Carbazole compound and organic electroluminescent device

Abstract

The purpose of the present invention is to provide a compound having a high refractive index of 450-750 nm in a capping layer and a low extinction coefficient in order to improve the light extraction efficiency of an organic electroluminescent element. The present invention focuses on a specific carbazole compound having excellent thin film stability or durability, and a point at which a refractive index can be increased by adjusting a molecular structure, thereby designing a molecule and using the molecule as a material constituting a capping layer, thereby obtaining an organic electroluminescent device having excellent luminous efficiency.

Description

Technical Field

[0001] This invention relates to compounds suitable for various display devices, preferably compounds suitable for self-emissive electronic devices, and more particularly to carbazole compounds suitable for organic electroluminescent devices (hereinafter referred to as organic EL devices), organic EL devices using the compounds, electronic devices, and electronic apparatuses. Background Technology

[0002] Organic EL devices are self-emissive devices, and compared with liquid crystal devices, they have the advantages of excellent visibility and vivid display. Therefore, research on this topic is actively underway.

[0003] In 1987, CWTang et al. of Eastman Kodak developed a stacked structure device in which various materials performed different functions, thus realizing the practical application of organic EL devices using organic materials. They stacked phosphors capable of transporting electrons with organic materials capable of transporting holes, and emitted light by injecting bidirectional charges into the phosphor layer, achieving 1000 cd / m² at a low voltage below 10V. 2 The above high brightness (for example, see Patent Document 1 and Patent Document 2).

[0004] To date, many improvements have been made to the practical application of organic EL devices, further subdividing the functions of each layer in the stacked structure. The anode, hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, and cathode are formed sequentially on the substrate. High efficiency and durability are achieved by forming a light-emitting device with a bottom-emitting structure that emits light from the bottom (for example, see Non-Patent Literature 1).

[0005] Recently, light-emitting devices using metals with high work functions in the anode and employing top-emitting structures have been developed. In bottom-emitting structures with pixel circuits, the area of ​​the light-emitting portion is limited. In contrast, top-emitting devices extract light from above, thus the pixel circuits are not obstructed, and therefore have the advantage of obtaining a large area of ​​light-emitting portion. In top-emitting devices, semi-transparent electrodes such as lithium fluoride / aluminum / silver (LiF / Al / Ag) (e.g., see Non-Patent Literature 2), calcium / magnesium (Ca / Mg) (e.g., see Non-Patent Literature 3), and lithium fluoride / magnesium silver (LiF / MgAg) are used in the cathode.

[0006] In the aforementioned light-emitting devices, when light emitted from the light-emitting layer is incident on other films, total internal reflection occurs at the interface between the light-emitting layer and other films if the light is incident at an angle greater than a certain angle. Therefore, only a portion of the emitted light can be utilized. Recently, in order to improve light extraction efficiency, light-emitting devices in which a "coating layer" with a high refractive index is formed 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).

[0007] The effect of the capping layer in the top-emitting structure light-emitting device was observed. In the light-emitting device using tris(2-phenylpyridine)iridium (Ir(ppy)3) as the material, the current efficiency was 38 cd / A without the capping layer. In contrast, in the device using zinc selenide (ZnSe) with a thickness of 60 nm as the capping layer, the current efficiency was 64 cd / A, confirming an improvement of approximately 1.7 times. Furthermore, the maximum transmittance of the semi-transparent electrode and the capping layer did not necessarily coincide with the maximum efficiency; the maximum light extraction efficiency depended on the interference effect (see, for example, Non-Patent Literature 3).

[0008] Previously, high-resolution metal masks were proposed for the formation of capping layers. However, these masks deform under high temperatures, leading to reduced assembly precision. Therefore, zinc selenide, with a melting point exceeding 1100°C, cannot be deposited at the correct location within a high-precision metal mask, potentially negatively impacting the light-emitting device (see, for example, Non-Patent Document 3). Furthermore, capping layers composed of inorganic materials are unsuitable for sputtering processes, considering their potential negative impact on the light-emitting device.

[0009] Furthermore, as a capping layer to adjust the refractive index, a scheme using tris(8-hydroxyquinoline)aluminum (hereinafter referred to as Alq3) has been proposed (for example, see Non-Patent Literature 2). However, Alq3 is known to be an organic (EL) material commonly used in green light-emitting materials or electron transport materials, but it has weak absorption near 450 nm, close to the emission wavelength of blue light-emitting materials. Therefore, in the case of blue light-emitting devices, it suffers from problems of low color purity and low light extraction efficiency.

[0010] To improve the device characteristics of organic EL devices and significantly improve light extraction efficiency, materials with high refractive index, low extinction coefficient, and excellent film stability or durability are needed as the coating material.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: US5792557

[0014] Patent Document 2: US5639914

[0015] Patent Document 3: International Publication No. 2014 / 009310

[0016] Patent Document 4: KR2164767

[0017] Non-patent literature

[0018] Non-patent document 1: Proceedings of the 9th Workshop of the Chinese Society for Applied Physics, pp. 55-61 (2001)

[0019] Non-patent literature 2: Appl. Phys. Let., 78, 544 (2001)

[0020] Non-patent literature 3: Appl. Phys. Let., 82, 466 (2003)

[0021] Non-patent literature 4: Tetrahedron, 58, 9633 (2002)

[0022] Non-patent literature 5: Appl. Phys. Let., 98, 083302 (2011). Summary of the Invention

[0023] The object of this invention is to provide a compound with a high refractive index and a low extinction coefficient in the wavelength range of 450 nm to 750 nm, suitable as a material for a capping layer in an organic EL device. Furthermore, it provides an organic EL device in which the light extraction efficiency is improved by using the aforementioned compound.

[0024] The physical properties of compounds suitable for the capping layer of organic EL devices can be: (1) high refractive index; (2) low extinction coefficient; (3) vapor deposition capability; (4) stable thin film state; and (5) high glass transition temperature. Furthermore, the physical properties of the organic EL device to be provided by the present invention can be: (1) high light extraction efficiency; (2) colorless purity reduction; (3) light transmission without time change; and (4) long lifespan.

[0025] Therefore, to achieve the above objectives, the inventors focused on the excellent stability and durability of carbazole compounds in thin films, and developed a material with high refractive index and low extinction coefficient in the wavelength range of 450 nm to 750 nm by optimizing the molecular design. Furthermore, the results of fabricating organic EL devices using this compound and repeatedly evaluating the device characteristics confirmed that it could solve existing problems, thus completing this invention.

[0026] That is, according to the present invention, a carbazole compound and an organic EL device represented by the following general formula (A) or general formula (B) are provided.

