Compound and organic electroluminescent element using the same

Abstract

The present application aims at providing a compound having a high refractive index and a low extinction coefficient in the range of 450 nm to 750 nm for a cover layer in order to improve the light extraction efficiency of an organic EL element. The present application is based on the fact that a compound having a central benzene skeleton has excellent film stability and durability and that the refractive index can be increased by adjusting the molecular structure. By designing a molecule, a compound represented by the following general formula (1) is used as a constituent material for a cover layer, thereby obtaining an organic EL element having excellent luminous efficiency.

Description

Technical Field

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

[0002] Organic EL elements are self-emissive, therefore they are brighter, have better visibility, and can achieve clearer displays compared to liquid crystal elements, and thus have been actively researched.

[0003] In 1987, CWTang et al. of Eastman Kodak developed a layered structure element by distributing various functions among different materials, thus making organic EL elements using organic materials practical. They achieved 1000 cd / m² light emission at voltages below 10V by layering an electron-transporting phosphor with an organic material that can transport holes, and injecting both charges into the phosphor layer to induce luminescence. 2 The above high brightness (see, for example, Patent Document 1 and Patent Document 2).

[0004] To date, various improvements have been made to make organic EL elements practical, further subdividing the various functions of the stacked structure. In electroluminescent elements with an anode, hole injection layer, hole transport layer, light emission layer, electron transport layer, electron injection layer and cathode arranged sequentially on a substrate, high efficiency and durability are achieved by using a bottom-emitting structure that emits light from the bottom (see, for example, Non-Patent Literature 1).

[0005] In recent years, top-emitting light-emitting elements, which use a metal with a high work function as the anode and emit light from the top, have become increasingly common. In bottom-emitting structures where light is extracted from the bottom (where pixel circuitry is located), the area of ​​the light-emitting portion is limited. In contrast, in top-emitting light-emitting elements, since light is extracted from the top, the pixel circuitry is not obstructed, thus offering the advantage of a larger light-emitting portion. In top-emitting light-emitting elements, the cathode uses semi-transparent electrodes such as LiF / Al / Ag (e.g., see Non-Patent Document 2), Ca / Mg (e.g., see Non-Patent Document 3), and LiF / MgAg.

[0006] In such light-emitting elements, if light emitted from the light-emitting layer is incident on other films at an angle greater than a certain angle, total internal reflection will occur at the interface between the light-emitting layer and other films. Therefore, only a portion of the emitted light can be utilized. In recent years, to improve light extraction efficiency, light-emitting elements with a high-refractive-index "coating layer" disposed on the outside of a semi-transparent electrode with a low refractive index have been proposed (see, for example, Non-Patent Documents 2 and 3).

[0007] Regarding the effect of the capping layer in the light-emitting element with the top light-emitting structure, in a light-emitting element using Ir(ppy)3 as the light-emitting material, the current efficiency without the capping layer is 38 cd / A. In contrast, in a light-emitting element using ZnSe with a film thickness of 60 nm as the capping layer, an efficiency improvement of approximately 1.7 times (64 cd / A) was observed. Furthermore, it was shown that the maximum transmittance of the semi-transparent electrode and the capping layer does not necessarily coincide with the maximum efficiency, indicating that the maximum light extraction efficiency is determined by the interference effect (see, for example, Non-Patent Literature 3).

[0008] Previously, the use of high-precision metal masks in the formation of capping layers has been proposed. However, when used under high-temperature conditions, the following problems arise: the metal mask deforms due to heat, resulting in reduced alignment accuracy. Consequently, ZnSe with a melting point exceeding 1100°C (e.g., see Non-Patent Document 3) cannot be deposited at the correct position using a high-precision metal mask, potentially affecting the light-emitting element itself. Furthermore, even sputtering-based film deposition can affect the light-emitting element. Therefore, capping layers using inorganic materials are unsuitable.

[0009] In addition, as a capping layer to adjust the refractive index, the use of tris(8-hydroxyquinoline)aluminum (hereinafter abbreviated as Alq3) has been proposed (see, for example, non-patent literature 2). Alq3 is known as an organic EL material commonly used as a green light-emitting material or an electron transport material, but it has weak absorption around 450 nm. Therefore, when used in blue light-emitting elements, there is a problem of reduced color purity and reduced light extraction efficiency.

[0010] In order to improve the device characteristics of organic EL devices, and in order to significantly improve the light extraction efficiency, materials with high refractive index, low extinction coefficient, and excellent film stability or durability are sought as the coating layer.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: US5792557

[0014] Patent Document 2: US5639914

[0015] Patent Document 3: EP2684932

[0016] Patent Document 4: US20140225100

[0017] Non-patent literature

[0018] Non-patent literature 1: Proceedings of the 9th Lecture of the Chinese Society of 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: Appl. Phys. Let., 98, 083302 (2011) Summary of the Invention

[0022] The object of this invention is to provide a compound with a high refractive index and low extinction coefficient in the wavelength range of 450 nm to 750 nm, which can be used as a capping layer for organic EL elements. Furthermore, it provides an organic EL element in which the light extraction efficiency is improved by using the aforementioned compound.

[0023] The physical properties of compounds suitable for the capping layer of organic EL elements include: (1) high refractive index, (2) low extinction coefficient, (3) ability to be vapor-deposited, (4) stable thin film state, and (5) high glass transition temperature. Furthermore, the physical properties of the organic EL element that this invention aims to provide include: (1) high light extraction efficiency; (2) no decrease in color purity; (3) transmission of light without change over time; and (4) long lifespan.

[0024] Therefore, in order to achieve the above-mentioned objectives, the inventors focused on the excellent film stability and durability of compounds with a benzene skeleton as the center, and the fact that the refractive index can be increased by adjusting the molecular structure. They designed the molecule, fabricated an organic EL element using the compound as the material constituting the capping layer, and conducted in-depth evaluation of the characteristics of the element, resulting in the completion of the present invention.

[0025] That is, the present invention is the compound shown in the following general formula (1) and the organic EL element using the compound, specifically as follows.

[0026] 1) Compounds represented by the following general formula (1).

[0027]

[0028] In formula (1), B represents 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. Ar1 and Ar2 may be the same or different from each other and represent a divalent group of a substituted or unsubstituted aromatic hydrocarbon group, a divalent group of a substituted or unsubstituted aromatic heterocyclic group, a divalent group of a substituted or unsubstituted fused polycyclic aromatic group, or a single bond. A1 and A2 may be the same or different from each other and represent a monovalent group as shown in the following general formula (2).

[0029]

[0030] In formula (2), R1 to R8 may be the same or different from each other, representing the bonding site, hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano, nitro, alkyl group with 1 to 6 carbon atoms of optional substituent, cycloalkyl group with 5 to 10 carbon atoms of optional substituent, alkenyl group with 2 to 6 carbon atoms of optional substituent, alkoxy group with 1 to 6 carbon atoms of optional substituent, cycloalkoxy group with 5 to 10 carbon atoms of optional substituent, substituted or unsubstituted aryloxy group, substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted fused polycyclic aromatic group, and any one of R1 to R8 represents the bonding site. X1 to X8 can be chosen to be the same or different from each other, representing nitrogen atoms or carbon atoms. X1 to X8 are 0 to 2 nitrogen atoms, and in the case of nitrogen atoms, there are no R1 to R8 atoms that can form bonds.

[0031] 2) The compound according to 1), wherein the aforementioned A1 and A2 are monovalent groups represented by the following general formulas (3a), (3b) or (3c).

