14) An electronic device using the electronic element described in 13).

[0042] A, B, C, and L in general formula (a-1) and general formula (b-1) １ , L ２ , L ３and R, the "aromatic hydrocarbon group", the "aromatic heterocyclic group", or the "fused polycyclic aromatic group" in the "substituted or unsubstituted aromatic hydrocarbon group", "substituted or unsubstituted aromatic heterocyclic group", or "substituted or unsubstituted fused polycyclic aromatic group" specifically includes a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, a triphenylenyl group, a pyridyl group, a pyrimidinyl group, a triazinyl group, group, a furyl group, a pyrrolyl group, a thienyl group, a quinolyl group, an isoquinolyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a carbazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, a naphthyridinyl group, a phenanthrolinyl group, an acridinyl group, and a carbolinyl group, and further examples include groups selected from aryl groups having 6 to 30 carbon atoms and heteroaryl groups having 2 to 20 carbon atoms.

[0043] In the "linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent", "cycloalkyl group having 5 to 10 carbon atoms which may have a substituent", "linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent", "linear or branched alkyloxy group having 1 to 6 carbon atoms which may have a substituent", "cycloalkyloxy group having 5 to 10 carbon atoms which may have a substituent", or "substituted or unsubstituted aryloxy group" represented by R in general formula (b-1), Specific examples of the "straight-chain or branched alkyloxy group having 5 to 10 carbon atoms," "cycloalkyloxy group having 5 to 10 carbon atoms," or "aryloxy group" include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a vinyl group, an allyl group, an isopropenyl group, a 2-butenyl group, a methyloxy group, an ethyloxy group, an n-propyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, a 1-adamantyloxy group, a phenyloxy group, a tolyloxy group, and a biphenyloxy group.

[0044] A, B, C, and L in general formula (a-1) and general formula (b-1) １ , L ２ , L ３and R, "substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", "substituted fused polycyclic aromatic group", "linear or branched alkyl group of 1 to 6 carbon atoms which may have a substituent", "cycloalkyl group of 5 to 10 carbon atoms which may have a substituent", "linear or branched alkenyl group of 2 to 6 carbon atoms which may have a substituent", "linear or branched alkyloxy group of 1 to 6 carbon atoms which may have a substituent", "cycloalkyloxy group of 5 to 10 carbon atoms which may have a substituent", or "substituted aryloxy group" specifically include deuterium atoms, cyano groups, nitro groups; halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; silyl groups such as trimethylsilyl groups and triphenylsilyl groups; linear or branched alkyl groups of 1 to 6 carbon atoms such as methyl groups, ethyl groups, and propyl groups; linear or branched alkyloxy groups of 1 to 6 carbon atoms such as methyloxy groups, ethyloxy groups, and propyloxy groups; vinyl alkenyl groups such as a group or an allyl group; aryloxy groups such as a phenyloxy group or a tolyloxy group; arylalkyloxy groups such as a benzyloxy group or a phenethyloxy group; aromatic hydrocarbon groups or condensed polycyclic aromatic groups such as a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, or a triphenylenyl group; pyridyl group, thienyl group, furyl group, Examples thereof include a pyrrolyl group, a quinolyl group, an isoquinolyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a carbazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbolinyl group, and the like, as well as an aryl group having 6 to 30 carbon atoms or a heteroaryl group having 2 to 20 carbon atoms, and these substituents may be further substituted with the substituents exemplified above.Furthermore, a benzene ring substituted with these substituents or a plurality of substituents substituted on the same benzene ring may be bonded to each other via a single bond, a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom to form a ring.

[0045] In the amine compound having an azabenzoxazole ring structure of the present invention, L in the general formula (a-1) １ , L ２ and L ３ is preferably a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted naphthylene group from the viewpoint of the absorption coefficient and the refractive index, and more preferably a single bond, an unsubstituted phenylene group, or an unsubstituted naphthylene group.

[0046] In the amine compound having an azabenzoxazole ring structure of the present invention, one of R in each of the general formulae (b-4) and (b-5) is L in the general formula (a-1). １ , L ２ or L ３ and the other two are preferably hydrogen atoms in terms of the absorption coefficient and refractive index.

[0047] The amine compound having an azabenzoxazole ring structure of the present invention preferably has a glass transition temperature of 100° C. or higher in terms of stability when formed into a thin film.

[0048] In the organic EL element of the present invention, the thickness of the capping 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.

[0049] In the organic EL element of the present invention, the capping layer has an extinction coefficient of 0.2 or more in the wavelength range of 400 nm to 410 nm, and －５ In terms of suppressing deterioration inside the element, it is preferable that the absorbance in the absorption spectrum of 100 mol / L 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.

[0050] In the organic EL element of the present invention, the refractive index of the capping layer is preferably 1.85 or more in the wavelength range of 450 nm to 750 nm from the viewpoint of light extraction efficiency, and more preferably 1.90 or more.

[0051] In the organic EL device of the present invention, the capping layer may be formed as a mixed layer of two or more different compounds or a laminate of layers containing each of these compounds alone, provided that at least one of the compounds is the amine compound having an azabenzoxazole ring structure of the present invention.