[0027] 1) Carbazole compounds represented by the following general formula (A) or general formula (B).

[0028] Chemical Formula 1

[0029]

[0030] Chemical formula 2

[0031]

[0032] In general formulas (A) and (B), Ar, A, and B represent substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups, or substituted or unsubstituted fused polycyclic aromatic groups, respectively. However, at least one of A and B is a substituted or unsubstituted oxazolopyridinyl group or a substituted or unsubstituted oxazolopyrazinyl group. L1 to L3 represent single bonds, unsubstituted divalent aromatic hydrocarbon groups, unsubstituted divalent aromatic heterocyclic groups, or unsubstituted divalent fused polycyclic aromatic groups.

[0033] 2) The carbazole compounds described in 1) are represented by the following general formula (C) or general formula (D).

[0034] Chemical formula 3

[0035]

[0036] Chemical Formula 4

[0037]

[0038] Ar, A, B and L1 to L3 in general formula (C) or general formula (D) are as defined in general formula (A) or general formula (B) above.

[0039] 3) In the carbazole compounds described in 2), L1 to L3 in the above general formula (C) or general formula (D) are single bonds, unsubstituted phenylene or unsubstituted naphthylene.

[0040] 4) In the carbazole compounds described in 3), L1 to L3 in the above general formula (C) or general formula (D) are single bonds, unsubstituted 1,4-phenylene or unsubstituted 2,6-naphthylene.

[0041] 5) In the carbazole compounds described in 4), Ar, A and B in the above general formula (C) or general formula (D) are substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted quinolinyl, substituted or unsubstituted isoquinolinyl, substituted or unsubstituted quinoxalinyl, substituted or unsubstituted phenanthryl, substituted or unsubstituted phenanthrone, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophenyl, substituted or unsubstituted benzoxazolyl, substituted or unsubstituted benzothiazolyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothiaphenyl, substituted or unsubstituted oxazolopyridyl or substituted or unsubstituted oxazolopyrazinyl.

[0042] 6) In the carbazole compounds described in 5), Ar in the above general formula (C) or general formula (D) is an unsubstituted phenyl, an unsubstituted naphthyl, an unsubstituted quinolinyl, an unsubstituted isoquinolinyl, an unsubstituted quinoxalinyl, an unsubstituted phenanthryl, an unsubstituted phenanthrone, an unsubstituted dibenzofuranyl, an unsubstituted dibenzothiopheneyl, an unsubstituted benzoxazolyl, an unsubstituted benzothiazolyl, an unsubstituted benzofuranyl, an unsubstituted benzothiopheneyl, an unsubstituted oxazolopyridyl, or an unsubstituted oxazolopyrazinyl.

[0043] 7) In the carbazole compound described in 6), at least one of A and B in the above general formula (C) or general formula (D) is a substituted or unsubstituted 2-oxazolopyridyl, a substituted or unsubstituted 5-oxazolopyridyl, or a substituted or unsubstituted 2-oxazolopyrazinyl.

[0044] 8) In the carbazole compounds described in 7), A and B in the above general formula (C) or general formula (D) are substituted or unsubstituted 2-oxazolopyridyl, substituted or unsubstituted 5-oxazolopyridyl, or substituted or unsubstituted 2-oxazolopyrazinyl.

[0045] 9) An organic EL device having at least an anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode electrode, and a capping layer, wherein the capping layer comprises a carbazole compound represented by the above general formula (A) or general formula (B) as described in 1).

[0046] 10) The organic EL device described in 9) is characterized in that when the capping layer is formed to a thickness of 30 nm to 120 nm, the refractive index of the capping layer is 1.70 or higher in the range of wavelength of transmitted light of 450 nm to 750 nm.

[0047] 11) In the organic EL device described in 9), when the above-mentioned cover layer is a stacked or mixed layer formed of two or more compounds, at least one compound is a carbazole compound represented by the above-mentioned general formula (A) or general formula (B).

[0048] 12) An electronic device or electronic component having a pair of electrodes and at least one organic layer therebetween, wherein the organic layer comprises a carbazole compound represented by the general formula (A) or general formula (B) described in 1).

[0049] Specifically, the "aromatic hydrocarbon group," "aromatic heterocyclic group," or "fused polycyclic aromatic group" represented by Ar, A, or B in general formula (A) or general formula (B) can be selected from phenyl, biphenyl, terphenyl, naphthyl, anthraceneyl, phenanthrene, fluorenyl, spirodifluorenyl, indene, pyrene, perylene, fluoranyl, triphenylene, pyridyl, and pyridyl. The following groups are aryl groups formed from 6 to 30 carbon atoms or heteroaryl groups formed from 2 to 20 carbon atoms: pyrimidinyl, triazinyl, furanyl, pyrroleyl, thiopheneyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiopheneyl, indolyl, carbazoyl, benzoxazolyl, benzothiazoyl, oxazolopyridyl, oxazolopyrazinyl, quinoxalinyl, quinazolyl, benzoimidazoyl, pyrazolyl, dibenzofuranyl, dibenzothiopheneyl, naphridinyl, phenanthrene, acridineyl, and carbazoyl.

[0050] The “divalent aromatic hydrocarbon group,” “divalent aromatic heterocyclic group,” or “divalent fused polycyclic aromatic group” represented by L1 to L3 in general formula (A) or general formula (B) can be a divalent group with one hydrogen atom removed from the “aromatic hydrocarbon group,” “aromatic heterocyclic group,” or “divalent fused polycyclic aromatic group” represented by Ar, A, or B in general formula (A). For example, it can be a divalent group with one hydrogen atom removed from the specific group purified above.

[0051] Specifically, the "substituent" in general formula (A) or general formula (B) represented by Ar, A, and B as "substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", or "substituted fused polycyclic aromatic group" can be: deuterium atom, cyano, nitro; halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; silyl groups such as trimethylsilyl, triphenylsilyl; straight-chain or branched alkyl groups with 1 to 6 carbon atoms such as methyl, propyl; straight-chain or branched alkoxy groups with 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy; and alkenyl groups such as vinyl, allyl. ; aryloxy groups such as phenoxy and tolyoxy; arylalkoxy groups such as benzyloxy and phenethoxy; aromatic hydrocarbon groups or fused polycyclic aromatic groups such as phenyl, biphenyl, terphenyl, naphthyl, anthracene, phenanthryl, fluorenyl, spirodifluorenyl, indyl, pyrene, perylene, fluoranyl, and triphenylene; pyridyl, thiophene, furanyl, pyrroleyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiophene, indolyl, carbazoyl, benzoxazolyl, benzothiazoyl, quinoxalinyl, quinazolinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiaphene, carbazoyl, and phenanthrene ketone. In addition, aryl groups formed from 6 to 30 carbon atoms or heteroaryl groups formed from 2 to 20 carbon atoms can also be used, and these substituents can replace the purified substituents mentioned above. Furthermore, these substituents can also combine with the substituted benzene ring or multiple substituents substituted by the same benzene ring to form rings through the intervention of single bonds, substituted or unsubstituted methylene, oxygen or sulfur atoms.

