Compound and organic electroluminescent device using said compound

Abstract

The purpose of the present invention is to, in order to improve the light extraction efficiency of an organic EL element, provide a compound that has a low extinction coefficient and a high refractive index in a range of 450-750 nm in a capping layer.　According to the present invention, an organic EL element having excellent emission efficiency is obtained by designing a molecule while focusing attention to the fact that compounds having a central benzene backbone provide excellent stability and durability to a thin film and that the refractive index can be improved through adjustment of the molecular structure thereof, and by using a compound represented by general formula (1) as a material for a capping layer.

Description

[Technical Field]

[0001] The present invention relates to a compound suitable for a self-luminous electronic element suitable for various display devices, particularly a compound suitable for an organic electroluminescence element (hereinafter abbreviated as organic EL element), and an organic EL element using said compound. [Background technology]

[0002] Organic EL elements are self-luminous elements, and therefore are brighter and more visible than liquid crystal elements, enabling clearer displays, and therefore active research has been conducted on them.

[0003] In 1987, C.W. Tang and his colleagues at Eastman Kodak Company developed a layered structure element in which various roles were assigned to each material, making organic EL devices practical. They layered a phosphor capable of transporting electrons and an organic material capable of transporting holes, and injected both charges into the phosphor layer to emit light, achieving an luminance of 1000 cd / m at a voltage of 10 V or less. 2 Such high brightness has been achieved (see, for example, Patent Documents 1 and 2).

[0004] To date, many improvements have been made to the practical application of organic EL elements, and the various roles of the laminated structure have been further subdivided. In electroluminescent elements in which an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially provided on a substrate, high efficiency and durability have been achieved by light-emitting elements with a bottom emission structure that emits light from the bottom (see, for example, Non-Patent Document 1).

[0005] In recent years, light-emitting devices with a top-emission structure that uses a metal with a high work function as the anode and emits light from the top have come into use. In a bottom-emission structure in which light is extracted from the bottom where the pixel circuit is located, the area of ​​the light-emitting section is limited, whereas a light-emitting device with a top-emission structure has the advantage of being able to extract light from the top and not be obstructed by the pixel circuit, allowing for a larger light-emitting section. Light-emitting devices with a top-emission structure use semi-transparent electrodes such as LiF / Al / Ag (see, for example, Non-Patent Document 2), Ca / Mg (see, for example, Non-Patent Document 3), or LiF / MgAg as the cathode.

[0006] In such light-emitting devices, when light emitted from the light-emitting layer is incident on another film at an angle greater than a certain level, it is totally reflected at the interface between the light-emitting layer and the other film. As a result, only a portion of the emitted light can be utilized. In recent years, light-emitting devices have been proposed that provide a high-refractive-index "capping layer" on the outside of a semi-transparent electrode with a low refractive index in order to improve light extraction efficiency (see, for example, Non-Patent Documents 2 and 3).

[0007] The effect of the capping layer in a top-emission light-emitting device using Ir(ppy)3 as the light-emitting material was such that, while the current efficiency was 38 cd / A without the capping layer, the efficiency was improved by approximately 1.7 times to 64 cd / A in a light-emitting device using a 60 nm-thick ZnSe capping layer. It has also been shown that the maximum transmittance of the semi-transparent electrode and capping layer does not necessarily coincide with the maximum efficiency, and that the maximum light extraction efficiency is determined by the interference effect (see, for example, Non-Patent Document 3).

[0008] Conventionally, the use of high-resolution metal masks has been proposed for forming capping layers, but there is a problem in that heat can cause distortion in the metal mask when used under high-temperature conditions, resulting in reduced alignment accuracy. Therefore, ZnSe, which has a high melting point of 1100°C or higher (see, for example, Non-Patent Document 3), cannot be deposited in the correct position using high-resolution metal masks, which may affect the light-emitting element itself. Furthermore, even when deposited by sputtering, the effect on the light-emitting element is still significant, making capping layers made of inorganic materials unsuitable for use.

[0009] Additionally, the use of tris(8-hydroxyquinoline)aluminum (hereinafter abbreviated as Alq3) as a capping layer for adjusting the refractive index has been proposed (see, for example, Non-Patent Document 2). Alq3 is known as an organic EL material that is commonly used as a green light-emitting material or electron transport material, but because it has weak absorption around 450 nm, when used in blue light-emitting devices, there are problems such as a decrease in color purity and a decrease in light extraction efficiency.

[0010] To improve the device characteristics of organic EL devices and significantly increase light extraction efficiency, materials for the capping layer are required that have a high refractive index, a low extinction coefficient, and excellent thin-film stability and durability. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] US5792557 [Patent Document 2] US5639914 [Patent Document 3] EP2684932 [Patent Document 4] US20140225100 [Non-patent literature]

[0012] [Non-Patent Document 1] Proceedings of the 9th Seminar of the Japan Society of Applied Physics, pp. 55-61 (2001) [Non-patent document 2] Appl.Phys.Lett.,78,544(2001) [Non-patent document 3] Appl.Phys.Lett.,82,466(2003) [Non-patent document 4] Appl.Phys.Let.,98,083302(2011) Summary of the Invention

[0013] An object of the present invention is to provide a compound that can be used as a capping layer for an organic EL device, and that has a high refractive index and a low extinction coefficient in the wavelength range of 450 nm to 750 nm, and to provide an organic EL device that uses the compound to improve light extraction efficiency.

[0014] The physical properties of a compound suitable for the capping layer of an organic EL device include (1) a high refractive index, (2) a low extinction coefficient, (3) the ability to be vapor-deposited, (4) a stable thin film state, and (5) a high glass transition temperature. The physical properties of the organic EL device to be provided by the present invention include (1) a high light extraction efficiency, (2) no decrease in color purity, (3) light transmission without change over time, and (4) a long life.

[0015] In order to achieve the above object, the present inventors focused on the fact that compounds centered on a benzene skeleton have excellent thin film stability and durability, and that the refractive index can be improved by adjusting the molecular structure, designed a molecule, fabricated an organic EL device using the compound as a material constituting the capping layer, and thoroughly evaluated the characteristics of the device, which resulted in the completion of the present invention.

