Organic electroluminescent element and method for manufacturing the same

Abstract

The present application relates to an organic electroluminescent element and a production method thereof. Provided is an organic electroluminescent element which is an organic electroluminescent element having, in the stated order, an anode, a hole injection layer, a first hole transport layer, a second hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a cathode, and a capping layer, characterized in that the refractive index of the material of the capping layer is 1.90 or greater at a wavelength of 500 nm to 570 nm, the capping layer contains a compound (1-1) represented by the following formula (1-1), and the first hole transport layer contains a compound (3-1) represented by the following formula (3-1).

Description

[0001] This invention is a divisional application of the invention application with application number 202180014230.1 (international application number PCT / JP2021 / 005857), application date February 17, 2021, and invention title "organic electroluminescent element". Technical Field

[0002] This invention relates to compounds and elements suitable for use as self-emissive elements in various display devices, specifically to amine compounds having a benzoxazole ring structure and organic EL elements using such compounds.

[0003] This application claims priority based on Japanese Patent Application No. 2020-023986, filed in Japan on February 17, 2020, the contents of which are incorporated herein by reference. Background Technology

[0004] Because organic EL elements are self-emissive, they are brighter and have better visibility than liquid crystal elements, enabling them to display images vividly, and therefore have been actively researched.

[0005] In 1987, CWTang et al. of Eastman Kodak developed a stacked structure element that distributed various functions among different materials. This led to the development of organic EL elements using organic materials, which became practical devices. They stacked electron-transferring phosphors with hole-transferring organic materials, injecting the charges of both into the phosphor layer to induce luminescence. As a result, 1000 cd / m² was achieved using voltages below 10V. 2 The above high brightness (for example, see Patent Document 1 and Patent Document 2).

[0006] To date, many improvements have been made to facilitate the practical application of organic EL devices. For example, the various functions of the stacked structure have been further refined. Then, an organic EL device was fabricated in which an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially disposed on a substrate. This organic EL device has a bottom-emitting structure that emits light from the bottom, thus achieving high efficiency and durability (see, for example, Non-Patent Literature 1).

[0007] In recent years, metals with high work functions have been used for the anode, and top-emitting light-emitting elements with upward-emitting structures have been increasingly used. In bottom-emitting structures where light is extracted from the bottom (where pixel circuitry is present), the area of ​​the light-emitting portion is limited. In contrast, in top-emitting light-emitting elements, since light is extracted from the top, the pixel circuitry is not obstructed, thus offering the advantage of a wider light-emitting portion. In top-emitting light-emitting elements, semi-transparent electrodes such as LiF / Al / Ag (e.g., see Non-Patent Document 2), Ca / Mg (e.g., see Non-Patent Document 3), and LiF / MgAg are used as the cathode.

[0008] In such light-emitting elements, when light emitted from the light-emitting layer is incident on other films, if the light is incident at an angle greater than a certain angle, it will be totally reflected at the interface between the light-emitting layer and other films. Therefore, only a portion of the emitted light can be utilized. In recent years, in order to improve the light extraction efficiency, light-emitting elements with a "capping layer" with a high refractive index disposed on the outside of a semi-transparent electrode with a low refractive index have been proposed (for example, see Non-Patent Documents 2 and 3).

[0009] Regarding the effect of the capping layer in the light-emitting element of the top-emitting structure, this was confirmed using a light-emitting element in which Ir(ppy)3 is used as the luminescent material. In this light-emitting element, without the capping layer, the current efficiency is 38 cd / A, compared to 64 cd / A in a light-emitting element using ZnSe with a film thickness of 60 nm as the capping layer. An efficiency improvement of approximately 1.7 times can be observed. Furthermore, it was shown that the maximum transmittance of the semi-transparent electrode and the capping layer does not necessarily coincide with the maximum efficiency, indicating that the maximum light extraction efficiency is determined by interference effects (for example, see Non-Patent Document 3).

[0010] Previously, high-precision metal masks were used to form the capping layer. However, due to heat deformation of the metal mask under high-temperature conditions, the alignment accuracy decreased. Therefore, for ZnSe, with its melting point exceeding 1100°C (see, for example, Non-Patent Document 3), vapor deposition in the correct position is not possible using a high-precision metal mask, potentially affecting the light-emitting element itself. Furthermore, even film formation using sputtering methods can affect the light-emitting element; therefore, capping layers composed of inorganic materials are unsuitable.

[0011] Furthermore, examples of using tris(8-hydroxyquinoline) aluminum (hereinafter referred to as Alq3) as a capping layer to adjust the refractive index have been described (for example, see Non-Patent Document 2). Alq3 is known to be an organic EL material commonly used as a green light-emitting material or an electron transport material. However, Alq3 has weak absorption around 450 nm, which is used in cyan light-emitting materials. Therefore, in the case of cyan light-emitting elements containing a capping layer containing Alq3, there are problems of reduced color purity and reduced light extraction efficiency.

[0012] In addition, in components manufactured using conventional capping layers, there is also the problem that sunlight with wavelengths of 400nm to 410nm passes through, affecting the materials inside the component, resulting in reduced color purity and reduced light extraction efficiency.

[0013] To improve the characteristics of organic EL devices, the material used as the capping layer is specifically required to absorb sunlight with wavelengths from 400 nm to 410 nm without affecting the internal materials of the device. Furthermore, to significantly improve light extraction efficiency, the capping layer material is required to have a high absorption coefficient, high refractive index, and excellent film stability and durability.

[0014] Existing technical documents

[0015] Patent documents

[0016] Patent Document 1: Japanese Patent Application Publication No. 8-048656

[0017] Patent Document 2: Japanese Patent No. 3194657

[0018] Patent Document 3: International Publication No. 2014 / 009310

[0019] Patent Document 4: International Publication No. 2013 / 038627

[0020] Non-patent literature

[0021] Non-patent literature 1: Proceedings of the 9th Workshop of the Chinese Society of Applied Physics, pp. 55-61 (2001)

[0022] Non-patent literature 2: Appl. Phys. Let., 78, 544 (2001)

[0023] Non-patent literature 3: Appl. Phys. Let., 82, 466 (2003)

[0024] Non-patent literature 4: J.Org.Chem.,71,1802 (2006)

[0025] Non-patent literature 5: J.Org.Chcm.,60,7508 (1995)

[0026] Non-patent literature 6: Synth. Commun., 11, 513 (1981)

[0027] Non-patent literature 7: Appl. Phys. Lett., 98, 083302 (2011) Summary of the Invention

[0028] The problem that the invention aims to solve

[0029] The object of the present invention is to provide an organic EL element having a capping layer made of a material having the following characteristics, in order to improve the element characteristics of an organic EL element, and in particular, to absorb sunlight with wavelengths of 400 nm to 410 nm without affecting the material inside the element, and to significantly improve the light extraction efficiency.

