Organic electroluminescent element

Abstract

To provide an organic electroluminescent element including a capping layer made of materials that (1) have a high absorption coefficient, (2) have a high refractive index, (3) exhibit good thin-film stability, (4) have excellent durability, (5) have excellent light resistance, and (6) do not absorb in the blue, green, and red wavelength regions.SOLUTION: In view of the superior film stability and durability of arylamine-based materials having specific structures, amine compounds possessing a high refractive index and a specific benzoxazole ring structure are selected on the basis of the high absorbance at wavelengths between 400 nm and 410 nm in an absorption spectrum at a concentration of 10-5 mol / L. An organic EL element using the compounds as materials for the capping layer exhibits favorable device characteristics.SELECTED DRAWING: Figure 6

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 developed a layered structure element in which various roles were assigned to each material. This made organic EL elements practical. 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. As a result, they achieved an EL display of 1000 cd / m at a voltage of 10 V or less. 2 Such high brightness was obtained (see, for example, Patent Documents 1 and 2).

[0004] To date, many improvements have been made to organic EL devices for practical use. For example, the various roles of the laminated structure have been further subdivided. Organic EL devices have been fabricated 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. These organic EL devices have a bottom-emission structure that emits light from the bottom, achieving high efficiency and durability (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 a capping layer on a top-emission light-emitting device was confirmed using a light-emitting device that uses Ir(ppy)3 as the light-emitting material. In this light-emitting device, the current efficiency was 38 cd / A without a capping layer, whereas it was 64 cd / A when a 60 nm-thick ZnSe capping layer was used. An efficiency improvement of approximately 1.7 times was observed. It has also been shown that the maximum transmittance of the semitransparent electrode and capping layer does not necessarily coincide with the maximum efficiency, and that the maximum light extraction efficiency is determined by the interference effect (see, for example, Non-Patent 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, an example has been described in which 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-transporting material. However, because Alq3 has weak absorption around 450 nm, which is used as a blue-emitting material, blue light-emitting devices that include a capping layer made of Alq3 have problems such as reduced color purity and reduced 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, materials for the capping layer are required that can absorb sunlight with wavelengths of 400 to 410 nm without affecting the materials inside the device. Furthermore, to significantly improve light extraction efficiency, materials for the capping layer must have a high absorption coefficient, a high refractive index, and excellent thin-film stability and durability. [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 having the following properties, in order to improve the element characteristics of the organic EL element, particularly to absorb sunlight with a wavelength of 400 nm to 410 nm without affecting the materials inside the element, and to significantly improve the light extraction efficiency: (1) High extinction coefficient (2) High refractive index (3) The thin film has good stability, (4) Excellent durability (5) Excellent light resistance (6) A material that has no absorption in the blue, green, and red wavelength regions.

[0015] Capping layer materials suitable for the present invention have the following physical properties: (1) A high extinction coefficient; (2) A high refractive index, (3) Vapor deposition is possible. (4) The thin film is stable. (5) A high glass transition temperature. Furthermore, elements suitable for the present invention have the following physical characteristics: (1) Absorbing light in the range of 400 nm to 410 nm; (2) High light extraction efficiency, (3) No loss of color purity. (4) Transmitting light without changing over time; (5) Long life. [Means for solving the problem]

[0016] 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. -5 A material with high absorbance in the wavelength range of 400 to 410 nm in the absorption spectrum of 100 mol / L was selected. The benzoazole ring structure shown here is a structure in which a benzene ring is fused with a five-membered heterocyclic azole containing one or more nitrogen atoms. Organic EL devices using this compound as a material constituting the capping layer were fabricated, and the device characteristics were evaluated extensively, leading to the completion of the present invention.

[0017] That is, according to the present invention, the following organic EL device is provided.

