JP2003268362A - 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 an organic EL element, which radiates a blue color with high purity, and the organic EL element using the same. <P>SOLUTION: The material for the organic EL element comprises a compound bonding a heterocyclic group having nitrogen to an indole group. The organic EL element comprises one layer or a plurality of layers of organic thin films sandwiched between a cathode and an anode, where at least one of organic thin film layers is the organic EL element containing the above material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for an organic electroluminescence device and an organic electroluminescence device (organic EL device) using the material, and more particularly,
The present invention relates to an organic EL device having high color purity and emitting blue light.

[0002]

2. Description of the Related Art An organic EL element using an organic substance is expected to be used as a solid-state light emitting inexpensive large area full color display element, and many developments have been made. In general,
The organic EL element is composed of a light emitting layer and a pair of counter electrodes sandwiching the light emitting layer. In the light emission of the organic EL element, when an electric field is applied between both electrodes, electrons are injected from the cathode side,
This is a phenomenon in which holes are injected from the anode side, electrons are recombined with holes in the light emitting layer to generate an excited state, and energy is emitted as light when the excited state returns to the ground state. Known light emitting materials include chelate complexes such as tris (8-quinolinolato) aluminum complex, coumarin derivatives, tetraphenylbutadiene derivatives, bisstyrylarylene derivatives, and oxadiazole derivatives, and from them, blue to red. It has been reported that light emission in the visible region up to is obtained, and realization of a color display element is expected (for example, JP-A-8-239655, JP-A-7-138561 and JP-A-3-20).
No. 0289, etc.).

Recently, the organic EL element display has been put into practical use, but a full-color display element is under development. In particular, there is a demand for an organic EL element that has high color purity and luminous efficiency and emits blue light. As an attempt to solve these problems, for example, Japanese Patent Laid-Open No. 8-12
Japanese Patent Publication No. 600 discloses an element using a phenylanthracene derivative as a blue light emitting material. Phenylanthracene derivatives are used as blue light emitting materials, and are usually tris (8-quinolinolato) aluminum (Al
q) It is used as a laminate of the blue material layer with the complex layer, but the luminous efficiency, the life, and the blue purity were not sufficient as the levels for practical use. Japanese Unexamined Patent Publication No. 3-162481
Japanese Patent Application Laid-Open No. 2003-242242 discloses an element in which a dicyanomethylene-based compound is added to a light emitting layer, but the purity of blue color is insufficient. Japanese Unexamined Patent Publication No. 2001-81451 discloses a blue light emitting device in which an amine-based aromatic compound is added to a light emitting layer, and this light emitting device has CIE chromaticity (0.64, 0.33).
However, the driving voltage was as high as 10 V or more. Japanese Unexamined Patent Publication No. 2001-160489 discloses a device in which an azafluoranthene compound is added to a light emitting layer, but it emits light from yellow to green and does not yet emit blue having sufficiently high color purity.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and provides an organic EL device material having high color purity and emitting blue light and an organic EL device using the same. Is to provide.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that
The inventors have found that an organic EL device having a high blue purity can be obtained by using a compound having a nitrogen-containing heterocyclic group bonded as a host material, and have solved the present invention.

That is, the present invention provides a material for an organic EL device comprising a compound represented by the following general formula (1). (Ind-) _n M _m (1) [In the formula, Ind represents a substituted or unsubstituted indole group, M represents a substituted or unsubstituted nitrogen-containing heteroaromatic ring having 2 to 40 carbon atoms, and n, m is 1 to 3 respectively
Is an integer. Further, when n is 2 or more, Ind may be different from each other, and when m is 2 or more, M may be different from each other. Further, the present invention is an organic EL device in which an organic thin film layer consisting 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 provides an organic EL device containing the material for an organic EL device.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The material for an organic EL device of the present invention is
It comprises a compound represented by the following general formula (1). (Ind-) _n M _m (1) Ind is a substituted or unsubstituted indole group, and M is
It is a substituted or unsubstituted nitrogen-containing heteroaromatic ring having 2 to 40 carbon atoms, and n and m are each an integer of 1 to 3. Further, when n is 2 or more, Ind may be different from each other, and when m is 2 or more, M may be different from each other. Examples of the nitrogen-containing heteroaromatic ring in M include pyridine, pyrimidine, pyrazine, triazine, aziridine, azaindolizine, indolizine, imidazole, indole, isoindole, indazole, purine, pteridine, β-carboline, naphthyridine, quinoxaline, Quinazoline, terpyridine, bipyridine,
Examples thereof include acridine, phenanthroline and phenazine, and bipyridine, pyrazine, triazine, azaindolizine, indolizine and terpyridine are particularly preferable.