[0030] (1) High absorption coefficient, (2) High refractive index, (3) The film has good stability. (4) Excellent durability, (5) Excellent lightfastness, (6) Materials that do not absorb in the respective wavelength regions of cyan, green and red.

[0031] The material suitable for the capping layer of the present invention has the following physical properties.

[0032] (1) High absorption coefficient, (2) High refractive index, (3) Can be vapor-deposited, (4) The thin film is in a stable state. (5) High glass transition temperature.

[0033] In addition, the elements suitable for use in this invention have the following physical characteristics.

[0034] (1) Absorbs light from 400nm to 410nm. (2) High light extraction efficiency, (3) There is no decrease in color purity. (4) Allows light to pass through without changing over time. (5) Long lifespan.

[0035] Methods for solving problems

[0036] Therefore, in order to achieve the above-mentioned objectives, the inventors focused on the excellent stability and durability of aryl amine materials in thin films. Amine compounds with high refractive indices and specific benzo[a]azole ring structures were screened for concentrations of 10... -5 Materials with high absorbance in the 400 nm to 410 nm wavelength range in the absorption spectrum at a concentration of mol / L. The benzoxazole ring structure shown here refers to a structure formed by the fusion of a benzene ring with an azole in a 5-membered heterocycle containing one or more nitrogen atoms. Organic EL elements using this compound as a capping layer were fabricated, and the characteristics of the elements were thoroughly evaluated, resulting in the completion of this invention.

[0037] That is, according to the present invention, the following organic EL element is provided.

[0038] 1) An organic electroluminescent element having an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode and a capping layer in sequence, characterized in that the refractive index of the material of the capping layer is 1.90 or more at a wavelength of 500 nm to 570 nm, and the capping layer contains an amine compound represented by the following general formula (1).

[0039] [Chemistry 1]

[0040] (In the formula, R1 to R5 can be the same or different from each other, representing deuterium atom, fluorine atom, chlorine atom, cyano, nitro, a straight-chain or branched alkyl group with 1 to 6 carbon atoms that may have substituents, a cycloalkyl group with 5 to 10 carbon atoms that may have substituents, a straight-chain or branched alkenyl group with 2 to 6 carbon atoms that may have substituents, a straight-chain or branched alkoxy group with 1 to 6 carbon atoms that may have substituents, a cycloalkoxy group with 5 to 10 carbon atoms that may have substituents, 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 multiple R1 to R4 exist, a ring can be formed between adjacent R1 to R4.

[0041] X represents an oxygen atom, a sulfur atom, or a nitrogen atom. Y and Z represent oxygen or sulfur atoms.

[0042] In the case where X is an oxygen atom or a sulfur atom, X does not have R5.

[0043] Each Ar can be the same as or different from the others, representing a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a divalent group of a substituted or unsubstituted fused polycyclic aromatic group.

[0044] r1 to r3 represent integers from 0 to 4. r4 represents an integer from 0 to 3. 2) The organic electroluminescent element according to 1) above is characterized in that the amine compound is represented by the following general formula (1a).

[0045] [Chemistry 2]

[0046] (In the formula, R1~R5, X, Y, Z, r1~r4 are defined as in the general formula (1).)

[0047] 3) The organic electroluminescent element according to 1) or 2) above is characterized in that r1 to r4 in the above general formula (1) is 0.

[0048] 4) An organic electroluminescent element according to any one of 1) to 3) above, wherein the thickness of the capping layer is in the range of 30 nm to 120 nm.

[0049] 5) A method for manufacturing an organic electroluminescent element as described in any one of 1) to 4) above.

[0050] In general formulas (1) or (1a), R1 to R5 and Ar represent "substituted or unsubstituted aromatic hydrocarbon group", "substituted or unsubstituted aromatic heterocyclic group", or "substituted or unsubstituted fused polycyclic aromatic group". "Aromatic hydrocarbon group" refers to a ring structure in which the only atoms constituting the ring are carbon, exhibiting unfused aromaticity; "aromatic heterocyclic group" refers to a ring structure in which the atoms constituting the ring contain one or more types of atoms other than carbon, exhibiting aromaticity; and "fused polycyclic aromatic group" refers to a ring structure in which the only atoms constituting the ring are carbon, formed by the fusion of multiple aromatic rings. Specifically, examples of "aromatic hydrocarbon group" include phenyl, biphenyl, and terphenyl. In addition to these, aryl groups containing 6 to 30 carbon atoms and exhibiting unfused aromatic ring structures can also be listed. Examples of "aromatic heterocyclic groups" include pyridyl, pyrimidinyl, triazinyl, furanyl, pyrroloyl, thiopheneyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiopheneyl, indolyl, carbazoleyl, benzoxazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiopheneyl, naphridinyl, phenanthrololinyl, acridineyl, carbolinyl, etc. In addition to these, heteroaryl groups containing 2 to 20 carbon atoms can also be listed. Examples of "fused polycyclic aromatic groups" include naphthyl, anthraceneyl, phenanthyl, fluorenyl, spirodifluorenyl, indyl, pyreneyl, peryleneyl, fluoranthraceneyl, triphenylene, etc. In addition to these, aryl groups containing 6 to 30 carbon atoms and having a ring structure formed by the fusion of multiple aromatic rings can also be listed.