[0032]

[0033] The definitions of R1 to R8 in equations (3a), (3b) and (3c) are the same as those of R1 to R8 in equation (2).

[0034] 3) The compound according to 1) or 2), wherein the aforementioned B is substituted or unsubstituted, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiophenyl, fluorenyl, carbazoleyl, benzofuranyl or benzothiophenyl.

[0035] 4) An organic thin film comprising any one of the compounds described in 1) to 3) above, having a refractive index of 1.70 or higher in the wavelength range of 450 nm to 750 nm.

[0036] 5) An organic electroluminescent element 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 is the organic thin film described in 4) above.

[0037] 6) An electronic component having a pair of electrodes and at least one organic layer sandwiched therebetween, the organic layer comprising any one of the compounds described in 1) to 3) above.

[0038] 7) An electronic device comprising the electronic components described in 6).

[0039] In this invention, "unsubstituted" in the case of "substituted or unsubstituted" means that the hydrogen atom is not substituted by a substituent.

[0040] In this invention, "hydrogen atom" includes isotopes with different numbers of neutrons, namely protium and deuterium.

[0041] In this invention, the "substituent" in the case of "substituted or unsubstituted" can specifically include cyano, nitro, halogen atom, alkyl with 1 to 3 carbon atoms (substituted or unsubstituted), phenyl with substituted or unsubstituted, and alkoxy with 1 to 3 carbon atoms (substituted or unsubstituted).

[0042] The "aromatic hydrocarbon group", "aromatic heterocyclic group" or "fused polycyclic aromatic group" represented by B and Ar1-Ar2 in general formula (1) and R1-R8 in general formula (2) are specifically selected from phenyl, biphenyl, terphenyl, naphthyl, anthraceneyl, phenanthrene, fluorenyl, spirodifluorenyl, etc. Indene, pyrene, perylene, fluoranyl, benzophenanthrene, pyridyl, pyrimidinyl, triazine, furanyl, pyrroloyl, thiophene, quinolinyl, isoquinolinyl, benzofuranyl, benzothiophene, indolyl, carbazoyl, benzooxazolyl, benzothiazoyl, quinoxalinyl, benzoimidazoyl, pyrazolyl, dibenzofuranyl, dibenzothiophene, naphridyl, phenanthrolyl, acridineyl, and carbazoyl groups, including aryl groups with 6 to 30 carbon atoms or heteroaryl groups with 2 to 20 carbon atoms.

[0043] The terms R1 to R8 in general formula (2) refer to "alkyl group with 1 to 6 carbon atoms (optionally having substituents)," "cycloalkyl group with 5 to 10 carbon atoms (optionally having substituents)," "alkenyl group with 2 to 6 carbon atoms (optionally having substituents)," "alkoxy group with 1 to 6 carbon atoms (optionally having substituents)," "cycloalkoxy group with 5 to 10 carbon atoms (optionally having substituents)," or "substituted or unsubstituted aryloxy group," and include "alkyl group with 1 to 6 carbon atoms (optionally having substituents)," "alkyl group with 5 to 10 carbon atoms (optionally having substituents)," "alkoxy group with 5 to 10 carbon atoms," or "substituted or unsubstituted aryloxy group." The terms include "alkenyl groups with 2 to 6 carbon atoms (straight-chain or branched)," "alkoxy groups with 1 to 6 carbon atoms (straight-chain or branched)," "cycloalkoxy groups with 5 to 10 carbon atoms," or "aryloxy groups." Specifically, examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, vinyl, aryl, isopropenyl, 2-butenyl, methoxy, ethoxy, n-propoxy, cyclopentoxy, cyclohexoxy, 1-adamantylalkoxy, phenoxy, tolyloxy, and biphenyloxy, among others.

[0044] The "substituents" in B and Ar1-Ar2 of general formula (1) and R1-R8 of general formula (2), namely "substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", "substituted fused polycyclic aromatic group", "alkyl group with 1-6 carbon atoms of optional substituent", "cycloalkyl group with 5-10 carbon atoms of optional substituent" or "alkenyl group with 2-6 carbon atoms of optional substituent", specifically include deuterium atom, cyano, nitro; halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; silyl group such as trimethylsilyl, triphenylsilyl; alkyl group with 1-6 carbon atoms of methyl, ethyl, propyl, etc.; methoxy, ethoxy, propoxy Alkoxy groups with 1 to 6 carbon atoms, either straight-chain or branched; alkenyl groups such as vinyl and aryl; aryloxy groups such as phenoxy and tolyloxy; 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 benzophenanthryl; aryl groups with 6 to 30 carbon atoms or heteroaryl groups with 2 to 20 carbon atoms, such as pyridyl, thiophene, furanyl, pyrroleyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothiophene, indolyl, carbazoyl, benzooxazolyl, benzothiazoyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiophene, and carbazoyl, etc., which may be further substituted with the substituents exemplified above. In addition, adjacent substituents of a benzene ring that has these substituents or of a plurality of substituents that have substituted on the same benzene ring may optionally bond to each other via single bonds, substituted or unsubstituted methylene, oxygen or sulfur atoms to form a ring.

[0045] In general formula (1), A1 and A2 are represented by the aforementioned general formula (2), and any one of R1 to R8 is a monovalent group at the bonding site. The group represented by the aforementioned general formula (2) is preferably a monovalent group represented by the aforementioned general formula (3a), (3b), or (3c), and more preferably a group represented by the aforementioned general formula (3a) or (3c). Furthermore, A1 and A2 are preferably the same.

[0046] When A1 and A2 in general formula (1) are groups shown in the aforementioned general formula (3a), from the viewpoint of refractive index and heat resistance, the bonding sites are preferably R2, R3, R8 or R6. In addition, from the viewpoint of ease of synthesis, it is preferable that the groups among R2 to R8 that are not bonding sites are all hydrogen atoms.

[0047] When A1 and A2 in general formula (1) are groups represented by the aforementioned general formula (3c), from the viewpoint of refractive index and heat resistance, the bonding site is preferably R2. In addition, from the viewpoint of ease of synthesis, it is preferable that the groups among R1 to R8 that are not bonding sites are all hydrogen atoms.

[0048] From the viewpoint of refractive index and heat resistance, Ar1 and Ar2 in general formula (1) are each independently preferably selected from phenylene, pyridylene, pyrimidinylene and single bond.

[0049] B in general formula (1) is more preferably substituted or unsubstituted, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiophene, fluorenyl, carbazoyl, benzofuranyl or benzothiophene.

[0050] The compound of the aforementioned general formula (1) of the present invention preferably has a refractive index of 1.70 or more in the wavelength range of 450 nm to 700 nm, and particularly preferably 1.85 or more.

[0051] The compound represented by the aforementioned general formula (1) of the present invention has a high refractive index and a low extinction coefficient in the wavelength range of 450 nm to 750 nm. Therefore, by setting a cover layer with a higher refractive index than the semi-transparent electrode on the outside of the transparent or semi-transparent electrode of the organic EL element, an organic EL element that can significantly improve the light extraction efficiency can be obtained. Attached Figure Description

[0052] Figure 1 The diagram shows the structures of compounds (1-1) to (1-12) as examples of compounds of the present invention.

[0053] Figure 2 The diagram shows the structures of compounds (1-13) to (1-24) as examples of compounds of the present invention.

[0054] Figure 3 The diagram shows the structures of compounds (1-25) to (1-36) as examples of compounds of the present invention.

