JPH10270167A - Novel light emitting material, novel electron transport transport material and organic el element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel light emitting metallic complex, an electron transport metallic complex and a novel light emitting and electron transport metallic complex which are excellent in thin film formation and low in crystallization, and a highly efficient and long life organic EL element using these by using, as a light emitting material, a metallic complex having at least one 8-quinolinolato derivative material having substitutional radicals for particular four positions as a ligand. SOLUTION: A metallic complex is used as a light emitting element, the metallic complex having at least one 8-quinolinolato derivative material having substitutional radicals for four positions as a ligand, the derivative material being represented by an expression (in the expression, R is a group is selected independently out of a group including an alkyl radical, an alcoxide radical, di-alkyl amino radical, a cyano radical, halogen, a phenyl radical sometimes having a substitutional radical, a di-phenyl radical, a naphthyl radical and a styreyl radical), and thereby the active layer of a high luminance and highly efficient organic EL element. If R in the expression is an alkyl radical or an alcoxide radical, the number of carbons is preferably set to 1 to 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting material, an electron transporting material, a light emitting material and an electron transporting material comprising a metal complex having at least one 8-hydroxyquinoline having a substituent at the 4-position as a ligand. Organic E using it
It relates to the L element.

[0002]

2. Description of the Related Art An organic EL device is composed of an ultra-thin film of an organic compound having a thickness of about 1000.degree. An amorphous material is generally used because a crystalline material easily forms pinholes and has poor adhesion to a substrate. In addition, morphological change such as crystallization of an organic film is cited as one of the mechanisms of device deterioration, and the stability of a vapor-deposited film greatly affects the device life [Sato et al., Mol. Cr
yst. Liq. Cryst. , Vol. 253,
p143. (1994)]. For example, it has been reported that an amorphous uniform film immediately after film formation is gradually crystallized during storage or driving, causing separation of an electrode interface or an organic / organic interface, resulting in element deterioration. [E. M. Han et al., Chem. Lett. , P96
9. (1994)].

Conventionally, the following formula (A)

Embedded image Is widely used as a light emitting material and an electron transporting material of an organic EL device, and a high-luminance and high-efficiency device has been reported. [C. W. Ta
ng et al., Appl. Phys. Lett. , Vol.
51, p913. (1987); Appl. Ph
ys. , Vol. 65, p3610. (198
9)]. Alq can be formed into a film by a vacuum heating evaporation method.
By doping a trace amount of fluorescent dye in q,
An external quantum efficiency exceeding 2% has been obtained [C. W. T
ang et al. Appl. Phys. , Vol. 6
5, p3610 (1989)].

However, when Alq is used alone as the light emitting layer or the electron transport layer, the continuous driving life of the device is short [Sato et al., Mol. Cryst. Liq. Cr
yst. , Vol. 253, p143. (199
4)]. This is because Alq has high crystallinity, and the deposited film is composed of microcrystals having an average of 500 °, so that pinholes are likely to be generated and the film stability is low [C. W. Tang
Et al., Appl. Phys. Lett. , Vol. 5
1, p913. (1987)].

[0005]

Accordingly, the present invention provides a novel luminescent metal complex, an electron transporting metal complex, a novel luminescent / electron transporting metal complex having excellent thin film forming ability and low crystallinity.
An object of the present invention is to provide a highly efficient and long-life organic EL device using the same.

[0006]

Means for Solving the Problems A first aspect of the present invention is the following formula [I]

Embedded image Wherein R is an alkyl group, an alkoxy group, a dialkylamino group, a cyano group, a halogen, a phenyl group which may have a substituent, a diphenyl group, a naphthyl group and a styryl group. Which is a metal complex having at least one 8-quinolinolato derivative having a substituent at the 4-position represented by the formula (1) as a ligand.

A second aspect of the present invention is an electron transporting material, which is a metal complex having at least one 8-quinolinolato derivative having a substituent at the 4-position described in the general formula [I] as a ligand. About.

[0008] The third aspect of the present invention relates to an organic EL device using the luminescent material according to the first aspect.

A fourth aspect of the present invention relates to an organic EL device using the electron transporting material according to the second aspect.

A fifth aspect of the present invention relates to an organic EL device having a light-emitting layer in which the electron transporting material according to claim 2 is used as a host material and doped with a trace amount of a dye as a light-emitting center.