[0016] That is, the present invention relates to a compound represented by the following general formula (1) and an organic EL device using the compound, and specifically, the present invention is as follows.

[0017] 1) A compound represented by the following general formula (1):

[0018] [ka]

[0019] 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 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 and represent a monovalent group represented by the following general formula (2):

[0020] [ka]

[0021] In formula (2), R1 to R8 may be the same or different and represent a bonding site, a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms, an optionally substituted cycloalkyl group of 5 to 10 carbon atoms, an optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms, an optionally substituted linear or branched alkyloxy group of 1 to 6 carbon atoms, an optionally substituted cycloalkyloxy group of 5 to 10 carbon atoms, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group, and any one of R1 to R8 represents a bonding site. X1 to X8 may be the same or different and represent a nitrogen atom or a carbon atom, and the number of nitrogen atoms in X1 to X8 is 0 to 2, and when X1 to X8 are nitrogen atoms, they are not bonded to any of R1 to R8.

[0022] 2) The compound according to 1), wherein A1 and A2 are monovalent groups represented by the following general formula (3a), (3b), or (3c):

[0023] [ka]

[0024] R1 to R8 in formulas (3a), (3b) and (3c) have the same definitions as R1 to R8 in formula (2).

[0025] 3) The compound according to 1) or 2), wherein B is a substituted or unsubstituted naphthalenyl group, phenanthrenyl group, dibenzofuranyl group, dibenzothiophenyl group, fluorenyl group, carbazolyl group, benzofuranyl group, or benzothiophenyl group.

[0026] 4) An organic thin film containing the compound according to any one of 1) to 3) above, which has a refractive index of 1.70 or more in the wavelength range of 450 nm to 750 nm.

[0027] 5) An organic electroluminescence 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 in this order, wherein the capping layer is the organic thin film described in 4) above.

[0028] 6) An electronic device having a pair of electrodes and at least one organic layer sandwiched between them, wherein the organic layer contains the compound according to any one of 1) to 3) above.

[0029] 7) An electronic device comprising the electronic element according to 6).

[0030] In the present invention, "unsubstituted" in the term "substituted or unsubstituted" means that a hydrogen atom is not substituted with a substituent.

[0031] In the present invention, the term "hydrogen atom" includes isotopes with different numbers of neutrons, namely, protium and deuterium.

[0032] In the present invention, specific examples of the "substituent" in the term "substituted or unsubstituted" include a cyano group, a nitro group, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, and a substituted or unsubstituted alkoxy group having 1 to 3 carbon atoms.

[0033] The "aromatic hydrocarbon group", "aromatic heterocyclic group" or "fused polycyclic aromatic group" in the "substituted or unsubstituted aromatic hydrocarbon group", "substituted or unsubstituted aromatic heterocyclic group" or "substituted or unsubstituted fused polycyclic aromatic group" represented by B and Ar1 to Ar2 in general formula (1) and R1 to R8 in general formula (2) specifically includes a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, a triphenylenyl group, a Examples of the aryl group include a group selected from aryl groups having 6 to 30 carbon atoms and heteroaryl groups having 2 to 20 carbon atoms, such as a pyridyl group, a pyrimidinyl group, a triazinyl group, a furyl group, a pyrrolyl group, a thienyl group, a quinolyl group, an isoquinolyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, a naphthyridinyl group, a phenanthrolinyl group, an acridinyl group, and a carbolinyl group.

[0034] In the general formula (2), R1 to R8 represent "a linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent", "a cycloalkyl group having 5 to 10 carbon atoms which may have a substituent", "a linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent", "a linear or branched alkyloxy group having 1 to 6 carbon atoms which may have a substituent", "a cycloalkyl group having 5 to 10 carbon atoms which may have a substituent", "a linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent", "a linear or branched alkyloxy group having 1 to 6 carbon atoms which may have a substituent", "a cycloalkyloxy group having 5 to 10 carbon atoms which may have a substituent", or "a substituted or unsubstituted aryloxy group" and "a linear or branched alkyl group having 1 to 6 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a linear or branched alkenyl group having 2 ... cycloalkyl group having 2 to 6 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a cycloalkyl group having 2 to 6 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a cycloalkyl group having 2 to 6 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a cycloalkyl group having 5 to 10 carbon atoms", "a cycloalkyl group Specific examples of the "linear or branched alkyloxy group having 5 to 6 carbon atoms," "cycloalkyloxy group having 5 to 10 carbon atoms," or "aryloxy group" include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a vinyl group, an aryl group, an isopropenyl group, a 2-butenyl group, a methyloxy group, an ethyloxy group, an n-propyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, a 1-adamantyloxy group, a phenyloxy group, a tolyloxy group, and a biphenyloxy group.

[0035] Examples of the "substituent" in the "substituted aromatic hydrocarbon group," "substituted aromatic heterocyclic group," "substituted fused polycyclic aromatic group," "optionally substituted linear or branched alkyl group of 1 to 6 carbon atoms," "optionally substituted cycloalkyl group of 5 to 10 carbon atoms," or "optionally substituted linear or branched alkenyl group of 2 to 6 carbon atoms," represented by B and Ar1 to Ar2 in general formula (1) and R1 to R8 in general formula (2) specifically include a deuterium atom, a cyano group, a nitro group; a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a silyl group such as a trimethylsilyl group or a triphenylsilyl group; a linear or branched alkyl group of 1 to 6 carbon atoms such as a methyl group, an ethyl group, or a propyl group; a linear or branched alkyloxy group of 1 to 6 carbon atoms such as a methyloxy group, an ethyloxy group, or a propyloxy group; an alkenyl group such as a vinyl group or an aryl group; a phenyloxy group, aryloxy groups such as an oxy group or a tolyloxy group; arylalkyloxy groups such as a benzyloxy group or a phenethyloxy group; aromatic hydrocarbon groups or condensed polycyclic aromatic groups such as a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, or a triphenylenyl group; pyridyl groups, thienyl groups, furyl groups, pyrrolyl groups, Examples of the substituents include an aryl group having 6 to 30 carbon atoms, such as a benzoyl group, an isoquinolyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, and a carbolinyl group, and these substituents may be further substituted with the substituents exemplified above. Furthermore, adjacent benzene rings substituted with these substituents, or multiple substituents substituted on the same benzene ring, may be bonded to each other via a single bond, a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom to form a ring.

