organic electroluminescence element

Abstract

The purpose of the present invention is to provide an organic EL element having high efficiency, low drive voltage, and a long lifespan by using a material for an organic EL element having excellent hole injection / transport performance, excellent electronic blocking ability, and excellent stability and durability in a thin film state and further by combining the material with various materials for the organic EL element having excellent hole and electron injection / transport performance, excellent electronic blocking ability, and excellent stability and durability in a thin film state so that characteristics of the materials can be effectively exhibited.　The present invention is an organic electroluminescence device which has at least a hole transport layer, a light emitting layer, and an electron transport layer from a positive electrode side between the positive electrode and the negative electrode in this order and in which the hole transport layer contains a triarylamine compound having a specific structure.

Description

[Technical Field]

[0001] The present invention relates to an organic electroluminescent element, which is a self-emitting element suitable for various display devices, and more particularly to an organic electroluminescent element (hereinafter abbreviated as organic EL element) using a specific arylamine 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 active research has been conducted on them.

[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, making 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, achieving an EL brightness of 1000 cd / m at a voltage of 10 V or less. 2 Such high brightness has been achieved (see, for example, Patent Documents 1 and 2).

[0004] To date, many improvements have been made to organic EL devices for practical use, and high efficiency and durability have been achieved by further subdividing the role of each layer in the laminated structure to form an electroluminescent device 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 provided in this order on a substrate (see, for example, Non-Patent Document 1).

[0005] Furthermore, attempts have been made to utilize triplet excitons in order to further improve luminous efficiency, and the use of phosphorescent compounds has been investigated (see, for example, Non-Patent Document 2). Furthermore, devices that utilize light emission by thermally activated delayed fluorescence (TADF) have also been developed. In 2011, Adachi et al. of Kyushu University achieved an external quantum efficiency of 5.3% using a device that uses a thermally activated delayed fluorescence material (see, for example, Non-Patent Document 3).

[0006] The light-emitting layer can also be prepared by doping a charge-transporting compound, generally called a host material, with a fluorescent compound, a phosphorescent compound, or a material that emits delayed fluorescence. As described in the aforementioned non-patent document, the selection of organic materials in an organic EL device has a significant impact on various properties of the device, such as efficiency and durability (see, for example, non-patent document 2).

[0007] In organic EL devices, charges injected from both electrodes recombine in the light-emitting layer to emit light. However, it is important to efficiently transfer both charges (holes and electrons) to the light-emitting layer, making it necessary to achieve a device with excellent carrier balance. Furthermore, by improving hole injection and electron blocking properties (blocking electrons injected from the cathode), the probability of holes and electrons recombining can be increased, and by confining excitons generated in the light-emitting layer, high luminous efficiency can be achieved. Therefore, the role of hole transport materials is important, and hole transport materials with high hole injection properties, high hole mobility, high electron blocking properties, and high durability against electrons are required.

[0008] Furthermore, the heat resistance and amorphous nature of the material are also important factors in determining the lifespan of the element. Materials with low heat resistance will undergo thermal decomposition even at low temperatures due to the heat generated when the element is in operation, causing the material to deteriorate. Materials with low amorphous nature will undergo crystallization of the thin film even in a short period of time, causing the element to deteriorate. For this reason, the materials used must have high heat resistance and good amorphous nature.

[0009] N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (NPD) and various aromatic amine derivatives have been known to be hole transport materials used in organic EL devices up to now (see, for example, Patent Document 1 and Patent Document 2). NPD has good hole transport ability, but its glass transition temperature (Tg), which is an index of heat resistance, is low at 96°C, and crystallization occurs under high temperature conditions, resulting in a deterioration of device characteristics (see, for example, Non-Patent Document 4). In addition, among the aromatic amine derivatives described in the above patent documents, there are those with a hole mobility of 10 -3 cm2 Although compounds with excellent mobility of 1 / Vs or more are known (see, for example, Patent Documents 1 and 2), their electron blocking properties are insufficient, so some electrons pass through the light-emitting layer, preventing improvements in luminous efficiency. For this reason, in order to further improve efficiency, materials with better electron blocking properties, more stable thin films, and high heat resistance are needed. Furthermore, although highly durable aromatic amine derivatives have been reported (see, for example, Patent Document 3), they were used as charge transport materials in electrophotographic photoreceptors, and there have been no examples of their use in organic EL devices.

[0010] Arylamine compounds having a substituted carbazole structure have been proposed as compounds with improved properties such as heat resistance and hole injection properties (see, for example, Patent Document 4 and Patent Document 5). However, in devices using these compounds in the hole injection layer or hole transport layer, although the heat resistance and luminous efficiency have been improved, they are still not sufficient, and further reduction in driving voltage and further improvement in luminous efficiency are required.

[0011] To improve the device characteristics and increase the yield of device fabrication, there is a demand for devices that combine materials with excellent hole and electron injection and transport properties, thin film stability, and durability, allowing holes and electrons to be recombined with high efficiency, have high luminous efficiency, low driving voltage, and a long lifespan.

[0012] Furthermore, in order to improve the device characteristics of organic EL devices, there is a demand for devices that combine materials with excellent hole and electron injection and transport properties, thin film stability, and durability, and that have a good carrier balance, high efficiency, low driving voltage, and long life. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] US5792557 [Patent Document 2] US5639914 [Patent Document 3] US7799492 [Patent Document 4] US8021764 [Patent Document 5] US8394510 [Patent Document 6] Korean Patent Publication No. 10-2018-0051356 [Patent Document 7] EP2684932 [Non-patent literature]

[0014] [Non-Patent Document 1] Proceedings of the 9th Seminar of the Japan Society of Applied Physics, pp. 55-61 (2001) [Non-patent document 2] Proceedings of the 9th Seminar of the Japan Society of Applied Physics, pp. 23-31 (2001) [Non-patent document 3] Appl.Phys.Let.,98,083302(2011) [Non-patent document 4] Proceedings of the 3rd Regular Meeting of the Organic EL Symposium, pages 13-14 (2006) Summary of the Invention

[0015] The object of the present invention is to provide an organic EL device that is highly efficient, has a low driving voltage, and has a long life, by using a material for organic EL devices that has excellent hole injection / transport performance, electron blocking ability, and stability and durability in a thin film state, and by combining the material with various other materials for organic EL devices that have excellent hole and electron injection / transport performance, electron blocking ability, stability and durability in a thin film state, so that the properties of each material can be effectively exhibited.

[0016] The physical properties that the organic compound used in the present invention should have include (1) good hole injection properties, (2) high hole mobility, (3) a stable thin film state, and (4) excellent heat resistance.The physical properties that the organic EL device to be provided by the present invention should have include (1) high luminous efficiency and power efficiency, (2) low practical driving voltage, and (3) long life.

[0017] In order to achieve the above object, the present inventors have intensively investigated various triarylamine compounds, focusing on the advantages of triarylamine compounds in terms of their excellent hole injection / transport capabilities and thin film stability and durability, and have found that holes injected from the anode side can be efficiently transported when a triarylamine compound having a specific structure is used as a material for the hole transport layer. As a result, the present invention has been completed.