[0052] The amine compound having an azabenzoxazole ring structure represented by general formula (a-1) of the present invention has the following characteristics: (1) a high absorption coefficient, (2) a high refractive index in the wavelength range of 450 nm to 750 nm, (3) vapor deposition is possible, (4) the thin film state is stable, and (5) heat resistance is high. When the compound of the present invention is used as a material for a capping layer that is provided on the outer side of a transparent or semitransparent electrode of an organic EL device and has a higher refractive index than the semitransparent electrode, it is possible to significantly improve the light extraction efficiency and obtain an organic EL device in which material deterioration inside the device is suppressed.

[0053]

[0023] Figure 1 shows the structures of compounds (1) to (12) as exemplary compounds of the present invention. Figure 2 shows the structures of compounds (13) to (27) as exemplary compounds of the present invention. Figure 3 shows the structures of compounds (28) to (42) as exemplary compounds of the present invention. Figure 4 shows the structures of compounds (43) to (54) as exemplary compounds of the present invention. Figure 5 shows the structures of compounds (55) to (66) as exemplary compounds of the present invention. Figure 6 shows the structures of compounds (67) to (81) as exemplary compounds of the present invention. Figure 7 shows the structures of compounds (82) to (96) as exemplary compounds of the present invention. Figure 8 shows the structures of compounds (97) to (111) as exemplary compounds of the present invention. Figure 9 shows the structures of compounds (112) to (126) as exemplary compounds of the present invention. Figure 10 shows the structures of compounds (127) to (138) as exemplary compounds of the present invention. Figure 11 shows the structures of compounds (139) to (153) as exemplary compounds of the present invention. Figure 12 shows the structures of compounds (154) to (165) as exemplary compounds of the present invention. Figure 13 shows the structures of compounds (166) to (173) as exemplary compounds of the present invention. 1 is a diagram showing the configurations of organic EL elements according to an example of the present invention and a comparative example;

[0054] The amine compounds of the present invention having an azabenzoxazole ring structure represented by the general formula (a-1) are novel compounds, and the azabenzoxazole derivatives that form the main skeleton of these compounds can be synthesized by known methods as described below (see, for example, Non-Patent Document 4). Furthermore, the amine compounds of the present invention having an azabenzoxazole ring structure represented by the general formula (a-1) can be synthesized by carrying out a coupling reaction using a copper catalyst, a palladium catalyst, or the like, using the synthesized halogenated azabenzoxazole derivative and an arylamine. Alternatively, the amine compounds of the present invention having an azabenzoxazole ring structure represented by the general formula (a-1) can be similarly synthesized by converting a halogenated azabenzoxazole derivative into a boronic acid ester derivative and then subjecting it to a coupling reaction with a halogenated arylamine (see, for example, Non-Patent Documents 5 and 6).

[0055]

[0056] Among the amine compounds having an azabenzoxazole ring structure represented by general formula (a-1) that are suitably used in the organic EL element of the present invention, specific examples of preferred compounds are shown in FIGS. 1 to 13, but the present invention is not limited to these compounds.

[0057] The purification of the amine compound having an azabenzoxazole ring structure represented by the general formula (a-1) is not particularly limited, and can be carried out by known methods used for purifying organic compounds, such as purification by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization purification using a solvent, crystallization purification, and sublimation purification. The compound can be identified by NMR analysis. It is preferable to measure the melting point, glass transition point (Tg), and refractive index as physical property values. The melting point is an index of vapor deposition property, the glass transition point (Tg) is an index of stability in the thin film state, and the refractive index is an index of improvement in light extraction efficiency.

[0058] The melting point and glass transition point (Tg) can be measured using a powder with a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS).

[0059] The refractive index and extinction coefficient can be measured by forming an 80 nm thin film on a silicon substrate and using a spectrophotometer (F10-RT-UV, manufactured by Filmetrics).

[0060] The absorbance is measured at a concentration of 10 in toluene. －５ The solution was adjusted to mol / L, and the extinction coefficient was 5.0 x 10 in toluene. －６ mol / L, 1.0×10 －５ mol / L, 1.5×10 －５ mol / L and 2.0 x 10 －５ The measurement can be carried out using solutions adjusted to four different concentrations (mol / L) with an ultraviolet-visible-near infrared spectrophotometer (V-650, manufactured by JASCO Corporation).

[0061] Examples of the structure of the organic EL device of the present invention include, for example, a top-emission light-emitting element having an anode, a hole transport layer, an emitting layer, an electron transport layer, a cathode, and a capping layer, which are sequentially arranged on a glass substrate, or 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 emitting layer, an element having a hole blocking layer between the emitting layer and the electron transport layer, or an element having an electron injection layer between the electron transport layer and the cathode. In these multilayer structures, one organic layer can serve as several layers, for example, a structure that serves both as a hole injection layer and a hole transport layer, a structure that serves both as a hole transport layer and an electron blocking layer, a structure that serves both as a hole blocking layer and an electron transport layer, or a structure that serves both as an electron transport layer and an electron injection layer. It is also possible to use a structure in which two or more organic layers having the same function are stacked, such as a structure in which two hole transport layers are stacked, a structure in which two light-emitting layers are stacked, a structure in which two electron transport layers are stacked, or a structure in which two capping layers are stacked.