[0052] Preferably, L1 to L3 in general formula (A) or general formula (B) are single bonds or unsubstituted 1,4-phenylene, and preferably, L1 is a single bond.

[0053] Preferably, Ar in general formula (A) or general formula (B) is an unsubstituted phenyl group or an unsubstituted naphthyl group, and more preferably, it is an unsubstituted naphthyl group.

[0054] Preferably, A and B in general formula (A) or general formula (B) are substituted or unsubstituted oxazolopyridinyl groups, and more preferably, they are substituted or unsubstituted 2-oxazolopyridinyl or substituted or unsubstituted 5-oxazolopyridinyl groups.

[0055] In the carbazole compounds of the present invention represented by general formula (C) or general formula (D), Ar, A, B and L1 to L3 are the same as defined in general formula (A) or general formula (B) above, and the specific examples or preferred examples of each substituent are also the same as described above.

[0056] In organic EL devices, preferably, the thickness of the aforementioned capping layer is in the range of 30 nm to 120 nm, and more preferably, in the range of 40 nm to 80 nm.

[0057] The carbazole compound of the present invention has the following advantages: (1) high refractive index in the wavelength range of 450 nm to 750 nm; (2) low extinction coefficient; (3) vapor deposition capability; (4) stable thin film state; and (5) high heat resistance. Therefore, the light extraction efficiency can be significantly improved by providing a capping layer on the outside of the transparent or semi-transparent electrode of the organic EL device. Attached Figure Description

[0058] Figure 1 The diagram illustrates the structure of compounds 1 to 12 of the carbazole compounds of the present invention.

[0059] Figure 2 A diagram illustrating the structure of compounds 13-27, which are carbazole compounds exemplified by the present invention.

[0060] Figure 3 A diagram illustrating the structure of compounds 28 to 38, which are carbazole compounds exemplified by the present invention.

[0061] Figure 4 A diagram illustrating the structure of compounds 39 to 50, which are carbazole compounds exemplified by the present invention.

[0062] Figure 5 A diagram illustrating the structure of compounds 51 to 65, which are carbazole compounds exemplified by the present invention.

[0063] Figure 6 A diagram illustrating the structure of compounds 66-79, which are carbazole compounds exemplified by the present invention.

[0064] Figure 7 A diagram showing the structure of compounds 80-89, which are carbazole compounds exemplified by the present invention.

[0065] Figure 8 A diagram showing the structure of compounds 90 to 100, which are illustrative examples of carbazole compounds of the present invention.

[0066] Figure 9 A diagram illustrating the structure of compounds 101 to 111, which are carbazole compounds exemplified by the present invention.

[0067] Figure 10 A diagram illustrating the structure of compounds 112-121, which are carbazole compounds exemplified by the present invention.

[0068] Figure 11 A diagram illustrating the structure of compounds 122-135, which are carbazole compounds exemplified by the present invention.

[0069] Figure 12 A diagram illustrating the structure of compounds 136-148, which are carbazole compounds exemplified by the present invention.

[0070] Figure 13 A diagram illustrating the structure of compounds 149-160, which are carbazole compounds exemplified by the present invention.

[0071] Figure 14 A diagram illustrating the structure of compounds 161-171, which are carbazole compounds exemplified by the present invention.

[0072] Figure 15 The figure illustrates an example of the structure of the organic EL device of the present invention.

[0073] Explanation of reference numerals in the attached figures

[0074] 1: Glass substrate

[0075] 2: Transparent anode

[0076] 3: Hole injection layer

[0077] 4: Hole transport layer

[0078] 5: Emissive layer

[0079] 6: Electron transport layer

[0080] 7: Electron injection layer

[0081] 8: Cathode

[0082] 9: Covering layer Detailed Implementation

[0083] Although the carbazole compound described above in this invention is a novel compound, related compounds can also be synthesized by known coupling reactions via palladium catalysts, etc. (for example, see Non-Patent Literature 4).

[0084] In the carbazole compounds of the present invention, preferred compounds include, for example... Figures 1 to 14 As shown, but not limited to these compounds.

[0085] The purification of the carbazole compounds described above in this invention is not particularly limited, and can be carried out using known methods used in the purification of organic compounds, such as purification by column chromatography, purification by adsorption of silica gel, activated carbon, bleaching clay, etc., purification by recrystallization of solvents or crystallization purification, sublimation purification, etc. The identification of the compounds can be carried out by nuclear magnetic resonance spectroscopy (NMR) analysis.

[0086] Preferably, the physical properties of the carbazole compound of the present invention are determined by measuring its melting point, glass transition temperature (Tg), refractive index, and extinction coefficient. The melting point can be used as an indicator of vapor deposition performance, the glass transition temperature (Tg) can be used as an indicator of thin film stability, and the refractive index and extinction coefficient can be used as indicators of improved light extraction efficiency.

[0087] Melting point and glass transition temperature (Tg) can be determined using a high-sensitivity differential scanning calorimeter (Bruker AXS, DSC3100SA) for powders.

[0088] After an 80 nm thin film was prepared on a silicon substrate, the refractive index and extinction coefficient were measured using a spectrophotometer (F10-RT-UV manufactured by Filmmetrics).

[0089] In the structure of organic EL devices, for example, in the case of a top-emitting structure light-emitting device, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a capping layer can be sequentially formed on a glass substrate. Furthermore, there are structures with a hole injection layer between the anode and the hole transport layer, an electron blocking layer between the hole transport layer and the light-emitting layer, a hole blocking layer between the light-emitting layer and the electron transport layer, and an electron injection layer between the electron transport layer and the cathode. In these multilayer structures, several layers can perform multiple functions; for example, a structure can combine the functions of a hole injection layer and a hole transport layer, a hole transport layer and an electron blocking layer, a hole blocking layer and an electron transport layer, or an electron transport layer and an electron injection layer. Moreover, organic layers with the same function can be stacked in two or more layers; for example, a structure can have two stacked hole transport layers, two stacked light-emitting layers, two stacked electron transport layers, or two stacked capping layers.