[0018] That is, the present invention provides the following organic EL device. 1) An organic electroluminescence element having at least a hole transport layer, a light-emitting layer, and an electron transport layer in this order from the anode side between an anode and a cathode, wherein the hole transport layer contains a triarylamine compound represented by the following general formula (1):

[0019] [ka] (In the formula, A represents a monovalent group represented by the following general formula (2-1). B represents a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group. C represents a monovalent group represented by the following general formula (2-1), a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group.

[0020] [ka] (In the formula, the dashed line represents the binding site. R1 represents 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. n is the number of R1 and represents an integer of 0 to 3. When n is 2 or 3, multiple R1s bonded to the same benzene ring may be the same or different, and 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. L1 represents a divalent group of a substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocycle, or a substituted or unsubstituted condensed polycyclic aromatic ring. m is the number of L1 and represents an integer of 1 to 3. When m is 2 or 3, L1 may be the same or different from each other. Ar1 and Ar2 may be the same or different and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group.

[0021] The organic electroluminescence device according to 1) above, wherein the monovalent group represented by the general formula (2-1) is a monovalent group represented by the following general formula (2-2):

[0022] [ka] (In the formula, Ar1, Ar2, L1, m, n, and R1 are defined the same as in the general formula (2-1).)

[0023] 3) The organic electroluminescence device according to 1) above, wherein the monovalent group represented by the general formula (2-1) is a monovalent group represented by the following general formula (2-3):

[0024] [ka] (In the formula, Ar1, Ar2, n, and R1 are defined the same as in the general formula (2-1). p represents 0 or 1.)

[0025] 4) The organic electroluminescence device according to 1) above, wherein the monovalent group represented by the general formula (2-1) is a monovalent group represented by the following general formula (2-4):

[0026] [ka] (In the formula, Ar1 and Ar2 are defined the same as in the general formula (2-1). p represents 0 or 1.)

[0027] 5) The organic electroluminescence device according to any one of 1) to 4), wherein the hole transport layer is composed of two layers, a first hole transport layer and a second hole transport layer, and the first hole transport layer contains a triarylamine compound represented by general formula (1).

[0028] Specific examples of the "aromatic hydrocarbon group", "aromatic heterocyclic group" or "condensed polycyclic aromatic group" in the "substituted or unsubstituted aromatic hydrocarbon group", "substituted or unsubstituted aromatic heterocyclic group" or "substituted or unsubstituted condensed polycyclic aromatic group" represented by R1 in the general formulae (2-1) to (2-3) include a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoren ... Examples of such groups include fluoranthenyl, triphenylenyl, pyridyl, pyrimidinyl, triazinyl, furyl, pyrrolyl, thienyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, naphthyridinyl, phenanthrolinyl, acridinyl, and carbolinyl. Other examples include aryl groups having 6 to 30 carbon atoms and heteroaryl groups having 2 to 30 carbon atoms.

[0029] Specific examples of the "aryloxy group" in the "substituted or unsubstituted aryloxy group" represented by R1 in the general formulae (2-1) to (2-3) include a phenyloxy group, a biphenylyloxy group, a terphenylyloxy group, a naphthyloxy group, an anthracenyloxy group, a phenanthrenyloxy group, a fluorenyloxy group, an indenyloxy group, a pyrenyloxy group, and a perylenyloxy group.

[0030] Specific examples of the "C-C linear or branched alkyl group," "C-C cycloalkyl group," or "C-C linear or branched alkenyl group" in the "C-C linear or branched alkyl group which may have a substituent," "C-C cycloalkyl group which may have a substituent," or "C-C linear or branched alkenyl group which may have a substituent" represented by R1 in the general formulae (2-1) to (2-3) include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, vinyl, allyl, isopropenyl, and 2-butenyl.

[0031] Specific examples of the "C 1 to C 6 linear or branched alkyloxy group" or "C 5 to C cycloalkyloxy group" in the "C 1 to C 6 linear or branched alkyloxy group which may have a substituent" or "C 5 to C cycloalkyloxy group" represented by R1 in the general formulae (2-1) to (2-3) include methyloxy, ethyloxy, n-propyloxy, isopropyloxy, n-butyloxy, tert-butyloxy, n-pentyloxy, n-hexyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, cyclooctyloxy, 1-adamantyloxy, and 2-adamantyloxy.

[0032] Examples of the "substituent" in the "substituted aromatic hydrocarbon group," "substituted aromatic heterocyclic group," "substituted fused polycyclic aromatic group," "substituted aryloxy group," "optionally substituted C 1 to C 6 linear or branched alkyl group," "optionally substituted C cycloalkyl group," "optionally substituted C 2 to C 6 linear or branched alkenyl group," "optionally substituted C 1 to C 6 linear or branched alkyloxy group," or "optionally substituted C 2 to C 10 linear alkyloxy group" represented by R1 in the general formulae (2-1) to (2-3) 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 methyloxy group, an ethyloxy group, a propyloxy group, etc. a straight-chain or branched alkyloxy group having 1 to 6 carbon atoms; an alkenyl group such as a vinyl group or an allyl group; an aryloxy group such as a phenyloxy group or a tolyloxy group; an arylalkyloxy group such as a benzyloxy group or a phenethyloxy group; a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, a triphenylenyl group, or the like Examples include aromatic hydrocarbon groups or condensed polycyclic aromatic groups; and aromatic heterocyclic groups such as pyridyl, thienyl, furyl, pyrrolyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, and carbolinyl groups, and these substituents may be further substituted with the substituents exemplified above.Furthermore, these substituents and the benzene ring on which they are substituted, or multiple substituents on the same benzene ring, may be bonded to each other via a single bond, a substituted or unsubstituted methylene group, a substituted or unsubstituted amine group, an oxygen atom, or a sulfur atom to form a ring.

[0033] The "substituted or unsubstituted aromatic hydrocarbon group," "substituted or unsubstituted aromatic heterocyclic group," and "substituted or unsubstituted fused polycyclic aromatic group" represented by Ar1 and Ar2 in the general formulae (2-1) to (2-4) are the same as the "substituted or unsubstituted aromatic hydrocarbon group," "substituted or unsubstituted aromatic heterocyclic group," and "substituted or unsubstituted fused polycyclic aromatic group" represented by R1 in the general formulae (2-1) to (2-3).

[0034] The "substituted or unsubstituted aromatic hydrocarbon group," "substituted or unsubstituted aromatic heterocyclic group," and "substituted or unsubstituted fused polycyclic aromatic group" represented by B and C in general formula (1) are the same as the "substituted or unsubstituted aromatic hydrocarbon group," "substituted or unsubstituted aromatic heterocyclic group," and "substituted or unsubstituted fused polycyclic aromatic group" represented by R1 in the general formulae (2-1) to (2-3).

[0035] In the "divalent group of a substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocycle, or a substituted or unsubstituted fused polycyclic aromatic" represented by L1 in the general formulas (2-1) and (2-2), the "aromatic hydrocarbon", "aromatic heterocycle", or "fused polycyclic aromatic" in the "substituted or unsubstituted aromatic hydrocarbon", "substituted or unsubstituted aromatic heterocycle", or "substituted or unsubstituted fused polycyclic aromatic" specifically includes benzene, biphenyl, terphenyl, tetrakisphenyl, styrene, naphthyl, phenyl ... Examples of such an alkylene include thalene, anthracene, acenaphthalene, fluorene, phenanthrene, indane, pyrene, triphenylene, pyridine, pyrimidine, triazine, pyrrole, furan, thiophene, quinoline, isoquinoline, benzofuran, benzothiophene, indoline, carbazole, carboline, benzoxazole, benzothiazole, quinoxaline, benzimidazole, pyrazole, dibenzofuran, dibenzothiophene, naphthyridine, phenanthroline, and acridine.