[0036] A1 and A2 in general formula (1) are monovalent groups represented by general formula (2) and bond to any one of R1 to R8. The group represented by general formula (2) is preferably a monovalent group represented by general formula (3a), (3b), or (3c), more preferably a group represented by general formula (3a) or (3c). It is also preferable that A1 and A2 are the same.

[0037] When A1 and A2 in general formula (1) are groups represented by general formula (3a), from the viewpoints of refractive index and heat resistance, it is preferable that the bonding site is R2, R3, R8, or R6. Furthermore, from the viewpoint of ease of synthesis, it is preferable that all of R2 to R8 that are not bonding sites are hydrogen atoms.

[0038] When A1 and A2 in general formula (1) are groups represented by general formula (3c), it is preferable that the bonding site is R2 from the viewpoints of refractive index and heat resistance. Furthermore, it is preferable that all of R1 to R8 that are not bonding sites are hydrogen atoms from the viewpoint of ease of synthesis.

[0039] In view of refractive index and heat resistance, Ar1 and Ar2 in general formula (1) are preferably each independently selected from a phenylene group, a pyridylene group, a pyrimidinylene group, and a single bond.

[0040] As B in general formula (1), a substituted or unsubstituted naphthalenyl group, phenanthrenyl group, dibenzofuranyl group, dibenzothiophenyl group, fluorenyl group, carbazolyl group, benzofuranyl group or benzothiophenyl group is more preferred.

[0041] The compound of the present invention represented by the general formula (1) preferably has a refractive index of 1.70 or more, particularly preferably 1.85 or more, in the wavelength range of 450 nm to 700 nm.

[0042] The compound of the present invention represented by the general formula (1) has a high refractive index in the wavelength range of 450 nm to 750 nm and a low extinction coefficient. Therefore, by providing the compound on the outer side of the transparent or semitransparent electrode of an organic EL element and using it as a capping layer having a higher refractive index than the semitransparent electrode, an organic EL element can be obtained that can significantly improve the light extraction efficiency. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 shows the structures of compounds (1-1) to (1-12) as examples of the compounds of the present invention. [Figure 2] FIG. 1 shows the structures of compounds (1-13) to (1-24) as examples of the compounds of the present invention. [Figure 3] FIG. 1 shows the structures of compounds (1-25) to (1-36) as examples of the compounds of the present invention. [Figure 4] FIG. 1 shows the structures of compounds (1-37) to (1-45) as examples of the compounds of the present invention. [Figure 5] FIG. 1 shows the structures of compounds (1-46) to (1-50) as examples of the compounds of the present invention. [Figure 6] 1 is a diagram showing an example of the configuration of an organic EL element of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] Among the compounds of the present invention represented by the general formula (1), specific examples of preferred compounds are shown in Figs. 1 to 5, but the compounds are not limited to these.

[0045] The compound of the present invention represented by the general formula (1) is a novel compound, but can be synthesized according to a known method utilizing a cross-coupling reaction or the like.

[0046] The method for purifying the compound represented by the general formula (1) of the present invention is not particularly limited, and examples thereof include known methods used for purifying organic compounds, such as purification by column chromatography, adsorption purification using silica gel, activated carbon, or activated clay, recrystallization or crystallization using a solvent, and sublimation purification. The compound can be identified by NMR analysis. Furthermore, it is preferable to measure the melting point, glass transition temperature (Tg), and refractive index as physical property values.

[0047] The melting point and glass transition temperature (Tg) were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS) using powdered compounds.

[0048] The refractive index was measured by forming an 80 nm thin film on a silicon substrate and using a spectrophotometer (F10-RT-UV, manufactured by Filmetrics).

[0049] Examples of the structure of the organic EL device of the present invention include, for example, a top-emission light-emitting device that is composed of an anode, a hole transport layer, an emitting layer, an electron transport layer, a cathode, and a capping layer, arranged in this order on a glass substrate, a device that has a hole injection layer between the anode and the hole transport layer, a device that has an electron blocking layer between the hole transport layer and the emitting layer, a device that has a hole blocking layer between the emitting layer and the electron transport layer, and a device that has an electron injection layer between the electron transport layer and the cathode. In these multilayer structures, one organic layer can serve as several layers, for example, a structure that serves both as a hole injection layer and a hole transport layer, a structure that serves both as a hole transport layer and an electron blocking layer, a structure that serves both as a hole blocking layer and an electron transport layer, or a structure that serves both as an electron transport layer and an electron injection layer. It is also possible to use a structure in which two or more organic layers having the same function are stacked, such as a structure in which two hole transport layers are stacked, a structure in which two light-emitting layers are stacked, a structure in which two electron transport layers are stacked, or a structure in which two capping layers are stacked.

[0050] The total thickness of each layer of the organic EL element is preferably about 200 nm to 750 nm, more preferably about 350 nm to 600 nm. The thickness of the capping layer is preferably, for example, 30 nm to 120 nm, more preferably 40 nm to 80 nm. In this case, good light extraction efficiency can be obtained. The thickness of the capping layer can be appropriately changed depending on the type of light-emitting material used in the light-emitting element, the thickness of the organic EL element other than the capping layer, etc.

[0051] For the anode of the organic EL device of the present invention, an electrode material with a large work function such as ITO or gold is used.

[0052] For the hole injection layer of the organic EL device of the present invention, arylamine compounds having a structure in which three or more triphenylamine structures are linked in the molecule by a single bond or a divalent group not containing a heteroatom, for example, starburst-type triphenylamine derivatives, arylamine compounds such as various triphenylamine tetramers, porphyrin compounds typified by copper phthalocyanine, acceptor heterocyclic compounds such as hexacyanoazatriphenylene, and coating-type polymer materials can be used.

