JP2007284684A - Material for organic electroluminescent element and organic electroluminescent element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for organic electroluminescent element imparting an organic electroluminescent element with high color purity and emitting blue based light and to provide an organic electroluminescent element using the same. <P>SOLUTION: The material for organic electroluminescent element comprises a compound having a (substituted) aryl indole group or diaryl indole group and (substituted) 6-30C meta-aromatic ring group. The organic electroluminescent element comprises an organic thin film layer comprising one or more layers held between anode and cathode, wherein at least one layer in the organic thin film layers is composed of the prescribed material for organic electroluminescent element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic electroluminescent element material and an organic electroluminescent element (organic EL element) using the same, and particularly relates to an organic EL element having high color purity and emitting blue light.

An organic EL element using an organic substance is considered to be promising for use as an inexpensive large-area full-color display element of a solid light emitting type, and many developments have been made. In general, an organic EL element is composed of a light emitting layer and a pair of counter electrodes sandwiching the layer.
When an electric field is applied between the electrodes, the organic EL element emits light by injecting electrons from the cathode side, injecting holes from the anode side, and recombining the electrons with holes in the light emitting layer. This is a phenomenon in which energy is generated and emitted as light when the excited state returns to the ground state.
Luminescent materials such as chelate complexes such as tris (8-quinolinolato) aluminum complex, coumarin derivatives, tetraphenylbutadiene derivatives, bisstyrylarylene derivatives, oxadiazole derivatives and the like are known as luminescent materials. It has been reported that light emission in the visible region can be obtained, and realization of a color display element is expected (for example, JP-A-8-239655, JP-A-7-138561, JP-A-3-200809). Issue gazette).

Recently, practical use of organic EL element displays has been started, but full-color display elements are under development. In particular, there is a demand for organic EL elements that have high color purity and luminous efficiency and emit blue light.
In order to solve these problems, for example, JP-A-8-12600 discloses a device using a phenylanthracene derivative as a blue light emitting material. The phenylanthracene derivative is used as a blue light emitting material, and is usually used as a laminate of the blue material layer with a tris (8-quinolinolato) aluminum (Alq) complex layer. The level used was insufficient. Japanese Patent Application Laid-Open No. 2001-288462 discloses a blue light-emitting element using an amine-based aromatic compound in a light-emitting layer, but its luminous efficiency is inadequate at 2 to 4 cd / A. Japanese Patent Application Laid-Open No. 2001-160489 discloses a device in which an azafluoranthene compound is added to a light emitting layer, but it does not emit blue light with sufficiently high color purity from yellow to green light emission.

  The present invention has been made to solve the above-described problems, and provides an organic EL element material having high color purity and emitting blue light and an organic EL element using the same.

  As a result of intensive studies to solve the above problems, the present inventors have used a compound in which a group having a cycloalkane skeleton or a metaphenylene group is bonded to a group having an indole skeleton as a host material. The present inventors have found that a high organic EL element can be obtained and solved the present invention.

That is, this invention provides the organic EL element material which consists of a compound represented by the following general formula (1) or (2).
(Ind−) _n L (1)
Ind (-L) _m (2)
[In the formula, Ind is a group having a substituted or unsubstituted indole skeleton represented by the following (A), L is a group having a substituted or unsubstituted cycloalkane skeleton having 5 to 30 carbon atoms, or the following ( The substituted or unsubstituted C6-C30 metaaromatic cyclic group represented by B), n and m are each an integer of 1 to 3.