[0036] The "divalent group of a substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocycle, or a substituted or unsubstituted fused polycyclic aromatic group" represented by L1 in general formulas (2-1) and (2-2) represents a divalent group obtained by removing two hydrogen atoms from the above-mentioned "aromatic hydrocarbon," "aromatic heterocycle," or "fused polycyclic aromatic group." When these divalent groups have a substituent, examples of the "substituent" include the same as those listed for the "substituent" of the "substituted aromatic hydrocarbon group," "substituted aromatic heterocycle," and "substituted fused polycyclic aromatic group" represented by R1 in the general formulas (2-1) to (2-3), and the possible embodiments are also the same.

[0037] As the monovalent group represented by general formula (2-1) representing A in general formula (1), a monovalent group represented by general formula (2-2) is preferred, a monovalent group represented by general formula (2-3) is more preferred, and a monovalent group represented by general formula (2-4) is particularly preferred.

[0038] In the general formulae (2-1) to (2-4), Ar1 and Ar2 are preferably a "substituted or unsubstituted aromatic hydrocarbon group" or a "substituted or unsubstituted condensed polycyclic aromatic group", more preferably a substituted or unsubstituted phenyl group, naphthyl group, or biphenylyl group, and particularly preferably an unsubstituted phenyl group or an unsubstituted naphthyl group.

[0039] B in general formula (1) is preferably a "substituted or unsubstituted aromatic hydrocarbon group" or a "substituted or unsubstituted condensed polycyclic aromatic group", and more preferably a substituted or unsubstituted phenyl group, naphthyl group, biphenylyl group, phenanthrenyl group, or fluorenyl group.

[0040] C in general formula (1) is preferably a "substituted or unsubstituted aromatic hydrocarbon group" or a "substituted or unsubstituted condensed polycyclic aromatic group", and more preferably a substituted or unsubstituted phenyl group, naphthyl group, biphenylyl group, phenanthrenyl group, or fluorenyl group.

[0041] The triarylamine compound represented by the general formula (1) used in the present invention has the following properties: (1) good hole injection properties, (2) high hole mobility, (3) a stable thin film state, and (4) excellent heat resistance. Therefore, it can be suitably used as a constituent material of the hole transport layer of the organic EL device of the present invention.

[0042] The organic EL device of the present invention, which uses the triarylamine compound represented by the general formula (1) used in the present invention as a constituent material of the hole transport layer, can make maximum use of the hole mobility of the triarylamine compound, and can achieve high efficiency, low driving voltage, and long life because it uses a triarylamine compound that has excellent amorphous properties and is stable in a thin film state.

[0043] Furthermore, in the organic EL device of the present invention, when the hole transport layer is composed of two layers, a first hole transport layer and a second hole transport layer, the first hole transport layer contains the triarylamine compound represented by general formula (1), which not only provides excellent hole injection properties but also blocks electron migration, thereby realizing an organic EL device with higher efficiency and longer life. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 shows structural formulas of compounds 1-1 to 1-12 as examples of triarylamine compounds represented by general formula (1). [Figure 2] FIG. 1 shows the structural formulas of compounds 1-13 to 1-24 as examples of triarylamine compounds represented by general formula (1). [Figure 3] FIG. 1 shows the structural formulas of compounds 1-25 to 1-36 as examples of triarylamine compounds represented by general formula (1). [Figure 4] FIG. 1 shows the structural formulas of compounds 1-37 to 1-48 as examples of triarylamine compounds represented by general formula (1). [Figure 5] FIG. 1 shows the structural formulas of compounds 1-49 to 1-60, which are examples of triarylamine compounds represented by general formula (1). [Figure 6] FIG. 1 shows the structural formulas of compounds 1-61 to 1-72 as examples of triarylamine compounds represented by general formula (1). [Figure 7] FIG. 1 shows the structural formulas of compounds 1-73 to 1-84 as examples of triarylamine compounds represented by general formula (1). [Figure 8] FIG. 1 shows the structural formulas of compounds 1-85 to 1-96 as examples of triarylamine compounds represented by general formula (1). [Figure 9] FIG. 1 shows the structural formulas of compounds 1-97 to 1-105 as examples of triarylamine compounds represented by general formula (1). [Figure 10] 1 is a diagram showing an example of the configuration of an organic EL element of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] Among the triarylamine compounds represented by the general formula (1) that are suitably used in the organic EL device of the present invention, specific examples of preferred compounds are shown in Figs. 1 to 9, but the present invention is not limited to these compounds.

[0046] The triarylamine compound represented by general formula (1) can be purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, sublimation purification, etc. The compound can be identified by NMR analysis. It is preferable to measure the melting point, glass transition point (Tg), and HOMO level (ionization potential) 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 HOMO level is an indicator of hole transport properties and hole blocking properties. The compound used in the organic EL device of the present invention is preferably purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, sublimation purification, etc., and then finally by sublimation purification.

[0047] The melting point and glass transition point (Tg) can be measured, for example, by a high-sensitivity differential scanning calorimeter (manufactured by Bruker AXS, DSC3100SA) using a powder.

[0048] The HOMO level can be determined, for example, by forming a 100 nm thin film on an ITO substrate and measuring it with an ionization potential measuring device (PYS-202, manufactured by Sumitomo Heavy Industries, Ltd.).

[0049] The organic EL device of the present invention may have a structure comprising, in order on a substrate, an anode, a hole transport layer, an emitting layer, an electron transport layer, and a cathode; a hole injection layer between the anode and the hole transport layer; a hole blocking layer between the emitting layer and the electron transport layer; or an electron injection layer between the electron transport layer and the cathode. These multilayer structures may, for example, be configured to function both as a hole injection layer and a hole transport layer, or as an electron injection layer and an electron transport layer. Furthermore, two or more organic layers having the same function may be stacked, such as a two-layer hole transport layer, a two-layer emitting layer, or a two-layer electron transport layer.

[0050] In the structure of the organic EL device of the present invention, the hole transport layer preferably comprises two layers: a first hole transport layer and a second hole transport layer. The first hole transport layer preferably contains a triarylamine compound represented by the general formula (1) that exhibits a suitable energy level and has good hole transport capability, primarily to efficiently transport injected holes to the light-emitting layer. It is more preferable that the first hole transport layer be composed of a triarylamine compound represented by the general formula (1). Furthermore, the second hole transport layer preferably functions as an electron-blocking layer adjacent to the light-emitting layer, preventing electrons from passing through to the hole-transporting layer. This electron blocking is also closely related to the device's lifetime. That is, the structure of the organic EL device of the present invention can more efficiently inject holes into the light-emitting layer and confine electrons injected from the electron transport layer to the light-emitting layer in the light-emitting layer, thereby further improving the device's luminous efficiency and lifetime.

[0051] The anode of the organic EL device of the present invention is made of an electrode material with a large work function, such as ITO or gold.The hole injection layer of the organic EL device of the present invention can be made of triphenylamine-based materials such as starburst triphenylamine derivatives and various triphenylamine tetramers, porphyrin compounds represented by copper phthalocyanine, acceptor heterocyclic compounds such as hexacyanoazatriphenylene, or coating-type polymer materials.