[0053] The hole-transport layer of the organic EL device of the present invention can be formed using benzidine derivatives such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (hereinafter abbreviated as TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (hereinafter abbreviated as NPD), and N,N,N',N'-tetrabiphenylylbenzidine; 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter abbreviated as TAPC); and arylamine compounds having two triphenylamine structures linked by a single bond or a divalent group not containing a heteroatom, such as N,N,N',N'-tetrabiphenylylbenzidine. Arylamine compounds having three or more triphenylamine structures linked by a single bond or a divalent group not containing a heteroatom, such as various triphenylamine trimers and tetramers, can also be used. Furthermore, as the hole injection / transport layer, a coating type polymer material such as poly(3,4-ethylenedioxythiophene) (hereinafter abbreviated as PEDOT) / poly(styrene sulfonate) (hereinafter abbreviated as PSS) can be used.

[0054] Furthermore, in the hole injection layer or hole transport layer, materials that are normally used for these layers can be doped with P, such as trisbromophenylaminehexachloroantimony or radialene derivatives (see, for example, Patent Document 3), or polymer compounds having a structure of a benzidine derivative such as TPD in their partial structure.

[0055] The electron blocking layer of the organic EL device of the present invention can be made of compounds having electron blocking properties, such as carbazole derivatives such as 4,4',4''-tri(N-carbazolyl)triphenylamine (hereinafter abbreviated as TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (hereinafter abbreviated as mCP), and 2,2-bis(4-carbazol-9-yl-phenyl)adamantane (hereinafter abbreviated as Ad-Cz), and compounds having a triphenylsilyl group and a triarylamine structure, such as 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene.

[0056] The light-emitting layer of the organic EL device of the present invention can be formed using light-emitting materials such as metal complexes of quinolinol derivatives, including Alq3, various metal complexes, anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, and polyparaphenylenevinylene derivatives. The light-emitting layer can also be formed using a host material and a dopant material. Anthracene derivatives are preferred as the host material. In addition to the light-emitting materials, other suitable materials include heterocyclic compounds having an indole ring as a fused ring substructure, heterocyclic compounds having a carbazole ring as a fused ring substructure, carbazole derivatives, thiazole derivatives, benzimidazole derivatives, and polydialkylfluorene derivatives. Furthermore, dopant materials include quinacridone, coumarin, rubrene, perylene, and their derivatives, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives. Green light-emitting materials are particularly preferred.

[0057] Phosphorescent emitters can also be used as light-emitting materials. Examples of phosphorescent emitters include metal complexes of iridium, platinum, and the like. Examples include green phosphorescent emitters such as Ir(ppy)3, blue phosphorescent emitters such as FIrpic and FIr6, and red phosphorescent emitters such as Btp2Ir(acac). Green phosphorescent emitters are particularly preferred. Examples of host materials that can be used include hole-injecting and transporting host materials such as carbazole derivatives, such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as CBP), TCTA, and mCP. Examples of electron-transporting host materials include p-bis(triphenylsilyl)benzene (hereinafter abbreviated as UGH2) and 2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter abbreviated as TPBI).

[0058] The phosphorescent light-emitting material is preferably doped into the host material by co-evaporation in a range of 1 to 30 weight percent based on the entire light-emitting layer to avoid concentration quenching.

[0059] Furthermore, it is also possible to use materials that emit delayed fluorescence, such as CDCB derivatives such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN, as light-emitting materials (see, for example, Non-Patent Document 4).

[0060] The hole-blocking layer of the organic EL device of the present invention can be made of compounds having hole-blocking properties, such as phenanthroline derivatives such as bathocuproine (hereinafter abbreviated as BCP), metal complexes of quinolinol derivatives such as aluminum(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (hereinafter abbreviated as BAlq), various rare earth complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, and benzoazole derivatives. These materials may also serve as materials for the electron-transporting layer.

[0061] For the electron transport layer of the organic EL device of the present invention, metal complexes of quinolinol derivatives such as Alq3 and BAlq, various metal complexes, triazole derivatives, triazine derivatives, pyrimidine derivatives, oxadiazole derivatives, pyridine derivatives, benzimidazole derivatives, benzoazole derivatives, thiadiazole derivatives, anthracene derivatives, carbodiimide derivatives, quinoxaline derivatives, pyridoindole derivatives, phenanthroline derivatives, and silole derivatives can be used.

[0062] The electron injection layer of the organic EL device of the present invention can be made of alkali metal salts such as lithium fluoride and cesium fluoride, alkaline earth metal salts such as magnesium fluoride, metal complexes of quinolinol derivatives such as lithium quinolinol, metal oxides such as aluminum oxide, or metals such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs). Furthermore, by appropriately selecting the electron transport layer and the cathode, the electron injection layer can be omitted.

[0063] Furthermore, in the electron injection layer or electron transport layer, materials normally used for these layers can be doped with N-type metals such as cesium.

[0064] For the cathode of the organic EL element of the present invention, an electrode material having a low work function such as aluminum, an alloy having an even lower work function such as a magnesium-silver alloy, a magnesium-calcium alloy, a magnesium-indium alloy, or an aluminum-magnesium alloy, ITO, IZO, or the like is used as the electrode material.

[0065] As the capping layer of the organic EL device of the present invention, an organic thin film containing the compound represented by the general formula (1) is used. From the viewpoint of improving light extraction efficiency, the organic thin film used as the capping layer, which contains the compound represented by the general formula (1), preferably has a refractive index of 1.70 or more, particularly preferably 1.85 or more, in the wavelength range of 450 nm to 750 nm.

[0066] The materials used for each layer constituting the organic EL device described above may be formed into a film alone, or may be mixed with other materials to form a film and use the resulting film as a single layer, or may be laminated structures of layers formed alone, layers formed as a mixture, or layers formed as a mixture with layers formed alone. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0067] Although the organic EL element having a top emission structure has been described above, the present invention is not limited to this and can be similarly applied to an organic EL element having a bottom emission structure or an organic EL element having a dual emission structure that emits light from both the top and bottom. In these cases, the electrode in the direction in which light is extracted from the light-emitting element to the outside must be transparent or semi-transparent.

