organic electroluminescence element

Abstract

[Problem] In order to absorb sunlight having a wavelength of 400-410 nm and improve light extraction efficiency without affecting the materials in the interior of an element, the present invention provides an organic electroluminescence element equipped with a capping layer formed from a material that has a high light absorption coefficient at wavelengths of 400-410 nm, a high refractive index, suitable thin film stability, and excellent durability and light resistance and that does not absorb light in any of the red, green, and yellow wavelength ranges. [Solution] An arylamine-based material having a specific structure in the present invention has excellent thin film stability and durability, so a material having high absorbance at wavelengths of 400-410 nm in the absorption spectrum for a concentration of 10-5 mol / L of an amine compound having a specific benzazole ring structure and a high refractive index is selected and used as a material for forming a capping layer in an organic electroluminescence element in order to obtain an organic electroluminescence element exhibiting suitable element characteristics.

Description

[Technical Field]

[0001] The present invention relates to a compound and an element suitable for an organic electroluminescence element (hereinafter abbreviated as organic EL element), which is a self-luminous element suitable for various display devices, and more particularly to an amine compound having a benzoazole ring structure and an organic EL element using the compound. [Background technology]

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

[0003] In 1987, C.W. Tang and his colleagues at 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 that can transport electrons and an organic material that can transport holes, and by injecting both charges into the phosphor layer to emit light, they achieved a brightness of 1000 cd / m at a voltage of 10 V or less. 2 Such high brightness has become possible (see, for example, Patent Documents 1 and 2).

[0004] To date, many improvements have been made to the practical application of organic EL elements, and the various roles of the laminated structure have been further subdivided. In electroluminescent elements in which an anode, a hole injection layer, a hole transport layer, an emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially provided on a substrate, high efficiency and durability have been achieved by 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 of being able to extract light from the top and not be obstructed by the pixel circuit, allowing for a larger light-emitting section. Light-emitting devices with a top-emission structure use semi-transparent electrodes such as LiF / Al / Ag (see, for example, Non-Patent Document 2), Ca / Mg (see, for example, Non-Patent Document 3), or LiF / MgAg as the cathode.

[0006] In such light-emitting devices, when light emitted from the light-emitting layer is incident on another film at an angle greater than a certain level, it 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 top-emission light-emitting devices is Ir(ppy) In a light-emitting device using 3 as the light-emitting material, the current efficiency was 38 cd / A when there was no capping layer, whereas in a light-emitting device using a 60 nm thick ZnSe capping layer, the efficiency improved by approximately 1.7 times to 64 cd / A. It has also been shown that the maximum points of transmittance of the semi-transparent electrode and capping layer do not necessarily coincide with the maximum points of efficiency, and that the maximum point of light extraction efficiency is determined by the interference effect (see, for example, Non-Patent Document 3).

[0008] Conventionally, the use of high-resolution metal masks has been proposed for forming capping layers, but there is a problem in that the metal masks can become distorted by heat when used under high-temperature conditions, resulting in reduced alignment accuracy. ZnSe has a high melting point of 1100°C or higher (see, for example, Non-Patent Document 3), making it impossible to deposit it in the correct position using a high-resolution metal mask, which may affect the light-emitting element itself. Furthermore, even when film formation is performed using the sputtering method, the light-emitting element is affected, so capping layers made of inorganic constituent materials are not suitable for use.

[0009] In addition, when tris(8-hydroxyquinoline)aluminum (hereinafter abbreviated as Alq3) is used as a capping layer to adjust the refractive index (see, for example, Non-Patent Document 2), Alq3 is known as an organic EL material that is generally used as a green emitting material or electron transport material, but because it has weak absorption in the vicinity of 450 nm, which is used as a blue emitting material, there are problems with blue light emitting devices in that it reduces color purity and light extraction efficiency.

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

[0011] To improve the device characteristics of organic EL devices, particularly those that can absorb sunlight with wavelengths of 400 to 410 nm without affecting the materials inside the device, and to significantly improve light extraction efficiency, materials with high absorption coefficients, high refractive indices, and excellent thin-film stability and durability are required as capping layer materials. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 8-048656 [Patent Document 2] Patent No. 3194657 [Patent Document 3] International Publication No. 2014 / 009310 [Patent Document 4] International Publication No. 2013 / 038627 [Non-patent literature]

[0013] [Non-Patent Document 1] Proceedings of the 9th Seminar of the Japan Society of Applied Physics, pp. 55-61 (2001) [Non-patent document 2] Appl.Phys.Lett.,78,544(2001) [Non-patent document 3] Appl.Phys.Lett.,82,466(2003) [Non-patent document 4] J. Org. Chem., 71, 1802 (2006) [Non-Patent Document 5] J. Org. Chcm., 60, 7508 (1995) [Non-patent document 6] Synth.Commun.,11,513(1981) [Non-Patent Document 7] Appl.Phys.Lett.,98,083302(2011) Summary of the Invention [Problem to be solved by the invention]

[0014] The object of the present invention is to provide an organic EL element having a capping layer made of a material that (1) has a high absorption coefficient for light with wavelengths of 400 nm to 410 nm, (2) a high refractive index, (3) good thin film stability, (4) excellent durability, (5) excellent light resistance, and (6) does not absorb light in the blue, green, and red wavelength regions, in order to improve the element characteristics of the organic EL element, particularly to prevent the absorption of sunlight light with wavelengths of 400 nm to 410 nm from affecting the materials inside the element, and to significantly improve the light extraction efficiency.