Further, Ind in the above general formula (1),
Substituents for M include halogen atoms such as chlorine, bromine and fluorine, carbazole groups, hydroxyl groups, substituted or unsubstituted amino groups, nitro groups, cyano groups, silyl groups, trifluoromethyl groups, carbonyl groups, carboxyl groups. ,
Substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted arylalkyl group, substituted or unsubstituted aromatic group, substituted or unsubstituted heteroaromatic heterocyclic group, substituted or unsubstituted An aralkyl group, a substituted or unsubstituted aryloxy group,
Examples thereof include a substituted or unsubstituted alkyloxy group and the like. Among these, a fluorine atom, a phenyl group, a naphthyl group, a pyridyl group, a pyrazyl group, a pyrimidyl group, a cyano group, a substituted or unsubstituted alkyl group, and a substituted or unsubstituted aralkyl group are preferable.

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

[Chemical 1]

[0010]

[Chemical 2]

The compound of the general formula (1) of the present invention has a singlet energy gap of 2.8 to 3.8 eV,
It is preferably 2.9 to 3.6 eV. Organic E of the present invention
The L element is an organic EL 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, and at least one layer of the organic thin film layer is an organic EL element comprising the compound of the general formula (1). Contains element materials. In addition, organic E
It is preferable that the light emitting layer of the L element contains an organic EL element material comprising the compound of the general formula (1). The organic EL device of the present invention emits blue light and has a purity of (0.12,
It is as high as 0.11) to (0.16, 0.19). This is because the material for organic EL devices comprising the compound of the general formula (1) of the present invention has a wide energy gap. The material for an organic EL device of the present invention is preferably a host material for an organic EL device. This host material is capable of injecting holes and electrons, and has a function of transporting holes and electrons and recombining to emit fluorescence.

The compound of the general formula (1) of the present invention is
It is considered that the singlet energy gap is as high as 2.8 to 3.8 eV and the triplet energy gap is also high, and it is also useful as an organic host material for a phosphorescent device. Here, the phosphorescent device is a substance having a higher emission intensity based on the transition from the triplet level energy state to the ground singlet level state than other substances, for example, Periodic Table 7 to An organic electroluminescence device utilizing so-called phosphorescence, which contains 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 device, singlet excitons and triplet excitons are mixed in the generated molecular excitons, and the singlet excitons and the triplet excitons are generally It is said that the triplet excitons are generated more in the ratio of 1: 3. Further, in an organic EL element using ordinary fluorescence, the number of excitons contributing to light emission is 1
Triplet excitons, which are triplet excitons, are non-emissive.
Therefore, the triplet excitons are eventually consumed as heat, and the singlet excitons having a low production rate emit light. Therefore, in the organic EL element, of the energy generated by the recombination of holes and electrons, the energy transferred to the triplet excitons causes a large loss.

Therefore, by utilizing the compound of the present invention in a phosphorescent device, the energy of triplet excitons can be used for light emission, so that it is considered that the luminous efficiency three times that of a device using fluorescence can be obtained. . When the compound of the present invention is used in a light emitting layer of a phosphorescent device, it excites a phosphorescent organometallic complex containing a metal selected from Groups 7 to 11 contained in the layer.
It has an excited triplet level in an energy state higher than the singlet level, gives a more stable thin film shape, has a high glass transition temperature (Tg: 80 to 160 ° C.), and has holes and / or electrons. It is considered that it can be efficiently transported, is electrochemically and chemically stable, and that impurities that become traps or quench light emission are unlikely to be generated during production 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 for transporting holes injected from the anode or electrons injected from the cathode to the light emitting material. Further, it is preferable that the light emitting material has extremely high fluorescence quantum efficiency, high hole transporting ability and electron transporting ability, and forms a uniform thin film. The multilayer organic EL device includes (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.