[0068] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. [Example]

[0069] [Example 1] <Synthesis of Exemplary Compound (1-1)> A reaction vessel was charged with 12.5 g of 1,3-dibromo-5-chlorobenzene, 24.8 g of 3-quinolylboronic acid pinacol ester, 19.2 g of potassium carbonate, 130 ml of toluene, 40 ml of ethanol, and 40 ml of water. After mixing, 1.6 g of tetrakis(triphenylphosphine)palladium(0) was added and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was dispersed and washed at 80°C. Insoluble matter was filtered off, and the filtrate was concentrated to obtain a 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 3,3'-(5-chloro-1,3-phenylene)bisquinoline as a white powder (71.34% yield).

[0070] A reaction vessel was charged with 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-dioxaborolan-2-yl)phenyl]dibenzofuran, 5.8 g of tripotassium phosphate, 50 ml of 1,4-dioxane, and 15 ml of water. After mixing, 0.4 g of tris(dibenzylideneacetone)dipalladium(0) and 0.4 g of tricyclohexylphosphine were added and heated under reflux overnight. After cooling, water and methanol were added and stirred, and the precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C. Insoluble matter was filtered, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 5.1 g of a white powder (yield: 65.1%).

[0071] The structure of the obtained white powder was identified using NMR. 1 The following 26 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-1). 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).

[0072] [ka]

[0073] [Example 2] <Synthesis of exemplary compound (1-3)> Synthesis was performed in the same manner as in Example 1, except that 4,4,5,5-tetramethyl-2-[4-(9-phenanthrenyl)phenyl]-1,3,2-dioxaborolane was used instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]dibenzofuran in Example 1, and 4.2 g (yield 57.4%) of a white powder was obtained.

[0074] The structure of the obtained white powder was identified using NMR. 1 The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-3). 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).

[0075] [ka]

[0076] [Example 3] <Synthesis of exemplary compound (1-49)> A reaction vessel was charged with 5.0 g of 3-(4-chlorophenyl)dibenzothiophene, 7.0 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,3-phenylene]diquinoline, 9.7 g of potassium carbonate, 0.7 g of tris(dibenzylideneacetone)dipalladium(0), and 0.9 g of tricyclohexylphosphine, and the mixture was refluxed overnight in a 1,4-dioxane / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C, and insoluble matter was filtered. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 5.8 g of a white powder (yield 64.3%).

[0077] The structure of the obtained white powder was identified using NMR. 1 The following 26 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-49). 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).

[0078] [ka]

[0079] [Example 4] <Synthesis of exemplary compound (1-46)> A reaction vessel was charged with 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-dioxaborolan-2-yl)-1,3-phenylene]diquinoline, 3.5 g of potassium carbonate, and 0.3 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with toluene at 100°C, the insoluble matter was filtered, and the filtrate was concentrated to obtain a 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 a white powder (47.8% yield).

[0080] The structure of the obtained white powder was identified using NMR. 1 The following 31 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-46). 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).

[0081] [ka]

[0082] [Example 5] <Synthesis of exemplary compound (1-47)> A reaction vessel was charged with 5.0 g of 3-bromo-9-(2-naphthalenyl)-9H-carbazole, 6.5 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,3-phenylene]diquinoline, 3.7 g of potassium carbonate, and 0.3 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with toluene at 100°C. Insoluble matter was filtered off, and the filtrate was concentrated to obtain a 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 a white powder (48.9% yield).

[0083] The structure of the obtained white powder was identified using NMR. 1 The following 29 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-47). 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).

[0084] [ka]

[0085] [Example 6] <Synthesis of exemplary compound (1-48)> A reaction vessel was charged with 6.0 g of 9-(4-bromophenyl)-9H-carbazole, 9.0 g of 3,3'-[5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,3-phenylene]diquinoline, 5.2 g of potassium carbonate, and 0.4 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C. Insoluble matter was filtered off, and the filtrate was concentrated to obtain a 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 a white powder (yield 63.7%).

[0086] The structure of the obtained white powder was identified using NMR. 1 The following 27 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-48). 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).

[0087] [ka]

[0088] [Example 7] <Synthesis of exemplary compound (1-17)> A reaction vessel was charged with 5.0 g of 5-chloro-2-(4-phenanthren-9-yl-phenyl)-pyrimidine, 6.9 g of 1,3-bis(quinolin-3-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-benzene, 2.8 g of potassium carbonate, and 0.4 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with toluene at 100°C, and insoluble matter was filtered. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 4.3 g of a white powder (47.6% yield).

[0089] The structure of the obtained white powder was identified using NMR. 1 The following 30 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-17). 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).

[0090] [ka]

[0091] [Example 8] <Synthesis of exemplary compound (1-18)> A reaction vessel was charged with 4.5 g of 5-bromo-2-(4-phenanthren-9-yl-phenyl)-pyridine, 5.5 g of 1,3-bis(quinolin-3-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-benzene, 2.3 g of potassium carbonate, and 0.3 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100 °C. Insoluble matter was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: ethyl acetate / dichloroethane) to obtain 5.3 g of a white powder (yield: 73.0%).

[0092] The structure of the obtained white powder was identified using NMR. 1 The following 31 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-18). 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).

[0093] [ka]

[0094] [Example 9] <Synthesis of exemplary compound (1-21)> A reaction vessel was charged with 12.5 g of 1,3-dibromo-5-chlorobenzene, 16.8 g of 8-quinolineboronic acid, 19.2 g of potassium carbonate, 130 ml of toluene, 40 ml of ethanol, and 40 ml of water. After mixing, 1.6 g of tetrakis(triphenylphosphine)palladium(0) was added and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was extracted with toluene. The resulting organic layer was subjected to dispersion washing at 80°C, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with acetone, and the precipitated solid was collected to obtain 12.1 g of 8,8'-(5-chloro-1,3-phenylene)bisquinoline as a white powder (71.34% yield).

[0095] A reaction vessel was charged with 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-dioxaborolan-2-yl)phenyl]dibenzofuran, 6.6 g of tripotassium phosphate, 60 ml of 1,4-dioxane, and 18 ml of water. After mixing, 0.4 g of tris(dibenzylideneacetone)dipalladium(0) and 0.4 g of tricyclohexylphosphine were added and heated under reflux overnight. After cooling, water and methanol were added and stirred, and the precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C. Insoluble matter was filtered, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 6.7 g of a white powder (75.0% yield).