[0015] The physical properties of the capping layer material suitable for the present invention are: (1) a high absorption coefficient for light with a wavelength of 400 nm to 410 nm; (2) a high refractive index; (3) the ability to be vapor-deposited; (4) a stable thin film; and (5) a high glass transition temperature. 、 The physical properties of the organic EL device of the present invention include: (1) absorption of light having 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) long life. 、 can be given. [Means for solving the problem]

[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 an amine compound having a specific benzoazole ring structure with a high refractive index. twist, concentration 10 -5 Materials with high absorbance in the wavelength range of 400 nm to 410 nm in the absorption spectrum of 1 mol / L were selected, and organic EL devices were fabricated using these 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, according to the present invention, the following organic EL device is provided.

[0018] 1) An organic EL device having at least an anode electrode, a hole transport layer, an emitting layer, an electron transport layer, a cathode electrode, and a capping layer in this order, wherein the capping layer has a refractive index of 1.90 or more in the wavelength range of 500 nm to 570 nm, and contains an amine compound having a benzoazole ring structure represented by the following general formula (1):

[0019] [ka] (1) (wherein R1 to R3 may be the same or different and are each a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms, an optionally substituted cycloalkyl group of 5 to 10 carbon atoms, an optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms, an optionally substituted linear or branched alkyloxy group of 1 to 6 carbon atoms, an optionally substituted cycloalkyloxy group of 5 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or un ... or an unsubstituted fused polycyclic aromatic group, or a substituted or unsubstituted aryloxy group, and when a plurality of these groups are bonded to the same benzene ring, they may be bonded to each other to form a ring, or each group may be bonded to the benzene ring to form a ring. X, Y, and Z may be the same or different and represent an oxygen atom or a sulfur atom, Ar1 to Ar3 may be the same or different and represent a substituted or unsubstituted aromatic hydrocarbon divalent group, a substituted or unsubstituted aromatic heterocyclic divalent group, or a substituted or unsubstituted fused polycyclic aromatic divalent group, r1 to r3 may be the same or different and represent an integer of 0 to 4.

[0020] 2) The organic EL device according to 1) above, wherein the amine compound having a benzazole ring structure is represented by the following general formula (1a):

[0021] [ka] (1a) (In the formula, R1 to R3, X, Y, Z, and r1 to r3 are as defined in the general formula (1) above.)

[0022] 3) The organic EL device according to 1) or 2) above, wherein all of r1 to r3 are 0 in the general formula (1) or general formula (1a).

[0023] 4) The organic EL device according to the above 1), wherein the thickness of the capping layer is within the range of 30 nm to 120 nm.

[0024] 5) The organic EL device according to 1) or 2) above, wherein in the general formula (1) or (1a), all of X, Y, and Z are oxygen atoms.

[0025] 6) The organic EL device according to 1) or 2) above, wherein in the general formula (1) or (1a), any two of X, Y, and Z are oxygen atoms.

[0026] 7) The organic EL device according to 1) or 2) above, wherein in the general formula (1) or (1a), any one of X, Y, and Z is an oxygen atom.

[0027] 8) The organic EL device according to 1) or 2) above, wherein in the general formula (1) or (1a), all of X, Y, and Z are sulfur atoms.

[0028] 9) The organic EL device according to 1) above, wherein in the general formula (1), all of Ar1, Ar2, and Ar3 are divalent groups of substituted or unsubstituted aromatic hydrocarbons.

[0029] 10) The organic EL device according to 1) above, wherein in the general formula (1), any two of Ar1, Ar2, and Ar3 are divalent groups of substituted or unsubstituted aromatic hydrocarbons.

[0030] 11) The organic EL device according to 1) above, wherein in the general formula (1), any one of Ar1, Ar2, and Ar3 is a divalent group of a substituted or unsubstituted aromatic hydrocarbon.

[0031] 12) The organic EL device according to 1) above, wherein in the general formula (1), all of Ar1, Ar2, and Ar3 are divalent groups of a substituted or unsubstituted aromatic heterocycle.

[0032] 13) The organic EL device according to 1) above, wherein in the general formula (1), all of Ar1, Ar2, and Ar3 are substituted or unsubstituted fused polycyclic aromatic divalent groups.

[0033] 14) A method of using an amine compound having a refractive index of 1.90 or more in the wavelength range of 500 nm to 570 nm and having a benzoazole ring structure represented by the following general formula (1) or general formula (1a) in a capping layer of an organic EL device.

[0034] [ka] (1) (wherein R1 to R3 may be the same or different and are each a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms, an optionally substituted cycloalkyl group of 5 to 10 carbon atoms, an optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms, an optionally substituted linear or branched alkyloxy group of 1 to 6 carbon atoms, an optionally substituted cycloalkyloxy group of 5 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or un ... or an unsubstituted fused polycyclic aromatic group, or a substituted or unsubstituted aryloxy group, and when a plurality of these groups are bonded to the same benzene ring, they may be bonded to each other to form a ring, or each group may be bonded to the benzene ring to form a ring. X, Y, and Z may be the same or different and represent an oxygen atom or a sulfur atom, Ar1 to Ar3 may be the same or different and represent a substituted or unsubstituted aromatic hydrocarbon divalent group, a substituted or unsubstituted aromatic heterocyclic divalent group, or a substituted or unsubstituted fused polycyclic aromatic divalent group, r1 to r3 may be the same or different and represent an integer of 0 to 4.

[0035] [ka] (1a) (In the formula, R1 to R3, X, Y, Z, and r1 to r3 are as defined in the general formula (1) above.)

[0036] Specific examples of the "aromatic hydrocarbon group", "aromatic heterocyclic group" or "condensed polycyclic aromatic group" in the "substituted or unsubstituted aromatic hydrocarbon group", "substituted or unsubstituted aromatic heterocyclic group" or "substituted or unsubstituted condensed polycyclic aromatic group" represented by R1 to R3 in general formula (1) or (1a) include 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 pyrid ... The alkyl group is selected from a dialkyl group, a pyrimidinyl group, a triazinyl 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, 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, 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. Furthermore, when a plurality of these groups are bonded to the same benzene ring, they 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, or each group may be bonded to the benzene ring to which it is bonded via a single bond, a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom to form a ring.