[0051] R1 to R5 in general formula (1) or (1a) represent "a straight-chain or branched alkyl group having 1 to 6 carbon atoms that may have substituents", "a cycloalkyl group having 5 to 10 carbon atoms that may have substituents", "a straight-chain or branched alkenyl group having 2 to 6 carbon atoms that may have substituents", "a straight-chain or branched alkoxy group having 1 to 6 carbon atoms that may have substituents", "a cycloalkoxy group having 5 to 10 carbon atoms that may have substituents", or "a substituted or unsubstituted aryloxy group". The terms "alkyl group with 1 to 6 carbon atoms (straight-chain or branched)," "cycloalkyl group with 5 to 10 carbon atoms," "alkenyl group with 2 to 6 carbon atoms (straight-chain or branched)," "alkoxy group with 1 to 6 carbon atoms (straight-chain or branched)," "cycloalkoxy group with 5 to 10 carbon atoms," or "aryloxy group" are used. Specifically, examples of "alkyl group with 1 to 6 carbon atoms (straight-chain or branched)" include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and n-hexyl. Examples of "cycloalkyl group with 5 to 10 carbon atoms" include cyclopentyl, cyclohexyl, 1-adamantyl, and 2-adamantyl. Examples of "alkenyl group with 2 to 6 carbon atoms (straight-chain or branched)" include vinyl, allyl, isopropenyl, and 2-butenyl. Examples of "alkoxy groups with 1 to 6 carbon atoms, either straight-chain or branched" include methoxy, ethoxy, and propoxy. Examples of "cycloalkoxy groups with 5 to 10 carbon atoms" include cyclopentoxy, cyclohexoxy, and 1-adamantoxy. Examples of "aryloxy groups" include phenoxy, tolyloxy, and biphenyloxy.

[0052] The "substituents" in general formulas (1) or (1a), represented by R1 to R5 and Ar, specifically include "substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", "substituted fused polycyclic aromatic group", "linear or branched alkyl group having 1 to 6 carbon atoms with substituents", "cycloalkyl group having 5 to 10 carbon atoms with substituents", or "linear or branched alkenyl group having 2 to 6 carbon atoms with substituents", specifically, in addition to deuterium, cyano, nitro; halogen atoms such as fluorine, chlorine, bromine, and iodine; silyl groups such as trimethylsilyl and triphenylsilyl; linear or branched alkyl groups such as methyl, ethyl, and propyl with 1 to 6 carbon atoms; and linear or branched alkyl groups such as methoxy, ethoxy, and propoxy with 1 to 6 carbon atoms. Alkyl groups; vinyl, allyl, and other alkenyl groups; phenoxy, tolyloxy, and other aryloxy groups; benzyloxy, phenethoxy, and other arylalkoxy groups; phenyl, biphenyl, terphenyl, naphthyl, anthracene, phenanthrene, fluorenyl, spirodifluorenyl, indyl, pyrene, perylene, fluoranyl, triphenylene, and other aromatic hydrocarbon groups or fused polycyclic aromatic groups; pyridyl, thiophene, furanyl, pyrroleyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiophene, indolyl, carbazoyl, benzooxazolyl, benzothiazoyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiophene, carbazoyl, etc., and may also include aryl groups containing 6 to 30 carbon atoms or heteroaryl groups containing 2 to 20 carbon atoms, etc., and these substituents may be further substituted with the substituents exemplified above. In addition, these substituents can form rings with the substituted benzene ring or with multiple substituents on the same benzene ring via single bonds, substituted or unsubstituted methylene, oxygen or sulfur atoms.

[0053] Furthermore, in the organic EL element of the present invention, Ar in the above general formula (1) or (1a) is preferably a substituted or unsubstituted aromatic hydrocarbon group, more preferably a substituted or unsubstituted phenyl group.

[0054] Furthermore, in the organic EL element of the present invention, the thickness of the capping layer is preferably in the range of 30 nm to 120 nm, and more preferably in the range of 40 nm to 80 nm.

[0055] Furthermore, in the organic EL element of the present invention, the wavelength of light transmitted through the above-mentioned capping layer is in the range of 500 nm to 570 nm, and the refractive index of the capping layer is preferably 1.90 or more, more preferably 2.00 or more.

[0056] Furthermore, in the organic EL element of the present invention, the above-mentioned capping layer can be manufactured by stacking or forming a hybrid layer of two or more different constituent materials.

[0057] The effects of the invention

[0058] Regarding the organic EL element of the present invention, by having a capping layer with a higher refractive index than the semi-transparent electrode disposed outside the transparent or semi-transparent electrode, an organic EL element capable of significantly improving light extraction efficiency can be obtained. Furthermore, capping is possible. Therefore, no damage is caused to the light-emitting element, and a high-precision mask can be used to optimize the extraction efficiency of light of each color. Additionally, it is suitable for application in full-color displays, enabling the display of images with good color purity, vividness, and brightness.

[0059] In the organic EL element of the present invention, a material with high absorption coefficient, high refractive index, and excellent film stability, durability, and lightfastness is used as the capping layer material. Therefore, compared with conventional organic EL elements, it is unaffected by sunlight, maintains color purity, and can significantly improve light extraction efficiency. Furthermore, a high-efficiency, long-life organic EL element can be achieved. Attached Figure Description

[0060] Figure 1 This is a diagram showing the structures of compounds (1-1) to (1-12) as amine compounds represented by general formulas (1) and (1a).

[0061] Figure 2 This is a diagram showing the structures of compounds (1-13) to (1-24) that are amine compounds represented by general formulas (1) and (1a).

[0062] Figure 3 This is a diagram showing the structures of compounds (1-25) to (1-36) that are amine compounds represented by general formulas (1) and (1a).

[0063] Figure 4 This is a diagram showing the structures of compounds (1-37) to (1-48) that are amine compounds represented by general formulas (1) and (1a).

[0064] Figure 5 This is a diagram showing the structure of compounds (1-49) to (1-60) as amine compounds represented by general formulas (1) and (1a).

[0065] Figure 6 This diagram illustrates the configuration of organic EL elements in Examples 12-19 and Comparative Examples 1-4. Detailed Implementation

[0066] The amine compounds represented by the above general formula (1) or (1a) in this embodiment are novel compounds having a benzoazole ring structure. The benzoazole derivatives that form the main skeleton of these compounds can be synthesized, for example, by methods known to the public (see, for example, Non-Patent Document 4). Furthermore, the amine compounds represented by the above general formula (1) or (1a) in this embodiment can be synthesized by coupling the synthesized halobenzoazole derivative with an aryl amine using a copper catalyst, palladium catalyst, or the like. Additionally, the amine compounds represented by the above general formula (1) or (1a) in this embodiment can also be synthesized similarly by coupling the halobenzoazole derivative with a boric acid derivative or a borate ester derivative and a haloaryl amine (see, for example, Non-Patent Documents 5 and 6).