[0096] The structure of the obtained white powder was identified using NMR. 1 The following 26 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-21). 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).

[0097] [ka]

[0098] [Example 10] <Synthesis of exemplary compound (1-22)> Synthesis was performed in the same manner as in Example 9, except that 4-(2-naphthyl)phenylboronic acid was used instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]dibenzofuran in Example 9, and 3.2 g (yield 54.9%) of a white powder was obtained.

[0099] The structure of the obtained white powder was identified using NMR. 1 The following 26 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-22). 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).

[0100] [ka]

[0101] [Example 11] <Synthesis of exemplary compound (1-23)> Synthesis was carried out in the same manner as in Example 9, except that 4,4,5,5-tetramethyl-2-[4-(9-phenanthrenyl)phenyl]-1,3,2-dioxaborolane was used instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]dibenzofuran in Example 9, to obtain 8.8 g (yield 55.0%) of a white powder.

[0102] The structure of the obtained white powder was identified using NMR. 1The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-23). 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).

[0103] [ka]

[0104] [Example 12] <Synthesis of exemplary compound (1-24)> Synthesis was performed in the same manner as in Example 9, except that 2-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]dibenzothiophene was used instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]dibenzofuran in Example 9, and 6.7 g (yield 46.0%) of a white powder was obtained.

[0105] The structure of the obtained white powder was identified using NMR. 1 The following 26 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-24). 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).

[0106] [ka]

[0107] [Example 13] <Synthesis of exemplary compound (1-50)> Synthesis was performed in the same manner as in Example 9, except that 4,4,5,5-tetramethyl-2-[4-(phenanthren-2-yl)phenyl]-1,3,2-dioxaborolane was used instead of 3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]dibenzofuran in Example 9, and 11.0 g (yield 72.8%) of a white powder was obtained.

[0108] The structure of the obtained white powder was identified using NMR. 1 The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-50). 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).

[0109] [ka]

[0110] [Example 14] <Synthesis of exemplary compound (1-33)> A reaction vessel was charged with 20.8 g of 1,3-dibromo-5-chlorobenzene, 29.1 g of 2-naphthaleneboronic acid, 31.9 g of potassium carbonate, 200 ml of toluene, 60 ml of ethanol, and 60 ml of water. After mixing, 2.6 g of tetrakis(triphenylphosphine)palladium(0) was added and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was extracted with toluene. The resulting organic layer was subjected to dispersion washing at 80°C, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with toluene and acetone. The precipitated solid was collected, yielding 24.0 g (85.5% yield) of a white powder of 2,2'-(5-chloro-1,3-phenylene)bis-naphthalene.

[0111] A reaction vessel was charged with 10.0 g of 2,2'-(5-chloro-1,3-phenylene)bis-naphthalene, 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. After mixing, 0.8 g of tris(dibenzylideneacetone)dipalladium(0) and 0.8 g of tricyclohexylphosphine were added and the mixture was heated under reflux and stirred overnight. After cooling, water and methanol were added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with toluene at 80°C, and the insoluble matter was filtered. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with toluene, and the precipitated solid was collected to obtain 10.5 g of a white powder (71.9% yield).

[0112] The structure of the obtained white powder was identified using NMR. 1 The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-33). 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).

[0113] [ka]

[0114] [Example 15] <Synthesis of exemplary compound (1-31)> Synthesis was performed in the same manner as in Example 14, except that 4,4,5,5-tetramethyl-2-[4-(9-phenanthrenyl)phenyl]-1,3,2-dioxaborolane was used instead of 4-(2-naphthyl)phenylboronic acid in Example 14, and 11.4 g (yield 79.3%) of a white powder was obtained.

[0115] The structure of the obtained white powder was identified using NMR. 1The following 30 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-31). 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).

[0116] [ka]

[0117] [Example 16] <Synthesis of exemplary compound (1-34)> Synthesis was carried out in the same manner as in Example 14, except that 2-[4-(9,9-dimethyl-9H-fluoren-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was used instead of 4-(2-naphthyl)phenylboronic acid in Example 14, and 3.3 g (yield 42.0%) of a white powder was obtained.

[0118] The structure of the obtained white powder was identified using NMR. 1 The following 34 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-34). 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).

[0119] [ka]

[0120] [Example 17] <Synthesis of exemplary compound (1-35)> Synthesis was carried out in the same manner as in Example 14, except that 2-[4-(9,9-diphenyl-9H-fluoren-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was used instead of 4-(2-naphthyl)phenylboronic acid in Example 14, and 5.9 g (yield 79.0%) of a white powder was obtained.

[0121] The structure of the obtained white powder was identified using NMR. 1 The following 38 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-35). 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).

[0122] [ka]

[0123] [Example 18] <Synthesis of exemplary compound (1-30)> Synthesis was performed in the same manner as in Example 14, except that 2-[4-(dibenzofuran-3-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was used instead of 4-(2-naphthyl)phenylboronic acid in Example 14, and 9.5 g (yield 77.0%) of a white powder was obtained.

[0124] The structure of the obtained white powder was identified using NMR. 1 The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-30). 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).

[0125] [ka]

[0126] [Example 19] <Synthesis of exemplary compound (1-36)> Synthesis was carried out in the same manner as in Example 14, except that 9-phenyl-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-9H-carbazole was used instead of 4-(2-naphthyl)phenylboronic acid in Example 14, and 11.1 g (yield 73.5%) of a white powder was obtained.

[0127] The structure of the obtained white powder was identified using NMR. 1 The following 33 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-36). 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).

[0128] [ka]

[0129] [Example 20] <Synthesis of exemplary compound (1-38)> A reaction vessel was charged with 4.5 g of 5-chloro-2-(4-phenanthren-9-yl-phenyl)-pyrimidine, 6.7 g of 2-[3,5-di(naphthalen-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 2.5 g of potassium carbonate, and 0.4 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C. Insoluble matter was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with monochlorobenzene, and the precipitated solid was collected to obtain 1.8 g of a white powder (yield 22.2%).