[0062] The total thickness of the layers of the organic EL element is preferably about 200 nm to 750 nm, more preferably about 350 nm to 600 nm. 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. The thickness of the capping layer can be appropriately changed depending on the type of light-emitting material used in the light-emitting element, the thickness of the organic EL element other than the capping layer, and the like.

[0063] For the anode of the organic EL element of the present invention, an electrode material having a large work function, such as ITO or gold, is used.

[0064] The hole injection layer of the organic EL device of the present invention can be formed using arylamine compounds having three or more triphenylamine structures in the molecule, linked by a single bond or a divalent group containing no heteroatoms, such as starburst triphenylamine derivatives and various triphenylamine tetramers. Porphyrin compounds, such as copper phthalocyanine, heterocyclic acceptor compounds such as hexacyanoazatriphenylene, and polymeric coating materials can also be used. These materials can be formed into films alone or mixed with other materials to form a single layer. They can also be used as a laminated structure consisting of layers formed alone, layers formed in a mixture, or layers formed in a mixture with other layers. These materials can be formed into thin films by known methods, such as vapor deposition, spin coating, or inkjet printing.

[0065] For the hole transport layer of the organic EL device of the present invention, benzidine derivatives such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (hereinafter abbreviated as TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (hereinafter abbreviated as NPD), and N,N,N',N'-tetrabiphenylylbenzidine; 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter abbreviated as TAPC); etc. can be used. In particular, it is preferable to use an arylamine compound having two triphenylamine structures in the molecule linked by a single bond or a divalent group not containing a heteroatom, such as N,N,N',N'-tetrabiphenylylbenzidine. It is also preferable to use arylamine compounds having three or more triphenylamine structures in the molecule, linked by single bonds or divalent groups not containing heteroatoms, such as various triphenylamine trimers and tetramers. These compounds may be formed into films alone or mixed with other materials to form a single layer. They may also be used as laminates of layers formed alone, layers formed in a mixture, or layers formed in a mixture with other layers. Furthermore, coating-type polymer materials such as poly(3,4-ethylenedioxythiophene) (hereinafter abbreviated as PEDOT) and poly(styrene sulfonate) (hereinafter abbreviated as PSS) can be used as hole injection / transport layers. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0066] Furthermore, in the hole injection layer or the hole transport layer, it is possible to use materials that are typically used for the layer, such as those doped with P-trisbromophenylaminehexachloroantimony, radialene derivatives (see, for example, Patent Document 3), or polymer compounds having a structure of a benzidine derivative such as TPD in their partial structure.

[0067] For the electron blocking layer of the organic EL device of the present invention, compounds having an electron blocking effect can be used, such as carbazole derivatives such as 4,4',4''-tri(N-carbazolyl)triphenylamine (hereinafter abbreviated as TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (hereinafter abbreviated as mCP), and 2,2-bis(4-carbazol-9-yl-phenyl)adamantane (hereinafter abbreviated as Ad-Cz); and compounds having a triphenylsilyl group and a triarylamine structure, typified by 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene. These materials may be formed into a film by themselves, or may be mixed with other materials to form a single layer, or may be laminated with other layers formed by themselves, other layers formed by mixing, or a layer formed by mixing and forming a layer formed by mixing. These materials can be formed into a thin film by known methods such as vapor deposition, spin coating, ink jetting, etc.

[0068] The light-emitting layer of the organic EL element of the present invention is ３Examples of suitable materials include metal complexes of quinolinol derivatives such as quinolinol derivatives (e.g., quinolinol derivatives), various other metal complexes, anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, and polyparaphenylenevinylene derivatives. The light-emitting layer may also be composed of a host material and a dopant material. Anthracene derivatives are preferably used as the host material. In addition to the light-emitting materials, other suitable materials include heterocyclic compounds having an indole ring as a fused ring substructure, heterocyclic compounds having a carbazole ring as a fused ring substructure, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, and polydialkylfluorene derivatives. Examples of suitable dopant materials include quinacridone, coumarin, rubrene, perylene, and derivatives thereof, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives. These may be formed alone, or may be mixed with other materials to form a single layer, or may be stacked with other layers formed alone, other layers formed as a mixture, or a layer formed alone and a layer formed as a mixture.

[0069] It is also possible to use a phosphorescent emitter as the light-emitting material. As the phosphorescent emitter, a phosphorescent emitter of a metal complex such as iridium or platinum can be used, and Ir(ppy) ３ green phosphorescent emitters such as FIrpic and FIr6; blue phosphorescent emitters such as Btp ２ A red phosphorescent emitter such as Ir(acac) can be used. As a host material, hole-injecting / transporting host materials such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as CBP) and carbazole derivatives such as TCTA and mCP can be used. As an electron-transporting host material, p-bis(triphenylsilyl)benzene (hereinafter abbreviated as UGH2) and 2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter abbreviated as TPBI) can be used, allowing for the fabrication of high-performance organic EL devices.

[0070] In order to avoid concentration quenching, the phosphorescent light-emitting material is preferably doped into the host material by co-evaporation in an amount ranging from 1 to 30 weight percent based on the entire light-emitting layer.