[0018] 1) An organic electroluminescence element having an anode, a hole transport layer, an emitting layer, an electron transport layer, a cathode, and a capping layer in this order, wherein the refractive index of the material of the capping layer is 1.90 or more in the wavelength range of 500 nm to 570 nm, and the capping layer contains an amine compound represented by the following general formula (1):

[0019] [ka] (wherein R1 to R5 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 fused polycyclic aromatic group, or a substituted or unsubstituted aryloxy group; When there are a plurality of each of R1 to R4, adjacent ones may form a ring. X represents an oxygen atom, a sulfur atom, or a nitrogen atom; Y and Z each represent an oxygen atom or a sulfur atom. However, when X is an oxygen atom or a sulfur atom, X does not have R5. Ar may be the same or different and represent a divalent group of a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group. r1 to r3 represent integers from 0 to 4, r4 represents an integer from 0 to 3.

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

[0021] [ka] (In the formula, R1 to R5, X, Y, Z, and r1 to r4 are as defined in the general formula (1) above.)

[0022] 3) The organic electroluminescence device according to 1) or 2) above, wherein r1 to r4 in the general formula (1) are 0.

[0023] 4) The organic electroluminescence device according to any one of the above 1) to 3), wherein the thickness of the capping layer is within the range of 30 nm to 120 nm.

[0024] 5) A method for producing an organic electroluminescence element according to any one of 1) to 4) above.

[0025] In the "substituted or unsubstituted aromatic hydrocarbon group," "substituted or unsubstituted aromatic heterocyclic group," or "substituted or unsubstituted fused polycyclic aromatic group" represented by R1 to R5 and Ar in general formula (1) or (1a), the "aromatic hydrocarbon group," "aromatic heterocyclic group," or "fused polycyclic aromatic group" refers to an "aromatic hydrocarbon group" having a ring structure in which the ring is composed solely of carbon atoms and exhibits aromaticity, an "aromatic heterocyclic group" having a ring structure in which the ring is composed of one or more atoms other than carbon, and exhibits aromaticity, and a "fused polycyclic aromatic group" having a ring structure in which the ring is composed solely of carbon atoms and in which multiple aromatic rings are fused. Specific examples of the "aromatic hydrocarbon group" include phenyl, biphenylyl, and terphenylyl groups. Other examples include aryl groups having a ring structure in which the ring is composed of 6 to 30 carbon atoms and exhibits aromaticity. Examples of the "aromatic heterocyclic group" include a pyridyl 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. In addition to these, examples of the "aromatic heterocyclic group" include a heteroaryl group having 2 to 20 carbon atoms. Examples of the "condensed polycyclic aromatic group" include 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, and a triphenylenyl group, and also include an aryl group having a ring structure in which multiple aromatic rings are condensed and which has 6 to 30 carbon atoms.

[0026] The "linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent", the "cycloalkyl group having 5 to 10 carbon atoms which may have a substituent", the "linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent", the "linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent", the "linear or branched alkenyl group having 1 ... cycloalkyl group having 1 to 6 carbon atoms which may have a substituent", the "substituted or unsubstituted aryloxy group" represented by R1 to R5 in the general formula (1) or (1a) Specific examples of "C1-C6 linear or branched alkyl group," "C5-C10 cycloalkyl group," "C2-C6 linear or branched alkenyl group," "C1-C6 linear or branched alkyloxy group," "C5-C10 cycloalkyloxy group," or "aryloxy group" include "C1-C6 linear or branched alkyl group," such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and n-hexyl. Examples of "C5-C10 cycloalkyl group" include cyclopentyl, cyclohexyl, 1-adamantyl, and 2-adamantyl. Examples of "C2-C6 linear or branched alkenyl group" include vinyl, allyl, isopropenyl, and 2-butenyl. Examples of the "straight-chain or branched alkyloxy group having 1 to 6 carbon atoms" include a methyloxy group, an ethyloxy group, an n-propyloxy group, etc. Examples of the "cycloalkyloxy group having 5 to 10 carbon atoms" include a cyclopentyloxy group, a cyclohexyloxy group, an 1-adamantyloxy group, etc. Examples of the "aryloxy group" include a phenyloxy group, a tolyloxy group, and a biphenyloxy group.