（Ｘは、置換もしくは無置換の炭素数６〜４０のアリール基、置換もしくは無置換の炭素数７〜４０のアリールアルキル基、又は置換もしくは無置換の炭素数６〜４０のアリールオキシ基、Ｒは、置換もしくは無置換の炭素数１〜４０のアルキル基、置換もしくは無置換の炭素数６〜４０のアリール基、置換もしくは無置換の炭素数７〜４０のアリールアルキル基、又は置換もしくは無置換の炭素数６〜４０のアリールオキシ基であり、ｑは０〜２の整数である。）

（ｐは、１〜４の整数である。）〕
また、本発明は、陰極と陽極間に一層又は複数層からなる有機薄膜層が挟持されている有機ＥＬ素子において、該有機薄膜層の少なくとも１層が、前記有機ＥＬ素子用材料を含有する有機ＥＬ素子を提供するものである。

(X is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 40 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 40 carbon atoms, R Is substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, substituted or unsubstituted aryl group having 6 to 40 carbon atoms, substituted or unsubstituted arylalkyl group having 7 to 40 carbon atoms, or substituted or unsubstituted And an aryloxy group having 6 to 40 carbon atoms, q is an integer of 0 to 2.)

(P is an integer of 1 to 4)]
Further, the present invention provides an organic EL device in which one or more organic thin film layers are sandwiched between a cathode and an anode, wherein at least one of the organic thin film layers contains the organic EL device material. An EL element is provided.

  As described above in detail, when the organic electroluminescent element material comprising the compound represented by the general formula (1) or (2) of the present invention is used, the light emission efficiency and the color purity are high, and blue light is emitted. An organic electroluminescence element is obtained. For this reason, the organic electroluminescent element of this invention is very useful as a light source etc. of various electronic devices.

The organic EL device material of the present invention comprises a compound represented by the following general formula (1) or (2).
(Ind−) _n L (1)
Ind (-L) _m (2)
Ind is a group having a substituted or unsubstituted indole skeleton represented by the following (A), and is preferably an arylindole group or a diarylindole group.

Ind substituents include halogen atoms such as chlorine, bromine and fluorine, indole groups, cyano groups, silyl groups, trifluoromethyl groups, perfluoroaryl groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted aryls. Group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkyloxy group, and the like. Of these, a fluorine atom, a paraphenylene group, a tolyloromethyl group, and a perfluoroaryl group are preferable.
n and m are integers of 1 to 3, respectively.

X is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 40 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 40 carbon atoms.
Examples of the aryl group having 6 to 40 carbon atoms include phenyl group, naphthyl group, anthryl group, phenanthryl group, naphthacenyl group, pyrenyl group, fluorenyl group, biphenyl group, terphenyl group, phenylanthralyl group, and fluoranthenyl group. Among these, a phenyl group, a naphthyl group, a biphenyl group, a terphenyl group, a pyrenyl group, and a phenylanthralyl group are preferable.
Examples of the arylalkyl group having 7 to 40 carbon atoms include benzyl group, α-methylbenzyl group, cinnamyl group, α-ethylbenzyl group, α, α-dimethylbenzyl group, 4-methylbenzyl group, 4-ethylbenzyl group. Group, 2-tert-butylbenzyl group, 4-n-octylbenzyl group, naphthylmethyl group, diphenylmethyl group and the like. Among these, benzyl group, α-methylbenzyl group and diphenylmethyl group are preferable.
Examples of the aryloxy group having 6 to 40 carbon atoms include a phenoxy group, a naphthyloxy group, an ankle oxy group, a pyrenyloxy group, a biphenyloxy group, a fluoranthenyloxy group, a chrysenyloxy group, and a perylenyloxy group. Of these, a phenoxy group, a tolyloxy group, and a biphenyloxy group are preferable.

  As the substituent of X, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkyloxy group, a substituted Or an unsubstituted heteroaromatic double group etc. are mentioned. Of these, a fluorine atom, a paraphenylene group, a benzyl group, and a phenoxy group are preferable.