[0067] [Chemistry 3]

[0068] Among the amine compounds represented by the above general formula (1) or (1a) suitable for use in the organic EL element of this embodiment, specific examples of preferred compounds are shown below. Figures 1-5 However, it is not limited to these compounds.

[0069] For the purification of compounds represented by general formula (1) or (1a), purification is carried out by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization using solvents, crystallization, sublimation purification, etc. For the identification of compounds, NMR analysis is used. As physical properties, melting point, glass transition temperature (Tg), and refractive index are determined. Melting point is used as an indicator of vapor deposition properties, glass transition temperature (Tg) is used as an indicator of the stability of the thin film state, and refractive index is used as an indicator related to the improvement of light extraction efficiency.

[0070] Regarding melting point and glass transition temperature (Tg), powder was used via a high-sensitivity differential scanning calorimeter (Bulkar). Measured by DSC3100SA (manufactured by Ethics).

[0071] In terms of refractive index and extinction coefficient, an 80 nm thin film was fabricated on a silicon substrate and measured using a spectrophotometer (Filmetrics, F10-RT-UV).

[0072] Regarding absorbance, the concentration was adjusted to 10 using toluene solvent. -5 The concentration was determined to be 5.0 × 10⁻⁶ mol / L. For the absorbance coefficient, a toluene solution was used to adjust the concentration to 5.0 × 10⁻⁶. -6 mol / L, 1.0×10 -5 mol / L, 1.5×10 -5 mol / L, 2.0×10-5 The concentrations of the four mol / L were determined using a UV-Vis-NIR spectrophotometer (Japan Spectrophotometer, V-650).

[0073] As for the structure of the organic EL element in this embodiment, for example, in the case of a top-emitting light-emitting element, a multilayer structure can be cited, which consists of an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a capping layer sequentially on a glass substrate. Other examples include structures with a hole injection layer between the anode and the hole transport layer, structures with an electron blocking layer between the hole transport layer and the light-emitting layer, structures with a hole blocking layer between the light-emitting layer and the electron transport layer, and structures with an electron injection layer between the electron transport layer and the cathode. In these multilayer structures, several organic layers can be omitted or combined. For example, it can be configured as both a hole injection layer and a hole transport layer, both a hole transport layer and an electron blocking layer, both a hole blocking layer and an electron transport layer, or both an electron transport layer and an electron injection layer. Furthermore, it can be configured by stacking two or more organic layers with the same function. For example, it can also be a configuration formed by stacking two hole transport layers, a configuration formed by stacking two light-emitting layers, a configuration formed by stacking two electron transport layers, or a configuration formed by stacking two capping layers, etc.

[0074] The total thickness of all layers in the organic EL element is preferably about 200 nm to 750 nm, more preferably about 350 nm to 600 nm. Furthermore, the thickness of the capping layer is preferably, for example, 30 nm to 120 nm, more preferably 40 nm to 80 nm. In this case, good light extraction efficiency is obtained. It should be noted that the thickness of the capping layer can be appropriately varied depending on the type of light-emitting material used in the light-emitting element, the thickness of the organic EL element other than the capping layer, etc.

[0075] As the anode of the organic EL element in this embodiment, an electrode material with a high work function, such as ITO or gold, is used.

[0076] As the hole injection layer of the organic EL element in this embodiment, arylamine compounds with a structure in which three or more triphenylamine structures are linked by single bonds or divalent groups without heteroatoms can be used. Examples of such arylamine compounds include starburst-type triphenylamine derivatives, various triphenylamine tetramers, porphyrin compounds represented by copper phthalocyanine, acceptor heterocyclic compounds such as hexacyanoazitrimethylene, and coating-type polymers. They can be formed into films individually, or used as monolayers mixed with other materials to form films. In addition, they can be stacked structures of layers formed individually, layers mixed to form films, or layers formed individually and layers mixed to form films. In addition to vapor deposition, these materials can also be used to form thin films by known methods such as spin coating and inkjet printing.

[0077] As the hole transport layer of the organic EL element in this embodiment, benzidine derivatives such as N,N'-diphenyl-N,N'-bis(m-tolyl)benzidine (hereinafter referred to as TPD), N,N'-diphenyl-N,N'-bis(α-naphthyl)benzidine (hereinafter referred to as NPD), and N,N,N',N'-tetraphenylbenzidine can be used; 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter referred to as TAPC) and the like can also be used. In particular, arylamine compounds having a structure in which two triphenylamine structures are linked by a single bond or a divalent group without heteroatoms are preferred. Examples of such arylamine compounds include N,N,N',N'-tetraphenylbenzidine. Furthermore, arylamine compounds having a structure in which three or more triphenylamine structures are linked by a single bond or a divalent group without heteroatoms are preferred. Examples of such arylamine compounds include various triphenylamine trimers and tetramers. They can be formed into films individually, or used as monolayers mixed with other materials to form films. Furthermore, they can be stacked as layers formed individually, layers mixed together, or layers formed individually and layers mixed together. Additionally, coating-type polymers such as poly(3,4-ethylenedioxythiophene) (hereinafter referred to as PEDOT) / poly(styrene sulfonic acid) (hereinafter referred to as PSS) can be used as hole injection and transport layers. Besides vapor deposition, these materials can also be used to form films using known methods such as spin coating and inkjet printing.

[0078] Furthermore, in the hole injection layer or hole transport layer, substances obtained by further p-doping the material normally used in this layer with tribromophenylamine hexachloroantimony, axial ene derivatives (for example, see Patent Document 3), etc., can be used. Additionally, polymeric compounds having structures containing benzidine derivatives such as TPD in part of their structure can be used.

[0079] As the electron blocking layer of the organic EL element in this embodiment, carbazole derivatives such as 4,4',4''-tris(N-carbazole-9-yl)triphenylamine (hereinafter referred to as TCTA), 9,9-bis[4-(carbazole-9-yl)phenyl]fluorene, 1,3-bis(carbazole-9-yl)phenyl (hereinafter referred to as mCP), and 2,2-bis(4-carbazole-9-yl-phenyl)adamantane (hereinafter referred to as Ad-Cz), as well as compounds with triphenylsilyl and triarylamine structures, represented by 9-[4-(carbazole-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene, can be used. These compounds are compounds with electron blocking properties. They can be formed into films individually, or used as monolayers mixed with other materials to form films. They can be in the form of layers formed individually, layers mixed together, or stacked structures of layers formed individually and layers mixed together. Besides vapor deposition, these materials can also be thin film formed using known methods such as spin coating and inkjet printing.