[0027] Examples of the "substituent" in the "substituted aromatic hydrocarbon group," "substituted aromatic heterocyclic group," "substituted fused polycyclic aromatic group," "C 1 to C 6 linear or branched alkyl group which may have a substituent," "C 5 to C 10 cycloalkyl group which may have a substituent," or "C 2 to C 6 linear or branched alkenyl group which may have a substituent," represented by R1 to R5 and Ar 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 6 linear or branched alkyl group such as a methyl group, an ethyl group, or a propyl group; a C 1 to C 6 linear or branched alkyloxy group such as a methyloxy group, an ethyloxy group, or a propyloxy group; an alkenyl group such as a vinyl group or an allyl group; a phenyloxy group, a trimethylsilyl group, or a propyloxy group; aryloxy groups such as an oxy group; arylalkyloxy groups such as a benzyloxy group and 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, and a triphenylenyl group; pyridyl groups, thienyl groups, furyl groups, pyrrolyl groups, quinolyl groups, In addition to 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 carbolinyl group, etc., examples thereof 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. 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.

[0028] In the organic EL device of the present invention, Ar in the general formula (1) or (1a) is preferably a substituted or unsubstituted aromatic hydrocarbon group, more preferably a substituted or unsubstituted phenyl group.

[0029] In the organic EL device of the present invention, the thickness of the capping layer is preferably in the range of 30 nm to 120 nm, and more preferably in the range of 40 nm to 80 nm.

[0030] In the organic EL device of the present invention, the refractive index of the capping layer is preferably 1.90 or more, more preferably 2.00 or more, in the wavelength range of light transmitted through the capping layer from 500 nm to 570 nm.

[0031] 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]

[0032] 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, making it possible to obtain an organic EL element that can significantly improve light extraction efficiency. Furthermore, the capping layer can be easily removed. Therefore, the light extraction efficiency of each color can be optimized using a high-resolution mask without damaging the light-emitting element. Furthermore, the organic EL element can be suitably applied to full-color displays, making it possible to display clear, bright images with good color purity.

[0033] The organic EL device of the present invention uses a material for organic EL devices as the capping layer material, which has a high absorption coefficient, a high refractive index, and excellent thin film stability, durability, and light resistance. Therefore, compared to conventional organic EL devices, it is less affected by sunlight, maintains color purity, and significantly improves light extraction efficiency. Furthermore, it has become possible to realize an organic EL device with high efficiency and long life. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 shows the structures of compounds (1-1) to (1-12) as amine compounds represented by general formulas (1) and (1a). [Figure 2] FIG. 1 shows the structures of compounds (1-13) to (1-24) as amine compounds represented by general formulas (1) and (1a). [Figure 3] FIG. 1 shows the structures of compounds (1-25) to (1-36) as amine compounds represented by general formulas (1) and (1a). [Figure 4] FIG. 1 shows the structures of compounds (1-37) to (1-48) as amine compounds represented by general formulas (1) and (1a). [Figure 5] FIG. 1 shows the structures of compounds (1-49) to (1-60) as amine compounds represented by general formulas (1) and (1a). [Figure 6] FIG. 1 is a diagram showing the configurations of the organic EL devices of Examples 12 to 19 and Comparative Examples 1 to 4. DETAILED DESCRIPTION OF THE INVENTION

[0035] The amine compounds of this embodiment represented by general formula (1) or (1a) are novel compounds having a benzazole ring structure. 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 this embodiment represented by 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. Alternatively, the halogenated benzazole derivative can be converted into a boronic acid derivative or a boronic acid ester derivative, and then subjected to a coupling reaction with a halogenated arylamine to similarly synthesize the amine compounds of this embodiment represented by general formula (1) or (1a) (see, for example, Non-Patent Documents 5 and 6).

[0036] [ka]

[0037] Among the amine compounds represented by the general formula (1) or (1a) that are suitably used in the organic EL device of this embodiment, specific examples of preferred compounds are shown in Figures 1 to 5, but the compounds are not limited to these.

[0038] The compounds represented by general formula (1) or (1a) were purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using solvents, and sublimation purification, and the compounds were identified by NMR analysis. The melting point, glass transition point (Tg), and refractive index were measured as physical properties. The melting point is an indicator of vapor deposition properties, the glass transition point (Tg) is an indicator of the stability of the thin film state, and the refractive index is an indicator of the improvement of light extraction efficiency.