[0090] Preferably, the total thickness of all layers in the organic EL device is 200 nm to 750 nm, more preferably 350 nm to 600 nm. Furthermore, for example, preferably, the thickness of the capping layer is 30 nm to 120 nm, more preferably 40 nm to 80 nm. In this case, good light extraction efficiency is obtained. Moreover, the thickness of the capping layer can be appropriately varied according to the type of luminescent material used in the light-emitting device and the thickness of the organic EL device other than the capping layer.

[0091] Organic EL devices use indium tin oxide (ITO) and gold as the anode electrode materials with high work functions.

[0092] Materials for the hole injection layer of organic EL devices can be aromatic amine compounds with a structure in which three or more triphenylamine structures are linked by single bonds or divalent groups without heteroatoms. Examples include starburst-type triphenylamine derivatives, various triphenylamine tetramers, porphyrin compounds represented by copper phthalocyanine, acceptor polycyclic compounds such as hexacyanoazines and phenanthrene, and coating polymers. These materials can be used individually or as monolayers mixed with other materials. They can be stacked between individually formed layers, stacked between mixed layers, or stacked between individually formed layers and mixed layers. These materials can be formed into thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0093] The hole transport layer of organic EL devices can be made of benzidine derivatives such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (hereinafter referred to as TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine, and N,N,N',N'-tetraphenylbenzidine, as well as 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane. Particularly preferred are aromatic amine compounds having a structure in which two triphenylamine structures are linked by a single bond or a divalent group without heteroatoms, for example, N,N,N',N'-tetraphenylbenzidine. Furthermore, preferably, aromatic amine compounds having three or more triphenylamine structures linked by a single bond or a divalent group without heteroatoms are used, for example, various triphenylamine trimers and tetramers. These materials can be used individually or as monolayers mixed with other materials. They can be stacked in structures consisting of individually formed layers, mixed layers, or layers that are both individually and mixed. Furthermore, the hole injection and transport layers can use coating polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid). These materials can be used to form thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0094] Furthermore, as materials for the hole injection layer and hole transport layer, materials commonly used in this layer can be doped with dopants such as tribromoaniline hexachloroantimony and axial alkene derivatives (for example, see patent literature), as well as polymeric compounds having a benzidine derivative structure such as TPD as part of the structure.

[0095] Furthermore, electron blocking layers can be stacked on organic EL devices. Materials for the electron blocking layer can include carbazole derivatives such as 4,4',4”-tris(N-carbazole)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, as well as compounds with triphenylsilyl and triarylamine structures, represented by 9-[4-(carbazole-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene, which possess electron blocking properties. These materials can be used alone or as monolayers mixed with other materials. They can be stacked between individually formed layers, stacked between mixed layers, or stacked between individually formed layers and mixed layers. These materials can be used to form thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0096] The material for the light-emitting layer of an organic EL device can be a metal complex of quinoline derivatives such as Alq3, various metal complexes, anthracene derivatives, bis(styrene)benzene derivatives, pyrene derivatives, oxazole derivatives, and poly(p-phenylene)ethylene derivatives, etc. Furthermore, the light-emitting layer can be composed of a host material and a dopant material. Preferably, the host material is an anthracene derivative. In addition, the above-mentioned light-emitting materials, polycyclic compounds having a partial structure with an indole ring as a condensation ring, polycyclic compounds having a partial structure with a carbazole ring as a condensation ring, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, and polydialkylfluorene derivatives, etc., can be used. Furthermore, the dopant material can be quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, and aminostyrene derivatives, etc., preferably, a green light-emitting material is used. They can be used as individual films or as monolayers formed by mixing with other materials. They can be in the form of stacked structures between individually formed layers, stacked structures between mixed film-forming layers, or stacked structures between individually formed layers and mixed film-forming layers.

[0097] Furthermore, phosphorescent emitters can be used as luminescent materials. Phosphorescent emitters can be metal complexes such as iridium and platinum. For example, green phosphorescent emitters such as Ir(ppy)3, blue phosphorescent emitters such as Firpic and Fir6, and red phosphorescent emitters such as Btp2Ir(acac) can be used; green phosphorescent emitters are particularly preferred. In this case, the host material can be 4,4'-bis(N-carbazolyl)biphenyl or carbazole derivatives such as TCTA and mCP as the hole injection and transport host material, and p-bis(triphenylsilyl)benzene and 2,2',2”-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) can be used as the electron transport host material.

[0098] When coating the host material with phosphorescent luminescent material, in order to avoid concentration extinction, co-deposition is preferably performed in the range of 1 to 30 weight percentages relative to the total luminescent layer.

[0099] Furthermore, the luminescent material can also be a radioactively delayed fluorescence material such as PIC-TRZ, CC2TA, PXZ-TRZ, 4CzIPN, and other CDCB derivatives (see, for example, Non-Patent Literature 5). These materials can be formed into thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0100] Furthermore, hole-blocking layers can be stacked in organic EL devices. Materials for the hole-blocking layer can include phenanthroline derivatives such as copper hydroxide, metal complexes of quinolinone 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, and other compounds with hole-blocking properties. These materials can also be used as electron transport layer materials. They can be formed individually or as monolayers mixed with other materials, and can be in structures of stacked layers formed individually, stacked layers formed mixed, or stacked layers formed individually and mixed. These materials can be formed into thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0101] Electron transport layers in organic electroluminescent (EL) devices can utilize metal complexes of quinolinone 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, pyridinodole derivatives, phenanthroline derivatives, and silanol derivatives. These materials can be used individually or as monolayers mixed with other materials. They can be stacked in structures consisting of individually formed layers, mixed layers, or layers of both individually formed and mixed layers. These materials can be formed into thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0102] The electron injection layer of organic EL devices can use alkali metal salts such as lithium fluoride and cesium fluoride, alkaline earth metal salts such as magnesium fluoride, metal complexes of quinolinone derivatives such as lithium quinoline, metal oxides such as alumina, and metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs). The electron injection layer can be omitted by preferentially selecting the electron transport layer and the cathode.

[0103] Furthermore, the materials for the electron injection layer and the electron transport layer can be obtained by doping the N material commonly used in these layers with metals such as cesium.

[0104] The cathode materials of organic EL devices use metals with low work functions such as aluminum, magnesium-silver alloys, magnesium-calcium alloys, magnesium-indium alloys and aluminum-magnesium alloys with even lower work functions, as well as indium tin oxide and indium zinc oxide (IZO).