[0037] "C1 to C6 linear or branched alkyl group", "C5 to C cycloalkyl group", "C2 to C linear or branched alkenyl group" in "C1 to C6 linear or branched alkyl group which may have substituents", "C5 to C cycloalkyl group which may have substituents", "C2 to C linear or branched alkenyl group which may have substituents", "C1 to C linear or branched alkyloxy group which may have substituents", "C5 to C cycloalkyloxy group which may have substituents", or "substituted or unsubstituted aryloxy group" represented by R1 to R3 in general formula (1) or (1a) Specific examples of the "alkyloxy group," "linear or branched alkyloxy group having 1 to 6 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. Furthermore, when a plurality of these groups are bonded to the same benzene ring, they 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, or each group may be bonded to the benzene ring to which it is bonded via a single bond, a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom to form a ring.

[0038] Examples of the "substituent" in the "substituted aromatic hydrocarbon group," "substituted aromatic heterocyclic group," "substituted fused polycyclic aromatic group," "substituted C 1 to C 6 linear or branched alkyl group," "substituted C 5 to C cycloalkyl group," "substituted C 2 to C 6 linear or branched alkenyl group," "substituted C 1 to C 6 linear or branched alkyloxy group," "substituted C 5 to C cycloalkyloxy group," or "substituted aryloxy group" represented by R1 to R3 in general formula (1) or (1a) specifically include a deuterium atom, a cyano group, a nitro group; a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a silyl group such as a trimethylsilyl group or a triphenylsilyl group; a C 1 to C linear or branched alkyl group such as a methyl group, an ethyl group, or a propyl group; a methyloxy group, an ethyl ... linear or branched alkyloxy groups having 1 to 6 carbon atoms, such as oxy and propyloxy; alkenyl groups, such as vinyl and allyl; aryloxy groups, such as phenyloxy and tolyloxy; arylalkyloxy groups, such as benzyloxy and phenethyloxy; phenyl, biphenylyl, terphenylyl, naphthyl, anthracenyl, phenanthrenyl, fluorenyl, spirobifluorenyl, indenyl, Aromatic hydrocarbon groups or condensed polycyclic aromatic groups such as pyrenyl, perylenyl, fluoranthenyl, and triphenylenyl groups; pyridyl, thienyl, furyl, pyrrolyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, and carbolinyl groups; Aromatic heterocyclic groups Other examples include an aryl group having 6 to 30 carbon atoms and a heteroaryl group having 2 to 20 carbon atoms, and these substituents may be further substituted with the substituents exemplified above. These substituents may also 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.

[0039] In the "substituted or unsubstituted aromatic hydrocarbon divalent group," "substituted or unsubstituted aromatic heterocyclic group," or "substituted or unsubstituted fused polycyclic aromatic divalent group" represented by Ar1 to Ar3 in the general formula (1), the "aromatic hydrocarbon," "aromatic heterocyclic ring," or "fused polycyclic aromatic" in the "substituted or unsubstituted aromatic hydrocarbon," "substituted or unsubstituted aromatic heterocyclic ring," or "substituted or unsubstituted fused polycyclic aromatic" specifically includes benzene, biphenyl, terphenyl, tetrakisphenyl, styrene, styrene-2-phenyl ... Examples of the aromatic hydrocarbon include phenylene, naphthalene, anthracene, acenaphthalene, fluorene, phenanthrene, indane, pyrene, triphenylene, pyridine, pyrimidine, triazine, pyrrole, furan, thiophene, quinoline, isoquinoline, benzofuran, benzothiophene, indoline, carbazole, carboline, benzoxazole, benzothiazole, quinoxaline, benzimidazole, pyrazole, dibenzofuran, dibenzothiophene, naphthyridine, phenanthroline, and acridine.

[0040] The "divalent group of a substituted or unsubstituted aromatic hydrocarbon," "divalent group of a substituted or unsubstituted aromatic heterocycle," or "divalent group of a substituted or unsubstituted condensed polycyclic aromatic ring" represented by Ar1 to Ar3 in general formula (1) "Divalent aromatic hydrocarbon radical," "divalent aromatic heterocyclic radical," or "divalent condensed polycyclic aromatic radical" inrepresents a divalent group obtained by removing two hydrogen atoms from the above-mentioned "aromatic hydrocarbon," "aromatic heterocycle," or "fused polycyclic aromatic." These divalent groups may have a substituent, and examples of the substituent include the "substituted aromatic hydrocarbon group," "substituted aromatic heterocyclic group," "substituted fused polycyclic aromatic group," "substituted C linear or branched alkyl group," "substituted C cycloalkyl group," "substituted C linear or branched alkenyl group," "substituted C linear or branched alkyloxy group," "substituted C cycloalkyloxy group," or "substituted aryloxy group," which are represented by R1 to R3 in general formula (1) or (1a), and these substituents 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.

[0041] In general formula (1) or (1a), r1 to r3 may be the same or different and represent an integer of 0 to 4, preferably 0 to 2, and more preferably 0 or 1. It is further preferable that all of r1 to r3 are 0 (i.e., unsubstituted). In general formula (1) or (1a), X, Y, and Z may be the same or different and represent an oxygen atom or a sulfur atom, and it is preferable that at least one of X, Y, and Z is a sulfur atom. In general formula (1), Ar1 to Ar3 are preferably divalent groups of substituted or unsubstituted aromatic hydrocarbons, more preferably divalent groups (phenylene groups) obtained by removing two hydrogen atoms from substituted or unsubstituted benzene, and even more preferably divalent groups (phenylene groups) obtained by removing two hydrogen atoms from substituted or unsubstituted benzene.