[0052] The hole transport layer of the organic EL device of the present invention uses a triarylamine compound represented by the general formula (1) as a hole transport material. When the hole transport layer consists of two layers, a first hole transport layer and a second hole transport layer, the triarylamine compound represented by the general formula (1) is preferably used only in the first hole transport layer. Other hole transport materials that can be used in combination with or simultaneously with the triarylamine compound represented by the general formula (1) include benzidine derivatives such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (NPD), and N,N,N',N'-tetrabiphenylylbenzidine, 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (TAPC), triarylamine compounds, and various triphenylamine derivatives.

[0053] For the hole injection layer and the first hole transport layer, materials typically used for these layers can be doped with P, such as trisbromophenylaminehexachloroantimony or radialene derivatives (see, for example, Patent Document 7), and polymer compounds having a benzidine derivative structure such as TPD in their partial structure.

[0054] Materials that can be used for the second hole transport layer of the organic EL device of the present invention include compounds having an electron blocking effect, such as carbazole derivatives such as 4,4',4''-tri(N-carbazolyl)triphenylamine (TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (mCP), and 2,2-bis(4-carbazol-9-ylphenyl)adamantane (Ad-Cz), and compounds having a triphenylsilyl group and a triarylamine structure, typified by 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene.

[0055] The light-emitting layer of the organic EL device of the present invention can be formed using metal complexes of quinolinol derivatives such as Alq3, as well as various metal complexes, anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, polyparaphenylenevinylene derivatives, and the like. The light-emitting layer can also be formed using a host material and a dopant material. Anthracene derivatives are preferred as the host material. In addition to the light-emitting materials, heterocyclic compounds having an indole ring as a fused ring substructure, heterocyclic compounds having a carbazole ring as a fused ring substructure, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, polydialkylfluorene derivatives, and the like can also be used. The dopant material can also be pyrene derivatives, quinacridone, coumarin, rubrene, perylene, and their derivatives, benzopyran derivatives, indenophenanthrene derivatives, rhodamine derivatives, aminostyryl derivatives, and the like.

[0056] Phosphorescent emitters can also be used as light-emitting materials. Examples of phosphorescent emitters include metal complexes of iridium and platinum. Green emitters such as Ir(ppy)3, blue emitters such as FIrpic and FIr6, and red emitters such as Btp2Ir(acac) are commonly used. In these cases, hole-injecting and transporting host materials include carbazole derivatives such as 4,4'-di(N-carbazolyl)biphenyl (CBP), TCTA, and mCP. Electron-transporting host materials include p-bis(triphenylsilyl)benzene (UGH2) and 2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBI).

[0057] In order to avoid concentration quenching, the phosphorescent light-emitting material is preferably doped into the host material by co-evaporation in a range of 1 to 30 weight percent based on the entire light-emitting layer.

[0058] Furthermore, it is also possible to use materials that emit delayed fluorescence, such as CDCB derivatives such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN, as light-emitting materials (see, for example, Non-Patent Document 3).

[0059] The hole-blocking layer of the organic EL device of the present invention can be made of compounds having hole-blocking properties, such as phenanthroline derivatives such as bathocuproine (BCP) and metal complexes of quinolinol derivatives such as aluminum(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (hereinafter abbreviated as BAlq), as well as various rare earth complexes, triazole derivatives, triazine derivatives, and oxadiazole derivatives. These materials may also serve as materials for the electron-transporting layer.

[0060] For the electron transport layer of the organic EL device of the present invention, metal complexes of quinolinol derivatives such as Alq3 and BAlq, various metal complexes, triazole derivatives, triazine derivatives, oxadiazole derivatives, pyridine derivatives, pyrimidine derivatives, benzimidazole derivatives, thiadiazole derivatives, anthracene derivatives, carbodiimide derivatives, quinoxaline derivatives, pyridoindole derivatives, phenanthroline derivatives, silole derivatives, and the like can be used.

[0061] The electron injection layer of the organic EL device of the present invention can be made of alkali metal salts such as lithium fluoride and cesium fluoride, alkaline earth metal salts such as magnesium fluoride, metal complexes of quinolinol derivatives such as lithium quinolinol, metal oxides such as aluminum oxide, or metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs). Furthermore, the electron injection layer can be omitted by appropriately selecting the electron transport layer and the cathode.

[0062] 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.

[0063] The cathode of the organic EL device of the present invention is made of an electrode material having a low work function such as aluminum, or an alloy having an even lower work function such as a magnesium-silver alloy, a magnesium-indium alloy, or an aluminum-magnesium alloy.

[0064] The materials used for each layer constituting the organic EL device of the present invention may be formed into a film alone, or may be mixed with other materials to form a single layer, or may be laminated with other layers formed alone, other layers formed as a mixture, or a layer formed as a mixture with a layer formed alone. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing. [Example]

[0065] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.

[0066] [Synthesis Example 1] <Synthesis of bis(4-naphthalen-2-yl-phenyl)-(2',5'-diphenyl-biphenyl-4-yl)-amine (1-4)> A reaction vessel was charged with 10.0 g of bis(4-naphthalen-2-yl-phenyl)amine, 11.0 g of 4-bromo-2',5'-diphenyl-biphenyl, 0.1 g of palladium(II) acetate, 0.2 g of tri(t-butyl)phosphine, and 2.7 g of sodium t-butoxide, and the mixture was refluxed under stirring in toluene for 3 hours. After cooling, the mixture was filtered and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent, yielding 9.0 g of a white powder of bis(4-naphthalen-2-yl-phenyl)-(2',5'-diphenyl-biphenyl-4-yl)amine (1-4) (yield: 52.3%).

[0067] [ka]

[0068] The obtained white powder was 1 The following 39 hydrogen signals were detected by H-NMR (CDCl3), and the structure was identified. δ(ppm)=8.06(2H), 7.92(6H), 7.78(4H), 7.73(1H), 7.68(5H), 7.53(7H), 7.42(1H), 7.39-7.23(9H), 7.14(4H).

[0069] [Synthesis Example 2] Synthesis of (2',5'-diphenyl-biphenyl-4-yl)-(4-naphthalen-1-yl-phenyl)-phenanthren-9-yl-amine (1-58) A reaction vessel was charged with 8.5 g of (2',5'-diphenyl-biphenyl-4-yl)-(4-naphthalen-1-yl-phenyl)-amine, 4.8 g of 9-bromo-phenanthrene, 0.1 g of palladium(II) acetate, 0.3 g of tri(t-butyl)phosphine, and 2.3 g of sodium t-butoxide, and the mixture was refluxed under toluene for 3 hours with stirring. After cooling, the mixture was filtered and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent to obtain 8.3 g of a white powder of (2',5'-diphenyl-biphenyl-4-yl)-(4-naphthalen-1-yl-phenyl)-phenanthren-9-yl-amine (1-58) (yield: 73.1%).

[0070] [ka]

[0071] The obtained white powder was 1 The following 37 hydrogen signals were detected by H-NMR (CDCl3), and the structure was identified. δ(ppm)=8.79(1H), 8.75(1H), 8.14(1H), 8.03(1H), 7.92(1H), 7.85(2H), 7.72(6H) , 7.65(2H), 7.60(1H), 7.50(7H), 7.42(1H), 7.36(3H), 7.27-7.18(6H), 7.09(4H).