[0130] The structure of the obtained white powder was identified using NMR. 1 The following 32 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-38). 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).

[0131] [ka]

[0132] [Example 21] <Synthesis of exemplary compound (1-39)> A reaction vessel was charged with 5.0 g of 5-bromo-2-(4-phenanthren-9-yl-phenyl)-pyridine, 6.7 g of 2-[3,5-di(naphthalen-2-yl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 2.5 g of potassium carbonate, and 0.4 g of tetrakis(triphenylphosphine)palladium(0). The mixture was refluxed overnight in a toluene / EtOH / HO mixed solvent. After cooling, methanol was added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C. Insoluble matter was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with toluene, and the precipitated solid was collected to obtain 6.7 g of a white powder (yield 83.3%).

[0133] The structure of the obtained white powder was identified using NMR. 1 The following 33 hydrogen signals were detected by H-NMR (CDCl3), confirming that the compound was the exemplary compound (1-39). 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).

[0134] [ka]

[0135] [Example 22] <Synthesis of exemplary compound (1-25)> A reaction vessel was charged with 16.0 g of 1-bromo-3,5-dichlorobenzene, 28.3 g of 4,4,5,5-tetramethyl-2-[4-(9-phenanthrenyl)phenyl]-1,3,2-dioxaborolane, 19.6 g of potassium carbonate, 200 ml of toluene, 60 ml of ethanol, and 60 ml of water. After mixing, 1.6 g of tetrakis(triphenylphosphine)palladium(0) was added and the mixture was heated under reflux and stirred overnight. After cooling, the mixture was extracted with toluene. The resulting organic layer was subjected to dispersion washing at 80°C, and the filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with toluene and acetone. The precipitated solid was collected, yielding 21.2 g (75.0% yield) of a white solid phenanthrene derivative represented by the following formula (I-1).

[0136] [ka]

[0137] A reaction vessel was charged with 20.0 g of the phenanthrene derivative represented by formula (I-1), 28.0 g of bis(pinacolato)diboron, 14.8 g of potassium acetate, and 200 ml of N-N dimethylformamide. After mixing, 1.7 g of dichloro[1,1'-bis(diphenylphosphino)ferrocene]palladium and 5.6 g of tricyclohexylphosphine were added and the mixture was heated under reflux and stirred overnight. After cooling, water and methanol were added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with toluene at 80°C, and the insoluble matter was filtered. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with toluene and acetone. The precipitated solid was collected, yielding 22.1 g (75.8% yield) of a white solid of the phenanthrene derivative represented by formula (I-2) below.

[0138] [ka]

[0139] A reaction vessel was charged with 10.0 g of the phenanthrene derivative represented by 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. After mixing, 0.9 g of tris(dibenzylideneacetone)dipalladium(0) and 1.0 g of tricyclohexylphosphine were added and the mixture was heated under reflux and stirred overnight. After cooling, water and methanol were added and the mixture was stirred. The precipitated solid was collected. The mixture was dispersed and washed with monochlorobenzene at 100°C, and the insoluble matter was filtered. The filtrate was concentrated to obtain a crude product. The crude product was purified by crystallization with monochlorobenzene and acetone. The precipitated solid was collected and yielded 8.4 g of a white powder (yield 83.7%).

[0140] The structure of the obtained white powder was identified using NMR. 1 The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-25). 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).

[0141] [ka]

[0142] [Example 23] <Synthesis of exemplary compound (1-26)> Synthesis was carried out in the same manner as in Example 22, except that 6-chloroquinoline was used instead of 2-chloroquinoline in Example 22, to obtain 6.5 g (yield 73.6%) of a white powder.

[0143] The structure of the obtained white powder was identified using NMR. 1The following 28 hydrogen signals were detected by H-NMR (CDCl3), confirming that it was the exemplary compound (1-26). 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).

[0144] [ka]

[0145] [Example 24] The melting points and glass transition points of the compounds obtained in the above examples were measured using a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS). The results are summarized in Table 1.

[0146] [Table 1]

[0147] From the above results, it can be seen that many of the compounds obtained in the examples have glass transition points of 100° C. or higher, which indicates that the thin film state is stable.

[0148] [Example 25] Using the compound represented by general formula (1) obtained in the above example, an 80 nm thick vapor-deposited film was prepared on a silicon substrate, and the refractive index n and extinction coefficient k at wavelengths of 450 nm and 750 nm were measured using a spectrophotometer (F10-RT-UV, manufactured by Filmetrics). For comparison, measurements were also made on the comparative compound (2-1) and Alq3 of the following structural formula (see, for example, Patent Document 4). Both the compound of the present invention and the comparative compound had an extinction coefficient k of 0 in the wavelength range of 450 nm to 750 nm, and the measurement results of the refractive index n are summarized in Table 2.

[0149] [ka]

[0150] [Table 2]

[0151] As shown in Table 2, in the wavelength range of 450 nm to 750 nm, the compounds of the present invention have refractive indices equal to or greater than those of Alq3 and comparative compound (2-1). This indicates that an improvement in the light extraction efficiency can be expected in organic EL devices using the compounds of the present invention as constituent materials for the capping layer.