[0080] As the light-emitting layer of the organic EL element in this embodiment, in addition to metal complexes of hydroxyquinoline derivatives, primarily Alq3, various metal complexes, anthracene derivatives, bis(styrene)benzene derivatives, pyrene derivatives, oxazole derivatives, poly(p-phenylene)ethylene derivatives, etc., can also be used. Alternatively, the light-emitting layer can be composed of a host material and a dopant material. Anthracene derivatives are preferably used as the host material. Furthermore, in addition to the above-mentioned light-emitting materials, heterocyclic compounds with a partial structure having an indole ring as a fused ring, heterocyclic compounds with a partial structure having a carbazole ring as a fused ring, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, polydialkylfluorene derivatives, etc., can also be used. As dopant materials, quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, aminostyrene derivatives, etc., can be used; green light-emitting materials are particularly preferred. They can form films individually, or they can be used as monolayers mixed with other materials to form films. They can be layers that form films individually, layers that form films mixed together, or layers that form films individually and layers that form films mixed together.

[0081] Alternatively, phosphorescent emitters can be used as the luminescent material. Phosphorescent emitters can be metal complexes such as iridium and platinum. Green phosphorescent emitters such as Ir(ppy)3, cyan phosphorescent emitters such as Firpic and Fir6, and red phosphorescent emitters such as Btp2Ir(acac) are used, with green phosphorescent emitters being particularly preferred. As the host material, carbazole derivatives such as 4,4'-bis(N-carbazolyl)biphenyl (hereinafter referred to as CBP), TCTA, and mCP can be used as host materials for hole injection and transport. As the host material for electron transport, p-bis(triphenylsilyl)benzene (hereinafter referred to as UGH2) and 2,2',2”-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter referred to as TPBI) can be used. Using such host materials enables the fabrication of high-performance organic EL devices.

[0082] Regarding the doping of phosphorescent luminescent materials into the host material, in order to avoid concentration quenching, it is preferable to dopant by co-evaporation in a range of 1 to 30 weight percent relative to the total luminescent layer.

[0083] In addition, materials that emit delayed fluorescence, such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN CDCB derivatives, can also be used as luminescent materials. (For example, see Non-Patent Document 7) Besides vapor deposition, these materials can also be formed into thin films using known methods such as spin coating and inkjet printing.

[0084] As the hole-blocking layer of the organic EL element in this embodiment, metal complexes of phenanthroline derivatives such as copper bath (hereinafter referred to as BCP), metal complexes of hydroxyquinoline derivatives such as bis(2-methyl-8-quinoline)-4-phenylphenol aluminum(III) (hereinafter referred to as BAlq), various rare earth complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, benzo[a]azole derivatives, etc., can be used. These compounds have hole-blocking properties. These materials can also serve as electron transport layer materials. They can be formed into films individually, or used as monolayers mixed with other materials to form films. They can be in the form of layers formed individually, layers mixed together, or layers formed individually and layers mixed together in a stacked structure. In addition to vapor deposition, these materials can also be formed into thin films by known methods such as spin coating and inkjet printing.

[0085] As the electron transport layer of the organic EL element in this embodiment, in addition to metal complexes of hydroxyquinoline derivatives such as Alq3 and BAlq, various metal complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, pyridine derivatives, benzimidazole derivatives, benzoxazole derivatives, thiadiazole derivatives, anthracene derivatives, carbodiimide derivatives, quinoxaline derivatives, pyridinoline derivatives, phenanthroline derivatives, thiophene derivatives, etc., can be used as individual films, or as monolayers mixed with other materials to form films. They can form stacked structures of individual layers, mixed layers, or individual layers and mixed layers. In addition to vapor deposition, these materials can also be used to form thin films by known methods such as spin coating and inkjet printing.

[0086] As the electron injection layer of the organic EL element in this embodiment, alkali metal salts such as lithium fluoride and cesium fluoride; alkaline earth metal salts such as magnesium fluoride; metal complexes of hydroxyquinoline derivatives such as lithium hydroxyquinoline; metal oxides such as aluminum oxide; or metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs) can be used. In preferred selections of the electron transport layer and the cathode, these can be omitted.

[0087] Furthermore, in the electron injection layer or electron transport layer, a substance obtained by further N-doping a metal such as cesium with the material typically used in that layer can be used.

[0088] As the cathode of the organic EL element in this embodiment, an electrode material with a low work function, such as aluminum, is used; an alloy with an even lower work function, such as magnesium-silver alloy, magnesium-calcium alloy, magnesium-indium alloy, or aluminum-magnesium alloy; ITO; IZO, etc., are used as electrode materials.

[0089] As the capping layer for the organic EL element in this embodiment, amine compounds represented by the above general formula (1) or (1a) are preferably used. They can be formed into films individually, or they can be used as monolayers mixed with other materials to form films. They can be in a stacked structure of layers formed individually, layers mixed together, or layers formed individually and layers mixed together. In addition to vapor deposition, these materials can also be used to form thin films by known methods such as spin coating and inkjet printing.

[0090] It should be noted that the above description refers to organic EL elements with a top-emitting structure, but this embodiment is not limited to this. The same method can also be applied to organic EL elements with a bottom-emitting structure and organic EL elements with a dual-emitting structure that emits light from both the top and bottom sides. In these cases, the electrodes located in the direction that extracts light from the emitting element to the outside need to be transparent or semi-transparent.

[0091] The refractive index of the material constituting the capping layer is preferably greater than that of the adjacent electrodes. That is, the light extraction efficiency in the organic EL element is improved through the capping layer; however, for optimal light interference, a higher reflectivity at the interface between the capping layer and the material in contact with it is more effective. Therefore, the refractive index of the material constituting the capping layer is preferably greater than that of the adjacent electrodes; a refractive index of 1.90 or higher is acceptable, but 2.00 or higher is more preferable.