R is a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 40 carbon atoms, or a substituted or unsubstituted group. A substituted aryloxy group having 6 to 40 carbon atoms.
Examples of the alkyl group having 1 to 40 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, n-pentyl group, n- Hexyl group, n-heptyl group, n-octyl group, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 2-hydroxyisobutyl group, 1,2-dihydroxyethyl group, 1,3-dihydroxyisopropyl group 2,3-dihydroxy-t-butyl group, 1,2,3-trihydroxypropyl group, chloromethyl group, 1-chloroethyl group, 2-chloroethyl group, 2-chloroisobutyl group, 1,2-dichloroethyl group 1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group, 1,2,3-trichloropropyl group, bromomethyl group 1-bromoethyl group, 2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group, 1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group, 1,2,3-tri Bromopropyl group, iodomethyl group, 1-iodoethyl group, 2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group, 1,3-diiodoisopropyl group, 2,3-diiodo-t-butyl group, 1,2,3-triiodopropyl group, aminomethyl group, 1-aminoethyl group, 2-aminoethyl group, 2-aminoisobutyl group, 1,2-diaminoethyl group, 1,3-diaminoisopropyl group, 2 , 3-diamino-t-butyl group, 1,2,3-triaminopropyl group, cyanomethyl group, 1-cyanoethyl group, 2-cyanoethyl group, 2-cyanoethyl Butyl group, 1,2-dicyanoethyl group, 1,3-dicyanoisopropyl group, 2,3-dicyano-t-butyl group, 1,2,3-tricyanopropyl group, nitromethyl group, 1-nitroethyl group, 2 -Nitroethyl group, 2-nitroisobutyl group, 1,2-dinitroethyl group, 1,3-dinitroisopropyl group, 2,3-dinitro-t-butyl group, 1,2,3-trinitropropyl group, etc. It is done. Of these, a methyl group, an ethyl group, a propyl group, an n-hexyl group, an n-octyl group, and a t-butyl group are preferable.

  Examples of the aryl group having 6 to 40 carbon atoms, the arylalkyl group having 7 to 40 carbon atoms, and the aryloxy group having 6 to 40 carbon atoms are the same as the aryl group in X.

As the substituent of R, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkyloxy group, a substituted Or an unsubstituted heteroaromatic heterocyclic group etc. are mentioned. Of these, a fluorine atom, a paraphenylene group, a benzyl group, and a phenoxy group are preferable.
q is an integer of 0 to 2, preferably 1 to 2.

ｐは、１〜４の整数であり、１〜２であると好ましい。 L is a substituted or unsubstituted group having a C 5-30 cycloalkane skeleton, or a substituted or unsubstituted C 6-30 metaaromatic ring group represented by the following (B): A hexyl group, norbornene group, a group having an adamantane skeleton, or a metabiphenylene group is preferred.
Examples of the substituent for L include the same as those for Ind.

p is an integer of 1-4, and it is preferable in it being 1-2.

Specific examples of the compound represented by the general formula (1) of the present invention are shown below, but are not limited to these exemplified compounds.

Specific examples of the compound represented by the general formula (2) of the present invention are shown below, but are not limited to these exemplified compounds.

The compounds of the general formulas (1) and (2) of the present invention have a singlet energy gap of 2.8 to 3.8 eV, and preferably 2.9 to 3.6 eV.
In the organic EL device of the present invention, in which an organic thin film layer composed of one layer or a plurality of layers is sandwiched between a cathode and an anode, at least one layer of the organic thin film layer has the general formula (1) or ( 2) The organic EL element material which consists of a compound of 2) is contained. Moreover, it is preferable that the light emitting layer of an organic EL element contains the organic EL element material which consists of a compound of the said General formula (1) or (2).
The organic EL device of the present invention emits blue light and has a high purity of (0.12,0.10) to (0.17,0.20). This is because the organic EL device material comprising the compound of the general formula (1) or (2) of the present invention has a wide energy gap.
The organic EL device material of the present invention is preferably a host material for an organic EL device. The host material has a function of injecting holes and electrons, transporting holes and electrons, and recombining to emit fluorescence.