[0039] The melting point and glass transition temperature (Tg) were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS) using powder.

[0040] 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).

[0041] The absorbance was measured at a concentration of 10 in toluene. -5 The extinction coefficient was measured at a concentration of 5.0 × 10 in toluene solution. -6 mol / L, 1.0 x 10 -5 mol / L, 1.5 x 10 -5 mol / L, 2.0 × 10 -5 The concentrations were adjusted to four different mol / L and measured using an ultraviolet-visible-near infrared spectrophotometer (JASCO Corporation, V-650).

[0042] The organic EL device of this embodiment may have a top-emission structure, for example, a multilayer structure 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. Examples of the organic EL device include a multilayer structure having a hole injection layer between the anode and the hole transport layer, a multilayer structure having an electron blocking layer between the hole transport layer and the emitting layer, a multilayer structure having a hole blocking layer between the emitting layer and the electron transport layer, and a multilayer structure having 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 multiple layers. For example, a structure may serve as both a hole injection layer and a hole transport layer, a structure may serve as both a hole transport layer and an electron blocking layer, a structure may serve as both a hole blocking layer and an electron transport layer, or a structure may serve as both an electron transport layer and an electron injection layer. Furthermore, a structure in which two or more organic layers having the same function are stacked may also be used. For example, it is possible to use a structure in which two hole transport layers are laminated, a structure in which two light emitting layers are laminated, a structure in which two electron transport layers are laminated, a structure in which two capping layers are laminated, and the like.

[0043] 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 the organic EL element other than the capping layer, etc.

[0044] For the anode of the organic EL element of this embodiment, an electrode material with a large work function, such as ITO or gold, is used.

[0045] The hole injection layer of the organic EL device of this embodiment can be formed using 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 heteroatom. Examples of such arylamine compounds include starburst triphenylamine derivatives, various triphenylamine tetramers, porphyrin compounds such as copper phthalocyanine, acceptor heterocyclic compounds such as hexacyanoazatriphenylene, and polymeric coating materials. These compounds can be formed into films alone or as a single layer by mixing with other materials. They can also be used as a laminate 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, and inkjet printing.

[0046] The hole transport layer of the organic EL device of this embodiment can be formed using 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; or 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter abbreviated as TAPC). It is particularly 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. Examples of such arylamine compounds include N,N,N',N'-tetrabiphenylylbenzidine. It is also preferable to use an arylamine compound having three or more triphenylamine structures in the molecule linked by a single bond or a divalent group not containing a heteroatom. Examples of such arylamine compounds include various triphenylamine trimers and tetramers. These compounds may be used alone or as a single layer formed by mixing with other materials. They may also be used as a laminate structure consisting of layers formed by mixing alone, layers formed by mixing, or layers formed by mixing with other layers. Furthermore, a coating-type polymer material such as poly(3,4-ethylenedioxythiophene) (hereinafter abbreviated as PEDOT) / poly(styrene sulfonate) (hereinafter abbreviated as PSS) can be used as a hole injection / transport layer. These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0047] Furthermore, in the hole injection layer or hole transport layer, materials typically used for the layer can be further doped with P, such as trisbromophenylaminehexachloroantimony or radialene derivatives (see, for example, Patent Document 3). Also, polymer compounds having the structure of a benzidine derivative such as TPD in their partial structure can be used.

[0048] The electron blocking layer of the organic EL device of this embodiment can be formed from 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-ylphenyl)adamantane (hereinafter abbreviated as Ad-Cz), or 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 have electron blocking properties. 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.

[0049] The light-emitting layer of the organic EL device of this embodiment 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, polyparaphenylenevinylene derivatives, and the like. The light-emitting layer can also be formed using a host material and a dopant material. Anthracene derivatives are preferably used as the host material. In addition to the light-emitting materials described above, heterocyclic compounds having an indole ring as a partial structure of a fused ring, heterocyclic compounds having a carbazole ring as a partial structure of a fused ring, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, polydialkylfluorene derivatives, and the like can also be used. Furthermore, dopant materials can be used such as quinacridone, coumarin, rubrene, perylene, and derivatives thereof, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives, 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 other layers formed alone, other layers formed as a mixture, or a layer formed alone and a layer formed as a mixture.