[0071] Furthermore, materials that emit delayed fluorescence, such as CDCB derivatives such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN, can also be used as light-emitting materials (see, for example, Non-Patent Document 7). These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0072] For the hole-blocking layer of the organic EL device of the present invention, compounds having hole-blocking properties can be used, such as phenanthroline derivatives such as bathocuproine (hereinafter abbreviated as BCP), metal complexes of quinolinol derivatives such as aluminum(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (hereinafter abbreviated as BAlq), various rare earth complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, and benzoazole derivatives. These materials may also serve as materials for the electron-transporting layer. These materials may be formed alone or mixed with other materials to form a single layer, or may form a laminate structure of layers formed alone, layers formed in a mixture, or layers formed in a mixture with layers formed alone. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0073] The electron transport layer of the organic EL element of the present invention is ３Metal complexes of quinolinol derivatives such as BAlq, various other metal complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, pyridine derivatives, benzimidazole derivatives, benzoazole derivatives, thiadiazole derivatives, anthracene derivatives, carbodiimide derivatives, quinoxaline derivatives, pyridoindole derivatives, phenanthroline derivatives, silole derivatives, etc. can be used. These materials can be formed into films alone, or they can be mixed with other materials to form a single layer, or they can be laminated layers formed alone, mixed layers, or layers formed alone and mixed layers. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, inkjet printing, etc.

[0074] The electron injection layer of the organic EL device of the present invention can be made of alkali metal salts such as lithium fluoride and cesium fluoride, alkaline earth metal salts such as magnesium fluoride, metal complexes of quinolinol derivatives such as lithium quinolinol, metal oxides such as aluminum oxide, or metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs). However, this can be omitted by suitable selection of the electron transport layer and the cathode.

[0075] Furthermore, in the electron injection layer or electron transport layer, a material that is further doped with N-type metal such as cesium can be used in addition to the materials normally used in the layer.

[0076] As the cathode of the organic EL element of the present invention, an electrode material having a low work function such as aluminum, an alloy having an even lower work function such as a magnesium-silver alloy, a magnesium-calcium alloy, a magnesium-indium alloy, or an aluminum-magnesium alloy, ITO, IZO, or the like is used as the electrode material.

[0077] The capping layer of the organic EL device of the present invention uses an amine compound having an azabenzoazole ring structure represented by the general formula (a-1). These compounds may be formed into a film alone, or may be mixed with other materials to form a single layer, or may be laminated with other layers formed alone, other layers formed in a mixture, or layers formed in a mixture with other layers formed alone. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0078] Although the organic EL element having a top emission structure has been described above, the present invention is not limited to this and can be similarly applied to an organic EL element having a bottom emission structure or an organic EL element having a dual emission structure that emits light from both the top and bottom. In these cases, the electrode in the direction in which light is extracted from the light-emitting element to the outside must be transparent or semi-transparent.

[0079] The refractive index of the material constituting the capping layer is preferably higher than that of the adjacent electrode. That is, the capping layer improves the light extraction efficiency of the organic EL element, and this effect is more effective when the reflectance at the interface between the capping layer and the material in contact with the capping layer is higher, because the effect of light interference is greater. Therefore, the refractive index of the material constituting the capping layer is preferably higher than that of the adjacent electrode, and the refractive index may be 1.70 or higher, more preferably 1.80 or higher, and particularly preferably 1.85 or higher.

[0080] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0081] Example 1 Synthesis of bis(4-naphthalen-1-yl-phenyl)4′-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-amine: Compound (123) A reaction vessel purged with nitrogen was charged with 5.0 g of bis(4-naphthalen-1-yl-phenyl)-4-bromophenyl-amine, 3.1 g of 2-{4-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)-phenyl}-7-azabenzoxazole, 0.5 g of tetrakis(triphenylphosphine)palladium(0), and 1.8 g of potassium carbonate. ２ The mixture was refluxed overnight in a mixed solvent of 100 ml of methanol / H ２ O was added, and the mixture was filtered to collect the solid, yielding a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent, yielding 4.0 g (yield 66.7%) of a yellow powder of bis(4-naphthalen-1-yl-phenyl)4′-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-amine: compound (123).

[0082]

[0083] The structure of the resulting yellow powder was identified using NMR. 　１ H-NMR (CDCl ３ ) the following 33 hydrogen signals were detected: 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).

[0084] Example 2 Synthesis of 4′-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphthalen-1-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine: Compound (124) A reaction vessel purged with nitrogen was charged with 5.0 g of 4-bromophenyl-(4-naphthalen-1-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine, 3.1 g of 2-{4-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)-phenyl}-7-azabenzoxazole, 0.5 g of tetrakis(triphenylphosphine)palladium(0), and 1.8 g of potassium carbonate. The mixture was diluted with toluene / EtOH / H ２ The mixture was refluxed overnight in a mixed solvent of 100 ml of methanol / H ２ O was added, and the mixture was filtered to collect the solid, yielding a crude product. The crude product obtained was purified by crystallization using a monochlorobenzene / acetone mixed solvent, yielding 4.4 g (yield 73.3%) of a yellow powder of 4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphthalen-1-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine: compound (124).

[0085]

[0086] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ ) the following 33 hydrogen signals were detected: 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).