[0105] Preferably, the capping layer of the organic EL device uses the carbazole compounds described above in this invention. These can be formed individually or as monolayers mixed with other materials, and can be in structures of individually formed layers stacked together, mixed layers stacked together, or individually formed layers stacked with mixed layers stacked together. These materials can be formed into thin films using known methods such as vapor deposition, spin coating, and inkjet printing.

[0106] When the carbazole compound of the present invention is used to form a film, preferably, the refractive index of the film is 1.70 or higher, and more preferably, 1.85 or higher, in the wavelength range of light transmitted through the film being 450 nm to 700 nm.

[0107] Furthermore, while the above description focuses on organic EL devices with a top-emitting structure, the present invention is not limited thereto. It can also be applied to organic EL devices with a bottom-emitting structure or organic EL devices with a bidirectional emitting structure that emits light from both the top and bottom. In the above cases, preferably, the electrode located in the direction from which light is drawn out of the light-emitting device is transparent or semi-transparent.

[0108] Example

[0109] The following examples illustrate specific embodiments of the present invention, but without departing from the spirit of the present invention, the present invention is not limited to the following examples.

[0110] Example 1

[0111] Synthesis of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-phenyl-9H-carbazole (compound 33)

[0112] 10.5 g of 3,6-dibromo-9-phenyl-9H-carbazole, 17.7 g of 2-{4-(4,4,5,5-tetramethyl-1,3,2-dioxoboron-2-yl)phenyl}oxazolo[5,4-b]pyridine, 0.6 g of tetra(triphenylphosphine)palladium(0), and 10.9 g of potassium carbonate were added to a reaction vessel and refluxed and stirred overnight in a toluene / ethanol (EtOH) / water (H2O) mixture. After cooling, methanol (MeOH) was added, and the precipitated solid was filtered to obtain the crude product. The crude product was purified by recrystallization using monochlorobenzene to obtain 7.2 g of a pale yellow powder of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-phenyl-9H-carbazole (compound 33) (yield: 43.5%).

[0113] Chemical formula 5

[0114]

[0115] The structure of the obtained pale yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0116] pass 1 H-NMR (CDCl3) detected the following 25 hydrogen signals, thus confirming it as compound 33.

[0117] δ(ppm)=8.55(2H),8.42(4H),8.38(2H),8.10(2H),7.96(4H),7.79(2H),7.68(2H),7.66(2H),7.54(3H),7.38(6H).

[0118] Example 2

[0119] Synthesis of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(naphth-2-yl)-9H-carbazole (compound (47))

[0120] 10.0 g of 3,6-dibromo-9-(naphth-2-yl)-9H-carbazole, 15.7 g of 2-{4-(4,4,5,5-tetramethyl-1,3,2-dioxoboron-2-yl)phenyl}oxazolo[5,4-b]pyridine, 0.8 g of tetra(triphenylphosphine)palladium(0), and 9.2 g of potassium carbonate were added to a reaction vessel and stirred overnight in a toluene / ethanol / water mixture. After cooling, methanol (MeOH) was added, and the precipitated solid was filtered to obtain the crude product. The crude product was purified by recrystallization using monochlorobenzene to obtain 8.3 g of a pale yellow powder of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(naphth-2-yl)-9H-carbazole (compound 47) (yield: 54.9%).

[0121] Chemical Formula 6

[0122]

[0123] The structure of the obtained pale yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0124] pass 1 H-NMR (CDCl3) detected the following 27 hydrogen signals, thus confirming it as compound 47.

[0125] δ(ppm)=8.57(2H),8.42(4H),8.37(2H),8.14(1H),8.12(1H),8.10(2H),8 .02(1H),7.96(5H),7.79(2H),7.73(1H),7.64(2H),7.58(2H),7.38(2H).

[0126] Example 3

[0127] Synthesis of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(3,5-dimethylphenyl)-9H-carbazole (compound 164)

[0128] 8.0 g of 3,6-dimethyl-9-(3,5-dimethylphenyl)-9H-carbazole, 13.2 g of 2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoboronadien-2-yl)phenyl)oxazolo[5,4-b]pyridine, 7.7 g of potassium carbonate, 0.9 g of tetra(triphenylphosphine)palladium(0), 65 ml of toluene, 40 ml of ethanol, and 26 ml of water were injected into a reaction vessel that was replaced with nitrogen gas. The mixture was stirred overnight under reflux.

[0129] After the reaction was confirmed to be complete, the precipitate formed after the addition of methanol was filtered to obtain the crude product. The obtained solid was dissolved in heated monochlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The crude product obtained from the concentrated filtrate was purified by crystallization using monochlorobenzene solution to obtain 6.5 g of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(3,5-dimethylphenyl)-9H-carbazole (compound 164) (yield: 52.8%).

[0130] Chemical Formula 7

[0131]

[0132] The structure of the obtained yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0133] pass 1H-NMR (CDCl3) detected the signals of the following 31 hydrogen atoms.

[0134] δ(ppm)=8.56(2H),8.44(4H),8.40(2H),8.13(2H),7.98(4H),7.80(2H),7.55(2H),7.42-7.39(2H),7.28-7.26(4H),7.20(1H),2.50(6H).

[0135] Example 4

[0136] Synthesis of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(4-methylphenyl)-9H-carbazole (compound 165)

[0137] Add 8.0 g of 3,6-dibromo-9-(4-methylphenyl)-9H-carbazole, 13.7 g of 2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoboronadien-2-yl)phenyl)oxazolo[5,4-b]pyridine, 8.0 g of potassium carbonate, 0.9 g of tetra(triphenylphosphine)palladium(0), 70 ml of toluene, 42 ml of ethanol, and 28 ml of water to a reaction vessel in which nitrogen is replaced, and stir under reflux overnight.

[0138] After the reaction was confirmed to be complete, the precipitate formed after the addition of methanol was filtered to obtain the crude product. The obtained solid was dissolved in heated monochlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The crude product obtained from the concentrated filtrate was purified by crystallization using a monochlorobenzene / acetone mixed solvent to obtain 6.8 g of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(4-methylphenyl)-9H-carbazole (compound 165) (yield: 54.8%).

[0139] Chemical Formula 8

[0140]

[0141] The structure of the obtained pale yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0142] pass 1 H-NMR (CDCl3) detected the following 27 hydrogen signals.

[0143] δ(ppm)=8.54(2H),8.43(4H),8.39(2H),8.11(2H),7.96(4H),7.79(2H),7.53-7.47(6H),7.41-7.38(2H),2.55(3H).