[0042] In the organic EL device of the present invention, the thickness of the capping layer is in the range of 30 nm to 120 nm. InsidePreferably, the thickness is in the range of 40 nm to 80 nm. Inside It is more preferable that:

[0043] In the organic EL device of the present invention, the wavelength of light transmitted through the capping layer is in the range of 500 nm to 570 nm. Within In this case, the refractive index of the capping layer is preferably 1.90 or more, and more preferably 2.00 or more.

[0044] In the organic EL device of the present invention, the capping layer may be formed by laminating or mixing two or more different constituent materials. [Effects of the Invention]

[0045] The organic EL element of the present invention has a capping layer provided on the outside of the transparent or semitransparent electrode, which has a higher refractive index than the semitransparent electrode, thereby making it possible to obtain an organic EL element capable of significantly improving light extraction efficiency. Furthermore, by using an amine compound having a benzoazole ring structure represented by the general formula (1) or (1a) for the capping layer, the film can be formed at a temperature of 400°C or less, without damaging the light-emitting element, and the light extraction efficiency of each color can be optimized using a high-resolution mask. In addition, the organic EL element can be suitably applied to a full-color display, and has high color purity. often It is now possible to display clear and bright images.

[0046] The organic EL device of the present invention uses a capping layer material that has a high absorption coefficient for light with a wavelength of 400 nm to 410 nm, a high refractive index, and excellent thin film stability, durability, and light resistance, making it less susceptible to sunlight, maintains color purity, and significantly improves light extraction efficiency compared to conventional organic EL devices.Furthermore, it has become possible to realize a highly efficient, long-life organic EL device. [Brief explanation of the drawings]

[0047] [Figure 1]FIG. 1 shows structures of compounds (1-1) to (1-12) as amine compounds having a benzazole ring structure represented by general formula (1). [Figure 2] FIG. 1 shows structures of compounds (1-13) to (1-24) as amine compounds having a benzazole ring structure represented by general formula (1). [Figure 3] FIG. 1 shows structures of compounds (1-25) to (1-36) as amine compounds having a benzazole ring structure represented by general formula (1). [Figure 4] FIG. 1 shows structures of compounds (1-37) to (1-48) as amine compounds having a benzazole ring structure represented by general formula (1). [Figure 5] FIG. 1 shows structures of compounds (1-49) to (1-60) as amine compounds having a benzazole ring structure represented by general formula (1). [Figure 6] FIG. 1 shows structures of compounds (1-61) to (1-72) as amine compounds having a benzazole ring structure represented by general formula (1). [Figure 7] FIG. 1 shows the structures of compounds (1-73) to (1-84), which are amine compounds having a benzazole ring structure represented by general formula (1). [Figure 8] FIG. 1 shows the structures of compounds (1-85) to (1-96), which are amine compounds having a benzazole ring structure represented by general formula (1). [Figure 9] FIG. 1 shows the structures of compounds (1-97) to (1-106), which are amine compounds having a benzazole ring structure represented by general formula (1). [Figure 10] FIG. 1 shows the structures of compounds (1-107) to (1-120), which are amine compounds having a benzazole ring structure represented by general formula (1). [Figure 11] FIG. 1 shows the structures of compounds (1-121) to (1-132), which are amine compounds having a benzazole ring structure represented by general formula (1). [Figure 12]FIG. 1 shows the structures of compounds (1-133) to (1-140), which are amine compounds having a benzazole ring structure represented by general formula (1). [Figure 13] FIG. 1 is a diagram showing the configurations of the organic EL devices of Examples 7 to 9 and Comparative Examples 1 to 4. DETAILED DESCRIPTION OF THE INVENTION

[0048] The amine compounds of the present invention having a benzazole ring structure represented by the general formula (1) or (1a) are novel compounds, and the benzazole derivatives that form the main skeleton of these compounds can be synthesized by known methods, for example, as follows (see, for example, Non-Patent Document 4): Furthermore, the amine compounds of the present invention having a benzazole ring structure represented by the general formula (1) or (1a) can be synthesized by subjecting the synthesized halogenated benzazole derivative and an arylamine to a coupling reaction using a copper catalyst, a palladium catalyst, or the like. In addition, the amine compound having a benzazole ring structure represented by the general formula (1) or (1a) of the present invention can be similarly synthesized by converting a halogenated benzazole derivative into a boronic acid derivative or a boronic acid ester derivative and then carrying out a coupling reaction with a halogenated arylamine (see, for example, Non-Patent Documents 5 and 6). TIFF0007794640000005.tif56166

[0049] Among the amine compounds having a benzoazole ring structure represented by the general formula (1) or (1a) that are suitably used in the organic EL device of the present invention, specific examples of preferred compounds are shown in Figures 1 to 12, but the present invention is not limited to these compounds.

[0050] The amine compounds having a benzoazole ring structure represented by general formula (1) or (1a) and suitable for use in the organic EL device of the present invention were purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, and finally by sublimation purification. The compounds were identified by NMR analysis. The melting point, glass transition point (Tg), refractive index, extinction coefficient, and absorbance were measured as physical properties. The melting point is an index of vapor deposition properties, the glass transition point (Tg) is an index of the stability of the thin film state, the refractive index and extinction coefficient are indexes related to the improvement of light extraction efficiency, and the absorbance is an index related to the improvement of color purity and light extraction efficiency.

[0051] The melting point and glass transition temperature (Tg) were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS) using powder.

[0052] The refractive index and extinction coefficient were measured by forming an 80 nm thin film on a silicon substrate and using a spectrophotometer (F10-RT-UV, manufactured by Filmetrics).

[0053] The absorbance is measured at a concentration of 1.0 x 10 in toluene solution. -5 mol / L, and the extinction coefficient is 5.0 × 10 in toluene solution. -6 mol / L, 1.0 x 10 -5 mol / L, 1.5 x 10 -5 mol / L, and 2.0 × 10 -5 The solutions were prepared at four different concentrations (mol / L) and measured using an ultraviolet-visible-near infrared spectrophotometer (JASCO Corporation, V-650).