The metal for forming the metal complex includes Li, Na, K, Rb, Be, Mg, Ca, Sr,
Ba, Zn, Al, Ga, In, Sc, Y and rare earth metals can be mentioned.

The metal complex used in the present invention is characterized by having at least one 8-quinolinolato derivative having a substituent introduced at the 4-position as a ligand for the purpose of reducing crystallinity. That is, when there are a plurality of ligands coordinated to one metal atom, at least one of them has a substituent introduced at the 4-position represented by the general formula [I].
It must be a quinolinolato derivative. The substituent at the 4-position is located outside when viewed from the center metal of the complex, and steric hindrance of this substituent is expected to reduce the interaction between the complex molecules and reduce the crystallinity of the complex. . Therefore, it is considered that the amorphous property of the film is improved, and the element deterioration due to crystallization is suppressed, so that the element durability is improved.
Furthermore, it is considered that by forming a mixed ligand complex together with ligands having different structures, the symmetry of the complex was further reduced, and the amorphous property was further improved. As a result, element degradation due to crystallization can be suppressed, and continuous drive characteristics have been dramatically improved.

When R in the present invention is an alkyl group,
Usually, a straight-chain or branched one having 1 to 12 carbon atoms can be mentioned, and particularly preferably 1 to 4 carbon atoms.

When R in the present invention is an alkoxy group, the alkyl can be usually a straight-chain or branched alkyl having 1 to 12 carbon atoms.
It is preferably 4.

When R in the present invention is a phenyl group, a diphenyl group, a naphthyl group or a styryl group, there is no problem even if these have a substituent. The substituent may be an alkyl group, an alkoxy group, a dialkylamino group, a cyano group, a halogen group, or the like as described above.

Specific examples of the compound represented by the general formula [I] can be represented by the following formula groups (1) to (26).

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

One embodiment of the present invention is a metal complex having, as a ligand, only one kind of an 8-quinolinolato derivative having a substituent at the 4-position represented by the general formula [I]. For example, a metal complex having only the above (1) as a ligand (for example, see Example 1).

In another aspect of the present invention, at least one 8-quinolinolato derivative having a substituent at the 4-position represented by the general formula [I] and a compound represented by the general formula [I] Are metal complexes having, as ligands, at least one different compound for a light emitting material or at least one compound for an electron transporting material (Examples 2, 3, and 4)
reference).

In another aspect of the present invention,
8- having a substituent at the 4-position represented by the general formula [I]
A luminescent material including a metal complex having two or more compounds contained in the quinolinolato derivative as ligands is also included.

The light emitting material and the electron transporting material of the present invention can be used in combination with the above-mentioned various metal complexes. For example, a combination of the formulas (II) and (V), a combination of the formulas (II) and (VI), a combination of the formulas (II) and (VII), a formula (II) V] and the combination of (VI), the combination of the formulas (V) and (VII) below,
Combination use of the formulas (VI) and (VII),
I], [V], combined use with those of [VI],
[VI], combined use with [VII], formulas [V] and [V
Examples of the combination with I] and [VII] are given.

Other ligands which can be used in combination with the ligand according to the present invention represented by the formula [I] include the following chemical formulas (a) to (r).

[0025]

Embedded image

[0026]

Embedded image

Further, examples of the other ligand include:
Polycondensed ring type 8-quinolinolato derivatives represented by the general formulas [1], [2], [3], [4] and [5] of Japanese Patent Application No. 8-257664 filed by the present applicant and dicondensation Ring type 8-
Quinolinolato derivatives can also be exemplified.

Any of these metal complexes can be used as a light emitting material, an electron transporting material, and also as a light emitting material and an electron transporting material.

The specific structure of the device that can be used in the present invention is not particularly limited, but specific examples are as follows: anode / light-emitting layer / cathode, anode / hole transport layer / light-emitting layer / cathode, anode / hole Transport layer / emission layer / electron transport layer / cathode /, anode / hole injection layer / emission layer / cathode, anode / hole injection layer / hole transport layer / emission layer / cathode, anode / hole injection layer / positive Hole transport layer / light emitting layer /
Electron transport layer / cathode, and the like.