[0072] [Synthesis Example 3] Synthesis of (2',5'-diphenyl-biphenyl-4-yl)-(4-naphthalen-2-yl-phenyl)-phenanthren-9-yl-amine (1-59) A reaction vessel was charged with 8.0 g of (2',5'-diphenyl-biphenyl-4-yl)-(4-naphthalen-2-yl-phenyl)-amine, 4.5 g of 9-bromo-phenanthrene, 0.1 g of palladium(II) acetate, 0.2 g of tri(t-butyl)phosphine, and 2.2 g of sodium t-butoxide, and the mixture was refluxed under toluene for 3 hours with stirring. After cooling, the mixture was filtered and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization using a toluene / acetone mixed solvent to obtain 6.6 g of pale yellow powder of (2',5'-diphenyl-biphenyl-4-yl)-(4-naphthalen-2-yl-phenyl)-phenanthren-9-yl-amine (1-59) (yield: 61.7%).

[0073] [ka]

[0074] The obtained pale yellow powder was 1 The following 37 hydrogen signals were detected by H-NMR (CDCl3), and the structure was identified. δ(ppm)=8.79(1H), 8.74(1H), 8.09(1H), 8.01(1H), 7.86(4H), 7.75(1H), 7.71(5H) , 7.66(2H), 7.60(3H), 7.50(5H), 7.39(1H), 7.34-7.23(6H), 7.20(2H), 7.07(4H).

[0075] [Synthesis Example 4] Synthesis of (2”,5”-diphenyl-[1,1';4’,1”]terphenyl-4-yl)-(4-naphthalen-2-yl-phenyl)-phenyl-amine (1-69) A reaction vessel was charged with 6.0 g of (4-naphthalen-2-yl-phenyl)-phenyl-amine, 10.3 g of 4-bromo-2",5"-diphenyl-[1,1';4',1"]terphenyl, 0.1 g of palladium(II) acetate, 0.2 g of tri(t-butyl)phosphine, and 2.3 g of sodium t-butoxide, and the mixture was refluxed overnight in toluene. After cooling, the mixture was filtered and the filtrate was concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: dichloromethane / n-heptane) to obtain 7.1 g of (2",5"-diphenyl-[1,1';4',1"]terphenyl-4-yl)-(4-naphthalen-2-yl-phenyl)-phenyl-amine (1-69) as a white powder (yield: 51.7%).

[0076] [ka]

[0077] The obtained white powder was 1 The following 37 hydrogen signals were detected by H-NMR (CDCl3), and the structure was identified. δ(ppm)=8.04(1H), 7.91(3H), 7.73(5H), 7.66(2H), 7.56(2H), 7.51(7H), 7.42(1H), 7.39-7.18(15H), 7.10(1H).

[0078] [Synthesis Example 5] Synthesis of (2”,5”-diphenyl-[1,1';4’,1”]terphenyl-4-yl)-(4-phenanthren-9-yl-phenyl)-phenyl-amine (1-83) Into a reaction vessel, 11.0 g of (4-phenanthren-9-yl-phenyl)-phenyl-amine, 16.2 g of 4-bromo-2″,5″-[1,1′;4′,1″]terphenyl, 0.1 g of palladium(II) acetate, 0.3 g of tri(t-butyl)phosphine, and 3.7 g of sodium t-butoxide were charged, and the mixture was refluxed and stirred overnight under a toluene solvent. After cooling, the filtrate obtained by filtration was concentrated to obtain a crude product. The obtained crude product was purified by column chromatography (carrier: silica gel, eluent: dichloromethane / n-heptane) to obtain 11.2 g (yield: 48.5%) of a white powder of (2″,5″-diphenyl-[1,1′;4′,1″]terphenyl-4-yl)-(4-phenanthren-9-yl-phenyl)-phenyl-amine (1-83).

[0079] [Chemical Structure]

[0080] Regarding the obtained white powder, 1 39 hydrogen signals were detected by 1H-NMR (CDCl3), and the structure was identified. δ (ppm) = 8.81 (1H), 8.75 (1H), 8. 09 (1H), 7.93 (1H), 7.71 (7H), 7.65 - 7.44 (10H), 7.44 - 7.22 (17H), 7.11 (1H).

[0081] [Synthesis Example 6] [Synthesis of N-(3′-(naphthalen-2-yl)-[1,1′-biphenyl]-4-yl)-N-(4-(naphthalen)-2-yl)phenyl)-5′-phenyl-[1,1′:2′, 1″-terphenyl]-4-amine (1-96)] A reaction vessel was charged with 50.0 g of 4-bromoaniline, 113.9 g of 4,4,5,5-tetramethyl-2-[1,1':4',1''-terphenyl]-2'-yl-1,3,2-dioxaborolane, 350 mL of toluene, 88 mL of ethanol, 80.4 g of potassium carbonate, and 290 mL of water. 6.7 g of tetrakistriphenylphosphine palladium was added, and the mixture was refluxed and stirred for 14 hours. After cooling, the mixture was separated, and the organic layer was washed successively with water and saturated brine and dried over anhydrous magnesium sulfate. The desiccant was removed by filtration, and the filtrate was concentrated. 450 mL of heptane was added to the residue, and the mixture was stirred at room temperature overnight. The solid was collected by filtration to obtain 77.8 g of a yellow-white powder of [1,1':2',1'':4'',1''''-quaterphenyl]-4-amine (yield: 83.3%).

[0082] [ka]

[0083] A reaction vessel was charged with 55.0 g of [1,1':2',1'':4'',1'''-quaterphenyl]-4-amine, 74.9 g of 2-(4-bromophenyl)naphthalene, 28.0 g of sodium t-butoxide, 420 mL of toluene, 0.9 g of tris(dibenzylideneacetone)dipalladium, and 2.4 g of 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, and the mixture was refluxed and stirred for 15 hours. The mixture was cooled to 80°C, and the solids were removed by hot filtration using a funnel lined with Celite. The filtrate was heated and stirred, and 50 g of silica gel was added at 80°C. The mixture was stirred for 1 hour, and the solids were removed by hot filtration. The filtrate was concentrated, and the residue was recrystallized from a toluene / acetone mixed solvent to obtain 69.5 g (yield: 68.3%) of a yellowish-white powder of N-(4-(2-naphthyl)phenyl)-[1,1':2',1'':4'',1''''-quaterphenyl]-4-amine.

[0084] [ka]

[0085] A reaction vessel was charged with 69.5 g of N-(4-(2-naphthyl)phenyl)-[1,1':2',1'':4'',1'''-quaterphenyl]-4-amine, 45.1 g of 1-bromo-4-iodobenzene, 25.7 g of sodium t-butoxide, 700 mL of toluene, 2.5 g of copper iodide, and 2.3 g of N,N'-dimethylethylenediamine, and the mixture was refluxed and stirred for 16 hours. The mixture was cooled to 80°C, and the solid was removed by hot filtration using a funnel lined with Celite. The filtrate was concentrated, and the residue was purified by column chromatography (carrier: silica gel, eluent: dichloromethane / n-heptane) to obtain 59.4 g (yield: 65.5%) of a yellowish-white powder of N-(4-bromophenyl)-N-(4-(2-naphthyl)phenyl)-[1,1':2',1'':4'',1'''-quaterphenyl]-4-amine.