[0054] The organic EL device of the present invention may have a top-emission structure, for example, consisting of an anode, a hole-transport layer, an emitting layer, an electron-transport layer, a cathode, and a capping layer, arranged in this order on a glass substrate. It may also have a hole-injection layer between the anode and the hole-transport layer, an electron-blocking layer between the hole-transport layer and the emitting layer, a hole-blocking layer between the emitting layer and the electron-transport layer, or an electron-injection layer between the electron-transport layer and the cathode. In these multilayer structures, some organic layers may be omitted or may serve as both layers. For example, a layer may serve as both a hole-injection layer and a hole-transport layer, a layer may serve as both a hole-transport layer and an electron-blocking layer, a layer may serve as both a hole-blocking layer and an electron-transport layer, or a layer may serve as both an electron-transport layer and an electron-injection layer. It may also have a structure in which two or more organic layers having the same function are stacked, such as a layer with two hole-transport layers, a layer with two emitting layers, a layer with two electron-transport layers, or a layer with two capping layers.

[0055] The total thickness of each layer 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 each layer of the organic EL element other than the capping layer, and the like.

[0056] For the anode of the organic EL device of the present invention, an electrode material with a large work function such as ITO or gold is used.

[0057] The hole injection layer of the organic EL device of the present invention is a compound having a triphenylamine structure in the molecule. 2 an arylamine compound having a structure in which at least two aryl groups are linked by a single bond or a divalent group not containing a hetero atom, for example, arylamine compounds, such as benzidine derivatives, having a structure in which two triphenylamine structures are linked by a single bond or a divalent group that does not contain a heteroatom in the molecule; Materials such as starburst-type triphenylamine derivatives and various triphenylamine tetramers Also,Porphyrin compounds such as copper phthalocyanine, heterocyclic compounds with acceptor properties such as hexacyanoazatriphenylene, and polymeric coating materials can be used. These materials may be formed into films alone, or may be mixed with other materials to form a single layer, or may be laminated layers formed alone, mixed layers, or layers formed alone and mixed with each other. These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0058] 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 (TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (NPD), and N,N,N',N'-tetrabiphenylylbenzidine; arylamine compounds having a structure in which two triphenylamine structures are linked in the molecule by a single bond or a divalent group not containing a hetero atom, such as 1,1-bis[4-di(4-tolylamino)phenyl]cyclohexane (TAPC); or arylamine compounds with only one triphenylamine structure in the molecule It is also preferable to use an arylamine compound having a structure in which three or more triphenylamine structures are linked in the molecule by a single bond or a divalent group not containing a hetero atom, such as various triphenylamine trimers or tetramers. These may be used alone to form a film, or may be mixed with other materials to form a single layer. often Alternatively, the layer may be a laminate structure of layers formed independently, layers formed by mixing layers, or layers formed by mixing layers formed independently. Furthermore, a coating-type polymer material such as poly(3,4-ethylenedioxythiophene) (PEDOT) / poly(styrene sulfonate) (PSS) can be used as the hole injection / transport layer. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0059] In addition, in the hole injection layer or hole transport layer, the material usually used for the layer is further doped with P, such as trisbromophenylamine hexachloroantimony, radialene derivatives (see, for example, Patent Document 3). is preferable. A polymer compound having a structure of a benzidine derivative such as TPD in its partial structure can be used.

[0060] 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 (TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (mCP), and 2,2-bis(4-carbazol-9-ylphenyl)adamantane (Ad-Cz); and compounds having a triphenylsilyl group and a triarylamine structure, such as 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene. These compounds may be formed into a film alone or may be mixed with other materials to form a single layer. often The material may be a laminate of layers formed independently, layers formed by mixing, or layers formed by mixing layers formed independently. These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and ink jet printing.

[0061] The light-emitting layer of the organic EL device of the present invention can be formed using metal complexes of quinolinol derivatives such as Alq3, as well as various metal complexes, anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, poly(paraphenylenevinylene) derivatives, etc. The light-emitting layer can also be formed using a host material and a dopant material. Anthracene derivatives are preferred as the host material, but other materials that can be used include various metal complexes, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, poly(paraphenylenevinylene) derivatives, 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. Quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives can also be used as the dopant material, with green light-emitting materials being particularly preferred. These may be formed alone, or may be mixed with other materials to form a single layer, or may be stacked with layers formed alone, layers formed as a mixture, or layers formed as a mixture with a layer formed alone.

[0062] Phosphorescent materials can also be used as light-emitting materials. preferablePhosphorescent emitters include metal complexes of iridium and platinum. Green phosphorescent emitters such as Ir(ppy)3, blue phosphorescent emitters such as FIrpic and FIr6, and red phosphorescent emitters such as Btp2Ir(acac) are commonly used, with green phosphorescent emitters being particularly preferred. Hole-injecting and transporting host materials include carbazole derivatives such as 4,4'-di(N-carbazolyl)biphenyl (CBP), TCTA, and mCP. Electron-transporting host materials include p-bis(triphenylsilyl)benzene (UGH2) and 2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBI), enabling the fabrication of high-performance organic EL devices.

[0063] 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.

[0064] It is also possible to use materials that emit delayed fluorescence, such as CDCB derivatives such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN, as light-emitting materials. Ru( For example, see Non-Patent Document 7. 。 These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and ink jet printing.

[0065] 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 (BCP), metal complexes of quinolinol derivatives such as aluminum (III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (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 as a single layer formed by mixing with other materials. oftenThe material may be a laminate of layers formed independently, layers formed by mixing, or layers formed by mixing layers formed independently. These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and ink jet printing.