[0087] Example 3 Synthesis of 4-(7-azabenzoxazol-2-yl)-phenyl-(4-naphthalen-1-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine: Compound (25) A nitrogen-purged reaction vessel was charged with 7.0 g of (4-naphthalen-1-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine, 5.0 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.1 g of palladium(II) acetate, 0.2 g of tri-t-butylphosphine, and 2.4 g of sodium t-butoxide, and the mixture was refluxed under stirring in a toluene solvent for 5 hours. After cooling, methanol was added to the system, which was then dispersed and washed, and the solid was collected by filtration to obtain a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 7.1 g (yield 69.5%) of a yellow powder of 4-(7-azabenzoxazol-2-yl)-phenyl-(4-naphthalen-1-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine: compound (25).

[0088]

[0089] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ ) the following 29 hydrogen signals were detected: 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).

[0090] Example 4 Synthesis of bis(4-naphthalen-2-yl-phenyl)-4-(7-azabenzoxazol-2-yl)-phenyl-amine: Compound (44) A nitrogen-purged reaction vessel was charged with 5.0 g of bis(4-naphthalen-2-yl-phenyl)-amine, 3.6 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.4 g of tris(dibenzylideneacetone)dipalladium(0), 0.4 g of tri-t-butylphosphine, and 1.7 g of sodium t-butoxide, and the mixture was refluxed overnight under stirring in a xylene solvent. After cooling, methanol was added to the system, which was then dispersed and washed, and the solid was collected by filtration to obtain a crude product. The crude product was purified by recrystallization using a monochlorobenzene solvent to obtain 3.2 g (yield 43.8%) of a yellow powder of bis(4-naphthalen-2-yl-phenyl)-4-(7-azabenzoxazol-2-yl)-phenyl-amine: compound (44).

[0091]

[0092] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ ) the following 29 hydrogen signals were detected: 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).

[0093] Example 5 Synthesis of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-naphthalen-1-yl-phenyl)-amine: Compound (140) A nitrogen-substituted reaction vessel was charged with 1.9 g of 4-(naphthalen-1-yl)-phenyl-amine, 5.2 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.2 g of tris(dibenzylideneacetone)dipalladium(0), 0.2 g of tri-t-butylphosphine, and 1.9 g of sodium t-butoxide, and the mixture was refluxed with stirring in a toluene solvent for 8 hours. After cooling, methanol was added to the system, and dispersion washing was performed. The solid was then filtered to obtain a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 3.8 g (yield 72.1%) of yellow powder of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-naphthalen-1-yl-phenyl)-amine: compound (140).

[0094]

[0095] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ The following 25 hydrogen signals were detected at δ (ppm): 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).

[0096] Example 6 Synthesis of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-carbazol-9-yl-phenyl)-amine Compound (144) 2.3 g of 4-(carbazol-9-yl)-phenyl-amine, 5.1 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.2 g of tris(dibenzylideneacetone)dipalladium(0), 0.2 g of tri-t-butylphosphine, and 2.0 g of sodium t-butoxide were placed in a nitrogen-purged reaction vessel and stirred under reflux in a toluene solvent for 6 hours. After cooling, methanol was added to the system for dispersion washing, and the solid was collected by filtration to obtain a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent, yielding 3.9 g (yield 67.7%) of yellow powder of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-(4-carbazol-9-yl-phenyl)-amine: compound (144).

[0097]

[0098] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ ) the following 26 hydrogen signals were detected: 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).

[0099] Example 7 Synthesis of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-[1,1′]binaphthalenyl-4-yl-amine: Compound (146) A nitrogen-purged reaction vessel was charged with 5.0 g of [1,1′]binaphthalenyl-4-yl-amine, 11.2 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.5 g of tris(dibenzylideneacetone)dipalladium(0), 0.6 g of tri-t-butylphosphine, and 5.4 g of sodium t-butoxide, and the mixture was refluxed overnight under stirring in a toluene solvent. After cooling, methanol was added to the system, which was then dispersed and washed, and the solid was collected by filtration to obtain a crude product. The crude product was purified by crystallization using a tetrahydrofuran / acetone mixed solvent to obtain 8.2 g (yield 67.2%) of yellow powder of bis(4-(7-azabenzoxazol-2-yl)-phenyl)-[1,1′]binaphthalenyl-4-yl-amine: compound (146).

[0100]

[0101] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ ) the following 27 hydrogen signals were detected: δ (ppm) = 8.32 (2H), 8.22 (4H), 8.05-7.98 (5H), 7.64 (1H), 7.60-7.31 (15H).

[0102] Example 8 Synthesis of 4-(7-azabenzoxazol-2-yl)-phenyl-(4'-(naphthalen-1-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: Compound (166) A reaction vessel purged with nitrogen was charged with 10.0 g of (4'-(naphthalen-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(dibenzylideneacetone)dipalladium(0), 0.2 g of tri-t-butylphosphine, and 3.0 g of sodium t-butoxide, and the mixture was refluxed overnight under stirring in a toluene solvent. After allowing to cool, the mixture was filtered, and the obtained filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent, yielding 8.6 g (yield 61.0%) of a yellow powder of 4-(7-azabenzoxazol-2-yl)-phenyl-(4'-(naphthalen-1-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: compound (166).

[0103]

[0104] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ ) the following 31 hydrogen signals were detected: 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).