[0092] As an example of the method for manufacturing the organic EL element in this embodiment, for example, such as Figure 6 As shown, a method for manufacturing a metal anode 2 by pre-forming a reflective ITO electrode as a metal anode on a glass substrate 1, and then sequentially depositing a hole injection layer 3, a first hole transport layer 4, a second hole transport layer 5, a light-emitting layer 6, an electron transport layer 7, an electron injection layer 8, a cathode 9, and a capping layer 10 thereon. The capping layer 10 contains an amine compound represented by the above general formula (1) or formula (1a).

[0093] The embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments as long as it does not depart from its spirit.

[0094] Example

[0095] [Example 1]

[0096] <Synthesis of Exemplary Compound (1-18)>

[0097] Add 7.0 g of 4-(3-dibenzofuranyl)aniline, 16.3 g of 2-(4-bromophenyl)benzoxazole, 7.8 g of sodium tert-butoxide, and 70 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.7 g of tris(dibenzylacetone)dipalladium(O) and 0.7 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0098] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization with toluene solvent was collected to obtain 12.3 g of yellow powder of the illustrative compound (1-18) (yield 70.6%).

[0099] [Chemistry 4]

[0100] The structure of the obtained yellow powder was identified using NMR.

[0101] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0102] δ (ppm) = 8.23-8.20 (4H), 8.05-7.99 (2H), 7.84-7.50 (10H), 7.41-7.32 (11H).

[0103] [Example 2]

[0104] <Synthesis of Exemplary Compound (1-6)>

[0105] Add 6.1 g of 4-(3-dibenzofuranyl)aniline, 15.0 g of 2-(4-bromophenyl)benzothiazole, 6.8 g of sodium tert-butoxide, and 60 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.7 g of tris(dibenzylacetone)dipalladium(O) and 0.6 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0106] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization with toluene solvent was collected to obtain yellow powder of the illustrative compounds (1-6): 9.1 g (yield 57.1%).

[0107] [Chemistry 5]

[0108] The structure of the obtained yellow powder was identified using NMR.

[0109] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0110] 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).

[0111] [Example 3]

[0112] <Synthesis of Exemplary Compound (1-17)>

[0113] Add 5.3 g of 4-(4-dibenzofuranyl)aniline, 12.3 g of 2-(4-bromophenyl)benzoxazole, 5.9 g of sodium tert-butoxide, and 50 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.6 g of tris(dibenzylacetone)dipalladium(O) and 0.5 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0114] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization with toluene solvent was collected to obtain 6.8 g of yellow powder of the illustrative compound (1-17) (yield 51.5%).

[0115] [Chemistry 6]

[0116] The structure of the obtained yellow powder was identified using NMR.

[0117] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0118] 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).

[0119] [Example 4]

[0120] <Synthesis of Exemplary Compound (1-5)>

[0121] Add 5.3 g of 4-(4-dibenzofuranyl)aniline, 13.1 g of 2-(4-bromophenyl)benzothiazole, 5.9 g of sodium tert-butoxide, and 100 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.6 g of tris(dibenzylacetone)dipalladium(O) and 0.5 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0122] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization with toluene solvent was collected to obtain yellow powder of the illustrative compounds (1-5): 7.5 g (yield 54.15%).

[0123] [Chemistry 7]

[0124] The structure of the obtained yellow powder was identified using NMR.

[0125] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0126] δ(ppm)=8.10-7.91(12H), 7.68-7.64(2H), 7.54-7.33(13H).

[0127] [Example 5]

[0128] <Synthesis of Exemplary Compound (1-19)>

[0129] Add 7.0 g of 4-(2-dibenzofuranyl)aniline, 16.3 g of 2-(4-bromophenyl)benzoxazole, 7.8 g of sodium tert-butoxide, and 70 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.7 g of tris(dibenzylacetone)dipalladium(O) and 0.7 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0130] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization with toluene solvent was collected to obtain yellow powder of exemplary compound (1-19): 9.9 g (yield 56.9%).

[0131] [Chemistry 8]

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

[0133] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0134] 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).

[0135] [Example 6]

[0136] <Synthesis of Exemplary Compound (1-7)>

[0137] Add 5.0 g of 4-(2-dibenzofuranyl)aniline, 12.3 g of 2-(4-bromophenyl)benzothiazole, 5.6 g of sodium tert-butoxide, and 50 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.5 g of tris(dibenzylacetone)dipalladium(O) and 0.5 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0138] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization purification using monochlorobenzene solvent was collected to obtain 8.5 g of yellow powder of the illustrative compounds (1-7) (yield 65.0%).

[0139] [Chemistry 9]

[0140] The structure of the obtained yellow powder was identified using NMR.

[0141] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0142] 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).

[0143] [Example 7]

[0144] <Synthesis of Exemplary Compound (1-13)>

[0145] Add 5.0 g of 4-(4-dibenzothiophene)aniline, 11.0 g of 2-(4-bromophenyl)benzoxazole, 5.2 g of sodium tert-butoxide, and 50 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.5 g of tris(dibenzylacetone)dipalladium(O) and 0.4 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0146] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization with toluene solvent was collected to obtain 10.6 g of yellow powder of the illustrative compounds (1-13) (yield 88.2%).

[0147] [Chemistry 10]

[0148] The structure of the obtained yellow powder was identified using NMR.

[0149] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0150] 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).

[0151] [Example 8]

[0152] <Synthesis of Exemplary Compound (1-1)>

[0153] Add 5.0 g of 4-(4-dibenzothiophene)aniline, 11.6 g of 2-(4-bromophenyl)benzothiazole, 5.2 g of sodium tert-butoxide, and 50 ml of toluene to the reaction vessel, and purge with nitrogen for 30 minutes. Add 0.5 g of tris(dibenzylacetone)dipalladium(O) and 0.4 g of a 50% (w / v) toluene solution of tris-(tert-butyl)phosphine, and stir under reflux overnight.

[0154] After natural cooling, dispersion washing was carried out at 80°C, insoluble matter was filtered out, and the filtrate was concentrated to obtain crude product. The solid precipitated from the crude product by crystallization purification with monochlorobenzene solvent was collected to obtain a yellow powder of the illustrative compound (1-1): 9.1 g (yield 72.22%).

[0155] [Chemistry 11]

[0156] The structure of the obtained yellow powder was identified using NMR.

[0157] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0158] 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).

[0159] [Example 9]

[0160] For amine compounds represented by general formula (1) or (1a), a high-sensitivity differential scanning calorimeter (Burcal) is used. Melting point and glass transition temperature determined by E-E-S (manufactured by DSC3100SA).