In the light emitting layer, if necessary, in addition to the compound of the general formula (1) of the present invention, a further known host material,
A light emitting material, a doping material, a hole injecting material and an electron injecting material can be used and can be used in combination. When the organic EL element has a multi-layer structure, it is possible to prevent a decrease in brightness and life due to quenching, and it is possible to improve emission brightness and emission efficiency by using another doping material.
By using it in combination with another doping material that contributes to phosphorescence, conventional emission brightness and emission efficiency can be improved. Further, the hole injection layer, the light emitting layer, and the electron injection layer in the organic EL device of the present invention may each be formed by a layer structure of two or more layers. In that case, in the case of a hole injection layer, a layer that injects holes from the electrode is called a hole injection layer, and a layer that receives holes from the hole injection layer and transports the holes to the light emitting layer is called a hole transport layer. Similarly, in the case of the electron injection layer, the layer that injects electrons from the electrode is called an electron injection layer, and the layer that receives electrons from the electron injection layer and transports the electrons to the light emitting layer is called an electron transport layer. Each of these layers is selected and used depending on various factors such as the energy level of the material, heat resistance, and adhesion to 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 a material for an organic EL device, which is composed of the compound of the general formula (1).

As the light emitting material or the host material which can be used in the organic thin film layer together with the compound of the general formula (1) of the present invention,
Anthracene, naphthalene, phenanthrene, pyrene,
Tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, 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,
Examples thereof include, but are not limited to, pyran, thiopyran, polymethine, merocyanine, imidazole chelated oxinoid compound, quinacridone, rubrene, stilbene derivative and fluorescent dye.

The hole-injecting material has the ability to transport holes, has the effect of injecting holes from the anode, and has an excellent effect of injecting holes into the light-emitting layer or the light-emitting material. A compound that prevents excitons from moving to the electron injection layer or the electron injection material and has an excellent thin film forming ability is preferable. Specifically, phthalocyanine derivative, naphthalocyanine derivative, porphyrin derivative, oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole,
Hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine, and their derivatives, and polyvinylcarbazole, polysilane, conductive polymers, etc. Examples thereof include polymeric materials, but the present invention is not limited thereto.

Among these hole injecting materials, the more effective hole injecting materials are aromatic tertiary amine derivatives or phthalocyanine derivatives. Specific examples of the aromatic tertiary amine derivative include triphenylamine, tritolylamine, 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-methylphenyl) -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 and the like, or oligomers or polymers having these aromatic tertiary amine skeletons, but not limited thereto. Specific examples of the phthalocyanine (Pc) derivative include H ₂ Pc, CuPc and Co.
Pc, NiPc, ZnPc, PdPc, FePc, Mn
Pc, ClAlPc, ClGaPc, ClInPc, C
lSnPc, Cl ₂ SiPc, (HO) AlPc, (H
O) GaPc, VOPc, TiOPc, MoOPc, G
It is a phthalocyanine derivative such as aPc-O-GaPc and a naphthalocyanine derivative, but is not limited thereto.

The electron injecting material has an ability to transport electrons, has an electron injecting effect from the cathode, and an excellent electron injecting effect to the light emitting layer or the light emitting material. A compound that prevents migration to the hole injection layer and has an excellent thin film forming ability is preferable. Specifically, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylene tetracarboxylic acid, quinoxaline, fluorenylidene methane, anthraquinodimethane, anthrone and the like. However, the present invention is not limited to these.