In addition, the compounds of the general formulas (1) and (2) of the present invention are considered to have a high singlet energy gap of 2.8 to 3.8 eV and a high triplet energy gap. It is also useful as an organic host material.
Here, the phosphorescent element is a substance whose emission intensity based on a transition from an energy state of a triplet level to a state of a ground singlet level is higher than other substances, for example, a periodic table 7 to 7 It is an organic electroluminescent element utilizing phosphorescence, including a phosphorescent substance such as an organometallic complex containing at least one metal selected from Group 11.
In the light emitting layer of the organic EL element, the generated molecular excitons are a mixture of singlet excitons and triplet excitons, and singlet excitons and triplet excitons are generally It is said that more triplet excitons are generated at a ratio of 1: 3. In an organic EL element using normal fluorescence, excitons that contribute to light emission are singlet excitons, and triplet excitons are non-luminescent. For this reason, triplet excitons are eventually consumed as heat, and light is emitted from singlet excitons having a low generation rate. Therefore, in the organic EL element, the energy transferred to triplet excitons out of the energy generated by recombination of holes and electrons is a large loss.

  For this reason, when the compound of the present invention is used in a phosphorescent device, the energy of triplet excitons can be used for light emission, so that it is considered that the light emission efficiency three times that of the device using fluorescence can be obtained. In addition, when the compound of the present invention is used in a light emitting layer of a phosphorescent element, it has an energy state higher than an excited triplet level of a phosphorescent organometallic complex containing a metal selected from Group 7 to 11 contained in the layer. It has an excited triplet level, gives a more stable thin film shape, has a high glass transition temperature (Tg: 80 to 160 ° C.), can efficiently transport holes and / or electrons, It is considered that impurities that are chemically and chemically stable and that become traps or quench light emission are unlikely to occur during manufacture or use.

    The organic EL device of the present invention is a device in which one or more organic thin film layers are formed between the anode and the cathode as described above. In the case of the single layer type, a light emitting layer is provided between the anode and the cathode. The light emitting layer contains a light emitting material, and may further contain a hole injecting material or an electron injecting material in order to transport holes injected from the anode or electrons injected from the cathode to the light emitting material. Moreover, it is preferable that a luminescent material has extremely high fluorescence quantum efficiency, high hole transport ability, and electron transport ability, and forms a uniform thin film. As the multilayer organic EL device, (anode / hole injection layer / light emitting layer / cathode), (anode / light emitting layer / electron injection layer / cathode), (anode / hole injection layer / light emitting layer / electron injection layer) / Cathode) and the like are stacked in a multilayer structure.

In addition to the compound of the general formula (1) or (2) of the present invention, further known host materials, light emitting materials, doping materials, hole injection materials, and electron injection materials are used for the light emitting layer as necessary. Can also be used in combination. The organic EL element has a multi-layer structure, which can prevent a decrease in luminance and lifetime due to quenching, and other doping materials can improve emission luminance and luminous efficiency or contribute to phosphorescence emission. By using it in combination with a material, the conventional light emission luminance and light emission efficiency can be improved.
In addition, the hole injection layer, the light emitting layer, and the electron injection layer in the organic EL device of the present invention may be formed of two or more layers. In that case, in the case of the hole injection layer, the layer that injects holes from the electrode is referred to as a hole injection layer, and the layer that receives holes from the hole injection layer and transports holes to the light emitting layer is referred to as a hole transport layer. Similarly, in the case of an electron injection layer, a layer that injects electrons from an electrode is referred to as an electron injection layer, and a layer that receives electrons from the electron injection layer and transports electrons to a light emitting layer is referred to as an electron transport layer. Each of these layers is selected and used depending on factors such as the energy level of the material, heat resistance, adhesion with the organic thin film layer or the metal electrode.
In the organic EL device of the present invention, the electron transport layer and the hole transport layer may contain an organic EL device material comprising the compounds of the general formulas (1) and (2).

  Examples of the light emitting material or host material that can be used in the organic thin film layer together with the compound represented by the general formula (1) or (2) of the present invention include anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, and naphthaloperylene. , Perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, imine, Diphenylethylene, vinylanthracene, diaminoanthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, imidazole chelating ester Shinoido compounds, quinacridone, rubrene, and stilbene derivatives and fluorescent dyes, and the like, but is not limited thereto.