[0161] Melting point Glass transition temperature

[0162] Compound of Example 1 - °C 121 °C

[0163] Compound of Example 2 - °C 119 °C

[0164] Compound of Example 3 - °C 125 °C

[0165] Compound of Example 4 - °C 122 °C

[0166] Compound of Example 5 - °C 121 °C

[0167] Compound of Example 6 - °C 118 °C

[0168] Compound of Example 7 247℃ 127℃

[0169] Compound of Example 8 - °C 126 °C

[0170] Amine compounds represented by general formula (1) or (1a) have glass transition temperatures above 100°C, indicating that the thin film state is stable.

[0171] [Example 10]

[0172] An 80 nm thick vapor-deposited film was fabricated on a silicon substrate using an amine compound represented by general formula (1) or (1a). For the fabricated samples, 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, comparative compounds (2-1), (2-2), (2-3), and (2-4) with the following structural formulas were also measured (see, for example, Patent Document 4). The measurement results are summarized in Table 1.

[0173] [Chemistry 12]

[0174] [Chemistry 13]

[0175] [Chemistry 14]

[0176] [Chemistry 15]

[0177] [Table 1]

[0178] Thus, the compound of the present invention has a refractive index of 1.90 or higher at wavelengths from 500 nm to 570 nm, which is equal to or higher than that of the comparative compound, and this can be expected to improve the light extraction efficiency in organic EL devices. Furthermore, regarding the extinction coefficient at wavelengths from 400 nm to 410 nm, the comparative compound has an extinction coefficient of 0.03 to 0.45, while the compound of the present invention has an extinction coefficient of 0.53 to 1.08. This demonstrates sufficient absorption of sunlight at wavelengths from 400 nm to 410 nm without affecting the materials inside the device.

[0179] [Example 11]

[0180] Regarding absorbance, using the compound of the present invention, the concentration is adjusted to 10 with a toluene solution. -5The absorbance was measured at wavelengths of 400 nm and 410 nm using a toluene solution at a concentration of mol / L. Regarding the absorbance coefficient, the concentration was adjusted to 5 × 10⁻⁶ mol / L. -6 mol / L, 1×10 -5 mol / L, 1.5×10 -5 mol / L, 2.0×10 -5 Four concentrations of mol / L were measured using a UV-Vis-NIR spectrophotometer (Japan Spectrophotometer, V-650), and the absorbance coefficients were calculated from the standard curve. For comparison, the comparative compounds (2-1), (2-2), (2-3), and (2-4) with the above structural formulas were also measured. The results are summarized in Table 2.

[0181] [Table 2]

[0182] Thus, regarding absorbance at a wavelength of 400 nm, the comparative compound has an absorbance of 0.02 to 0.60, while the compound of the present invention has an absorbance of 0.74 to 1.38. The compound of the present invention has a large value. Regarding absorbance at 410 nm, the comparative compound has an absorbance of 0.00 to 0.21, while the compound of the present invention has an absorbance of 0.27 to 1.18. The compound of the present invention has a large value. This shows that the compound of the present invention sufficiently absorbs sunlight at wavelengths of 400 nm to 410 nm, and furthermore, regarding the absorbance coefficient, the compound of the present invention has a value of 100,000 or more. That is, it shows that the compound of the present invention sufficiently absorbs light under the same concentration conditions. In addition, it shows that, regarding thin films, the thicker the film, the more sufficient the light absorption, making it a material with excellent lightfastness.

[0183] [Example 12]

[0184] Regarding organic EL devices, such as Figure 6 As shown, a reflective ITO electrode is pre-formed on a glass substrate 1 as a metal anode 2, and a hole injection layer 3, a first hole transport layer 4, a second hole transport layer 5, a light-emitting layer 6, an electron transport layer 7, an electron injection layer 8, a cathode 9, and a capping layer 10 are sequentially deposited on it.

[0185] Specifically, a glass substrate 1, consisting of a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film, was ultrasonically cleaned in isopropanol for 20 minutes and then dried on a heating plate heated to 250°C for 10 minutes. After a 2-minute UV ozone treatment, the ITO-coated glass substrate was placed in a vacuum evaporation machine, and the pressure was reduced to below 0.001 Pa. Next, as a hole injection layer 3, an electron acceptor (Acceptor-1) and a compound (3-1) of the following structural formula were binary deposited at a deposition rate of Acceptor-1:compound (3-1) = 3:97, covering the metal anode 2, to form a 10 nm thick film. On this hole injection layer 3, a first hole transport layer 4, consisting of a compound (3-1) of the following structural formula, was formed with a thickness of 70 nm. On the first hole transport layer 4, a compound (3-2) of the following structural formula is formed as a second hole transport layer 5 with a film thickness of 10 nm. On the second hole transport layer 5, a light-emitting layer 6 is formed by binary deposition of compounds (3-3) and (3-4) of the following structural formulas at a deposition rate ratio of (3-3):(3-4) = 5:95, with a film thickness of 40 nm. On the light-emitting layer 6, a electron transport layer 7 is formed by binary deposition of compounds (3-5) and (3-6) of the following structural formulas at a deposition rate ratio of (3-5):(3-6) = 50:50, with a film thickness of 30 nm. On the electron transport layer 7, a lithium fluoride is formed as an electron injection layer 8 with a film thickness of 1 nm.

[0186] On the electron injection layer 8, a magnesium-silver alloy is formed as the cathode 9 with a film thickness of 12 nm. Finally, as the capping layer 10, the compounds of Example 1 (1-18) are formed with a film thickness of 60 nm. The characteristics of the manufactured organic EL element are measured in atmospheric air at room temperature.

[0187] The results of measuring the luminescence properties of the manufactured organic EL elements by applying a DC voltage are summarized in Table 3.