Among these electron injecting materials, a more effective electron injecting material is a metal complex compound or a nitrogen-containing five-membered ring derivative. Specific examples of the metal complex compound include lithium 8-hydroxyquinolinate, bis (8-hydroxyquinolinate) zinc, and bis (8-hydroxyquinolinate).
Copper, bis (8-hydroxyquinolinato) manganese, tris (8-hydroxyquinolinato) aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, Bis (10-hydroxybenzo [h] quinolinate) 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-quinolinate) (2-
Examples thereof include, but are not limited to, naphtholate) gallium and the like.

The nitrogen-containing five-membered derivative is preferably an oxazole, thiazole, oxadiazole, thiadiazole or triazole derivative. In particular,
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-phenyloxadiazolyl) -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)
Examples thereof include, but are not limited to, benzene and the like.

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

At least one of the organic EL devices of the present invention is
Having an inorganic compound layer between the electrode and the organic thin film layer
You may stay. Preferred mineralization used for inorganic compound layers
Compounds include alkali metal oxides and alkaline earth oxides
Compounds, rare earth oxides, alkali metal halides, alkali
Re-earth halide, rare earth halide, SiO_X,
AlO_X, SiN_X, SiON, AlON, GeO_X,
LiO_X, LiON, TiO_X, TiON, TaO_X,
TaON, TaN_X, C, various oxides, nitrides, oxidation
It is a nitride. In particular, the component of the layer in contact with the anode is S
iO_X, AlO _X, SiN_X, SiON, AlON, G
eO_X, C form a stable injection interface layer, which is preferable. Well
In particular, as the component of the layer in contact with the cathode, LiF, Mg
F₂, CaF₂, MgF₂, NaF are preferred.

In order to make the organic EL device of the present invention emit light efficiently, it is desirable that at least one surface thereof is sufficiently transparent in the emission wavelength region of the device. It is also desirable that the substrate is transparent. The transparent electrode is made of the above-mentioned conductive material and is set by a method such as vapor deposition or sputtering so as to ensure a predetermined translucency. The electrodes on the light emitting surface are
It is desirable that the light transmittance is 10% or more. The board is
Although it is not limited as long as it has mechanical and thermal strength and transparency, examples thereof include a glass substrate and a transparent resin film. As a transparent resin film,
Polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone,
Polyether sulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, polyvinylidenefluor Ride, polyester, polycarbonate, polyurethane, polyimide, polyetherimide, polyimide, polypropylene and the like can be mentioned.

In the organic EL device of the present invention, a protective layer may be provided on the surface of the device or the entire device may be protected by silicone oil, resin or the like in order to improve stability against temperature, humidity and atmosphere. Is. For formation of each layer of the organic EL device of the present invention, any one of dry film forming methods such as vacuum deposition, sputtering, plasma, ion plating and wet film forming methods such as spin coating, dipping and flow coating can be applied. You can Although the film thickness of each layer is not particularly limited, it is necessary to set an appropriate film thickness. If the film thickness is too thick, a large applied voltage is required to obtain a constant light output, and the light emission efficiency deteriorates. If the film thickness is too thin, pinholes and the like will occur, and even if an electric field is applied, sufficient emission brightness cannot be obtained. The normal film thickness is preferably in the range of 5 nm to 10 μm, but 10 nm to
The range of 0.2 μm is more preferable.

In the case of the wet film forming method, the materials forming each layer are ethanol, chloroform, tetrahydrofuran,
The thin film is formed by dissolving or dispersing in a suitable solvent such as dioxane, and any solvent may be used. Also,
Appropriate resins and additives may be used in any of the layers in order to improve film-forming properties and prevent pinholes in the film. Examples of usable resins include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethylmethacrylate, polymethylacrylate and cellulose, and copolymers thereof, poly-N-vinyl. Examples thereof include photoconductive resins such as carbazole and polysilane, and conductive resins such as polythiophene and polypyrrole. Further, examples of the additive include an antioxidant, an ultraviolet absorber, a plasticizer and the like. As described above, by using the compound of the general formula (1) 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. The element is preferably used for, for example, an electrophotographic photoconductor, a flat light emitter such as a flat panel display for a wall-mounted TV, a copying machine, a printer, a light source of a backlight of a liquid crystal display or instruments, a display plate, a marker lamp, an accessory, and the like. To be

[0027]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Synthesis Example 1 (Synthesis of Compound (A2)) A synthetic route of the compound (A2) is shown below.