[0105] Example 9 Synthesis of 4-(7-azabenzoxazol-2-yl)-phenyl-(4′-(dibenzothiophen-4-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: Compound (167) A reaction vessel purged with nitrogen was charged with 12.0 g of (4′-(dibenzothiophen-4-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine, 6.7 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.6 g of tris(dibenzylideneacetone)dipalladium(0), 0.5 g of tri-t-butylphosphine, and 3.2 g of sodium t-butoxide, and the mixture was refluxed overnight with stirring in a toluene solvent. After allowing to cool, the mixture was filtered, and the obtained filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent, yielding 9.5 g (yield 58.0%) of a yellow powder of 4-(7-azabenzoxazol-2-yl)-phenyl-(4'-(dibenzothiophen-4-yl)-biphenyl-4-yl)-(4-(benzofuran-2-yl)-phenyl)-amine: compound (167).

[0106]

[0107] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ The following 31 hydrogen signals were detected at δ (ppm): 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).

[0108] Example 10 Synthesis of 4-(7-azabenzoxazol-2-yl)-phenyl-(4-(dibenzothiophen-4-yl)-phenyl)-(4′-(benzofuran-2-yl)-biphenyl-4-yl)-amine: Compound (168) A reaction vessel purged with nitrogen was charged with 7.0 g of (4-(dibenzothiophen-4-yl)-phenyl)-(4′-(benzofuran-2-yl)-biphenyl-4-yl)-amine, 4.4 g of 4-bromo-(7-azabenzoxazol-2-yl)-benzene, 0.4 g of tris(dibenzylideneacetone)dipalladium(0), 0.3 g of tri-t-butylphosphine, and 1.9 g of sodium t-butoxide, and the mixture was refluxed overnight under stirring in a toluene solvent. After allowing to cool, methanol was added to the system, and dispersion washing was performed, and the solid was collected by filtration to obtain a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent, yielding 8.5 g (yield 89.8%) of a yellow powder of 4-(7-azabenzoxazol-2-yl)-phenyl-(4-(dibenzothiophen-4-yl)-phenyl)-(4′-(benzofuran-2-yl)-biphenyl-4-yl)-amine: compound (168).

[0109]

[0110] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ The following 31 hydrogen signals were detected at δ (ppm): 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).

[0111] Example 11 Synthesis of 4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphthalen-2-yl-phenyl)-(4-phenanthrene-9-yl-phenyl)-amine: Compound (172) A nitrogen-purged reaction vessel was charged with 6.0 g of (4-naphthalen-2-yl-phenyl)-(4-phenanthrene-9-yl-phenyl)amine, 4.3 g of 2-(4'-chloro-biphenyl-4-yl)-7-azabenzoxazole, 0.4 g of tris(dibenzylideneacetone)dipalladium(0), 0.3 g of tri-t-butylphosphine, and 1.8 g of sodium t-butoxide, and the mixture was refluxed overnight under stirring in a toluene solvent. After cooling, methanol was added to the system, and the mixture was dispersed and washed. The solid was then filtered to obtain a crude product. The crude product was purified by crystallization using a monochlorobenzene / acetone mixed solvent, yielding 5.1 g (yield 54.0%) of a yellow powder of 4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-naphthalen-2-yl-phenyl)-(4-phenanthren-9-yl-phenyl)-amine: compound (172).

[0112]

[0113] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ The following 35 hydrogen signals were detected at δ (ppm): 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).

[0114] Example 12 Synthesis of 4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-dibenzofuran-3-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine: Compound (173) A nitrogen-purged reaction vessel was charged with 6.0 g of (4-dibenzofuran-3-yl-phenyl)-(4-naphthalen-2-yl-phenyl)amine, 4.4 g of 2-(4'-chloro-biphenyl-4-yl)-7-azabenzoxazole, 0.4 g of tris(dibenzylideneacetone)dipalladium(0), 0.3 g of tri-t-butylphosphine, and 1.9 g of sodium t-butoxide, and the mixture was refluxed overnight under stirring in xylene solvent. After cooling, methanol was added to the system, and the mixture was dispersed and washed. The solid was then filtered to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent to obtain 2.5 g (yield 26.3%) of a yellow powder of 4'-(7-azabenzoxazol-2-yl)-biphenyl-4-yl-(4-dibenzofuran-3-yl-phenyl)-(4-naphthalen-2-yl-phenyl)-amine: compound (173).

[0115]

[0116] The structure of the resulting yellow powder was identified using NMR. １ H-NMR (CDCl ３ The following 33 hydrogen signals were detected at δ (ppm): 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).

[0117] [Example 13] The melting points and glass transition points of the compounds obtained in the above examples were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS). The measurement results are summarized in Table 1.

[0118]

[0119] The above results show that the compounds obtained in the examples have glass transition points of 100° C. or higher and are stable in thin film state.

[0120] [Example 14] Using the compound obtained in the above example, a vapor-deposited film having a thickness of 80 nm was prepared on a silicon substrate, and the refractive index n and extinction coefficient k at wavelengths of 400 nm and 410 nm were measured using a spectrophotometer (F10-RT-UV, manufactured by Filmetrics). For comparison, the comparative compound (2-1) and Alq ３ The measurement results are summarized in Table 2.