[0188] [Chemistry 16]

[0189] [Chemistry 17]

[0190] [Chemistry 18]

[0191] [Chemistry 19]

[0192] [Chemistry 20]

[0193] [Chemistry 21]

[0194] [Chemistry 22]

[0195] [Chemistry 23]

[0196] [Example 13]

[0197] Except that in Example 12, compounds (1-6) of Example 2 were used instead of compounds (1-18) of Example 1 as the material for the capping layer 10, the organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0198] [Chemistry 24]

[0199] [Example 14]

[0200] Except that in Example 12, compounds (1-17) of Example 3 were used instead of compounds (1-18) of Example 1 as the material for the capping layer 10, the organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0201] [Chemistry 25]

[0202] [Example 15]

[0203] Except that in Example 12, compounds (1-5) of Example 4 were used instead of compounds (1-18) of Example 1 as the material for the capping layer 10, the organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0204] [Chemistry 26]

[0205] [Example 16]

[0206] Except that in Example 12, compounds (1-19) of Example 5 were used instead of compounds (1-18) of Example 1 as the material for the capping layer 10, the organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0207] [Chemistry 27]

[0208] [Example 17]

[0209] Except that in Example 12, compounds (1-7) of Example 6 were used instead of compounds (1-18) of Example 1 as the material for the capping layer 10, the organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0210] [Chemistry 28]

[0211] [Example 18]

[0212] Except that in Example 12, compounds (1-13) of Example 7 were used instead of compounds (1-18) of Example 1 as the material for the capping layer 10, the organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0213] [Chemistry 29]

[0214] [Example 19]

[0215] Except that in Example 12, 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 organic EL element was manufactured under the same conditions. The characteristics of the manufactured organic EL element were measured in atmospheric air at room temperature. The results of the measurement of the luminescence characteristics of the manufactured organic EL element when a DC voltage was applied are summarized in Table 3.

[0216] [Chemistry 30]

[0217] [Comparative Example 1]

[0218] For comparison, organic EL elements were manufactured under the same conditions, except that in Example 7, the comparative compound (2-1) with a film thickness of 60 nm was used instead of compound (1-18) of Example 1 as the capping layer 10. The characteristics of the manufactured organic EL elements were measured in atmospheric air at room temperature. The results of the luminescence characteristics obtained by applying a DC voltage to the manufactured organic EL elements are summarized in Table 3.

[0219] [Chemistry 31]

[0220] [Comparative Example 2]

[0221] For comparison, organic EL elements were manufactured under the same conditions, except that in Example 7, the comparative compound (2-2) with a film thickness of 60 nm was used instead of compound (1-18) of Example 1 as the capping layer 10. The characteristics of the manufactured organic EL elements were measured in atmospheric air at room temperature. The results of the luminescence characteristics obtained by applying a DC voltage to the manufactured organic EL elements are summarized in Table 3.

[0222] [Chemistry 32]

[0223] [Comparative Example 3]

[0224] For comparison, organic EL elements were manufactured under the same conditions, except that in Example 7, comparative compounds (2-3) with a film thickness of 60 nm were used instead of compounds (1-18) from Example 1 as the capping layer 10. The characteristics of the manufactured organic EL elements were measured in atmospheric air at room temperature. The results of the luminescence characteristics obtained by applying a DC voltage to the manufactured organic EL elements are summarized in Table 3.

[0225] [Chemistry 33]

[0226] [Comparative Example 4]

[0227] For comparison, organic EL elements were manufactured under the same conditions, except that in Example 7, comparative compounds (2-4) with a film thickness of 60 nm were formed instead of compounds (1-18) of Example 1 as the capping layer 10. The characteristics of the manufactured organic EL elements were measured in atmospheric air at room temperature. The results of the luminescence characteristics obtained by applying a DC voltage to the manufactured organic EL elements are summarized in Table 3.

[0228] [Chemistry 34]

[0229] Table 3 summarizes the results obtained from measuring the lifetime of organic EL devices manufactured in Examples 12-19 and Comparative Examples 1-4. The lifetime of the devices is used as the measurement result for a 10 mA / cm² test. 2 When driven by a constant current, the time it takes for the initial brightness to decay to 95% when it is set to 100% is measured.

[0230] [Table 3]

[0231] As shown in Table 3, for a current density of 10 mA / cm² 2 Regarding the driving voltage, it is approximately the same in the elements using comparative examples 1-4 and the elements of embodiments 12-19 of the present invention. In contrast, the elements of embodiments 12-19 of this embodiment show significant improvements in brightness, luminous efficiency, power efficiency, and lifetime compared to the elements using comparative examples 1-4. This demonstrates that by including a material with a high refractive index suitable for the organic EL element of this embodiment in the capping layer, the light extraction efficiency can be significantly improved.

[0232] Industrial availability

[0233] As described above, the amine compound represented by general formula (1), suitable for use in the organic EL element of the present invention, has a high absorption coefficient, a high refractive index, can significantly improve light extraction efficiency, and has a stable thin film state, thus making it an excellent compound for use in organic EL elements. By using this compound to manufacture organic EL elements, high efficiency can be obtained while improving durability and lightfastness in a way that absorbs sunlight without affecting the internal materials of the element. In addition, by using this compound, which does not have absorption in the respective wavelength regions of cyan, green, and red, it is particularly suitable for displaying images with good color purity, vividness, and brightness. For example, it can be gradually developed for applications in household appliances and lighting.

[0234] Explanation of reference numerals in the attached figures

[0235] 1. Glass substrate

[0236] 2 Metal Anode

[0237] 3. Hole injection layer

[0238] 4 First Hole Transport Layer

[0239] 5. Second Hole Transport Layer

[0240] 6. Light-emitting layer

[0241] 7. Electron Transport Layer

[0242] 8 Electron Injection Layer

[0243] 9 Cathode

[0244] 10 capping layers

Claims

1. An organic electroluminescent element, comprising, in sequence, an anode, a hole injection layer, a first hole transport layer, a second hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a cathode, and a capping layer, characterized in that, The refractive index of the capping layer material is greater than 1.90 at wavelengths between 500 nm and 570 nm. The capping layer contains a compound (1-1) represented by the following formula (1-1). The first hole transport layer contains a compound (3-1) represented by the following formula (3-1). 。 2. The organic electroluminescent element according to claim 1, wherein, The thickness of the capping layer is in the range of 30nm to 120nm.

3. A method for manufacturing an organic electroluminescent element, wherein the method for manufacturing an organic electroluminescent element as described in claim 1 or 2 is characterized in that, include: The anode is a reflective ITO electrode, and the process of forming the reflective ITO electrode on a glass substrate; And a process of vapor deposition on the product formed by the aforementioned process, in the order of hole injection layer, first hole transport layer, second hole transport layer, light-emitting layer, electron transport layer, electron injection layer, cathode, and capping layer.

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