[0028]

[Chemical 3]

2-p-biphenyl-1H-indole
4.3 g (16 mmol), 4'-chloro- [2,2 ';6',
2 ″] terpyridine 5.2 g (19 mmol), copper powder 1.8 g, 1
8-Crown-6 1.5g, and potassium carbonate 2.4g (17mm
ol) was added, 30 mL of o-dichlorobenzene was added as a solvent, and the mixture was heated to 200 ° C. using a silicon oil bath under a nitrogen stream and reacted for 48 hours. After completion of the reaction, suction filtration was performed using a Nutsche filter before cooling, and the obtained filtrate was concentrated with an evaporator. 30 mL of methanol was added to the obtained oily substance, and the precipitated solid was filtered under reduced pressure to obtain a gray solid.
The solid obtained was recrystallized from benzene to give 3.0 g of white crystals.
(Yield 38%) was obtained. The obtained crystal is 90MHz ¹ H-N
It was confirmed by MR and FD-MS (Field Diffusion Mass Analysis) that it was the target substance (A2). The measurement results of FD-MS are shown below. FD-MS, calcd for C ₃₅ H ₂₄ N ₄ = 500, found, m / z = 500 (M
⁺ , 100). Furthermore, the obtained compound is dissolved in toluene to give 10 to 5 mol.
/ L of the solution, the absorption spectrum was measured with a spectrophotometer, and the value of the energy gap was calculated from the wavelength at the absorption edge and shown in Table 1.

Synthesis Example 2 (Synthesis of Compound (A20)) The synthetic route of the compound (A20) is shown below.

[0031]

[Chemical 4]

In Synthesis Example 1, 2-p-biphenyl-
Instead of 1H-indole, 5-fluoro-2,3-
The same operation was performed except that diphenyl-H-indole was used to obtain 2.2 g of white crystals (yield 27%). The obtained crystal was confirmed to be the target product (A20) by 90 MHz ¹ H-NMR and FD-MS. In addition, FD-MS
The measurement results of are shown below. FD-MS, calcd for C ₃₅ H ₂₃ N ₄ = 518, found, m / z = 518 (M
^+, 100). Further, determine the value of the energy gap in the same manner as in Synthesis Example 1 for the obtained compound are shown in Table 1.

Synthesis Example 3 (Synthesis of Compound (A5)) The synthetic route of the compound (A5) is shown below.

[0034]

[Chemical 5]

In Synthesis Example 1, 4'-chloro- [2,
2 ′; 6 ′, 2 ″] terpyridine was used instead of 2-chloro-imidazo [1,2-a] pyridine.
The same operation was performed to obtain 1.5 g of white crystals (yield 24%).
The obtained crystal was confirmed to be the target product (A5) by 90 MHz ¹ H-NMR and FD-MS. Also, FD
-MS measurement results are shown below. FD-MS, calcd for C ₂₇ H ₁₉ N ₃ = 385, found, m / z = 385 (M
^+, 100). Further, determine the value of the energy gap in the same manner as in Synthesis Example 1 for the obtained compound are shown in Table 1.

[0036]

[Table 1]