[0086] [ka]

[0087] A reaction vessel was charged with 12.0 g of N-(4-bromophenyl)-N-(4-(2-naphthyl)phenyl)-[1,1':2',1'':4'',1'''-quaterphenyl]-4-amine, 5.3 g of 3-(2-naphthyl)phenylboronic acid, 84 mL of toluene, 21 mL of ethanol, 4.9 g of potassium carbonate, and 18 mL of water. 0.4 g of tetrakistriphenylphosphine palladium was added, and the mixture was refluxed and stirred for 14 hours. After cooling, 84 mL of methanol was added, and the precipitated solid was collected by filtration. 70 mL of water and 70 mL of methanol were added to the solid, and the mixture was refluxed and dispersed for 1 hour for washing. The solid was collected by filtration, 140 mL of toluene was added, and the mixture was heated to 100 °C once. After removing the water and methanol, the mixture was cooled to 80 °C, 7 g of silica gel and 7 g of activated clay were added, and the mixture was stirred for 1 hour. The solid was removed by filtration, and the filtrate was concentrated. 140 mL of acetone was added to the residue, and the mixture was stirred at room temperature overnight. The solid was then collected by filtration. The solid was recrystallized from a toluene / acetone mixed solvent to obtain 11.3 g (yield: 79.6%) of a yellowish-white powder of N-(3'-(naphthalen-2-yl)-[1,1'-biphenyl]-4-yl)-N-(4-(naphthalen)-2-yl)phenyl)-5'-phenyl-[1,1':2',1''-terphenyl]-4-amine.

[0088] [ka]

[0089] The obtained yellowish white powder was 1 The following 43 hydrogen signals were detected by H-NMR (CDCl3), and the structure was identified. δ(ppm)=8.09(1H), 8.01(1H), 7.77-7.92(8H), 7.43-7.73(19H), 7.21-7.38(10H), 7.04-7.13(4H).

[0090] [Synthesis Example 7] <Synthesis of N,9,9-triphenyl-N-(4’-phenyl-[1,1’:2’,1’’:4’’,1’’’-quarterphenyl]-4’’’-yl)-9H-fluorene-2-amine (1-97)> Into a reaction vessel, 20.0 g of 2’-chloro-[1,1’:4’,1’’-terphenyl], 29.5 g of N-phenyl-4’-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1’-biphenyl]-4-amine, 200 mL of 1,4-dioxane, 32.1 g of potassium phosphate, and 60 mL of water were charged. 2.1 g of tris(dibenzylideneacetone)dipalladium and 2.1 g of tricyclohexylphosphine were added, and the mixture was refluxed with stirring for 14 hours. After cooling, 200 mL of methanol was added, and the precipitated solid was collected by filtration. 360 mL of chlorobenzene was added to the solid, and the mixture was heated to 100 °C once and then cooled to 80 °C. 9 g of silica gel and 9 g of activated clay were added, and the mixture was stirred for 1 hour. The solid was removed by filtration, and the filtrate was concentrated. 360 mL of acetone was added to the residue, and the mixture was stirred at room temperature overnight. The solid was collected by filtration to obtain 30.6 g (yield: 85.5%) of a pale yellowish white powder of N,4’-diphenyl-[1,1’:2’,1’’:4’’,1’’’-terphenyl]-4’’’-amine.

[0091]

Chemical formula

[0092] Into a reaction vessel were charged 20.0 g of N,4'-diphenyl-[1,1':2',1'':4'',1'''-terphenyl]-4'''-amine, 18.5 g of 2-bromo-9,9-diphenyl-9H-fluorene, 200 mL of toluene, and 6.1 g of sodium t-butoxide. 0.1 g of tris(dibenzylideneacetone)dipalladium and 0.2 g of a 50% toluene solution of tri(t-butyl)phosphine were added, and the mixture was refluxed with stirring for 14 hours. After cooling to 80 °C, hot filtration was performed using a funnel lined with celite to remove solids. The filtrate was heated and stirred, and 12 g of silica gel and 12 g of activated clay were added at 80 °C and stirred for 1 hour. The solids were removed by filtration, and the filtrate was concentrated. The residue was recrystallized from a toluene / acetone mixed solvent to obtain 21.4 g (yield: 64.1%) of a yellowish-white powder of N,9,9-triphenyl-N-(4'-phenyl-[1,1':2',1'':4'',1'''-quarterphenyl]-4'''-yl)-9H-fluorene-2-amine (1-97).

[0093] [Chemical formula]

[0094] Regarding the obtained yellowish-white powder, 1 43 hydrogen signals as follows were detected by 1H-NMR (CDCl3) to identify the structure. δ (ppm) = 7.64 - 7.71 (5H), 7.58 - 7.60 (lH), 7.51 - 7.53 (lH), 7.41 - 7.48 (6H), 7.30 - 7.38 (3H), 7.14 - 7.24 (21H), 6.98 - 7.09 (6H).

[0095] [Synthesis Example 8] [Synthesis of N-([1,1'-biphenyl]-4-yl)-5'-(naphthalen-2-yl)-N-(4-(naphthalen-2-yl)phenyl)-[1,1':2',1''-terphenyl]-4-amine (1-102)] A reaction vessel was charged with 31.0 g of 4-bromo-2-chloro-1,1'-biphenyl, 22.0 g of 2-naphthaleneboronic acid, 240 mL of toluene, 60 mL of ethanol, 24.1 g of potassium carbonate, and 80 mL of water. 1.3 g of tetrakistriphenylphosphine palladium was added and the mixture was refluxed and stirred for 15 hours. After cooling, the mixture was separated and the organic layer was washed with water. The organic layer was stirred and heated to 100°C once to confirm the absence of water. 20 g of silica gel was added and the mixture was stirred for 1 hour. The solid was removed by hot filtration, and the filtrate was concentrated. The residue was recrystallized from a toluene / heptane mixed solvent to obtain 25.6 g of 2-(2-chloro-[1,1'-biphenyl]-4-yl)naphthalene as a gray powder (yield: 63.5%).

[0096] [ka]

[0097] A reaction vessel was charged with 20.0 g of 2-(2-chloro-[1,1'-biphenyl]-4-yl)naphthalene, 24.8 g of N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-[1,1'-biphenyl]-4-amine, 160 mL of 1,4-dioxane, 27.0 g of potassium phosphate, and 60 mL of water. 1.8 g of tris(dibenzylideneacetone)dipalladium and 1.8 g of tricyclohexylphosphine were added, and the mixture was refluxed and stirred for 12 hours. After cooling, the mixture was concentrated. The residue, from which water remained, was extracted with toluene, and the organic layer was washed successively with water and saturated brine and dried over anhydrous magnesium sulfate. The desiccant was removed by filtration, and the filtrate was stirred and heated. 20 g of silica gel was added at 80°C. After stirring for 1 hour, the solid was removed by hot filtration, and the filtrate was concentrated. The residue was recrystallized using toluene solvent to obtain 26.0 g (yield: 78.0%) of a yellowish-white powder of N-([1,1'-biphenyl]-4-yl)-5'-(naphthalen-2-yl)-[1,1':2',1''-terphenyl]-4-amine.