[0144] Example 5

[0145] Synthesis of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-phenyl-9H-carbazole (compound 166)

[0146] Add 5.0 g of 3,6-dibromo-9-phenyl-9H-carbazole, 8.8 g of 6-methyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoboronadien-2-yl)phenyl)oxazolo[5,4-b]pyridine, 5.2 g of potassium carbonate, 0.6 g of tetra(triphenylphosphine)palladium(0), 35 ml of toluene, 15 ml of ethanol, and 10 ml of water to a reaction vessel in which nitrogen is replaced, and stir under reflux overnight.

[0147] After the reaction was confirmed to be complete, the precipitate formed after the addition of methanol and water was filtered to obtain a solid. The obtained solid was dissolved in heated dichlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The crude product obtained from the concentrated filtrate was purified by crystallization using dichlorobenzene solvent to obtain 5.0 g of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-phenyl-9H-carbazole (compound 166) (yield: 60.8%).

[0148] Chemical formula 9

[0149]

[0150] The structure of the obtained yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0151] pass 1 H-NMR (CDCl3) detected the following 29 hydrogen signals.

[0152] δ(ppm)=8.55(2H),8.42(4H),8.21(2H),7.97-7.91(6H),7.80(2H),7.72-7.54(7H),2.53(6H).

[0153] Example 6

[0154] Synthesis of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(4-ethylphenyl)-9H-carbazole (compound 167)

[0155] Add 7.0 g of 3,6-dibromo-9-(4-ethylphenyl)-9H-carbazole, 12.1 g of 6-methyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoboronadien-2-yl)phenyl)oxazolo[5,4-b]pyridine, 6.8 g of potassium carbonate, 0.8 g of tetra(triphenylphosphine)palladium(0), 35 ml of toluene, 21 ml of ethanol, and 14 ml of water to a reaction vessel in which nitrogen is replaced, and stir under reflux overnight.

[0156] After the reaction was confirmed to be complete, the precipitate formed after the addition of methanol and water was filtered to obtain a solid. The obtained solid was dissolved in heated dichlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The crude product obtained from the concentrated filtrate was purified by crystallization using dichlorobenzene solvent to obtain 6.0 g of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(4-ethylphenyl)-9H-carbazole (compound 167) (yield: 53.8%).

[0157] Chemical Formula 10

[0158]

[0159] The structure of the obtained white powder was identified using nuclear magnetic resonance spectroscopy.

[0160] pass 1 H-NMR (CDCl3) detected the following 33 hydrogen signals.

[0161] δ(ppm)=8.55(2H),8.42(4H),8.21(2H),7.96(4H),7.92(2H),7.80(2H),7.57-7.50(6H),2.86(2H),2.54(6H),1.40(3H).

[0162] Example 7

[0163] Synthesis of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(4-methylphenyl)-9H-carbazole (compound 168)

[0164] Add 8.0 g of 3,6-dibromo-9-(4-methylphenyl)-9H-carbazole, 13.6 g of 6-methyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoboronadien-2-yl)phenyl)oxazolo[5,4-b]pyridine, 8.0 g of potassium carbonate, 0.7 g of tetra(triphenylphosphine)palladium(0), 56 ml of toluene, 24 ml of ethanol, and 16 ml of water to a reaction vessel in which nitrogen is replaced, and stir under reflux overnight.

[0165] After the reaction was confirmed to be complete, the precipitate formed after the addition of methanol and water was filtered to obtain a solid. The obtained solid was dissolved in heated dichlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The crude product obtained from the concentrated filtrate was purified by crystallization using dichlorobenzene solvent to obtain 7.8 g of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(4-methylphenyl)-9H-carbazole (compound 168) (yield: 60.1%).

[0166] Chemical Formula 11

[0167]

[0168] The structure of the obtained yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0169] pass 1 H-NMR (CDCl3) detected the following 31 hydrogen signals.

[0170] δ(ppm)=8.57(2H),8.42(4H),8.22(2H),7.98-7.92(6H),7.80(2H),7.54-7.42(6H),2.56(3H),2.54(6H).

[0171] Example 8

[0172] Synthesis of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(naphth-2-yl)-9H-carbazole (compound 169)

[0173] Add 7.5 g of 3,6-dibromo-9-(naphth-2-yl)-9H-carbazole, 12.3 g of 6-methyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborhexacyclopentadien-2-yl)phenyl)oxazolo[5,4-b]pyridine, 6.9 g of potassium carbonate, 0.8 g of tetra(triphenylphosphine)palladium(0), 38 ml of toluene, 23 ml of ethanol, and 15 ml of water to a reaction vessel in which nitrogen is replaced, and stir under reflux overnight.

[0174] After the reaction was confirmed to be complete, the precipitate formed after the addition of methanol was filtered to obtain a solid. The obtained solid was dissolved in heated dichlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The unpurified product obtained from the concentrated filtrate was purified by crystallization using dichlorobenzene solvent to obtain 7.2 g of 3,6-bis{4-(6-methyloxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(naphth-2-yl)-9H-carbazole (compound 169) (yield: 61.4%).

[0175] Chemical Formula 12

[0176]

[0177] The structure of the obtained pale yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0178] pass 1 H-NMR (CDCl3) detected the following 31 hydrogen signals.

[0179] δ(ppm)=8.56(2H),8.43(4H),8.22-8.14(4H),8.05(1H),7.98(5H),7.92(2H),7.82(2H),7.75(1H),7.66(2H),7.61(2H),2.54(6H).

[0180] Example 9

[0181] Synthesis of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(pyridin-3-yl)-9H-carbazole (compound 170)

[0182] Add 14.0 g of 3,6-bis(4,4,5,5-tetramethyl-1,3,2-dioxoboron-2-yl)-9-(pyridin-3-yl)-9H-carbazole, 16.3 g of 2-(4-bromophenyl)oxazolo[5,4-b]pyridine, 19.5 g of potassium carbonate, 3.3 g of tetra(triphenylphosphine)palladium(0), 150 ml of toluene, 100 ml of ethanol, and 150 ml of water to a reaction vessel in which nitrogen is replaced, and stir under reflux overnight.

[0183] After the reaction was confirmed to be complete, the precipitate was filtered to obtain a solid. The obtained solid was dissolved in heated monochlorobenzene, silica gel was added and stirred, and then filtered through diatomaceous earth. The crude product obtained from the concentrated filtrate was purified by crystallization using a monochlorobenzene solution to obtain 2.2 g of 3,6-bis{4-(oxazolo[5,4-b]pyridin-2-yl)phenyl}-9-(pyridin-3-yl)-9H-carbazole (compound 170) (yield: 12.4%).

[0184] Chemical formula 13

[0185]

[0186] The structure of the obtained yellow powder was identified using nuclear magnetic resonance spectroscopy.