[0066] For the electron transport layer of the organic EL device of the present invention, metal complexes of quinolinol derivatives such as Alq3 and BAlq, as well as various 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 may be formed into a film alone, or may be mixed with other materials to form a film as a single layer. often The material may be a laminate of layers formed independently, layers formed by mixing, or layers formed by mixing layers formed independently. These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and ink jet printing.

[0067] 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, in the preferred selection of the electron transport layer and the cathode, this can be omitted.

[0068] Furthermore, in the electron injection layer or electron transport layer, a material that is further doped with N-doping of a metal such as cesium can be used in addition to the materials that are normally used in the layer.

[0069] For 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.

[0070] The capping layer of the organic EL device of the present invention preferably uses an amine compound having a benzoazole ring structure represented by the general formula (1) or (1a). These compounds may be formed into a film alone, or may be mixed with different materials to form a single layer, or may be laminated with layers formed alone, layers formed as a mixture, or layers formed as 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.

[0071] 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.

[0072] 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, but 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. A refractive index of 1.90 or higher is sufficient, and 2.00 or higher is more preferable.

[0073] 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. [Example]

[0074] <Synthesis of Exemplary Compound (1-1)> A reaction vessel was charged with bis[4-(benzoxazol-2-yl )centre 12.3 g of phenylamine, 9.2 g of 2-(4-bromophenyl)benzoxazole, 4.4 g of sodium tert-butoxide, and 130 ml of toluene were added, and the mixture was irradiated with ultrasound for 30 minutes while passing nitrogen gas through it. Ri( 0.3 g of a 50% (w / v) toluene solution of tert-butylphosphine was added and stirred overnight under reflux. After cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered off, and the resulting filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent, and the precipitated solid was collected to obtain 10.0 g (yield 54.9%) of yellow powder of exemplary compound (1-1).

[0075] [ka] (1-1)

[0076] The structure of the resulting yellow powder was identified using NMR. 1 The following 24 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.25-8.21(6H), 7.82-7.76(3H), 7.63-7.57(3H), 7.41-7.32(12H). [Example]

[0077] <Synthesis of Exemplary Compound (1-2)> A reaction vessel was charged with bis[4-(benzoxazol-2-yl )centre 12.3 g of phenylamine, 9.7 g of 2-(4-bromophenyl)benzothiazole, 4.4 g of sodium tert-butoxide, and 130 ml of toluene were added, and the mixture was irradiated with ultrasound for 30 minutes while passing nitrogen gas through it. Ri( 0.3 g of a 50% (w / v) toluene solution of tert-butylphosphine was added and stirred overnight under reflux. After cooling, the mixture was dispersed and washed at 80°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent, and the precipitated solid was collected to obtain 14.5 g (77.5% yield) of a yellow powder of exemplary compound (1-2).

[0078] [ka] (1-2)

[0079] The structure of the resulting yellow powder was identified using NMR. 1 The following 24 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.24-8.21(4H), 8.09-8.06(3H), 7.92-7.89(1H), 7.80-7.77(2H), 7.60-7.58(2H), 7.51(1H), 7.41-7.29(11H). [Example]

[0080] <Synthesis of exemplary compound (1-4)> A reaction vessel was charged with 6.0 g of 2-(4-aminophenyl)benzothiazole, 16.2 g of 2-(4-bromophenyl)benzothiazole, 7.6 g of sodium tert-butoxide, and 150 ml of toluene, and the mixture was irradiated with ultrasound for 30 minutes while passing nitrogen gas through it. Ri( 0.2 g of a 50% (w / v) toluene solution of tert-butylphosphine was added and stirred overnight under reflux. After cooling, the mixture was dispersed and washed at 80°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent, and the precipitated solid was collected to obtain 10.2 g (yield 59.6%) of yellow powder of exemplary compound (1-4).

[0081] [ka] (1-4)

[0082] The structure of the resulting yellow powder was identified using NMR. 1 The following 24 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.10-8.05(9H), 7.92-7.90(3H), 7.54-7.48(3H), 7.42-7.37(3H), 7.31-7.27(6H). [Example]

[0083] The melting point and glass transition temperature (Tg) of the amine compound having a benzoazole ring structure represented by general formula (1) or (1a) were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS). Melting point Glass transition point (Tg) Compound of Example 1 277°C 126°C Compound of Example 2 274°C 123°C Compound of Example 3 270°C 119°C

[0084] The amine compounds having a benzazole ring structure represented by general formula (1) or (1a) have a glass transition point of 100° C. or higher, which indicates that they are stable in the thin film state. [Example]

[0085] An amine compound having a benzoazole ring structure represented by general formula (1) or (1a) was used to form an 80 nm thick vapor-deposited film on a silicon substrate, and the refractive index n at wavelengths of 400 nm, 410 nm, 500 nm, and 570 nm and the 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 made on comparative compounds (2-1), (2-2), (2-3), and (2-4) with the following structural formulas (see, for example, Patent Document 4). The measurement results are summarized in Table 1.

[0086] [ka] (2-1)

[0087] [ka] (2-2)

[0088] [ka] (2-3)

[0089] [ka] (2-4)

[0090] [Table 1]

[0091] Thus, the compounds of the present invention have a refractive index of 1.90 or more in the wavelength range of 500 nm to 570 nm, which is higher than that of the comparative compounds (2-1), (2-2), (2-3), and (2-4), indicating that they are expected to improve the light extraction efficiency in organic EL devices. In addition, the extinction coefficients in the wavelength range of 400 nm to 410 nm of the comparative compounds (2-1), (2-2), (2-3), and (2-4) are less than 0.5, whereas the compounds of the present invention have larger values, indicating that they absorb sunlight with wavelengths of 400 nm to 410 nm well and do not affect the materials inside the device. [Example]

[0092] The compound of the present invention was used in a toluene solution at a concentration of 1.0 × 10 -5 The absorbance at wavelengths of 400 nm and 410 nm was measured using a UV-visible-near-infrared spectrophotometer (JASCO Corporation, V-650). The extinction coefficient was 5.0 × 10 in toluene solution. -6 mol / L, 1.0 x 10 -5 mol / L, 1.5 x 10 -5 mol / L, and 2.0 × 10 -5 The compounds were prepared at four different concentrations (mol / L) and measured using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation, V-650), and the extinction coefficients were calculated from the calibration curve. For comparison, the comparative compounds (2-1), (2-2), (2-3), and (2-4) with the above structural formulas were also measured. The measurement results are summarized in Table 2.