[0152] [Example 26] The organic EL devices prepared using the compounds of the present invention as constituent materials for the capping layer were subjected to characteristic measurements in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0153] As shown in Figure 6, the organic EL device was fabricated by depositing a hole injection layer 3, a hole transport layer 4, an emitting layer 5, an electron transport layer 6, an electron injection layer 7, a cathode 8, and a capping layer 9 in this order on a glass substrate 1 on which a reflective ITO electrode had previously been formed as a metal anode 2. Specifically, a glass substrate 1 on which a 50 nm thick ITO film, a 100 nm thick silver alloy reflective film, and a 5 nm thick ITO film were sequentially formed was subjected to ultrasonic cleaning in isopropyl alcohol for 20 minutes and then dried on a hot plate heated to 250°C for 10 minutes. After that, UV ozone treatment was performed for 2 minutes, and the ITO-coated glass substrate was placed in a vacuum deposition machine and the pressure was reduced to 0.001 Pa or less. Subsequently, a hole injection layer 3 was formed covering the transparent anode 2 by binary deposition of an electron acceptor (Acceptor-1) of the following structural formula and a compound (3-1) of the following structural formula at a deposition rate ratio of Acceptor-1:Compound (3-1) = 3:97, resulting in a thickness of 10 nm. On this hole injection layer 3, a hole transport layer 4 was formed by depositing a compound (3-1) having the following structural formula to a thickness of 140 nm. On this hole transport layer 4, a compound (3-2) having the following structural formula and a compound (3-3) having the following structural formula were deposited by binary deposition at a deposition rate ratio of (3-2):(3-3)=5:95 to form an emitting layer 5 having a thickness of 20 nm. On this light-emitting layer 5, an electron transport layer 6 was formed by binary deposition of a compound (3-4) having the following structural formula and a compound (3-5) having the following structural formula at a deposition rate ratio of (3-4):(3-5)=50:50 to a thickness of 30 nm. On this electron transport layer 6, an electron injection layer 7 was formed of lithium fluoride to a thickness of 1 nm. On this electron injection layer 7, a cathode 8 made of magnesium silver alloy was formed to a thickness of 12 nm. Finally, the compound (1-1) of Example 1 was formed as a capping layer 9 to a thickness of 60 nm.

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157] [Example 27] An organic EL device was fabricated under the same conditions as in Example 26, except that the capping layer 9 was formed to a thickness of 60 nm using compound (1-3) of Example 2 instead of compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0158] [Example 28] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-46) of Example 4 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0159] [Example 29] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-47) of Example 5 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0160] [Example 30] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-48) of Example 6 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0161] [Example 31] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-17) of Example 7 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0162] [Example 32] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-18) of Example 8 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0163] [Example 33] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-21) of Example 9 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0164] [Example 34] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-22) of Example 10 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0165] [Example 35] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-23) of Example 11 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0166] [Example 36] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-24) of Example 12 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0167] [Example 37] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-33) of Example 14 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0168] [Example 38] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-31) of Example 15 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0169] [Example 39] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-34) of Example 16 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0170] [Example 40] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-35) of Example 17 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 2.

[0171] [Example 41] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-30) of Example 18 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0172] [Example 42] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-36) of Example 19 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0173] [Example 43] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-38) of Example 20 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0174] [Example 44] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-39) of Example 21 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0175] [Example 45] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-25) of Example 22 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0176] [Example 46] An organic EL device was fabricated under the same conditions as in Example 26, except that the compound (1-26) of Example 23 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) of Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0177] [Comparative Example 1] For comparison, an organic EL device was fabricated under the same conditions as in Example 26, except that Alq3 was formed to a thickness of 60 nm as the capping layer 9 instead of the compound (1-1) in Example 1. The characteristics of the fabricated organic EL device were measured in the air at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0178] Comparative Example 2 For comparison, an organic EL device was fabricated under the same conditions as in Example 26, except that compound (2-1) was formed to a thickness of 60 nm as capping layer 9 instead of compound (1-1) in Example 1. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature, and the measurement results of the light-emitting characteristics when a DC voltage was applied are summarized in Table 3.

[0179] The device life was measured using the organic EL devices fabricated in the above examples and comparative examples, and the results are summarized in Table 2. The device life was 10 mA / cm 2 The time required for the initial luminance to decay to 95% of 100% when the device was driven at a constant current of 100% was measured.

[0180] [Table 3]

[0181] As shown in Table 3, a current density of 10 mA / cm 2The driving voltage at this time was almost the same for the devices of Comparative Examples 1 and 2 and the devices of Examples 26 to 46, whereas the devices of Examples showed significant improvements in all of the luminance, luminous efficiency, power efficiency, and device life compared to the comparative examples. This indicates that the compound represented by general formula (1) of the present invention is a material that can be suitably used for the capping layer, and can increase the refractive index of the capping layer, thereby significantly improving the light extraction efficiency of the organic EL device. [Industrial Applicability]

[0182] The compound of the present invention has a high refractive index, can significantly improve light extraction efficiency, and is stable in a thin film state, making it an excellent compound suitable for use in organic EL devices. Furthermore, organic EL devices fabricated using the compound of the present invention can achieve high efficiency. Furthermore, by using the compound of the present invention, which has no absorption in the blue, green, and red wavelength regions, it is particularly suitable for displaying clear, bright images with good color purity. For example, it is expected to be used in home appliances and lighting. [Explanation of symbols]

[0183] 1. Glass substrate 2 transparent anode 3. Hole injection layer 4. Hole transport layer 5. Light-emitting layer 6 Electron transport layer 7 Electron injection layer 8 cathode 9 Capping Layer

Claims

1. A compound represented by the following general formula (1): 【Chemistry 1】 (In the formula, B represents a group selected from a phenyl group, a naphthalenyl group, a phenanthrenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a 9,9-dimethylfluorenyl group, and a 9,9-diphenylfluorenyl group. Ar １ represents a divalent group selected from a phenylene group, a pyridylene group, and a pyrimidinylene group, Ar ２ represents a divalent group selected from a phenylene group, a pyridylene group, and a pyrimidinylene group, or a single bond. A1 and A2 may be the same or different and represent a monovalent group represented by the following general formula (3a) or (3c): 【Chemistry 2】 (In formula (3a), R ２ ~R ８ represents a binding site, and R ２ ~R ８ All of the atoms that are not binding sites represent hydrogen atoms. In formula (3c), R １ ~R ８ represents a binding site, and R １ ~R ８ All atoms that are not bonding sites represent hydrogen atoms.)

2. 2. An organic thin film comprising the compound according to claim 1, which has a refractive index of 1.70 or more in the wavelength range of 450 nm to 750 nm.

3. an organic electroluminescence 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 in this order; An organic electroluminescence device, wherein the capping layer is the organic thin film according to claim 2 .

4. An electronic device having a pair of electrodes and at least one organic layer sandwiched between them, An electronic device, wherein the organic layer comprises the compound according to claim 1 .

5. An electronic device comprising the electronic element according to claim 4.

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