[0121]

[0122]

[0123] As shown in Table 2, the comparative compound (2-1) and Alq ３ The refractive index at a wavelength of 450 nm of the compound (2-1) was 1.88 to 1.93, whereas the refractive index of the compound of the present invention was 2.29 to 2.52. ３ The refractive index at a wavelength of 750 nm of the compound (2-1) was 1.73 to 1.78, whereas the refractive index of the compound of the present invention was 1.89 to 1.95. This indicates that the use of the compound of the present invention can be expected to improve the light extraction efficiency in an organic EL device. ３ The extinction coefficient of the compound of the present invention in the wavelength range of 400 nm to 410 nm was 0.06 to 0.16, whereas the extinction coefficient of the compound of the present invention was 0.53 to 1.08. This indicates that the compound of the present invention effectively absorbs sunlight with a wavelength of 400 nm to 410 nm, and that its use as a capping layer can suppress the influence on materials inside the device.

[0124] [Example 15] Using the compound of the present invention, －５ A toluene solution of 5×10 mol / L was prepared, and the absorbance at wavelengths of 400 nm and 410 nm was measured using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation, V-650). －６ mol / L, 1 x 10 －５ mol / L, 1.5×10 －５ mol / L and 2.0 x 10 －５Toluene solutions of four different concentrations (mol / L) were prepared and measured using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation, V-650). The extinction coefficients were calculated from the calibration curves obtained. ３ The absorbance was measured in the same manner as above, and the extinction coefficient was calculated. The results are shown in Table 3.

[0125]

[0126] As shown in Table 3, the absorbance at wavelengths of 400 nm to 410 nm was higher for the comparative compound (2-1) and Alq ３ The absorbance of the compound of the present invention at wavelengths of 400 nm to 410 nm was 0.02 to 0.07, whereas the absorbance of the compound of the present invention was a large value of 0.36 to 1.35. This indicates that the compound of the present invention can effectively absorb sunlight at wavelengths of 400 nm to 410 nm. Furthermore, the compound of the present invention has an absorption coefficient of 70,000 or more, which is a larger value than the absorption coefficient of the comparative compound. In other words, the compound of the present invention absorbs light better than the comparative compound under the same concentration conditions.

[0127] [Example 16] An organic EL device was produced using the compound (123) obtained in Example 1, and its characteristics were measured in air at room temperature. The organic EL device was produced by vapor-depositing a hole injection layer 3, a hole transport layer 4, an emitting layer 5, an electron transport layer 6, an electron injection layer 7, a cathode 8, and a capping layer 9 in this order on a glass substrate 1 on which a reflective ITO electrode was previously formed as a transparent anode 2, as shown in Figure 14.

[0128] Specifically, a glass substrate 1 on which a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film were sequentially formed was subjected to ultrasonic cleaning in isopropyl alcohol for 20 minutes and then dried for 10 minutes on a hot plate heated to 250°C. After that, UV ozone treatment was performed for 2 minutes, and the ITO-coated glass substrate was placed in a vacuum deposition machine and the pressure was reduced to 0.001 Pa or less. Subsequently, a hole injection layer 3 was formed covering the transparent anode 2 by binary deposition of an electron acceptor (Acceptor-1) of the following structural formula and a compound (3-1) of the following structural formula at a deposition rate ratio of Acceptor-1:Compound (3-1) = 3:97, resulting in a thickness of 10 nm. On this hole injection layer 3, a hole transport layer 4 was formed of a compound (3-1) of the following structural formula to a thickness of 140 nm. On this hole transport layer 4, a light-emitting layer 5 was formed by binary deposition of a compound (3-2) having the following structural formula and a compound (3-3) having the following structural formula at a deposition rate ratio of (3-2):(3-3)=5:95 to a thickness of 20 nm. On this light-emitting layer 5, a compound (3-4) having the following structural formula and a compound (3-5) having the following structural formula were formed by binary deposition of a compound (3-4):(3-5) having the following structural formula at a deposition rate ratio of (3-4):(3-5)=50:50 to a thickness of 30 nm. On this electron transport layer 6, lithium fluoride was formed as an electron injection layer 7 to a thickness of 1 nm. On this electron injection layer 7, a magnesium-silver alloy was formed as a cathode 8 to a thickness of 12 nm. Finally, a capping layer 9 was formed by deposition of the compound (123) of Example 1 to a thickness of 60 nm.

[0129]

[0130] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (124) of Example 2 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0131] An organic EL device was fabricated under the same conditions as in Example 16, except that the capping layer 9 was formed to a thickness of 60 nm using compound (25) of Example 3 instead of compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0132] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (44) of Example 4 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0133] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (140) of Example 5 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0134] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (144) of Example 6 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0135] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (146) of Example 7 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0136] An organic EL device was fabricated under the same conditions as in Example 16, except that the capping layer 9 was formed to a thickness of 60 nm using compound (166) of Example 8 instead of compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0137] An organic EL device was fabricated under the same conditions as in Example 16, except that the capping layer 9 was formed to a thickness of 60 nm using compound (167) of Example 9 instead of compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0138] [Example 25] An organic EL device was fabricated under the same conditions as in Example 16, except that compound (168) of Example 10 was used as capping layer 9 instead of compound (123) of Example 1, to form a film having a thickness of 60 nm. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature. The measurement results of the light-emitting characteristics when a DC voltage was applied to the fabricated organic EL device are summarized in Table 4.