[0098] [ka]

[0099] Into the reaction vessel, 24.6 g of N-([1,1'-biphenyl]-4-yl)-5'-(naphthalen-2-yl)-[1,1':2',1''-terphenyl]-4-amine, 14.7 g of 2-(4-bromophenyl)naphthalene, 250 mL of toluene, and 6.8 g of sodium t-butoxide were charged. 0.4 g of tris(dibenzylideneacetone)dipalladium and 0.4 g of a 50% toluene solution of tri(t-butyl)phosphine were added, and the mixture was refluxed with stirring for 4 hours. After cooling to 80°C, hot filtration was performed using a funnel lined with celite to remove the solids. The filtrate was heated and stirred, and at 80°C, 17 g of silica gel and 17 g of activated clay were added and stirred for 1 hour. The solids were removed by filtration, and the filtrate was concentrated. The residue was purified by crystallization from a mixed solvent of toluene / acetone to obtain 21.0 g (yield: 61.5%) of a pale yellowish-white powder of N-([1,1'-biphenyl]-4-yl)-5'-(naphthalen-2-yl)-N-(4-(naphthalen-2-yl)phenyl)-[1,1':2',1''-terphenyl]-4-amine (1-102).

[0100]

Chemical formula

[0101] Regarding the obtained pale yellowish-white powder, 1 39 hydrogen signals were detected by 1H-NMR (CDCl3) to identify the structure. δ(ppm)=8.14(1H), 8.01(1H), 7.82 - 7.93(8H), 7.71 - 7.77(2H), 7.39 - 7.63(13H), 7.05 - 7.32(14H).

[0102] [Synthesis Example 9] <Synthesis of N-([1,1'-biphenyl]-4-yl)-5'-phenyl-N-(4-(3-phenylnaphthalen-1-yl)phenyl)-[1,1':2',1''-terphenyl]-4-amine (1-103)>[[]] ​A reaction vessel was charged with 32.7 g of 2'-bromo-[1,1':4',1''-terphenyl], 24.8 g of N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-[1,1'-biphenyl]-4-amine, 320 mL of toluene, 90 mL of ethanol, 21.9 g of potassium carbonate, and 80 mL of water. 1.2 g of tetrakistriphenylphosphine palladium was added, and the mixture was refluxed and stirred for 13 hours. After cooling, the precipitated solid was collected by filtration, and 250 mL of methanol and 250 mL of water were added. The mixture was refluxed for 1 hour, dispersed, washed, and then collected by filtration. 750 mL of toluene was added to the solid, stirred, and heated to 100°C once. After confirming the removal of methanol and water, the mixture was cooled to 80°C. 10 g of silica gel was added, and the mixture was stirred for 1 hour. The solid was then removed by hot filtration. The filtrate was concentrated, and the residue was crystallized using an acetone solvent to obtain 33.0 g (yield: 65.9%) of a yellowish-white powder of N-([1,1'-biphenyl]-4-yl)-5'-phenyl-[1,1':2',1''-terphenyl]-4-amine.

[0103] [ka]

[0104] A reaction vessel was charged with 10.2 g of N-([1,1'-biphenyl]-4-yl)-5'-phenyl-[1,1':2',1''-terphenyl]-4-amine, 7.0 g of 1-(4-bromophenyl)-3-phenylnaphthalene, 70 mL of toluene, and 2.8 g of sodium t-butoxide. 0.1 g of palladium acetate and 0.4 g of a 50% toluene solution of tri(t-butyl)phosphine were added, and the mixture was refluxed and stirred for 4 hours. After cooling to room temperature, methanol was added, and the precipitated solid was collected by filtration. 300 mL of toluene was added to the solid, and the mixture was stirred and heated to 80°C. 7 g of silica gel and 7 g of activated clay were added, and the mixture was stirred for 1 hour. The solid was removed by hot filtration, and the filtrate was concentrated. The residue was recrystallized from a dichloromethane / acetone mixed solvent to obtain 10.9 g (yield: 74.2%) of a white powder of N-([1,1'-biphenyl]-4-yl)-5'-phenyl-N-(4-(3-phenylnaphthalen-1-yl)phenyl)-[1,1':2',1''-terphenyl]-4-amine (1-103).

[0105] [ka]

[0106] The obtained white powder was 1 The following 41 hydrogen signals were detected by H-NMR (CDCl3), and the structure was identified. δ(ppm)=8.01-8.03(2H), 7.94-7.96(1H), 7.58-7.77(9H), 7.22-7.53(25H), 7.08-7.15(4H).

[0107] The glass transition temperatures of the triarylamine compounds represented by general formula (1) obtained in Synthesis Examples 1 to 9 were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS). The results are shown below. Compound of Synthesis Example 1: 107.1°C Compound of Synthesis Example 2: 131.2°C Compound of Synthesis Example 3: 129.7°C Compound of Synthesis Example 4: 110.0°C Compound of Synthesis Example 5: 127.9°C Compound of Synthesis Example 6: 109.5°C Compound of Synthesis Example 7: 136.2°C Compound of Synthesis Example 8: 109.1°C Compound of Synthesis Example 9: 118.7°C

[0108] The above measurement results show that the triarylamine compound represented by general formula (1) used in the present invention has a glass transition point of 100° C. or higher and is stable in a thin film state.

[0109] Using the triarylamine compounds represented by general formula (1) obtained in Synthesis Examples 1 to 9, vapor-deposited films with a thickness of 100 nm were prepared on ITO substrates, and the HOMO levels (ionization potentials) were measured using an ionization potential measurement device (PYS-202, manufactured by Sumitomo Heavy Industries, Ltd.). The results are shown below. Compound of Synthesis Example 1: 5.67 eV Compound of Synthesis Example 2: 5.72 eV Compound of Synthesis Example 3: 5.75 eV Compound of Synthesis Example 4: 5.72 eV Compound of Synthesis Example 5: 5.76 eV Compound of Synthesis Example 6: 5.69 eV Compound of Synthesis Example 7: 5.68 eV Compound of Synthesis Example 8: 5.67 eV Compound of Synthesis Example 9: 5.73 eV

[0110] The above measurement results show that the triarylamine compounds represented by general formula (1) obtained in Synthesis Examples 1 to 9 have a more favorable energy level compared to the HOMO level of 5.4 eV of common hole transport materials such as NPD and TPD, and have good hole transport ability.

[0111] [Example 1] An organic EL device was produced using the compound (1-4) obtained in Synthesis Example 1. As shown in Figure 10, the organic EL device was fabricated by depositing a hole injection layer 3, a first hole transport layer 4, a second hole transport layer 5, an emitting layer 6, an electron transport layer 7, an electron injection layer 8, a cathode 9, and a capping layer 10 in this order on a glass substrate 1 on which a reflective ITO electrode had previously been formed as a transparent anode 2.