[0055] Figure 4 The diagram shows the structures of compounds (1-37) to (1-45) as examples of compounds of the present invention.

[0056] Figure 5 The diagram shows the structures of compounds (1-46) to (1-50) as examples of compounds of the present invention.

[0057] Figure 6 This is a diagram illustrating an example of the structure of the organic EL element of the present invention. Detailed Implementation

[0058] Specific examples of preferred compounds of the compounds represented by the aforementioned general formula (1) of the present invention are shown below. Figures 1-5 However, it is not limited to these compounds.

[0059] The compound represented by the aforementioned general formula (1) of the present invention is a novel compound that can be synthesized by known methods such as cross-coupling reactions.

[0060] The purification method for the compound represented by the aforementioned general formula (1) of the present invention is not particularly limited, and known methods for purifying organic compounds, such as column chromatography purification; adsorption purification based on silica gel, activated carbon, or activated clay; and solvent-based recrystallization, crystallization, and sublimation purification, are listed. The compound can be identified by NMR analysis. Furthermore, as physical properties, the melting point, glass transition temperature (Tg), and refractive index are preferably determined.

[0061] Melting point and glass transition temperature (Tg) were determined using powdered compounds and a high-sensitivity differential scanning calorimeter (Bruker AXS KK, DSC3100SA).

[0062] The refractive index was measured by fabricating an 80 nm thin film on a silicon substrate and using a spectrophotometer (FILMETRICS F10-RT-UV).

[0063] As structures for the organic EL element of the present invention, for example, in the case of a top-emitting structure light-emitting element, examples include: an element that sequentially comprises an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a capping layer on a glass substrate; an element having a hole injection layer between the anode and the hole transport layer; an element having an electron blocking layer between the hole transport layer and the light-emitting layer; an element having a hole blocking layer between the light-emitting layer and the electron transport layer; and an element having an electron injection layer between the electron transport layer and the cathode. In these multilayer structures, one organic layer can perform the functions of several layers. For example, it can be configured to function as both a hole injection layer and a hole transport layer, both a hole transport layer and an electron blocking layer, both a hole blocking layer and an electron transport layer, and both an electron transport layer and an electron injection layer. In addition, it can be configured by stacking two or more organic layers with the same function, and it can also be configured to stack two hole transport layers, two light-emitting layers, two electron transport layers, and two capping layers.

[0064] The total film thickness of all layers in the organic EL element is preferably around 200 nm to 750 nm, more preferably around 350 nm to 600 nm. Furthermore, the thickness of the capping layer is preferably, for example, 30 nm to 120 nm, more preferably 40 nm to 80 nm. In this case, good light extraction efficiency can be obtained. It should be noted that the thickness of the capping layer can be appropriately varied depending on the type of light-emitting material used in the light-emitting element, the thickness of the organic EL element excluding the capping layer, etc.

[0065] As the anode of the organic EL element of the present invention, an electrode material with a high work function, such as ITO or gold, is used.

[0066] As the hole injection layer of the organic EL element of the present invention, arylamine compounds having a structure in which three or more triphenylamine structures are linked by single bonds or divalent groups without heteroatoms can be used, such as star-shaped triphenylamine derivatives, various triphenylamine tetramers and other arylamine compounds, porphyrin compounds represented by copper phthalocyanine, acceptor heterocyclic compounds such as hexacyanoazabenzophenanthrene, and coating-type polymer materials.

[0067] As the hole transport layer of the organic EL element of the present invention, 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 (hereinafter referred to as NPD), and N,N,N',N'-tetraphenylbenzidine can be used; 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter referred to as TAPC); and arylamine compounds having a structure in which two triphenylamine structures are linked by single bonds or divalent groups without heteroatoms, such as N,N,N',N'-tetraphenylbenzidine, can also be used. Additionally, arylamine compounds having a structure in which three or more triphenylamine structures are linked by single bonds or divalent groups without heteroatoms, such as various triphenylamine trimers and tetramers, can also be used. In addition, coating-type polymer materials such as poly(3,4-ethylenedioxythiophene) (hereinafter referred to as PEDOT) / polystyrene sulfonic acid (hereinafter referred to as PSS) can be used as the hole injection / transport layer.

[0068] In addition, in the hole injection layer or hole transport layer, materials obtained by doping P, a material commonly used in these layers, with antimony hexachloride tribromophenylamine or axial alkene derivatives (e.g., see Patent Document 3) can be used; or polymeric compounds whose partial structure has the structure of benzidine derivatives such as TPD can be used.

[0069] As the electron blocking layer of the organic EL element of the present invention, compounds with electron blocking effects can be used, such as 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)benzene (hereinafter referred to as mCP) and 2,2-bis(4-carbazole-9-yl-phenyl)adamantane (hereinafter referred to as Ad-Cz); compounds having triphenylsilyl and triarylamine structures represented by 9-[4-(carbazole-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene.

[0070] As the light-emitting layer of the organic EL element of the present invention, luminescent materials such as metal complexes of hydroxyquinoline derivatives, primarily Alq3, various metal complexes, anthracene derivatives, bis(styrene)benzene derivatives, pyrene derivatives, oxazole derivatives, and poly(p-phenylenevinylene) derivatives can be used. Furthermore, the light-emitting layer can be composed of a host material and a dopant material. As the host material, anthracene derivatives are preferred. In addition, based on the aforementioned luminescent materials, heterocyclic compounds with a partial structure having an indole ring as a fused ring, heterocyclic compounds with a partial structure having a carbazole ring as a fused ring, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, and polydialkylfluorene derivatives can be used. Furthermore, as dopant materials, quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, aminostyrene derivatives, etc., can be used; green luminescent materials are particularly preferred.

[0071] Alternatively, phosphorescent materials can also be used as luminescent materials. Phosphorescent materials can be metal complexes such as iridium and platinum, including green phosphorescent materials like Ir(ppy)3, blue phosphorescent materials like Firpic and Fir6, and red phosphorescent materials like Btp2Ir(acac). Green phosphorescent materials are particularly preferred. As the host material, for hole injection / transport, carbazole derivatives such as 4,4'-bis(N-carbazolyl)biphenyl (hereinafter referred to as CBP), TCTA, and mCP can be used. For electron transport, p-bis(triphenylsilyl)benzene (hereinafter referred to as UGH2) and 2,2',2”-(1,3,5-phenylene)tris(1-phenyl-1H-benzimidazole) (hereinafter referred to as TPBI) can be used.

[0072] To avoid concentration quenching, the phosphorescent luminescent material is preferably co-deposited in the host material at a rate of 1 to 30% by weight relative to the total luminescent layer.

[0073] Alternatively, materials that emit delayed fluorescence, such as PIC-TRZ, CC2TA, PXZ-TRZ, 4CzIPN, and other CDCB derivatives, can also be used as luminescent materials (see, for example, Non-Patent Literature 4).

[0074] As the hole-blocking layer of the organic EL element of the present invention, compounds with hole-blocking properties such as phenanthrene derivatives such as copper hydroxide (hereinafter referred to as BCP), metal complexes of hydroxyquinoline derivatives such as aluminum(III)bis(2-methyl-8-hydroxyquinoline)-4-phenylphenol salt (hereinafter referred to as BAlq), various rare earth complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, and benzo[a]azole derivatives can be used. These materials can also serve as electron transport layer materials.

[0075] As the electron transport layer of the organic EL element of the present invention, metal complexes of hydroxyquinoline derivatives, primarily 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, pyridinoindole derivatives, phenanthrene derivatives, and silicone derivatives can be used.