[0187] pass 1 H-NMR (CDCl3) detected the following 24 hydrogen signals.

[0188] δ(ppm)=9.02(1H),8.84(1H),8.56(2H),8.44(4H),8.40(2H),8.12(3H),7.97(4H),7.81(2H),7.73(1H),7.54(2H),7.42-7.38(2H).

[0189] Example 10

[0190] The melting point and glass transition temperature (Tg) of the compounds obtained in Examples 1-9 above were determined using a high-sensitivity differential scanning calorimeter (manufactured by Bruker AXS, DSC3100SA). The results are shown in Table 1.

[0191] Table 1

[0192] Melting point Glass transition temperature Compound (33) 346.0 - Compound (47) 338.0 162.5 Compound (164) 358.5 156.6 Compound (165) 334.6 154.0 Compound (166) 369.9 - Compound (167) 382.6 - Compound (168) 401.1 - Compound (169) 366.6 273 Compound (170) 345.1 -

[0193] The results above show that the carbazole compounds of the present invention obtained in Examples 1-9 have high melting points, but do not have a glass transition temperature or have a glass transition temperature above 100°C. This indicates that the film is stable.

[0194] Example 11

[0195] After preparing an 80 nm thick vapor-deposited film on a silicon substrate using the compounds obtained in Examples 1-9 above, the refractive index n and extinction coefficient k at wavelengths of 450 nm and 750 nm were measured using a spectrophotometer (Filmmetrics F10-RT-UV). Furthermore, for comparison, measurements were also performed on Alq3 and the comparative compound (CPL-1) with the following structural formula (see, for example, Patent Document 4). The measurement results are summarized in Table 2.

[0196] Chemical Formula 14

[0197]

[0198] Table 2

[0199]

[0200] As shown in Table 2, in the wavelength range of 450 nm to 750 nm, the carbazole compound of the present invention has extinction coefficient and refractive index values ​​that are equal to or higher than those of Alq3 and the comparative compound (CPL-1), thereby it is expected that by using the carbazole compound of the present invention as a constituent material of the capping layer, the light extraction efficiency in organic EL devices can be improved.

[0201] Example 12

[0202] As an example, such as Figure 15As shown, the organic EL device of the present invention is manufactured by first forming a reflective indium tin oxide as a transparent anode 2 on a glass substrate 1, and then sequentially depositing a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, an electron transport layer 6, an electron injection layer 7, a cathode 8, and a capping layer 9.

[0203] Specifically, an ITO glass substrate 1, with films formed in the following order—50 nm thick indium tin oxide, 100 nm thick silver alloy reflective film, and 5 nm thick indium tin oxide—was ultrasonically cleaned in isopropanol for 20 minutes and then dried on a hot plate heated to 250°C for 10 minutes. After undergoing ultraviolet (UV) ozone treatment for 2 minutes, the glass substrate with the indium tin oxide coating was placed in a vacuum evaporation machine, and the pressure was reduced to below 0.001 Pa. Next, an electron acceptor (Acceptor-1) and a compound (HTM-1) of the following structural formula were used as hole injection layers 3, and binary evaporation was performed to cover the transparent anode 2 at an evaporation rate ratio of Acceptor-1:compound (HTM-1) = 3:97, forming a film thickness of 10 nm.

[0204] A 140 nm thick compound (HTM-1) with the following structural formula is formed on the hole injection layer 3 as a hole transport layer 4. Compounds (EMD-1) and (EMH-1) with the following structural formulas are used as a light-emitting layer 5. Binary deposition is performed on the hole transport layer 4 at a deposition rate ratio of (EMD-1):(EMH-1) = 5:95, resulting in a film thickness of 20 nm. Compounds (ETM-1) and (ETM-2) with the following structural formulas are used as an electron transport layer 6. Binary deposition is performed on the light-emitting layer 5 at a deposition rate ratio of (ETM-1):(ETM-2) = 50:50, resulting in a film thickness of 30 nm. A 1 nm thick lithium fluoride film is formed on the electron transport layer 6 as an electron injection layer 7. A 12 nm thick magnesium-silver alloy film is formed on the electron injection layer 7 as a cathode 8.

[0205] Finally, compound (33) of Example 1 with a film thickness of 60 nm was formed as the capping layer 9. For the manufactured organic EL device, the characteristics were measured in the atmosphere at room temperature, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0206] Chemical Formula 15

[0207]

[0208] Example 13

[0209] Organic EL devices were manufactured under the same conditions, except that in Example 12, the compound (47) obtained in Example 2 was used instead of the compound (33) in Example 1 as the capping layer 9. For the manufactured organic EL devices, the characteristics were measured in the atmosphere at room temperature, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0210] Example 14

[0211] Organic EL devices were fabricated under the same conditions, except that in Example 12, the compound (164) obtained in Example 3 was used instead of the compound (33) in Example 1 as the capping layer 9. For the fabricated organic EL devices, the characteristics were measured at room temperature in the atmosphere, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0212] Example 15

[0213] Organic EL devices were fabricated under the same conditions, except that in Example 12, the compound (165) obtained in Example 4 was used instead of the compound (33) in Example 1 as the capping layer 9. For the fabricated organic EL devices, the characteristics were measured at room temperature in the atmosphere, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0214] Example 16

[0215] Organic EL devices were fabricated under the same conditions, except that in Example 12, the compound (166) obtained in Example 5 was used instead of the compound (33) in Example 1 as the capping layer 9. For the fabricated organic EL devices, the characteristics were measured at room temperature in the atmosphere, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0216] Example 17

[0217] Organic EL devices were fabricated under the same conditions, except that in Example 12, the compound (167) obtained in Example 6 was used instead of the compound (33) in Example 1 as the capping layer 9. For the fabricated organic EL devices, the characteristics were measured at room temperature in the atmosphere, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0218] Example 18

[0219] Organic EL devices were manufactured under the same conditions, except that in Example 12, the compound (168) obtained in Example 7 was used instead of the compound (33) in Example 1 as the capping layer 9. For the manufactured organic EL devices, the characteristics were measured at room temperature in the atmosphere, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0220] Example 19

[0221] Organic EL devices were fabricated under the same conditions, except that in Example 12, the compound (169) obtained in Example 8 was used instead of the compound (33) in Example 1 as the capping layer 9. For the fabricated organic EL devices, the characteristics were measured in the atmosphere at room temperature, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0222] Example 20

[0223] Organic EL devices were manufactured under the same conditions, except that in Example 12, the compound (170) obtained in Example 9 was used instead of the compound (33) in Example 1 as the capping layer 9. For the manufactured organic EL devices, the characteristics were measured at room temperature in the atmosphere, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0224] Comparative Example 1

[0225] For comparison, organic EL devices were fabricated under the same conditions, except that Alq3 was used in Example 12 instead of compound (33) in Example 1 as the capping layer 9. For the fabricated organic EL devices, characteristic measurements were performed at room temperature in atmospheric conditions, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0226] Comparative Example 2

[0227] For comparison, organic EL devices were manufactured under the same conditions, except that compound (CPL-1) was used in Example 12 instead of compound (33) in Example 1 as the capping layer 9. For the manufactured organic EL devices, characteristic measurements were performed at room temperature in atmospheric conditions, and the results of the luminescence characteristics measured after applying current and voltage are shown in Table 3.