[0093] [Table 2]

[0094] Thus, the absorbance at wavelengths of 400 nm to 410 nm for comparative compounds (2-1), (2-2), (2-3), and (2-4) is less than 0.7, whereas the compounds of the present invention have large values ​​of 0.7 or more, indicating that they absorb sunlight with wavelengths of 400 nm to 410 nm well. Furthermore, the compounds of the present invention also have large absorption coefficients compared to comparative compounds (2-1), (2-2), (2-3), and (2-4), indicating that they absorb light well under the same concentration conditions. For thin films, the thicker the film, the better the absorption, indicating that they are materials with excellent light resistance. [Example]

[0095] As shown in Figure 13, the organic EL device was fabricated by depositing a hole injection layer 3, a first hole transport layer 4, a second hole transport layer 5, an emitting layer 6, an electron transport layer 7, an electron injection layer 8, a cathode 9, and a capping layer 10 in this order on a glass substrate 1 on which a reflective ITO electrode had previously been formed as a metal anode 2.

[0096] Specifically, a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film were sequentially deposited on a glass substrate 1 as a metal anode 2. The substrate was then ultrasonically cleaned in isopropyl alcohol for 20 minutes and dried on a hot plate heated to 250°C for 10 minutes. After 2 minutes of UV ozone treatment, the ITO-coated glass substrate was placed in a vacuum deposition chamber and the pressure was reduced to 0.001 Pa or less. Next, a hole injection layer 3 was formed covering the metal 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 top of this hole injection layer 3, a first hole transport layer 4 was formed of a compound (3-1) of the following structural formula to a thickness of 70 nm. On the first hole transport layer 4, a second hole transport layer 5 was formed using a compound (3-2) of the following structural formula to a thickness of 10 nm. On the second hole transport layer 5, a light-emitting layer 6 was formed using a compound (3-3) of the following structural formula and a compound (3-4) of the following structural formula by binary deposition at a deposition rate ratio of compound (3-3):compound (3-4) = 5:95 to a thickness of 40 nm. On the light-emitting layer 6, a compound (3-5) of the following structural formula and a compound (3-6) of the following structural formula by binary deposition at a deposition rate ratio of compound (3-5):compound (3-6) = 50:50 to a thickness of 30 nm. On the electron transport layer 7, lithium fluoride was formed as an electron injection layer 8 to a thickness of 1 nm. On the electron injection layer 8, a cathode 9 was formed using a magnesium-silver alloy to a thickness of 12 nm. Finally, the compound (1-1) of Example 1 was formed to a thickness of 60 nm as a capping layer 10. The characteristics of the produced organic EL device were measured in the air at room temperature. The light-emitting characteristics of the fabricated organic EL devices were measured by applying a DC voltage, and the results are summarized in Table 3.

[0097] [ka] (Acceptor-1)

[0098] [ka] (3-1)

[0099] [ka] (3-2)

[0100] [ka] (3-3)

[0101] [ka] (3-4)

[0102] [ka] (3-5)

[0103] [ka] (3-6)

[0104] [ka] (1-1) [Example]

[0105] An organic EL device was fabricated under the same conditions as in Example 7, except that the compound (1-2) of Example 2 was used instead of the compound (1-1) of Example 1 as the material for the capping layer 10. The characteristics of the fabricated organic EL device were measured in the air at room temperature. Table 3 shows the results of measuring the light-emitting characteristics when a DC voltage was applied to the fabricated organic EL device.

[0106] [ka] (1-2) [Example]

[0107] An organic EL device was fabricated under the same conditions as in Example 7, except that the compound (1-4) of Example 3 was used instead of the compound (1-1) of Example 1 as the material for the capping layer 10. The characteristics of the fabricated organic EL device were measured in the air at room temperature. Table 3 shows the results of measuring the light-emitting characteristics when a DC voltage was applied to the fabricated organic EL device.

[0108] [ka] (1-4) [Comparative Example 1]

[0109] For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that a comparative compound (2-1) having the following structural formula was used as the material for the capping layer 10 instead of the compound (1-1) in Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature. The light-emitting characteristics of the fabricated organic EL devices were measured by applying a DC voltage, and the results are summarized in Table 3.

[0110] [ka] (2-1) Comparative Example 2

[0111] For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that the compound (1-1) used in Example 1 was replaced with a comparative compound (2-2) having the following structural formula as the material for the capping layer 10. The characteristics of the fabricated organic EL device were measured in the air at room temperature. The light-emitting characteristics of the fabricated organic EL devices were measured by applying a DC voltage, and the results are summarized in Table 3.

[0112] [ka] (2-2) Comparative Example 3

[0113] For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that the compound (1-1) used in Example 1 was replaced with a comparative compound (2-3) having the following structural formula as the material for the capping layer 10. The characteristics of the fabricated organic EL device were measured in the air at room temperature. The light-emitting characteristics of the fabricated organic EL devices were measured by applying a DC voltage, and the results are summarized in Table 3.

[0114] [ka] (2-3) Comparative Example 4

[0115] For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that a comparative compound (2-4) having the following structural formula was used as the material for the capping layer 10 instead of the compound (1-1) in Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature. The light-emitting characteristics of the fabricated organic EL devices were measured by applying a DC voltage, and the results are summarized in Table 3.