Example 1 A glass substrate (manufactured by Geomatic) with an ITO transparent electrode of 25 mm × 75 mm × 1.1 mm thickness was ultrasonically cleaned in isopropyl alcohol for 5 minutes and then UV ozone cleaning for 30 minutes. . Mount the glass substrate with the transparent electrode line after cleaning on the substrate holder of the vacuum evaporation system,
First, N, N′-bis (N, N′-diphenyl-4-aminophenyl) -N, having a film thickness of 60 nm is formed so as to cover the transparent electrode on the surface on which the transparent electrode line is formed.
An N-diphenyl-4,4′-diamino-1,1′-biphenyl film (TPD232 film) was formed. This TPD2
The 32nd film functions as a hole injection layer. Next, this TP
On the D232 film, 4,4'-bis [N-
A (1-naphthyl) -N-phenylamino] biphenyl film (NPD film) was formed. This NPD film functions as a hole transport layer. Furthermore, a film thickness of 40 nm is formed on this NPD film.
The above compound (A2) was deposited to form a film. At this time, the following compound (D1) was simultaneously deposited at a weight ratio of (A2) :( D1) of 40: 3. Since the compound (D1) emits blue light, it has a low singlet energy of 2.79 eV and is a light-emitting molecule. The mixed film of the compounds (A2) and (D1) functions as a light emitting layer. A film thickness of 20 on this film
The following Balq was deposited in nm. The Balq film functions as an electron injection layer. Thereafter, Li (Li source: manufactured by SAES Getter Co., Ltd.), which is a reducing dopant, and Alq are binary-deposited to form Alq: Li as a second electron injection layer (cathode).
A film (film thickness 10 nm) was formed. Metal Al was vapor-deposited on this Alq: Li film to form a metal cathode, and an organic EL device was manufactured. This device has a luminance of 1 at a DC voltage of 5.0V.
Highly efficient blue light emission with 75 cd / m ² and a luminous efficiency of 6.2 cd / A was obtained. The chromaticity coordinates are (0.14, 0.
16), and the color purity was high.

[0038]

[Chemical 6]

Examples 2 to 3 Organic EL devices were prepared in the same manner as in Example 1 except that the compounds shown in Table 2 were used instead of the compound (A2), and the direct current voltage, the emission luminance, and the Luminous efficiency, luminescent color and color purity were measured and are shown in Table 2.

Comparative Example 1 An organic EL device was prepared in the same manner as in Example 1 except that the following compound BCz, which was a conventionally known compound, was used in place of the compound (A2). The emission efficiency, emission color, and color purity were measured and are shown in Table 2.

[Chemical 7]

[0041]

[Table 2]

As shown in Table 2, the organic EL device using the compound of the present invention with respect to the conventionally known compound BCz of Comparative Example 1 was driven at a low voltage, and highly efficient blue light emission was obtained. To be Further, since the compound of the present invention has a wide energy gap, it is possible to mix luminescent molecules having a wide energy gap into the luminescent layer to emit light.

[0043]

As described in detail above, when the material for an organic electroluminescence device comprising the compound represented by the general formula (1) of the present invention is used, the luminous efficiency and color purity are high, and blue light is emitted. Thus, an organic electroluminescence device that can be obtained is obtained. Therefore, the organic electroluminescent element of the present invention is extremely useful as a light source for various electronic devices.

Claims (8)

[Claims] 1. A material for an organic electroluminescence device comprising a compound represented by the following general formula (1). (Ind-) _n M _m (1) [In the formula, Ind represents a substituted or unsubstituted indole group, M represents a substituted or unsubstituted nitrogen-containing heteroaromatic ring having 2 to 40 carbon atoms, and n, m is 1 to 3 respectively
Is an integer. Further, when n is 2 or more, Ind may be different from each other, and when m is 2 or more, M may be different from each other. ] 2. The singlet energy gap of the compound of the general formula (1) is 2.8 to 3.8 eV.
The material for an organic electroluminescent device according to item 1. 3. In an organic electroluminescence device in which an organic thin film layer consisting of one or a plurality of layers is sandwiched between a cathode and an anode, at least one of the organic thin film layers comprises
An organic electroluminescence device containing the material for organic electroluminescence device according to claim 1. 4. In an organic electroluminescence device having an organic thin film layer consisting of one layer or a plurality of layers sandwiched between a cathode and an anode, the light emitting layer contains an organic electroluminescence device material according to claim 1. Electroluminescent device. 5. The singlet energy gap of the material for an organic electroluminescence device is 2.8 to 3.8.
The organic electroluminescent element according to claim 4, which is eV. 6. The organic electroluminescence device according to claim 3, wherein the material for the organic electroluminescence device is an organic host material. 7. The organic electroluminescence device according to claim 3, further comprising an inorganic compound layer between at least one electrode and the organic thin film layer. 8. The organic electroluminescence device according to claim 3, which emits blue light.