[0076] As the electron injection layer of the organic EL element of the present invention, alkali metal salts such as lithium fluoride and cesium fluoride; alkaline earth metal salts such as magnesium fluoride; metal complexes of hydroxyquinoline derivatives such as lithium hydroxyquinoline; metal oxides such as aluminum oxide; or metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs) can be used. Furthermore, depending on the preferred selection of the electron transport layer and the cathode, the electron injection layer can be omitted.

[0077] Furthermore, in the electron injection layer or electron transport layer, materials obtained by doping metals such as cesium with N, which are commonly used in these layers, can be used.

[0078] As the cathode of the organic EL element of the present invention, electrode materials with low work function such as aluminum, alloys with even lower work function such as magnesium-silver alloys, magnesium-calcium alloys, magnesium-indium alloys, aluminum-magnesium alloys, ITO, IZO, etc. are used as electrode materials.

[0079] As the cover layer of the organic EL element of the present invention, an organic thin film containing the compound shown in the aforementioned general formula (1) is used.

[0080] From the viewpoint of improving light extraction efficiency, the organic thin film containing the compound shown in the aforementioned general formula (1) and used as the aforementioned coating layer preferably has a refractive index of 1.70 or more in the wavelength range of 450 nm to 750 nm, and particularly preferably 1.85 or more.

[0081] The materials used in each layer constituting the above-mentioned organic EL element can be formed into films individually or mixed with other materials. They can be used as monolayers or in a stacked structure of individually formed layers, mixed layers, or a stacked structure of individually formed layers and mixed layers. In addition to vapor deposition, these materials can be formed into thin films using known methods such as spin coating and inkjet printing.

[0082] It should be noted that the above description refers to organic EL elements with a top-emitting structure, but the present invention is not limited thereto, and can also be applied to organic EL elements with a bottom-emitting structure, and organic EL elements with a dual-emitting structure that emits light from both the top and bottom. In these cases, the electrodes existing along the direction from which light is extracted from the light-emitting element need to be transparent or semi-transparent.

[0083] The following describes specific embodiments of the present invention through examples, but the present invention is not limited to the following examples as long as it does not depart from its spirit.

[0084] Example

[0085] [Example 1]

[0086] <Synthesis of Exemplary Compound (1-1)>

[0087] 1,3-Dibromo-5-chlorobenzene: 12.5 g, 3-quinolinylboronic acid pinacol ester: 24.8 g, potassium carbonate: 19.2 g, toluene: 130 ml, ethanol: 40 ml, and water: 40 ml were added to a reaction vessel and mixed. Then, tetra(triphenylphosphine)palladium(O): 1.6 g was added, and the mixture was stirred under reflux overnight. After natural cooling, dispersion washing was performed at 80 °C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene and acetone, and the precipitated solid was collected to obtain 12.1 g of white powder of 3,3'-(5-chloro-1,3-phenylene)bisquinoline (yield 71.34%).

[0088] Add 5.0 g of 3,3'-(5-chloro-1,3-phenylene)bisquinoline, 5.6 g of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran, 5.8 g of tripotassium phosphate, 50 ml of 1,4-dioxane, and 15 ml of water to the reaction vessel and mix. Then add 0.4 g of tris(diphenylmethyleneacetone)dipalladium(O) and 0.4 g of tricyclohexylphosphine and stir under reflux overnight. After natural cooling, add water and methanol and stir. Collect the precipitated solid. Disperse and wash with monochlorobenzene at 100 °C, filter out the insoluble matter, and concentrate the filtrate to obtain the crude product. Purify the crude product by crystallization with monochlorobenzene and collect the precipitated solid to obtain 5.1 g of white powder (yield 65.1%).

[0089] The structure of the obtained white powder was identified using NMR.

[0090] use 1 H-NMR (CDCl3) detected the following 26 hydrogen signals, confirming it as an example compound (1-1).

[0091] δ(ppm)=9.34-9.34(2H),8.48-8.47(2H),8.21-8.19(2H),8.05-8.03(4H),8.00-7.94( 3H),8.90-7.85(5H),7.79-7.78(2H),7.69-7.60(4H),7.51-7.46(1H),7.39-7.35(1H).

[0092]

[0093] [Example 2]

[0094] <Synthesis of Exemplary Compound (1-3)>

[0095] Instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran in Example 1, 4,4,5,5-tetramethyl-2-[4-(9-phenanthyl)phenyl]-1,3,2-dioxaborane was used, and the same synthesis was performed as in Example 1 to obtain a white powder: 4.2 g (yield 57.4%).

[0096] The structure of the obtained white powder was identified using NMR.

[0097] use 1 H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-3).

[0098] δ(ppm)=9.37-9.36(2H),8.80(2H),8.51-8.50(2H),8.21-8.20(2H),8.10(2H),8.06-7.91(7H),7.80-7.26(11H).

[0099]

[0100] [Example 3]

[0101] <Synthesis of Exemplary Compound (1-49)>

[0102] 5.0 g of 3-(4-chlorophenyl)dibenzothiophene, 7.0 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-1,3-phenylene]diquinoline, 9.7 g of potassium carbonate, 0.7 g of tris(diphenylmethyleneacetone)dipalladium(O), and 0.9 g of tricyclohexylphosphine were added to the reaction vessel and refluxed with a 1,4-dioxane / H2O mixed solvent overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with monochlorobenzene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 5.8 g of white powder (yield 64.3%).

[0103] The structure of the obtained white powder was identified using NMR.

[0104] use 1 H-NMR (CDCl3) detected the following 26 hydrogen signals, confirming them as illustrative compounds (1-49).

[0105] δ(ppm)=9.36-9.35(2H),8.50(2H),8.23(1H),8.22-8.16(4H),8.06-8.04(3H),7 .97-7.96(2H),7.90-7.88(5H),7.81-7.76(3H),7.66-7.64(2H),7.50-7.48(2H).

[0106]

[0107] [Example 4]

[0108] <Synthesis of Exemplary Compound (1-46)>

[0109] 5.0 g of 3-(4-bromophenyl)-9-phenyl-9H-carbazole, 6.4 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-1,3-phenylene]diquinoline, 3.5 g of potassium carbonate, and 0.3 g of tetra(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with toluene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene and acetone, and the precipitated solid was collected to obtain 3.9 g of white powder (yield 47.8%).

[0110] The structure of the obtained white powder was identified using NMR.

[0111] use 1 H-NMR (CDCl3) detected the following 31 hydrogen signals, confirming them as illustrative compounds (1-46).

[0112] δ(ppm)=9.35(2H),8.48-8.44(3H),8.23-8.19(3H),8.06-8.02(3H),7.96(2H),7.92-7.8 7(4H),7.80-7.73(3H),7.66-7.60(6H),7.51-7.48(2H),7.44-7.43(2H),7.35-7.32(1H).

[0113]

[0114] [Example 5]

[0115] <Synthesis of Exemplary Compound (1-47)>

[0116] 5.0 g of 3-bromo-9-(2-naphthyl)-9H-carbazole, 6.5 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-1,3-phenylene]diquinoline, 3.7 g of potassium carbonate, and 0.3 g of tetrakis(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with toluene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene and acetone, and the precipitated solid was collected to obtain 4.1 g of white powder (yield 48.9%).

[0117] The structure of the obtained white powder was identified using NMR.

[0118] use 1 H-NMR (CDCl3) detected the following 29 hydrogen signals, confirming them as illustrative compounds (1-47).