[0116] [ka] (2-4)

[0117] The organic EL elements fabricated in Examples 7 to 9 and Comparative Examples 1 to 4 were used to measure the element lifetime, and the results are summarized in Table 3. The element lifetime was 10 mA / cm 2 When the device was driven at a constant current of 100%, the time required for the initial luminance to decay to 95% (95% decay) was measured.

[0118] [Table 3]

[0119] As shown in Table 3, a current density of 10 mA / cm 2 The driving voltage at this time was almost the same for the devices of Comparative Examples 1 to 4 and the devices of Examples 7 to 9, whereas the luminance, luminous efficiency, power efficiency, and device life were improved for the devices of Examples 7 to 9 compared to the devices of Comparative Examples 1 to 4. This indicates that the light extraction efficiency can be significantly improved by including in the capping layer a material with a high refractive index that is preferably used in the organic EL device of the present invention. [Industrial Applicability]

[0120] As described above, the amine compound having a benzoazole ring structure represented by general formula (1), which is suitable for use in the organic EL device of the present invention, has a high absorption coefficient for light with a wavelength of 400 nm to 410 nm, a high refractive index, significantly improved light extraction efficiency, and a stable thin film state, making it an excellent compound for use in organic EL devices. Fabricating an organic EL device using this compound not only achieves high efficiency, but also improves durability and light resistance so as not to absorb sunlight and affect the materials inside the device. Furthermore, using this compound, which does not absorb light in the blue, green, and red wavelength regions, is particularly suitable for displaying clear, bright images with good color purity. For example, this compound can be used in home appliances and lighting applications. [Explanation of symbols]

[0121] 1. Glass substrate 2 metal anode 3. Hole injection layer 4 First hole transport layer 5 Second hole transport layer 6. Light-emitting layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Capping Layer

Claims

1. An organic electroluminescence device comprising at least an anode electrode, a hole injection layer formed by doping a radialene derivative with phosphorus, a first hole transport layer formed of an arylamine compound having a structure in which two triphenylamine structures are linked in the molecule by a single bond or a divalent group not containing a heteroatom, a second hole transport layer formed of an arylamine compound having only one triphenylamine structure in the molecule, a light-emitting layer, an electron transport layer containing a pyrimidine derivative, a cathode electrode, and a capping layer in this order, wherein the capping layer has a refractive index of 1.90 or more in the wavelength range of 500 nm to 570 nm and contains an amine compound having a benzazole ring structure represented by the following general formula (1): 【Chemistry 1】 （１） (In the formula, R １ ~R ３ may be the same or different and represent a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms, an optionally substituted cycloalkyl group of 5 to 10 carbon atoms, an optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms, an optionally substituted linear or branched alkyloxy group of 1 to 6 carbon atoms, an optionally substituted cycloalkyloxy group of 5 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or a substituted or unsubstituted aryloxy group, and when a plurality of these groups are bonded to the same benzene ring, they may be bonded to each other to form a ring, or each group may be bonded to the benzene ring to which it is bonded to form a ring. X, Y, and Z may be the same or different and represent an oxygen atom or a sulfur atom, Ar １ ~Ar ３ may be the same or different and represent a divalent group of a substituted or unsubstituted aromatic hydrocarbon, a divalent group of a substituted or unsubstituted aromatic heterocycle, or a divalent group of a substituted or unsubstituted condensed polycyclic aromatic ring. １ ~r ３ may be the same or different and represent an integer of 0 to 4.

2. 2. The organic electroluminescence device according to claim 1, wherein the amine compound having a benzazole ring structure is represented by the following general formula (1a): 【Chemistry 2】 (1a) (In the formula, R １ ~R ３ , X, Y, Z, r １ ~r ３ is as defined in the general formula (1).

3. In the general formula (1) or general formula (1a), r １ ~r ３ 3. The organic electroluminescence device according to claim 1, wherein all of the following are 0:

4. 2. The organic electroluminescent device according to claim 1, wherein the capping layer has a thickness in the range of 30 nm to 120 nm.

5. A method for using an amine compound having a refractive index of 1.90 or more in the wavelength range of 500 nm to 570 nm and having a benzazole ring structure represented by the following general formula (1) or (1a) in a capping layer of an organic electroluminescence device having, in this order, at least an anode electrode, a hole injection layer formed by doping a radialene derivative with P, a first hole transport layer formed by an arylamine compound having a structure in which two triphenylamine structures in the molecule are linked by a single bond or a divalent group containing no heteroatom, a second hole transport layer formed by an arylamine compound having only one triphenylamine structure in the molecule, a light-emitting layer, an electron transport layer containing a pyrimidine derivative, a cathode electrode, and a capping layer: 【Transformation 3】 （１） (In the formula, R １ ~R ３ may be the same or different and represent a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms, an optionally substituted cycloalkyl group of 5 to 10 carbon atoms, an optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms, an optionally substituted linear or branched alkyloxy group of 1 to 6 carbon atoms, an optionally substituted cycloalkyloxy group of 5 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or a substituted or unsubstituted aryloxy group, and when a plurality of these groups are bonded to the same benzene ring, they may be bonded to each other to form a ring, or each group may be bonded to the benzene ring to which it is bonded to form a ring. X, Y, and Z may be the same or different and represent an oxygen atom or a sulfur atom, Ar １ ~Ar ３ may be the same or different and represent a divalent group of a substituted or unsubstituted aromatic hydrocarbon, a divalent group of a substituted or unsubstituted aromatic heterocycle, or a divalent group of a substituted or unsubstituted condensed polycyclic aromatic ring. １ ~r ３ may be the same or different and represent an integer of 0 to 4. 【Chemistry 4】 (1a) (In the formula, R １ ~R ３ , X, Y, Z, r １ ~r ３ is as defined in the general formula (1).

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