  The hole injection material has the ability to transport holes, has a hole injection effect from the anode, an excellent hole injection effect for the light emitting layer or the light emitting material, and excitons generated in the light emitting layer. A compound that prevents movement to the electron injection layer or the electron injection material and has an excellent thin film forming ability is preferable. Specifically, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyaryl Examples include alkane, stilbene, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine, and derivatives thereof, and polymer materials such as polyvinyl carbazole, polysilane, and conductive polymer. However, it is not limited to these.

Among these hole injection materials, more effective hole injection materials are aromatic tertiary amine derivatives or phthalocyanine derivatives. Specific examples of the aromatic tertiary amine derivative include triphenylamine, tolylamine, tolyldiphenylamine, N, N′-diphenyl-N, N ′-(3-methylphenyl) -1,1′-biphenyl-4, 4′-diamine, N, N, N ′, N ′-(4-methylphenyl) -1,1′-phenyl-4,4′-diamine, N, N, N ′, N ′-(4-methyl Phenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-diphenyl-N, N′-dinaphthyl-1,1′-biphenyl-4,4′-diamine, N, N′- (Methylphenyl) -N, N ′-(4-n-butylphenyl) -phenanthrene-9,10-diamine, N, N-bis (4-di-4-tolylaminophenyl) -4-phenyl-cyclohexane, etc. Or oligomers having these aromatic tertiary amine skeletons Or is a polymer, but is not limited thereto. Specific examples of the phthalocyanine (Pc) derivative include H ₂ Pc, CuPc, CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl ₂ SiPc, (HO) AlPc, (HO) GaPc, Although it is a phthalocyanine derivative and a naphthalocyanine derivative such as VOPc, TiOPc, MoOPc, and GaPc-O-GaPc, it is not limited thereto.

  As an electron injection material, it has the ability to transport electrons, has an electron injection effect from the cathode, an excellent electron injection effect for the light emitting layer or light emitting material, and a hole injection layer of excitons generated in the light emitting layer The compound which prevents the movement to and is excellent in thin film forming ability is preferable. Specifically, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, quinoxaline, fluorenylidenemethane, anthraquinodimethane, anthrone, etc. However, it is not limited to these.

  Among these electron injection materials, more effective electron injection materials are metal complex compounds or nitrogen-containing five-membered ring derivatives. Specific examples of the metal complex compound include 8-hydroxyquinolinate lithium, bis (8-hydroxyquinolinato) zinc, bis (8-hydroxyquinolinato) copper, bis (8-hydroxyquinolinato) manganese, tris ( 8-hydroxyquinolinato) aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis ( 10-hydroxybenzo [h] quinolinato) zinc, bis (2-methyl-8-quinolinato) chlorogallium, bis (2-methyl-8-quinolinato) (o-cresolate) gallium, bis (2-methyl-8-quinolinato) ) (1-Naphtholate) aluminum, bis (2-methyl-8-) Norinato) (2-naphtholato) gallium and the like, but not limited thereto.

  The nitrogen-containing five-membered derivative is preferably an oxazole, thiazole, oxadiazole, thiadiazole or triazole derivative. Specifically, 2,5-bis (1-phenyl) -1,3,4-oxazole, dimethyl POPOP, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5- Bis (1-phenyl) -1,3,4-oxadiazole, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) 1,3,4-oxadiazole, 2,5 -Bis (1-naphthyl) -1,3,4-oxadiazole, 1,4-bis [2- (5-phenyloxadiazolyl)] benzene, 1,4-bis [2- (5-phenyloxa) Diazolyl) -4-tert-butylbenzene], 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-thiadiazole, 2,5-bis (1-naphthyl) ) -1,3,4-thiadiazole, 1,4-bis 2- (5-phenylthiadiazolyl)] benzene, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-triazole, 2,5-bis (1- Naphthyl) -1,3,4-triazole, 1,4-bis [2- (5-phenyltriazolyl)] benzene and the like are exemplified, but not limited thereto.