[0050] Phosphorescent emitters can also be used as light-emitting materials. Examples of phosphorescent 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). Green phosphorescent emitters are particularly preferred. Examples of host materials that can be used include hole-injecting and transporting host materials such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as CBP), TCTA, and mCP, as well as carbazole derivatives. Examples of electron-transporting host materials include 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). Using these host materials allows for the fabrication of high-performance organic EL devices.

[0051] 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.

[0052] 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.

[0053] The hole-blocking layer of the organic EL device of this embodiment can be formed using metal complexes of phenanthroline derivatives such as bathocuproine (hereinafter abbreviated as BCP), 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 compounds have hole-blocking properties. 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 be stacked together with other layers, or with other layers, or with other layers. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0054] The electron transport layer of the organic EL device of this embodiment can be formed using 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, and silole derivatives. These materials can be formed into thin films by vapor deposition, spin coating, inkjet printing, or other known methods. These materials can be used 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 used to form thin films by vapor deposition, spin coating, inkjet printing, or other known methods.

[0055] The electron injection layer of the organic EL device of this embodiment 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). In a preferred selection of the electron transport layer and the cathode, this can be omitted.

[0056] Furthermore, in the electron injection layer or electron transport layer, a material that is further doped with N metal such as cesium in addition to the material normally used for the layer can be used.

[0057] As the cathode of the organic EL element of this embodiment, 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.

[0058] The capping layer of the organic EL device of this embodiment preferably uses an amine compound represented by the general formula (1) or (1a). These compounds may be formed alone or mixed with other materials to form a single layer. They may also be used in a laminated structure of layers formed alone, layers formed in a mixture, or layers formed in a mixture with layers formed alone. These materials can be used to form thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0059] Although the organic EL element having a top emission structure has been described above, this embodiment 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.

[0060] 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. A refractive index of 1.90 or higher is sufficient, and 2.00 or higher is more preferable.

[0061] 6, an example of a method for producing the organic EL device of this embodiment is to deposit 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 reflective ITO electrode previously formed as a metal anode 2 on a glass substrate 1. The capping layer 10 contains an amine compound represented by the general formula (1) or (1a).

[0062] 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]

[0063] [Example 1] <Synthesis of exemplary compound (1-18)> A reaction vessel was charged with 7.0 g of 4-(3-dibenzofuranyl)benzenamine, 16.3 g of 2-(4-bromophenyl)benzoxazole, 7.8 g of sodium t-butoxide, and 70 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.7 g of tris(dibenzylideneacetone)dipalladium(0) and 0.7 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added and the mixture was stirred overnight under reflux. After cooling, the mixture was subjected to dispersion washing at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene solvent, and the precipitated solid was collected to obtain 12.3 g (yield 70.6%) of exemplary compound (1-18) as a yellow powder.

[0064] [ka]

[0065] The structure of the resulting yellow powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.23-8.20(4H), 8.05-7.99(2H), 7.84-7.50(10H), 7.41-7.32(11H).

[0066] [Example 2] <Synthesis of exemplary compound (1-6)> A reaction vessel was charged with 6.1 g of 4-(3-dibenzofuranyl)benzenamine, 15.0 g of 2-(4-bromophenyl)benzothiazole, 6.8 g of sodium t-butoxide, and 60 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.7 g of tris(dibenzylideneacetone)dipalladium(0) and 0.6 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added, and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was dispersed and washed at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene solvent, and the precipitated solid was collected to obtain 9.1 g (yield 57.1%) of exemplary compound (1-6) as a yellow powder.

[0067] [ka]

[0068] The structure of the resulting yellow powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.09-8.20(8H), 7.94-7.91(2H), 7.83(1H), 7.72-7.61(4H), 7.52-7.49(3H), 7.42-7.30(9H).