[0119] δ(ppm)=9.37(2H),8.54-8.50(3H),8.28-8.26(1H),8.21-8.19(2H),8.12-8.10(4H) ,8.01-7.93(5H),7.83-7.70(4H),7.64-7.58(5H),7.51-7.46(2H),7.38-7.34(1H).

[0120]

[0121] [Example 6]

[0122] <Synthesis of Exemplary Compound (1-48)>

[0123] 6.0 g of 9-(4-bromophenyl)-9H-carbazole, 9.0 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-1,3-phenylene]diquinoline, 5.2 g of potassium carbonate, and 0.4 g of tetra(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with monochlorobenzene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with monochlorobenzene and acetone, and the precipitated solid was collected to obtain 6.8 g of white powder (yield 63.7%).

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

[0125] use 1 H-NMR (CDCl3) detected the following 27 hydrogen signals, confirming them as illustrative compounds (1-48).

[0126] δ(ppm)=9.37(2H),8.51-8.50(2H),8.22-8.16(4H),8.08-8.07(3H),8.01-7.95(4H) ,7.81-7.75(4H),7.66-7.62(2H),7.53-7.51(2H),7.47-7.43(2H),7.34-7.30(2H).

[0127]

[0128] [Example 7]

[0129] <Synthesis of Exemplary Compound (1-17)>

[0130] 5.0 g of 5-chloro-2-(4-phenanthrene-9-ylphenyl)pyrimidine, 6.9 g of 1,3-bis(quinolin-3-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)benzene, 2.8 g of potassium carbonate, and 0.4 g of tetra(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture and stirred overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with toluene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 4.3 g of white powder (yield 47.6%).

[0131] The structure of the obtained white powder was identified using NMR.

[0132] use 1 H-NMR (CDCl3) detected the following 30 hydrogen signals, confirming them as illustrative compounds (1-17).

[0133] δ(ppm)=9.34(2H),9.24(2H),8.80(1H),8.74(1H),8.69(2H),8.49(2H),8.21(2H),8.12(1H),8.0 3(2H),8.00(1H),7.97(2H),7.93(1H),7.80(2H),7.77(1H),7.74(2H),7.72-7.60(5H),7.57(1H).

[0134]

[0135] [Example 8]

[0136] <Synthesis of Exemplary Compound (1-18)>

[0137] 4.5 g of 5-bromo-2-(4-phenanthrene-9-yl-phenyl)-pyridine, 5.5 g of 1,3-bis(quinolin-3-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-benzene, 2.3 g of potassium carbonate, and 0.3 g of tetra(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture and stirred overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with monochlorobenzene solvent at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by column chromatography (support: silica gel, eluent: ethyl acetate / dichloroethane) to obtain a white powder: 5.3 g (yield: 73.0%).

[0138] The structure of the obtained white powder was identified using NMR.

[0139] use 1 H-NMR (CDCl3) detected the following 31 hydrogen signals, confirming them as illustrative compounds (1-18).

[0140] δ(ppm)=9.35(2H),8.16(1H),8.80(1H),8.74(1H),8.48(2H),8.25(2H),8.21(2H),8.17(1H),8.0 8(1H),8.05(2H),8.01(2H),7.96(2H),7.93(1H),7.79(2H),7.76(1H),7.74-7.60(7H),7.57(1H).

[0141]

[0142] [Example 9]

[0143] <Synthesis of Exemplary Compound (1-21)>

[0144] 12.5 g of 1,3-dibromo-5-chlorobenzene, 16.8 g of 8-quinoline boric acid, 19.2 g of potassium carbonate, 130 ml of toluene, 40 ml of ethanol, and 40 ml of water were added to the reaction vessel and mixed. Then, 1.6 g of tetra(triphenylphosphine)palladium(O) was added, and the mixture was stirred under reflux overnight. After natural cooling, the mixture was extracted with toluene, and the resulting organic layer was dispersed and washed at 80 °C. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with acetone, and the precipitated solid was collected to obtain 12.1 g of white powder of 8,8'-(5-chloro-1,3-phenylene)bisquinoline (yield 71.34%).

[0145] Add 5.7 g of 8,8'-(5-chloro-1,3-phenylene)bisquinoline, 6.3 g of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran, 6.6 g of tripotassium phosphate, 60 ml of 1,4-dioxane, and 18 ml of water to the reaction vessel and mix. Then add 0.4 g of tris(diphenylmethyleneacetone)dipalladium(O) and 0.4 g of tricyclohexylphosphine and stir under reflux overnight. After natural cooling, add water and methanol and stir. Collect the precipitated solid. Disperse and wash with monochlorobenzene at 100 °C, filter out the insoluble matter, and concentrate the filtrate to obtain the crude product. Purify the crude product by crystallization with monochlorobenzene and collect the precipitated solid to obtain 6.7 g of white powder (yield 75.0%).

[0146] The structure of the obtained white powder was identified using NMR.

[0147] use 1 H-NMR (CDCl3) detected the following 26 hydrogen signals, confirming them as illustrative compounds (1-21).

[0148] δ(ppm)=9.00-8.99(2H),8.24-8.21(2H),8.08-7.94(7H),7.89-7.85(5H),7.7 9-7.77(2H),7.70-7.63(3H),7.60-7.58(1H),7.48-7.42(3H),7.37-7.34(1H).

[0149]

[0150] [Example 10]

[0151] <Synthesis of Exemplary Compound (1-22)>

[0152] Instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran in Example 9, 4-(2-naphthyl)phenylboronic acid was used, and the same synthesis was performed as in Example 9 to obtain a white powder: 3.2 g (yield 54.9%).

[0153] The structure of the obtained white powder was identified using NMR.

[0154] use 1 H-NMR (CDCl3) detected the following 26 hydrogen signals, confirming them as illustrative compounds (1-22).

[0155] δ(ppm)=9.00-8.98(2H),8.24-8.21(2H),8.10-8.08(3H),8.04(1H),7.96-7.80(12H),7.67-7.63(2H),7.52-7.47(2H),7.46-7.42(2H).

[0156]

[0157] [Example 11]

[0158] <Synthesis of Exemplary Compound (1-23)>

[0159] Instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran in Example 9, 4,4,5,5-tetramethyl-2-[4-(9-phenanthyl)phenyl]-1,3,2-dioxaborane was used, and the same synthesis was performed as in Example 9, yielding a white powder: 8.8 g (yield 55.0%).

[0160] The structure of the obtained white powder was identified using NMR.

[0161] use 1H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-23).

[0162] δ(ppm)=9.01(2H),8.78-8.70(2H),8.22-8.19(2H),8.13-8.02(4H),7.97-7.83(7H),7.74(1H),7.68-7.53(8H),7.40(2H).

[0163]

[0164] [Example 12]

[0165] <Synthesis of Exemplary Compound (1-24)>

[0166] Instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran in Example 9, 2-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzothiophene was synthesized in the same manner as in Example 9, yielding a white powder: 6.7 g (yield 46.0%).

[0167] The structure of the obtained white powder was identified using NMR.

[0168] use 1 H-NMR (CDCl3) detected the following 26 hydrogen signals, confirming them as illustrative compounds (1-24).

[0169] δ(ppm)=9.00(2H),8.40(1H),8.23-8.20(3H),8.09-8.05(3H),7.96-7.74(11H),7.66-7.62(2H),7.47-7.40(4H).