Further, the charge injection property can be improved by adding an electron accepting material to the hole injecting material and an electron donating material to the electron injecting material.
As the conductive material used for the anode of the organic EL device of the present invention, a material having a work function larger than 4 eV is suitable, and carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum Palladium, etc. and their alloys, metal oxides such as tin oxide and indium oxide used for ITO substrates and NESA substrates, and organic conductive resins such as polythiophene and polypyrrole are used. As the conductive material used for the cathode, those having a work function smaller than 4 eV are suitable, and magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum, and alloys thereof are used. However, it is not limited to these. Examples of alloys include magnesium / silver, magnesium / indium, lithium / aluminum, and the like, but are not limited thereto. The ratio of the alloy is controlled by the temperature of the vapor deposition source, the atmosphere, the degree of vacuum, etc., and is selected to an appropriate ratio. If necessary, the anode and the cathode may be formed of two or more layers.

The organic EL device of the present invention may have an inorganic compound layer between at least one electrode and the organic thin film layer. Preferred inorganic compounds used in the inorganic compound layer include alkali metal oxides, alkaline earth oxides, rare earth oxides, alkali metal halides, alkaline earth halides, rare earth halides, SiO _x , AlO _x , SiN. _{X, SiON, AlON, GeO X} , LiO X, LiON, TiO X, TiON, TaO X, TaON, TaN X, C and various oxides, nitrides, and oxide nitrides. In particular, as the component of the layer in contact with the anode, SiO _x , AlO _x , SiN _x , SiON, AlON, GeO _x , and C are preferable to form a stable injection interface layer. In particular, LiF, MgF ₂ , CaF ₂ , MgF ₂ , and NaF are preferred as the components of the layer in contact with the cathode.

In order for the organic EL device of the present invention to emit light efficiently, it is desirable that at least one surface be sufficiently transparent in the light emission wavelength region of the device. The substrate is also preferably transparent.
The transparent electrode is set using the above-described conductive material so as to ensure a predetermined translucency by a method such as vapor deposition or sputtering. The electrode on the light emitting surface preferably has a light transmittance of 10% or more. The substrate is not limited as long as it has mechanical and thermal strength and is transparent, and examples thereof include a glass substrate and a transparent resin film. Transparent resin films include polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone. , Polysulfone, polyethersulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, Polyvinylidene fluoride, polyester, polycarbonate, polyurethane, polyimide, polyetherimide, polyimide, polypropylene, etc. It is.

The organic EL device of the present invention can be provided with a protective layer on the surface of the device, or the entire device can be protected with silicon oil, resin, or the like in order to improve stability against temperature, humidity, atmosphere, and the like.
Each layer of the organic EL device of the present invention can be formed by applying any one of dry deposition methods such as vacuum deposition, sputtering, plasma and ion plating, and wet deposition methods such as spin coating, dipping and flow coating. Can do. The thickness of each layer is not particularly limited, but must be set to an appropriate thickness. If the film thickness is too thick, a large applied voltage is required to obtain a constant light output, resulting in poor luminous efficiency. If the film thickness is too thin, pinholes and the like are generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. The normal film thickness is suitably in the range of 5 nm to 10 μm, more preferably in the range of 10 nm to 0.2 μm.

In the case of the wet film forming method, the material for forming each layer is dissolved or dispersed in an appropriate solvent such as ethanol, chloroform, tetrahydrofuran, dioxane or the like to form a thin film, and any solvent may be used. In any layer, an appropriate resin or additive may be used for improving the film formability and preventing pinholes in the film. Usable resins include polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, cellulose and other insulating resins and copolymers thereof, poly-N-vinyl. Examples thereof include photoconductive resins such as carbazole and polysilane, and conductive resins such as polythiophene and polypyrrole. Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.
As described above, by using the compound of the general formula (1) or (2) of the present invention for the organic thin film layer of the organic EL element, an organic EL element having high color purity and emitting blue light can be obtained. This organic EL element is, for example, an electrophotographic photosensitive member, a flat light emitter such as a flat panel display for a wall-mounted TV, a light source such as a copying machine, a printer, a backlight of a liquid crystal display or an instrument, a display board, a marker lamp, an accessory, etc. Is preferably used.

EXAMPLES Next, although this invention is demonstrated in more detail using an Example, this invention is not limited to these Examples.
Synthesis Example 1 (Synthesis of Compound (A1))
The synthesis route of compound (A1) is shown below.