[0069] [Example 3] <Synthesis of exemplary compound (1-17)> A reaction vessel was charged with 5.3 g of 4-(4-dibenzofuranyl)benzenamine, 12.3 g of 2-(4-bromophenyl)benzoxazole, 5.9 g of sodium t-butoxide, and 50 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.6 g of tris(dibenzylideneacetone)dipalladium(0) and 0.5 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added, and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was subjected to dispersion washing at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene solvent, and the precipitated solid was collected to obtain 6.8 g (yield 51.5%) of exemplary compound (1-17) as a yellow powder.

[0070] [ka]

[0071] The structure of the resulting yellow powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.24-8.20(4H), 8.05-7.96(4H), 7.80-7.77(2H), 7.68-7.59(4H), 7.51-7.36(13H).

[0072] [Example 4] <Synthesis of exemplary compound (1-5)> A reaction vessel was charged with 5.3 g of 4-(4-dibenzofuranyl)benzenamine, 13.1 g of 2-(4-bromophenyl)benzothiazole, 5.9 g of sodium t-butoxide, and 100 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.6 g of tris(dibenzylideneacetone)dipalladium(0) and 0.5 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added, and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was dispersed and washed at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene solvent, and the precipitated solid was collected to obtain 7.5 g (yield 54.15%) of exemplary compound (1-5) as a yellow powder.

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[0074] The structure of the resulting yellow powder was identified using NMR. 1The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.10-7.91(12H), 7.68-7.64(2H), 7.54-7.33(13H).

[0075] [Example 5] <Synthesis of exemplary compound (1-19)> A reaction vessel was charged with 7.0 g of 4-(2-dibenzofuranyl)benzenamine, 16.3 g of 2-(4-bromophenyl)benzoxazole, 7.8 g of sodium t-butoxide, and 70 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.7 g of tris(dibenzylideneacetone)dipalladium(0) and 0.7 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added, and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was subjected to dispersion washing at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene solvent, and the precipitated solid was collected to obtain 9.9 g (yield 56.9%) of exemplary compound (1-19) as a yellow powder.

[0076] [ka]

[0077] The structure of the resulting yellow powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.24-8.19(5H), 8.05-8.02(1H), 7.80-7.58(9H), 7.54-7.49(1H), 7.43-7.32(11H).

[0078] [Example 6] <Synthesis of exemplary compound (1-7)> A reaction vessel was charged with 5.0 g of 4-(2-dibenzofuranyl)benzenamine, 12.3 g of 2-(4-bromophenyl)benzothiazole, 5.6 g of sodium t-butoxide, and 50 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.5 g of tris(dibenzylideneacetone)dipalladium(0) and 0.5 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added, and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was dispersed and washed at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using monochlorobenzene solvent, and the precipitated solid was collected to obtain 8.5 g (yield 65.0%) of exemplary compound (1-7) as a yellow powder.

[0079] [ka]

[0080] The structure of the resulting yellow powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.20-8.19(1H), 8.09-8.03(6H), 7.94-7.91(2H), 7.75-7.61(5H), 7.54-7.49(3H), 7.43-7.30(10H).

[0081] [Example 7] <Synthesis of exemplary compound (1-13)> A reaction vessel was charged with 5.0 g of 4-(4-dibenzothienyl)benzenamine, 11.0 g of 2-(4-bromophenyl)benzoxazole, 5.2 g of sodium t-butoxide, and 50 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.5 g of tris(dibenzylideneacetone)dipalladium(0) and 0.4 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added and the mixture was stirred overnight under reflux. After cooling, the mixture was subjected to dispersion washing at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene solvent, and the precipitated solid was collected to obtain 10.6 g (yield 88.2%) of exemplary compound (1-13) as a yellow powder.

[0082] [ka]

[0083] The structure of the resulting yellow powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.25-8.18(6H), 7.91-7.88(1H), 7.81-7.78(4H), 7.63-7.49(6H), 7.41-7.34(10H).