In addition to the metal complex of the present invention, the organic compound which can be used as the light emitting layer and the electron transporting layer of the organic EL device of the present invention is not particularly limited, but various compounds such as p-terphenyl and quaterphenyl can be used. Ring compounds and their derivatives; condensed polycyclic hydrocarbon compounds such as naphthalene, tetracene, pyrene, coronene, chrysene, anthracene, diphenylanthracene, naphthacene, phenanthrene and derivatives thereof; phenanthroline, bathophenanthroline, phenanthridine, acridine, quinoline ,
Fused heterocyclic compounds such as quinoxaline and phenazine and derivatives thereof; fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, oxadiazole, aldazine,
Bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, oxine, aminoquinoline, imine,
Examples thereof include diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, quinacridone, rubrene, and derivatives thereof.

Also, JP-A-63-295695,
JP-A-8-22557, JP-A-8-81472, JP-A-5-9470, JP-A-5-1776
No. 4 discloses a metal chelate complex compound, particularly a metal chelated oxide compound.
Quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis [benzo (f) -8-quinolinolato] zinc, bis (2-methyl-8-quinolinolato) aluminum, tris (8-quinolinolato) indium,
Tris (5-methyl-8-quinolinolato) amylnium, 8-quinolinolatolithium, tris (5-chloro-
8-quinolinolato) gallium, bis (5-chloro-8-
A metal complex having at least one 8-quinolinolato or a derivative thereof such as (quinolinolato) calcium as a ligand can also be suitably used as the light emitting layer and the electron transport layer.

JP-A-5-202011, JP-A-7-2011
Oxadiazoles disclosed in JP-A-179394, JP-A-7-278124, JP-A-7-228579, triazines disclosed in JP-A-7-157473, JP-A-6-203963 Stilbene derivatives and distyryl arylene derivatives disclosed in JP-A-6-132080 and JP-A-6-88072, and styryl derivatives disclosed in JP-A-6-88072, JP-A-6-100857 and JP-A-6-86057. 2
The diolefin derivative disclosed in JP-A-07170 can also be suitably used as the light emitting layer and the electron transport layer.

Further, fluorescent brighteners such as benzoxazole-based, benzothiazole-based, and benzimidazole-based can be used, and examples thereof include those disclosed in JP-A-59-194393. Typical examples thereof include 2,5-bis (5,7-di-t-pentyl-2-benzooxazolyl) -1,3,4-thiazole,
4'-bis (5,7-di-t-pentyl-2-benzooxazolyl) stilbene, 4,4'-bis [5,7-di- (2-methyl-2-butyl) -2-benzo Oxazolyl] stilbene, 2,5-bis (5,7-di-t-pentyl-2-benzooxazolyl) thiophene, 2,5-
Bis [5- (α, α-dimethylbenzyl) -2-benzoxazolyl] thiophene, 2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl ] -3,4-diphenylthiophene, 2,5-bis (5-methyl-2-benzooxazolyl) thiophene,
4,4'-bis (2-benzoxazolyl) biphenyl, 5-methyl-2- {2- [4- (5-methyl-2-
Benzoxazoles such as benzoxazolyl) phenyl] vinyl} benzoxazole and 2- [2- (4-chlorophenyl) vinyl] naphtho (1,2-d) oxazole; 2,2 ′ (p-phenylenedivinylene) Benzothiazoles such as bisbenzothiazole, 2- ｛2
Examples thereof include benzimidazole-based fluorescent brighteners such as-[4- (2-benzimidazolyl) phenyl] vinyl} benzimidazole and 2- [2- (4-carboxyphenyl) vinyl] benzimidazole.

As the distyrylbenzene compound, for example, those disclosed in European Patent No. 0 375 582 can be used. Typical examples are 1,4-bis (2-methylstyryl) benzene,
1,4-bis (3-methylstyryl) benzene, 1,4
-Bis (4-methylstyryl) benzene, distyrylbenzene, 1,4-bis (2-ethylstyryl) benzene, 1,4-bis (3-ethylstyryl) benzene,
Examples thereof include 1,4-bis (2-methylstyryl) -2-methylbenzene and 1,4-bis (2-methylstyryl) -2-ethylbenzene.

A distyrylpyrazine derivative disclosed in JP-A-2-252793 can also be used as the light emitting layer and the electron transport layer. Typical examples are 2,
5-bis (4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) pyrazine, 2,5-bis [2
-(1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, 2,5-bis [2
-(4-biphenyl) vinyl] pyrazine, 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine and the like.