Under an Ar stream, 1,1-bis (p-bromophenyl) cyclohexane 4 g (10 mmol), 2,3-diphenylindole 6.5 g (24 mmol), Pd ₂ (dba) ₃ 400 mg, tri (t-butylphosphine 120 mg, 10 g of cesium carbonate was put into 100 mL of dehydrated toluene, and stirred vigorously at 100 ° C. for 12 hours, after which the precipitated crystals were collected by filtration, washed with 100 mL of methanol, and 4.4 g (5 7 mmol) (yield 57%), which was confirmed to be the target product (A1) by 1H-NMR and FD-MS (field diffusion mass analysis). The results are shown below.
_{FD-MS, calcd forC 58 H} 46 N 2 = 770, found, m / z = 770 (M +, 100).
Further, the obtained compound is dissolved in toluene to obtain a solution of 10 ⁻⁵ mol / liter, an absorption spectrum is measured with a spectrophotometer (U3410 manufactured by Hitachi, Ltd.), converted from the wavelength at the absorption edge, and the value of the energy gap. The results are shown in Table 1.

Synthesis Example 2 (Synthesis of Compound (A3))
The synthesis route of compound (A3) is shown below.

Under an Ar stream, 1,4-bis (p-bromophenyl) cyclohexane 3.9 g (10 mmol), 2-phenylindole 4.6 g (24 mmol), Pd ₂ (dba) ₃ 400 mg, tri (t-butylphosphine 120 mg, 10 g of cesium carbonate was put into 100 mL of dehydrated toluene and stirred vigorously at 100 ° C. for 12 hours, after which the precipitated crystals were collected by filtration, washed with 100 mL of methanol, and 4.0 g (6 0.5 mmol) (yield 65%), which was confirmed to be the target product (A3) by 1H-NMR and FD-MS, and the measurement results of FD-MS are shown below.
FD-MS, calcd for C ₄₆ H ₃₈ N ₂ = 618, found, m / z = 618 (M ⁺ , 100).
Further, the energy gap value of the obtained compound was determined in the same manner as in Synthesis Example 1 and is shown in Table 1.

Synthesis Example 3 (Synthesis of Compound (B1))
The synthesis route of compound (B1) is shown below.

A solution in which 4.2 g (10 mmol) of 3,5-dibromo-1,2-diphenylindole was dissolved in 30 mL of dehydrated THF and 17.4 g (36 mmol) of 1-adamantylmagnesium bromide was dissolved in 40 mL of trihydrofuran (THF) was added dropwise. The mixture was stirred under reflux in a nitrogen stream for 12 hours. After completion of the reaction, 6N hydrochloric acid was added and stirred. The organic layer was separated, washed with water, and dried over anhydrous magnesium chloride. The solvent was distilled off from the obtained extract with an evaporator to obtain a deeply colored solid. The obtained solid was recrystallized with benzene to obtain 2.4 g (yield 24%) of pale yellow crystals. This was confirmed to be the desired product (B1) by 1H-NMR and FD-MS. Moreover, the measurement result of FD-MS is shown below.
_{FD-MS, calcd forC 40 H} 43 N = 537, found, m / z = 537 (M +, 100).
Further, the energy gap value of the obtained compound was determined in the same manner as in Synthesis Example 1 and is shown in Table 1.