[0084] [Example 8] <Synthesis of Exemplary Compound (1-1)> A reaction vessel was charged with 5.0 g of 4-(4-dibenzothienyl)benzenamine, 11.6 g of 2-(4-bromophenyl)benzothiazole, 5.2 g of sodium t-butoxide, and 50 mL of toluene, and nitrogen gas was passed through for 30 minutes. 0.5 g of tris(dibenzylideneacetone)dipalladium(0) and 0.4 g of a 50% (w / v) toluene solution of tri-(t-butyl)phosphine were added, and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was subjected to dispersion washing at 80°C, insoluble matters were filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using monochlorobenzene solvent, and the precipitated solid was collected to obtain 9.1 g (yield 72.22%) of yellow powder of exemplary compound (1-1).

[0085] [ka]

[0086] The structure of the resulting yellow powder was identified using NMR. 1The following 27 hydrogen signals were detected by H-NMR (CDCl3). δ(ppm)=8.24-8.18(2H), 8.10-8.06(6H), 7.94-7.88(3H), 7.79-7.76(2H), 7.63-7.49(6H), 7.43-7.33(8H).

[0087] [Example 9] The melting point and glass transition point of the amine compound 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 Compound of Example 1 - °C 121 °C Compound of Example 2 - °C 119 °C Compound of Example 3 - °C 125 °C Compound of Example 4 - °C 122 °C Compound of Example 5 - °C 121 °C Compound of Example 6 - °C 118 °C Compound of Example 7 247°C 127°C Compound of Example 8 - °C 126 °C

[0088] The amine compounds 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.

[0089] [Example 10] An amine compound represented by general formula (1) or (1a) was used to prepare a vapor-deposited film with a thickness of 80 nm on a silicon substrate. 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 for the prepared sample using a spectrophotometer (F10-RT-UV, manufactured by Filmetrics). 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.

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[0094] [Table 1]

[0095] As described above, the compounds of the present invention have a refractive index of 1.90 or higher in the wavelength range of 500 nm to 570 nm, which is equal to or higher than that of the comparative compounds. This suggests that they can be expected to improve the light extraction efficiency of organic EL devices. Furthermore, the extinction coefficients of the comparative compounds in the wavelength range of 400 nm to 410 nm were 0.03 to 0.45, whereas the compounds of the present invention had extinction coefficients of 0.53 to 1.08. This indicates that the compounds of the present invention absorb sunlight in the wavelength range of 400 nm to 410 nm well and do not affect the materials inside the device.

[0096] [Example 11] Using the compound of the present invention, the absorbance was measured at a concentration of 10 -5 The absorbance was measured at wavelengths of 400 nm and 410 nm after adjusting the concentration to mol / L. The extinction coefficient was 5 × 10 -6 mol / L, 1×10 -5 mol / L, 1.5 x 10 -5 mol / L, 2.0 × 10 -5The concentrations were adjusted to four different values ​​(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.

[0097] [Table 2]

[0098] As shown, the absorbance at a wavelength of 400 nm for the comparative compounds is 0.02 to 0.60, while that for the compounds of the present invention is 0.74 to 1.38. The compounds of the present invention have large values. The absorbance at 410 nm for the comparative compounds is 0.00 to 0.21, while that for the compounds of the present invention is 0.27 to 1.18. The compounds of the present invention also have large values. This indicates that the compounds of the present invention absorb sunlight with wavelengths of 400 nm to 410 nm well, and that the compounds of the present invention also have an absorption coefficient of 100,000 or more. In other words, the compounds of the present invention absorb light well under the same concentration conditions. Furthermore, the compounds of the present invention absorb light well as the film thickness increases, indicating that they are materials with excellent light resistance.

[0099] [Example 12] As shown in Figure 6, 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 was previously formed as a metal anode 2.

[0100] 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 deposited in sequence was ultrasonically cleaned in isopropyl alcohol for 20 minutes and then dried on a hot plate heated to 250°C for 10 minutes. This was followed by a 2 minute UV ozone treatment, after which the ITO-coated glass substrate was placed in a vacuum deposition machine 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, to a thickness of 10 nm. On 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 this 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 this 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 (3-3):(3-4) = 5:95 to a thickness of 40 nm. On this 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 (3-5):(3-6) = 50:50 to a thickness of 30 nm. On this electron transport layer 7, lithium fluoride was formed as an electron injection layer 8 to a thickness of 1 nm. On this electron injection layer 8, a magnesium-silver alloy was formed to a thickness of 12 nm as a cathode 9. Finally, the compound (1-18) 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.