[0170]

[0171] [Example 13]

[0172] <Synthesis of Exemplary Compounds (1-50)>

[0173] Instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]dibenzofuran in Example 9, 4,4,5,5-tetramethyl-2-[4-(phenanthrene-2-yl)phenyl]-1,3,2-dioxaborane was used, and the same synthesis was performed as in Example 9 to obtain a white powder: 11.0 g (yield 72.8%).

[0174] The structure of the obtained white powder was identified using NMR.

[0175] use 1 H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-50).

[0176] δ(ppm)=9.00-8.99(2H),8.77-8.75(1H),8.72-8.70(1H),8.24-8.22(2H),8.16(1H),8.09-8.08(2H),8.04-8 .03(1H),7.99-7.94(3H),7.91-7.85(7H),7.83-7.76(2H),7.69-7.62(3H),7.62-7.58(1H),7.45-7.42(2H).

[0177]

[0178] [Example 14]

[0179] <Synthesis of Exemplary Compound (1-33)>

[0180] 20.8 g of 1,3-dibromo-5-chlorobenzene, 29.1 g of 2-naphthylboronic acid, 31.9 g of potassium carbonate, 200 ml of toluene, 60 ml of ethanol, and 60 ml of water were added to the reaction vessel and mixed. Then, 2.6 g of tetra(triphenylphosphine)palladium(O) was added, and the mixture was stirred under reflux overnight. After natural cooling, the mixture was extracted with toluene, and the resulting organic layer was dispersed and washed at 80 °C. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene and acetone, and the precipitated solid was collected to obtain 24.0 g of a white powder of 2,2'-(5-chloro-1,3-phenylene)bis-naphthalene (yield 85.5%).

[0181] 10.0 g of 2,2'-(5-chloro-1,3-phenylene)bisnaphthalene, 7.5 g of 4-(2-naphthyl)phenylboronic acid, 11.6 g of tripotassium phosphate, 100 ml of 1,4-dioxane, and 30 ml of water were added to the reaction vessel and mixed. Then, 0.8 g of tris(diphenylmethyleneacetone)dipalladium(O) and 0.8 g of tricyclohexylphosphine were added, and the mixture was stirred under reflux overnight. After natural cooling, water and methanol were added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with toluene at 80 °C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene, and the precipitated solid was collected to obtain 10.5 g of white powder (yield 71.9%).

[0182] The structure of the obtained white powder was identified using NMR.

[0183] use 1 H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-33).

[0184] δ(ppm)=8.20(2H),8.12(1H),8.06(1H),8.01-7.99(3H),7.97-7.94(5H),7.91-7.88(9H),7.83-7.81(1H),7.56-7.47(6H).

[0185]

[0186] [Example 15]

[0187] <Synthesis of Exemplary Compound (1-31)>

[0188] Instead of 4-(2-naphthyl)phenylboronic acid in Example 14, 4,4,5,5-tetramethyl-2-[4-(9-phenanthyl)phenyl]-1,3,2-dioxaborane was used, and synthesized in the same manner as in Example 14, yielding a white powder: 11.4 g (yield 79.3%).

[0189] The structure of the obtained white powder was identified using NMR.

[0190] use 1 H-NMR (CDCl3) detected the following 30 hydrogen signals, confirming them as illustrative compounds (1-31).

[0191] δ(ppm)=8.82-8.80(1H),8.76-8.74(1H),8.23(2H),8.09-7.95(7H),7.94-7.90(8H),7.77(1H),7.72-7.68(3H),7.67-7.50(7H).

[0192]

[0193] [Example 16]

[0194] <Synthesis of Exemplary Compound (1-34)>

[0195] Instead of 4-(2-naphthyl)phenylboronic acid in Example 14, 2-[4-(9,9-dimethyl-9H-fluoren-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborane was synthesized in the same manner as in Example 14, yielding a white powder: 3.3 g (yield 42.0%).

[0196] The structure of the obtained white powder was identified using NMR.

[0197] use 1 H-NMR (CDCl3) detected the following 34 hydrogen signals, confirming them as illustrative compounds (1-34).

[0198] δ(ppm)=8.20(2H),8.06(1H),8.01-7.95(6H),7.92-7.87(6H),7.83-7.81(3H),7.7 5(1H),7.73(1H),7.67(1H),7.55-7.52(4H),7.46(1H),7.36-7.35(2H),1.57(6H).

[0199]

[0200] [Example 17]

[0201] <Synthesis of Exemplary Compound (1-35)>

[0202] Instead of 4-(2-naphthyl)phenylboronic acid in Example 14, 2-[4-(9,9-diphenyl-9H-fluoren-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborane was used, and synthesized in the same manner as in Example 14, yielding a white powder: 5.9 g (yield 79.0%).

[0203] The structure of the obtained white powder was identified using NMR.

[0204] use 1 H-NMR (CDCl3) detected the following 38 hydrogen signals, confirming them as illustrative compounds (1-35).

[0205] δ(ppm)=8.18(2H),8.04(1H),7.99-7.84(11H),7.82-7.79(3H),7.71-7.6 7(4H),7.54-7.51(4H),7.44-7.42(1H),7.40-7.36(1H),7.29-7.22(11H).

[0206]

[0207] [Example 18]

[0208] <Synthesis of Exemplary Compound (1-30)>

[0209] Instead of 4-(2-naphthyl)phenylboronic acid in Example 14, 2-[4-(dibenzofuran-3-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborane was used, and synthesized in the same manner as in Example 14, yielding a white powder: 9.5 g (yield 77.0%).

[0210] The structure of the obtained white powder was identified using NMR.

[0211] use 1 H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-30).

[0212] δ(ppm)=8.21(2H),8.07-8.06(1H),8.05-7.97(7H),7.95(1H),7.92-7.8 3(9H),7.70-7.67(1H),7.62-7.60(1H),7.56-7.48(5H),7.39-7.37(1H).

[0213]

[0214] [Example 19]

[0215] <Synthesis of Exemplary Compound (1-36)>

[0216] Instead of 4-(2-naphthyl)phenylboronic acid in Example 14, 9-phenyl-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenyl]-9H-carbazole was used, and synthesized in the same manner as in Example 14, yielding a white powder: 11.1 g (yield 73.5%).

[0217] The structure of the obtained white powder was identified using NMR.

[0218] use 1 H-NMR (CDCl3) detected the following 33 hydrogen signals, confirming them as illustrative compounds (1-36).

[0219] δ(ppm)=8.44(1H),8.24-8.22(3H),8.06-8.05(1H),8.03-7.95(6H),7.93-7.88(8H) ,7.75-7.72(1H),7.65-7.60(4H),7.56-7.49(6H),7.45-7.44(2H),7.34-7.33(1H).

[0220]

[0221] [Example 20]

[0222] <Synthesis of Exemplary Compound (1-38)>

[0223] 4.5 g of 5-chloro-2-(4-phenanthrene-9-ylphenyl)pyrimidine, 6.7 g of 2-[3,5-di(naphthyl-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborane, 2.5 g of potassium carbonate, and 0.4 g of tetra(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with monochlorobenzene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 1.8 g of white powder (yield 22.2%).

[0224] The structure of the obtained white powder was identified using NMR.

[0225] use 1 H-NMR (CDCl3) detected the following 32 hydrogen signals, confirming them as illustrative compounds (1-38).

[0226] δ(ppm)=9.24(2H),8.81-8.79(1H),8.76-8.74(1H),8.70-8.67(2H),8.22(2H),8.16-8.1 5(1H),8.03-7.97(7H),7.94-7.89(5H),7.77-7.70(5H),7.68-7.64(1H),7.59-7.54(5H).