Example 1
A glass substrate with an ITO transparent electrode having a thickness of 25 mm × 75 mm × 1.1 mm (manufactured by Geomatic Co., Ltd.) was subjected to ultrasonic cleaning in isopropyl alcohol for 5 minutes and then UV ozone cleaning for 30 minutes. A glass substrate with a transparent electrode line after washing is mounted on a substrate holder of a vacuum deposition apparatus, and N, N ′ having a film thickness of 60 nm is first covered so that the transparent electrode is covered on the surface on which the transparent electrode line is formed. A bis (N, N′-diphenyl-4-aminophenyl) -N, N-diphenyl-4,4′-diamino-1,1′-biphenyl film (TPD232 film) was formed. This TPD232 film functions as a hole injection layer. Next, a 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl film (NPD film) having a thickness of 20 nm was formed on the TPD232 film. This NPD film functions as a hole transport layer. Further, the compound (A1) having a thickness of 40 nm was deposited on the NPD film to form a film. At the same time, the following compound (D1) was vapor-deposited at a weight ratio of (A1) :( D1) of 40: 3. Note that the compound (D1) is a light-emitting molecule having a singlet energy as low as 2.79 eV in order to emit blue light. A mixed film of the compounds (A1) and (D1) functions as a light emitting layer. On this film, the following Balq (Me is a methyl group) was formed to a thickness of 20 nm. The Balq film functions as an electron injection layer. Thereafter, Li (Li source: manufactured by Saesgetter), which is a reducing dopant, and Alq were vapor-deposited to form an Alq: Li film (film thickness: 10 nm) as a second electron injection layer (cathode). Metal Al was vapor-deposited on this Alq: Li film to form a metal cathode, thereby producing an organic EL device.
This element produced high-efficiency blue light emission with a direct-current voltage of 6.1 V and a light emission luminance of 134 cd / m ² and a light emission efficiency of 5.5 cd / A. Further, the chromaticity coordinates were (0.15, 0.17), and the color purity was high.

Examples 2 and 3
In Example 1, an organic EL device was produced in the same manner except that the compounds shown in Table 2 were used instead of the compound (A1). Similarly, direct current voltage, light emission luminance, light emission efficiency, light emission color, and color purity were obtained. Are shown in Table 2.

Comparative Example 1
In Example 1, an organic EL device was prepared in the same manner except that the following compound BCz, which is a conventionally known compound, was used instead of the compound (A1), and the direct current voltage, emission luminance, emission efficiency, emission color were similarly obtained. The color purity was measured and shown in Table 2.

Comparative Example 2
In Example 1, an organic EL device was prepared in the same manner except that the following compound (C2) described in JP-A No. 2001-288462 was used instead of the compound (A1), and the direct-current voltage and the emission luminance were similarly obtained. The light emission efficiency, light emission color, and color purity were measured and shown in Table 2.

  As shown in Table 2, the organic EL device using the compound of the present invention is low-voltage driven and has high-efficiency blue light emission compared to the conventionally known compounds BCz and (C2) of the comparative example. It is done. In addition, since the compound of the present invention has a wide energy gap, light emitting molecules having a wide energy gap can be mixed in the light emitting layer to emit light.

Claims (8)

The material for organic electroluminescent elements which consists of a compound represented by the following general formula (1) or (2).
(Ind−) _n L (1)
Ind (-L) _m (2)
[In the formula, Ind is a substituted or unsubstituted arylindole group or diarylindole group, L is a substituted or unsubstituted C6-C30 metaaromatic ring group represented by the following (B), n, m is an integer of 1 to 3, respectively.

(P is an integer of 1 to 4)]   The material for an organic electroluminescence device according to claim 1, wherein a singlet energy gap of the compounds of the general formulas (1) and (2) is 2.8 to 3.8 eV.   An organic electroluminescent element in which an organic thin film layer composed of one layer or a plurality of layers is sandwiched between a cathode and an anode, wherein at least one of the organic thin film layers comprises the material for an organic electroluminescent element according to claim 1. An organic electroluminescence element to be contained.   2. An organic electroluminescence device comprising a single layer or a plurality of organic thin film layers sandwiched between a cathode and an anode, wherein the light emitting layer contains the organic electroluminescence device material according to claim 1. .   The organic electroluminescent element according to claim 4, wherein a singlet energy gap of the organic electroluminescent element material is 2.8 to 3.8 eV.   The organic electroluminescence element according to claim 3 or 4, wherein the organic electroluminescence element material is an organic host material.   The organic electroluminescent element according to claim 3, further comprising an inorganic compound layer between at least one electrode and the organic thin film layer.   The organic electroluminescence device according to claim 3, which emits blue light.