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[0109] [Example 13] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-6) of Example 2 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. 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 3.

[0110] [ka]

[0111] [Example 14] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-17) of Example 3 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. 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 3.

[0112] [ka]

[0113] [Example 15] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-5) of Example 4 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. 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 3.

[0114] [ka]

[0115] [Example 16] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-19) of Example 5 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. The characteristics of the fabricated organic EL device were measured in air 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 3.

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[0117] [Example 17] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-7) of Example 6 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. 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 3.

[0118] [ka]

[0119] [Example 18] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-13) of Example 7 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. 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 3.

[0120] [ka]

[0121] [Example 19] An organic EL device was fabricated under the same conditions as in Example 12, except that compound (1-1) of Example 8 was used instead of compound (1-18) of Example 1 as the material for the capping layer 10. 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 3.

[0122] [ka]

[0123] [Comparative Example 1] For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that the capping layer 10 was formed to a thickness of 60 nm using a comparative compound (2-1) of the following structural formula instead of the compound (1-18) in Example 1. The characteristics of the fabricated organic EL device were measured in air 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 3.

[0124] [ka]

[0125] Comparative Example 2 For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that the capping layer 10 was formed to a thickness of 60 nm using comparative compound (2-2) of the following structural formula instead of compound (1-18) in Example 1. The characteristics of the fabricated organic EL device were measured in air 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 3.

[0126] [ka]

[0127] Comparative Example 3 For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that the capping layer 10 was formed to a thickness of 60 nm using a comparative compound (2-3) of the following structural formula instead of the compound (1-18) in Example 1. The characteristics of the fabricated organic EL device were measured in air 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 3.

[0128] [ka]

[0129] Comparative Example 4 For comparison, an organic EL device was fabricated under the same conditions as in Example 7, except that the capping layer 10 was formed to a thickness of 60 nm using a comparative compound (2-4) of the following structural formula instead of the compound (1-18) in Example 1. The characteristics of the fabricated organic EL device were measured in air 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 3.

[0130] [ka]

[0131] The organic EL devices fabricated in Examples 12 to 19 and Comparative Examples 1 to 4 were used to measure the device lifespan, and the results are summarized in Table 3. The device lifespan 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% was measured.

[0132] [Table 3]

[0133] 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 using the comparative compounds and the devices of Examples 12 to 19 of the present invention, whereas the luminance, luminous efficiency, power efficiency, and lifespan were significantly improved for the devices of Examples 12 to 19 of the present embodiment compared to the devices of Comparative Examples 1 to 4 using the comparative compounds. This shows 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 embodiment. [Industrial Applicability]

[0134] As described above, the amine compound represented by general formula (1), which is suitable for use in the organic EL device 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 for use in organic EL devices. By using this compound to prepare an organic EL device, high efficiency can be achieved, and durability and light resistance can be improved so that sunlight is absorbed and the materials inside the device are not affected. Furthermore, the use of 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]

[0135] 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 electroluminescent device having an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a capping layer in this order, the refractive index of the material of the capping layer is 1.90 or more at a wavelength of 500 nm to 570 nm; The capping layer contains a compound (1-1) represented by the following formula (1-1): The hole transport layer contains an arylamine compound having a structure in which two triphenylamine structures are linked in the molecule by a single bond or a divalent group containing no heteroatom. An organic electroluminescence element characterized by: 【Chemical 1】

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

3. A method for manufacturing the organic electroluminescence element according to claim 1 or 2, comprising: the anode is a reflective ITO electrode, the hole transport layer includes a first hole transport layer and a second hole transport layer, forming the reflective ITO electrode on a glass substrate; and a step of depositing a hole injection layer, the first hole transport layer, the second hole transport layer, the light-emitting layer, the electron transport layer, the electron injection layer, the cathode, and the capping layer in that order on the layer formed in the step.

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