[0112] Specifically, a glass substrate 1 on which a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film were sequentially formed was subjected to ultrasonic cleaning in isopropyl alcohol for 20 minutes and then dried on a hot plate heated to 250°C for 10 minutes. After 15 minutes of UV ozone treatment, the ITO-attached glass substrate was placed in a vacuum deposition machine and the pressure was reduced to 0.001 Pa or less. Subsequently, a hole injection layer 3 was formed covering the transparent anode 2 by binary deposition of an electron acceptor (Acceptor-1) of the following structural formula and the compound (1-4) obtained in Synthesis Example 1 at a deposition rate ratio of Acceptor-1:Compound (1-4) = 3:97, resulting in a thickness of 10 nm. On this hole injection layer 3, the compound (1-4) of Example 1 was formed as a first hole transport layer 4 to a thickness of 140 nm. On this hole transport layer 4, the following compound (HTM-1) was formed as a second hole transport layer 5 to a thickness of 5 nm. On this second hole transport layer 5, the light-emitting layer 6 was formed by binary deposition of the following compound (EMD-1) and the following compound (EMH-1) of the structural formula at a deposition rate ratio of compound (EMD-1):(EMH-1) = 5:95 to a thickness of 20 nm. On this light-emitting layer 6, a compound (ETM-1) having the following structural formula and a compound (ETM-2) having the following structural formula were deposited by binary deposition at a deposition rate ratio of compound (ETM-1):(ETM-2) = 50:50 to form an electron transport layer 7 having a film thickness of 30 nm. On this electron transport layer 7, an electron injection layer 8 was formed of lithium fluoride to a thickness of 1 nm. On this electron injection layer 8, a cathode 9 made of a magnesium-silver alloy was formed to a thickness of 12 nm. Finally, a compound (CPL-1) having the following structural formula was formed as a capping layer 10 to a thickness of 60 nm. The organic EL devices thus fabricated were subjected to measurement of their light-emitting properties by applying a DC voltage in the atmosphere at room temperature. The results are summarized in Table 1.

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] [Example 2] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-58) of Synthesis Example 2 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0119] [Example 3] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-59) of Synthesis Example 3 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0120] [Example 4] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-69) of Synthesis Example 4 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0121] [Example 5] An organic EL device was fabricated under the same conditions as in Example 2, except that compound (1-83) of Synthesis Example 5 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0122] [Example 6] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-96) of Synthesis Example 6 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0123] [Example 7] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-97) of Synthesis Example 7 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0124] [Example 8] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-102) of Synthesis Example 8 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0125] [Example 9] An organic EL device was fabricated under the same conditions as in Example 1, except that compound (1-103) of Synthesis Example 9 was used as the material for the first hole transport layer 4 instead of compound (1-4) of Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the air at room temperature. The results are summarized in Table 1.

[0126] [Comparative Example 1] For comparison, an organic EL device was fabricated under the same conditions as in Example 1, except that the compound (HTM-2) having the following structural formula was used as the material for the first hole transport layer 4 instead of the compound (1-4) in Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the atmosphere at room temperature. The results are summarized in Table 1.

[0127] [ka]

[0128] Comparative Example 2 For comparison, an organic EL device was fabricated under the same conditions as in Example 1, except that the compound (HTM-3) having the following structural formula was used as the material for the first hole transport layer 4 instead of the compound (1-4) in Synthesis Example 1. The light-emitting characteristics of the fabricated organic EL device were measured when a DC voltage was applied in the atmosphere at room temperature. The results are summarized in Table 1.

[0129] [ka]

[0130] The voltage, luminance, luminous efficiency and power efficiency in the examples and comparative examples shown in Table 1 were measured at a current density of 10 mA / cm 2 The value is the value when a current of 2000 cd / m is applied. 2 When driven at a constant current, the luminance was 1900 cd / m 2(equivalent to 95% of the initial brightness of 100%: 95% decay).

[0131] [Table 1]

[0132] As shown in Table 1, a current density of 10 mA / cm 2 The voltage when a current of 10 mA / cm was applied was 3.54 to 3.58 V in Comparative Examples 1 and 2, but was 3.43 to 3.52 V in Examples 1 to 9, which was clearly lower. 2 The luminous efficiency when a current of 100 kJ / A was passed was 8.77 to 8.97 cd / A in Comparative Examples 1 and 2, and was 9.99 to 10.78 cd / A in Examples 1 to 9, which was clearly higher. The power efficiency was also clearly higher, being 9.17 to 9.68 lm / W in Examples 1 to 9, and was 7.79 to 7.88 lm / W in Comparative Examples 1 and 2. Furthermore, the element lifetime (95% decay) was 328 to 353 hours in Comparative Examples 1 and 2, and was 383 to 536 hours in Examples 1 to 9, which was significantly longer.

[0133] As is clear from the above results, the triarylamine compound having a specific structure represented by general formula (1), which is used in the present invention as a material for the hole transport layer, more preferably the first hole transport layer, has a higher hole mobility than the conventional triarylamine compounds used in the comparative examples. Therefore, as shown in Examples 1 to 9, the organic EL devices of the present invention have a lower driving voltage, higher luminous efficiency, and a longer lifetime than the organic EL devices of the comparative examples. [Industrial Applicability]

[0134] The organic EL device using the triarylamine compound having a specific structure of the present invention has improved luminous efficiency and durability compared to conventional organic EL devices, and therefore can be applied to, for example, home appliances and lighting. [Explanation of symbols]

[0135] 1. Glass substrate 2 transparent anode 3. Hole injection layer 4 First hole transport layer 5 Second hole transport layer 6. Light-emitting layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Capping Layer

Claims

1. An organic electroluminescence device having, between an anode and a cathode, at least a first hole transport layer, a second hole transport layer, a light-emitting layer, and an electron transport layer, in this order from the anode side, wherein the first hole transport layer contains a triarylamine compound represented by the following general formula (1), and the second hole transport layer contains the following compound (HTM-1): 【Chemistry 1】 (In the formula, A represents a monovalent group represented by the following general formula (2-1): B represents a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused aromatic group. C represents a monovalent group represented by the following general formula (2-1), a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused aromatic group: 【Chemistry 2】 (In the formula, the dashed line represents the binding site. R １ represents a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms, an optionally substituted cycloalkyl group of 5 to 10 carbon atoms, an optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms, an optionally substituted linear or branched alkyloxy group of 1 to 6 carbon atoms, an optionally substituted cycloalkyloxy group of 5 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or a substituted or unsubstituted aryloxy group. n is R １ and represents an integer of 0 to 3. When n is 2 or 3, multiple R １ may be the same or different and 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. L １ represents a divalent group of a substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocycle, or a substituted or unsubstituted condensed polycyclic aromatic ring. m is L １ and represents an integer of 1 to 3. When m is 2 or 3, L １ may be the same or different from each other. Ar １ and Ar ２ may be the same or different and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group. 【Transformation 3】

2. 2. The organic electroluminescence device according to claim 1, wherein the monovalent group represented by the general formula (2-1) is a monovalent group represented by the following general formula (2-2): 【Chemistry 4】 (In the formula, Ar １ , Ar ２ , L １ , m, n and R １ has the same definition as in the general formula (2-1).

3. 2. The organic electroluminescence device according to claim 1, wherein the monovalent group represented by the general formula (2-1) is a monovalent group represented by the following general formula (2-3): 【Transformation 5】 (In the formula, Ar １ , Ar ２ , n and R １ has the same definition as in the general formula (2-1). p represents 0 or 1.

4. 2. The organic electroluminescence device according to claim 1, wherein the monovalent group represented by the general formula (2-1) is a monovalent group represented by the following general formula (2-4): 【Transformation 6】 (In the formula, Ar １ , Ar ２ has the same definition as in the general formula (2-1). p represents 0 or 1.

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