[0139] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (172) of Example 11 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0140] An organic EL device was fabricated under the same conditions as in Example 16, except that the compound (173) of Example 12 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) of Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0141] Comparative Example 1 For comparison, in Example 16, Alq was used as the capping layer 9 instead of the compound (123) in Example 1. ３ An organic EL device was fabricated under the same conditions as above, except that the layer was formed to a thickness of 60 nm. The characteristics of the fabricated organic EL device were measured in the air at room temperature.

[0142] For comparison, an organic EL device was fabricated under the same conditions as in Example 16, except that the comparative compound (2-1) having the above structural formula was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (123) in Example 1. The characteristics of the fabricated organic EL device were measured in air at room temperature.

[0143] The organic EL elements fabricated in Examples 16 to 27 and Comparative Examples 1 and 2 were used to measure the voltage, luminance, luminous efficiency, power efficiency, and element lifespan. The results are summarized in Table 4. The voltage, luminance, luminous efficiency, and power efficiency were measured at 10 mA / cm ２ The device life was measured by driving it at a constant current of 10 mA / cm. ２ The device was driven at a constant current of 100 Hz, and the time required for the initial luminance to decay to 95% of the initial luminance was measured.

[0144]

[0145] As shown in Table 4, the current density was 10 mA / cm ２ The driving voltage at 1000 kJ / s was almost the same for the elements of Comparative Examples 1 and 2 and the elements of Examples 16 to 27, whereas the luminance, luminous efficiency, power efficiency, and lifespan of the elements of Examples 16 to 27 were clearly improved compared to the elements of Comparative Examples 1 and 2. This indicates that the light extraction efficiency can be significantly improved by including in the capping layer a material having a high refractive index that is preferably used in the organic EL element of the present invention.

[0146] The amine compound having an azabenzoazole ring structure represented by general formula (a-1) of the present invention has a high absorption coefficient, a high refractive index, can significantly improve light extraction efficiency, and is stable in a thin film state, making it an excellent compound suitable for use in organic EL devices. By producing an organic EL device using this compound, high efficiency can be achieved, and durability and light resistance can be improved because the compound does not absorb sunlight and affect the materials inside the device. Furthermore, by using this compound that does not absorb light in the blue, green, and red wavelength regions, it is particularly suitable for displaying clear, bright images with good color purity. For example, this compound can be used in applications such as home appliances and lighting.

[0147] REFERENCE SIGNS LIST 1 Glass substrate 2 Transparent anode 3 Hole injection layer 4 Hole transport layer 5 Light-emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 9 Capping layer

Claims

1. An amine compound having an azabenzoxazole ring structure represented by the following general formula (a-1): 【Chemistry 1】 In the formula, A, B and C may be the same or different and each represent a group represented by the following general formula (b-4), a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, with the proviso that at least one of A, B and C is a group represented by the following general formula (b-4): L １ , L ２ and L ３ may be the same or different and each represent 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 condensed polycyclic aromatic group. 【Chemistry 2】 In the formula, R may be the same or different from each other, and L in the general formula (a-1) １ , L ２ Or L ３ a hydrogen atom, a deuterium atom, a chlorine atom, a cyano group, a nitro group, a trimethylsilyl group, a triphenylsilyl group, a linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 10 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent, a linear or branched alkyloxy group having 1 to 6 carbon atoms which may have a substituent, a cycloalkyloxy group having 5 to 10 carbon atoms which may have a substituent, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, and one R represents L in the general formula (a-1) １ , L ２ Or L ３ represents the binding site with

2. Among A, B and C in the general formula (a-1), the group other than the group represented by the general formula (b-4) is a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthrenyl group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted benzofuranyl group, a substituted or unsubstituted benzothiophenyl group, a substituted or unsubstituted indolyl group, a substituted or unsubstituted benzimidazolyl group, a substituted or unsubstituted imidazopyridyl group, a substituted or unsubstituted benzoxazolyl group, a substituted or unsubstituted benzothiazolyl group, a substituted or unsubstituted dibenzofuranyl group, or a substituted or unsubstituted dibenzothiophenyl group. The amine compound having an azabenzoxazole ring structure according to claim 1.

3. In the general formula (a-1), L １ , L ２ and L ３ is a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted biphenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted dibenzofuranylene group, or a substituted or unsubstituted dibenzothiophenylene group.

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

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

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

7. 7. An organic EL device 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 this order, wherein the capping layer contains the amine compound having an azabenzoxazole ring structure according to claim 1.

8. The extinction coefficient of the capping layer is 0.2 or more in the wavelength range of 400 nm to 410 nm, and the concentration is 10 －５ 8. The organic electroluminescence device according to claim 7, wherein the absorbance in a mol / L absorption spectrum is 0.2 or more in the wavelength range of 400 nm to 410 nm.

9. 8. The organic electroluminescence device according to claim 7, wherein the capping layer has a refractive index of 1.85 or more in the wavelength range of 450 nm to 750 nm.

10. 8. The organic EL device according to claim 7, wherein the capping layer is a mixed layer containing two or more compounds including the amine compound having an azabenzoxazole ring structure, or a laminate of layers containing each of the two or more compounds alone.

11. 7. An electronic device having a pair of electrodes and an organic layer sandwiched between them, the organic layer comprising the amine compound having an azabenzoxazole ring structure according to claim 1.

12. An electronic device using the electronic element according to claim 11.

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