[0228] Table 3 shows the results of measuring the device lifetime of the organic EL devices manufactured using the above examples and comparative examples. In this invention, a 10 mA / cm² measurement was performed. 2 When driven by a constant current, the lifetime is determined by measuring the time it takes for the brightness to decrease to 95% with an initial brightness of 100%.

[0229] Table 3

[0230]

[0231] As shown in Table 3, at a current density of 10 mA / cm² 2In comparison, the driving voltages of the devices in Comparative Examples 1 and 2 were almost identical to those in the devices of Examples 12-20. Conversely, the brightness, luminous efficiency, power efficiency, and device lifetime of all the devices in the examples were significantly improved compared to those in the comparative examples. This indicates that the carbazole compound of the present invention is a preferred material for use in the capping layer, and can significantly improve the light extraction efficiency of organic EL devices by increasing the refractive index of the capping layer.

[0232] Industrial availability

[0233] The carbazole compound of the present invention has a high refractive index, which can significantly improve light extraction efficiency and provides stable film properties, making it an excellent compound preferred for use as a capping layer in organic EL devices. Furthermore, organic EL devices manufactured using the carbazole compound of the present invention as a constituent material of the capping layer can achieve high efficiency. Moreover, when good color purity is required to display vivid and bright images, the compound of the present invention, which does not absorb in any wavelength region of blue, grass green, and red, is particularly preferred. For example, its application in household appliances or lighting equipment is expected to expand.

[0234] Its uses.

[0235] [Translation of text in attached image] 1: Glass substrate

[0236] 2: Transparent anode

[0237] 3: Hole injection layer

[0238] 4: Hole transport layer

[0239] 5: Emissive layer

[0240] 6: Electron transport layer

[0241] 7: Electron injection layer

[0242] 8: Cathode

[0243] 9: Covering layer

Claims

1. A carbazole compound, characterized in that, Represented by the following general formula (A) or general formula (B), In the general formula, Ar, A, and B represent substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups, or substituted or unsubstituted fused polycyclic aromatic groups, respectively, but at least one of A and B is a substituted or unsubstituted oxazolopyridinyl or a substituted or unsubstituted oxazolopyrazinyl. L1 to L3 represent aromatic hydrocarbon groups with single bonds and unsubstituted divalent groups, aromatic heterocyclic groups with unsubstituted divalent groups, or fused polycyclic aromatic groups with unsubstituted divalent groups.

2. The carbazole compound according to claim 1, characterized in that, It is represented by the following general formula (C) or general formula (D). Ar, A, B and L1 to L3 in general formula (C) or general formula (D) are as defined in general formula (A) or general formula (B) above.

3. The carbazole compound according to claim 2, characterized in that, In the above general formula (C) or general formula (D), L1 to L3 represent single bonds, unsubstituted phenylene or unsubstituted naphthylene.

4. The carbazole compound according to claim 3, characterized in that, In the above general formula (C) or general formula (D), L1 to L3 represent single-bonded, unsubstituted 1,4-phenylene or unsubstituted 2,6-naphthylene.

5. The carbazole compound according to claim 4, characterized in that, In general formula (C) or general formula (D) above, Ar, A and B represent substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted quinolinyl, substituted or unsubstituted isoquinolinyl, substituted or unsubstituted quinoxalinyl, substituted or unsubstituted phenanthryl, substituted or unsubstituted phenanthrone, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophenyl, substituted or unsubstituted benzoxazolyl, substituted or unsubstituted benzothiazolyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothiaphenyl, substituted or unsubstituted oxazolopyridyl or substituted or unsubstituted oxazolopyrazinyl.

6. The carbazole compound according to claim 5, characterized in that, In the above general formula (C) or general formula (D), Ar represents an unsubstituted phenyl, an unsubstituted naphthyl, an unsubstituted quinolinyl, an unsubstituted isoquinolinyl, an unsubstituted quinoxalinyl, an unsubstituted phenanthryl, an unsubstituted phenanthrone, an unsubstituted dibenzofuranyl, an unsubstituted dibenzothiophenyl, an unsubstituted benzoxazolyl, an unsubstituted benzothiazolyl, an unsubstituted benzofuranyl, an unsubstituted benzothiophenyl, an unsubstituted oxazolopyridyl, or an unsubstituted oxazolopyrazinyl.

7. The carbazole compound according to claim 6, characterized in that, At least one of A and B in general formula (C) or general formula (D) above represents substituted or unsubstituted 2-oxazolopyridyl, substituted or unsubstituted 5-oxazolopyridyl or substituted or unsubstituted 2-oxazolopyrazinyl.

8. The carbazole compound according to claim 7, characterized in that, In the above general formula (C) or general formula (D), A and B represent substituted or unsubstituted 2-oxazolopyridyl, substituted or unsubstituted 5-oxazolopyridyl, or substituted or unsubstituted 2-oxazolopyrazinyl.

9. An organic electroluminescent device, comprising at least, in sequence, an anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode electrode, and a capping layer, characterized in that, The aforementioned coating layer comprises the carbazole compound represented by the above general formula (A) or general formula (B) as described in claim 1.

10. The organic electroluminescent device according to claim 9, characterized in that, When the aforementioned covering layer is formed to a thickness of 30 nm to 120 nm, the refractive index of the aforementioned covering layer is 1.70 or higher in the range of wavelength of transmitted light of 450 nm to 750 nm.

11. The organic electroluminescent device according to claim 9, characterized in that, In the case where the aforementioned covering layer is a laminate or mixed layer formed of two or more compounds, at least one compound is a carbazole compound represented by the aforementioned general formula (A) or general formula (B).

12. An electronic device or electronic component having a pair of electrodes and at least one organic layer therebetween, characterized in that, The aforementioned organic layer comprises the carbazole compound represented by the above general formula (A) or general formula (B) as described in claim 1.

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