[0227]

[0228] [Example 21]

[0229] <Synthesis of Exemplary Compound (1-39)>

[0230] 5.0 g of 5-bromo-2-(4-phenanthrene-9-ylphenyl)-pyridine, 6.7 g of 2-[3,5-di(naphthyl-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborane, 2.5 g of potassium carbonate, and 0.4 g of tetra(triphenylphosphine)palladium(O) were added to a reaction vessel and refluxed with a toluene / EtOH / H2O mixture and stirred overnight. After natural cooling, methanol was added and stirred, and the precipitated solid was collected. The solid was dispersed and washed with monochlorobenzene at 100°C, and the insoluble matter was filtered off. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene, and the precipitated solid was collected to obtain 6.7 g of white powder (yield 83.3%).

[0231] The structure of the obtained white powder was identified using NMR.

[0232] use 1 H-NMR (CDCl3) detected the following 33 hydrogen signals, confirming them as illustrative compounds (1-39).

[0233] δ(ppm)=9.16(1H),8.81-8.79(1H),8.75-8.73(1H),8.25-8.21(4H),8.18-8.15(1H),8.12-8.11( 1H),8.02-7.96(8H),7.93-7.89(5H),7.76(1H),7.72-7.67(4H),7.63-7.61(1H),7.58-7.51(5H).

[0234]

[0235] [Example 22]

[0236] <Synthesis of Exemplary Compound (1-25)>

[0237] 16.0 g of 1-bromo-3,5-dichlorobenzene, 28.3 g of 4,4,5,5-tetramethyl-2-[4-(9-phenanthyl)phenyl]-1,3,2-dioxaborane, 19.6 g of potassium carbonate, 200 ml of toluene, 60 ml of ethanol, and 60 ml of water were added to the reaction vessel and mixed. Then, 1.6 g of tetra(triphenylphosphine)palladium(O) was added, and the mixture was stirred under reflux overnight. After natural cooling, the mixture was extracted with toluene, and the resulting organic layer was dispersed and washed at 80 °C. The filtrate was concentrated to obtain the crude product. The crude product was purified by crystallization with toluene and acetone, and the precipitated solid was collected to obtain 21.2 g of a white solid of the phenanthrene derivative shown in formula (I-1) (yield 75.0%).

[0238]

[0239] Add 20.0 g of the phenanthrene derivative shown in formula (I-1), 28.0 g of bis(pinacolyl)diboron, 14.8 g of potassium acetate, and 200 ml of N,N-dimethylformamide to the reaction vessel and mix. Then add 1.7 g of dichloro[1,1'-bis(diphenylphosphine)ferrocene]palladium and 5.6 g of tricyclohexylphosphine, and stir under reflux overnight. After natural cooling, add water and methanol and stir. Collect the precipitated solid. Disperse and wash with toluene at 80°C, filter out the insoluble matter, and concentrate the filtrate to obtain the crude product. Purify the crude product by crystallization with toluene and acetone, and collect the precipitated solid to obtain 22.1 g of the white solid of the phenanthrene derivative shown in formula (I-2) (yield 75.8%).

[0240]

[0241] Add 10.0 g of the phenanthrene derivative shown in formula (I-2), 5.9 g of 2-chloroquinoline, 14.6 g of tripotassium phosphate, 100 ml of 1,4-dioxane, and 30 ml of water to the reaction vessel and mix. Then add 0.9 g of tris(diphenylmethyleneacetone)dipalladium(O) and 1.0 g of tricyclohexylphosphine and stir under reflux overnight. After natural cooling, add water and methanol and stir. Collect the precipitated solid. Disperse and wash with monochlorobenzene at 100°C, filter out the insoluble matter, and concentrate the filtrate to obtain the crude product. Purify the crude product by crystallization with monochlorobenzene and acetone, and collect the precipitated solid to obtain 8.4 g of white powder (yield 83.7%).

[0242] The structure of the obtained white powder was identified using NMR.

[0243] use 1 H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-25).

[0244] δ(ppm)=8.97(1H),8.83-8.80(1H),8.77-8.75(1H),8.66-8.65(2H),8.33-8.31(2H),8.28-8.26(2H),8.15-8 .13(2H),8.06-8.04(1H),8.01-7.99(2H),7.96-7.94(1H),7.90-7.88(2H),7.80-7.76(3H),7.73-7.56(8H).

[0245]

[0246] [Example 23]

[0247] <Synthesis of Exemplary Compound (1-26)>

[0248] Instead of 2-chloroquinoline in Example 22, 6-chloroquinoline was used, and the same synthesis was performed as in Example 22 to obtain a white powder: 6.5 g (yield 73.6%).

[0249] The structure of the obtained white powder was identified using NMR.

[0250] use 1 H-NMR (CDCl3) detected the following 28 hydrogen signals, confirming them as illustrative compounds (1-26).

[0251] δ(ppm)=8.97-8.96(2H),8.82-8.80(1H),8.76-8.74(1H),8.29-8.26(4H),8.20-8.16(4H),8.08( 3H),8.04-8.02(1H),7.96-7.92(3H),7.77(1H),7.73-7.62(5H),7.60-7.56(1H),7.50-7.46(2H).

[0252]

[0253] [Example 24]

[0254] For the compounds obtained in the foregoing examples, the melting point and glass transition temperature were determined using a high-sensitivity differential scanning calorimeter (Bruker AXSK.K., DSC3100SA). The results are summarized in Table 1.

[0255] [Table 1]

[0256]

[0257] Based on the foregoing results, most of the compounds obtained in the examples have glass transition temperatures above 100°C, which indicates that the thin film is stable.

[0258] [Example 25]

[0259] Using the compound of general formula (1) obtained in the foregoing examples, an 80 nm thick vapor-deposited film was formed on a silicon substrate. The refractive index n and extinction coefficient k at wavelengths of 450 nm and 750 nm were measured using a spectrophotometer (FILMETRICS F10-RT-UV). For comparison, measurements were also performed on the comparative compound (2-1) and Alq3 with the following structural formula (see, for example, Patent Document 4). The extinction coefficient k of both the compound of the present invention and the comparative compound is 0 in the wavelength range of 450 nm to 750 nm. The results of the refractive index n measurements are summarized in Table 2.

[0260]

[0261] [Table 2]

[0262]

[0263] As shown in Table 2, the compounds of the present invention have refractive indices that are equal to or greater than those of Alq3 and comparative compound (2-1) in the wavelength range of 450 nm to 750 nm. This indicates that an improvement in light extraction efficiency can be expected in organic EL elements using the compounds of the present invention as the constituent material of the capping layer.

[0264] [Example 26]

[0265] For organic EL elements made using the compounds of the present invention as constituent materials of the capping layer, the characteristics were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0266] Organic EL components such as Figure 6 As shown, the material is prepared by vapor deposition in the following order: hole injection layer 3, hole transport layer 4, light emission layer 5, electron transport layer 6, electron injection layer 7, cathode 8, and capping layer 9, obtained by pre-forming a reflective ITO electrode as a metal anode 2 on a glass substrate 1.

[0267] Specifically, a glass substrate 1, obtained by sequentially depositing a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film, is ultrasonically cleaned in isopropanol for 20 minutes and then dried on a heating plate heated to 250°C for 10 minutes. Afterward, it undergoes a 2-minute UV ozone treatment, and the ITO-coated glass substrate is placed in a vacuum evaporation machine, with the pressure reduced to below 0.001 Pa. Next, with a transparent anode 2 covering the substrate, a binary evaporation process is performed on an electron acceptor (Acceptor-1) and a compound (3-1) of the following structural formula at a evaporation rate ratio of Acceptor-1:compound (3-1) = 3:97 to form a hole injection layer 3 with a film thickness of 10 nm.

[0268] On the hole injection layer 3, a compound (3-1) with the following structural formula is formed as a hole transport layer 4 with a film thickness of 140 nm.

[0269] On the hole transport layer 4, compound (3-2) with the following structural formula and compound (3-3) with the following structural formula are subjected to binary evaporation at a evaporation rate ratio of (3-2):(3-3)=5:95 to form a light-emitting layer 5 with a film thickness of 20nm.

[0270] On the light-emitting layer 5, compound (3-4) and compound (3-5) of the following structural formula are subjected to binary vapor deposition at a vapor deposition rate ratio of (3-4):(3-5)=50:50 to form an electron transport layer 6 with a film thickness of 30nm.

[0271] On the electron transport layer 6, lithium fluoride is formed as an electron injection layer 7 with a film thickness of 1 nm.

[0272] On the electron injection layer 7, a magnesium-silver alloy is formed as a cathode 8 with a film thickness of 12 nm.

[0273] Finally, the compound (1-1) of Example 1 was formed as a capping layer 9 with a film thickness of 60 nm.

[0274]

[0275] [Example 27]

[0276] In Example 26, instead of compound (1-1) of Example 1, compound (1-3) of Example 2 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0277] [Example 28]

[0278] In Example 26, instead of compound (1-1) of Example 1, compound (1-46) of Example 4 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0279] [Example 29]

[0280] In Example 26, instead of compound (1-1) of Example 1, compound (1-47) of Example 5 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0281] [Example 30]

[0282] In Example 26, instead of compound (1-1) of Example 1, compound (1-48) of Example 6 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0283] [Example 31]

[0284] In Example 26, instead of compound (1-1) of Example 1, compound (1-17) of Example 7 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0285] [Example 32]

[0286] In Example 26, instead of compound (1-1) of Example 1, compound (1-18) of Example 8 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0287] [Example 33]

[0288] In Example 26, instead of compound (1-1) of Example 1, compound (1-21) of Example 9 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0289] [Example 34]

[0290] In Example 26, instead of compound (1-1) of Example 1, compound (1-22) of Example 10 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0291] [Example 35]

[0292] In Example 26, instead of compound (1-1) of Example 1, compound (1-23) of Example 11 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0293] [Example 36]

[0294] In Example 26, instead of compound (1-1) of Example 1, compound (1-24) of Example 12 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0295] [Example 37]

[0296] In Example 26, instead of compound (1-1) of Example 1, compound (1-33) of Example 14 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0297] [Example 38]

[0298] In Example 26, instead of compound (1-1) of Example 1, compound (1-31) of Example 15 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0299] [Example 39]

[0300] In Example 26, instead of compound (1-1) of Example 1, compound (1-34) of Example 16 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0301] [Example 40]

[0302] In Example 26, instead of compound (1-1) of Example 1, compound (1-35) of Example 17 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 2.

[0303] [Example 41]

[0304] In Example 26, instead of compound (1-1) of Example 1, compound (1-30) of Example 18 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0305] [Example 42]

[0306] In Example 26, instead of compound (1-1) of Example 1, compound (1-36) of Example 19 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0307] [Example 43]

[0308] In Example 26, instead of compound (1-1) of Example 1, compound (1-38) of Example 20 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0309] [Example 44]

[0310] In Example 26, instead of compound (1-1) of Example 1, compound (1-39) of Example 21 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0311] [Example 45]

[0312] In Example 26, instead of compound (1-1) of Example 1, compound (1-25) of Example 22 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0313] [Example 46]

[0314] In Example 26, instead of compound (1-1) of Example 1, compound (1-26) of Example 23 was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0315] [Comparative Example 1]

[0316] For comparison, in Example 26, Alq3 was used instead of compound (1-1) from Example 1 to form a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in atmospheric conditions, and the results of the measurement of the luminescence characteristics with applied DC voltage are summarized in Table 3.

[0317] [Comparative Example 2]

[0318] For comparison, in Example 26, instead of compound (1-1) of Example 1, compound (2-1) was formed as a capping layer 9 with a film thickness of 60 nm. Otherwise, an organic EL element was fabricated under the same conditions. The characteristics of the fabricated organic EL element were measured at room temperature in the atmosphere, and the results of the measurement of the light emission characteristics with applied DC voltage are summarized in Table 3.

[0319] The organic EL devices fabricated using the foregoing examples and comparative examples were used to determine device lifetimes, and the results are summarized in Table 2. Device lifetime is measured at 10 mA / cm². 2 The time it takes for the constant current driven to decay to 95% of the initial brightness when the brightness is set to 100% is measured.

[0320] [Table 3]

[0321]

[0322] As shown in Table 3, for a current density of 10 mA / cm² 2 The driving voltage of Comparative Examples 1 and 2 is essentially the same as that of Examples 26 to 46. In contrast, significant improvements were observed in brightness, luminous efficiency, power efficiency, and device lifetime for all examples compared to the comparative examples. This indicates that the compound of general formula (1) of the present invention is a suitable material for use in the capping layer, which can increase the refractive index of the capping layer and thus significantly improve the light extraction efficiency of the organic EL element.

[0323] Industrial availability

[0324] The compounds of the present invention have a high refractive index, which significantly improves light extraction efficiency, and the thin film is stable, making them excellent compounds suitable for use in organic EL devices. Furthermore, organic EL devices fabricated using the compounds of the present invention achieve high efficiency. Moreover, by using the compounds of the present invention, which do not have absorption in the respective blue, green, and red wavelength regions, they are particularly suitable for applications requiring excellent purity and clear, bright images. Applications in, for example, household appliances and lighting are expected.

[0325] Explanation of reference numerals in the attached figures

[0326] 1. Glass substrate

[0327] 2. Transparent anode

[0328] 3. Hole injection layer

[0329] 4. Hole transport layer

[0330] 5. Light-emitting layer

[0331] 6. Electron transport layer

[0332] 7 Electron Injection Layer

[0333] 8 Cathode

[0334] 9. Covering layer

Claims

1. A compound represented by the following general formula (1), In formula (1), B represents a group selected from phenyl, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiopheneyl and fluorenyl groups substituted with methyl or phenyl; Ar1 represents a divalent group selected from phenylene, pyridylene, and pyrimidinylene; Ar2 represents a divalent group selected from phenylene, pyridinyl, and pyrimidinyl, or a single bond; A1 and A2 may be either the same or different from each other, representing the monovalent group shown in the following general formula (3a) or (3c). In formula (3a), any one of R2 to R8 represents a bonding site, and any group among R2 to R8 that is not a bonding site represents a hydrogen atom. In formula (3c), any one of R1 to R8 represents a bonding site, and any group among R1 to R8 that is not a bonding site represents a hydrogen atom.

2. An organic thin film comprising the compound of claim 1 having a refractive index of 1.70 or higher in the wavelength range of 450 nm to 750 nm.

3. An organic electroluminescent element, 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. The covering layer is the organic thin film as described in claim 2.

4. An electronic component having a pair of electrodes and at least one organic layer sandwiched therebetween, the organic layer comprising the compound of claim 1.

5. An electronic device comprising the electronic element of claim 4.

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