In addition, dimethylidin derivatives disclosed in European Patent No. 388768 and JP-A-3-231970 can be used as a material for the light emitting layer and the electron transport layer of the present invention. Typical examples are 1,
4-phenylenedimethylidin, 4,4'-phenylenedimethylidin, 2,5-xylylenedimethylidin,
2,6-naphthylenedimethylidin, 1,4-biphenyldimethylidin, 1,4-p-terephenylenedimethylidin, 9,10-anthracenediyldimethylidin, 4,4 ′-(2, 2-Di-t-butylphenylvinyl) biphenyl, 4,4 '-(2,2-diphenylvinyl) biphenyl, and derivatives thereof, and JP-A-6-49079 and JP-A-6-293778. Disclosed silanamin derivatives, JP-A-6-2
No. 79322, JP-A-6-279323, and polyfunctional styryl compounds disclosed in JP-A-6-279323.
Oxadiazole derivatives disclosed in JP-A-6-648 and JP-A-6-92947;
5, anthracene compounds disclosed in JP-A-6-145146, tetraphenylbutadiene compounds disclosed in JP-A-4-96990, and JP-A-3-2965.
No. 95, the coumarin derivative disclosed in JP-A-2-191694, the perylene derivative disclosed in JP-A-2-196885, and the organic trifunctional compound disclosed in JP-A-2-196885. Naphthalene derivative disclosed in 255,789, JP-A-2-28
Phthaloperinone derivatives disclosed in JP-A-9676 and JP-A-2-88689, JP-A-2-250
Styrylamine derivatives disclosed in JP-A-292-292 can be mentioned.

In the present invention, the arylamine compounds used as the hole injecting layer, the hole transporting layer, and the hole transporting light emitting layer are not particularly limited.
659, JP-A-6-203963, JP-A-6-215874, JP-A-7-145116, JP-A-7-222012, JP-A-7-157
473, JP-A-8-48656, JP-A-7-48
-126226, JP-A-7-188130, JP-A-8-40995, JP-A-8-4099
No. 6, JP-A-8-40997, JP-A-7-1
Preferred are arylamine compounds disclosed in JP-A-26225, JP-A-7-101911, and JP-A-7-97355. For example, N, N, N ', N'
-Tetraphenyl-4,4'-diaminophenyl, N,
N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diaminobiphenyl, 2,2-bis (4-di-p-tolylaminophenyl) propane,
N, N ', N'-tetra-p-tolyl-4,4'-diaminobiphenyl, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N,
N'-di (4-methoxyphenyl) -4,4'-diaminobiphenyl, N, N, N ', N'-tetraphenyl-
4,4'-diaminodiphenyl ether, 4,4'-bis (diphenylamino) quadriphenyl, 4-N,
N-diphenylamino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-diphenylaminostilbenzene, N-phenylcarbazole, 1,1-
Bis (4-di-p-triaminophenyl) -cyclohexyl, 1,1-bis (4-di-p-triaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) -Phenylmethane,
N, N, N-tri (p-tolyl) amine, 4- (di-p
-Tolylamino) -4 '-[4 (di-p-tolylamino) styryl] stilbene, N, N, N', N'-tetra-p-tolyl-4,4'-diamino-biphenyl,
N, N, N ', N'-tetraphenyl-4,4'-diamino-biphenyl N-phenylcarbazole, 4,4'
-Bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl, 4,4 ″ -bis [N- (1-naphthyl) -N-phenyl-amino] p-terphenyl, 4,
4'-bis [N- (2-naphthyl) -N-phenyl-amino] biphenyl, 4,4'-bis [N- (3-acenaphthenyl) -N-phenyl-amino] biphenyl,
5-bis [N- (1-naphthyl) -N-phenyl-amino] naphthalene, 4,4'-bis [N- (9-anthryl) -N-phenyl-amino] biphenyl, 4,4 "-
Bis [N- (1-anthryl) -N-phenyl-amino] p-terphenyl, 4,4'-bis [N- (2-phenanthryl) -N-phenyl-amino] biphenyl,
4,4'-bis [N- (8-fluoranthenyl) -N-
Phenyl-amino] biphenyl, 4,4'-bis [N-
(2-pyrenyl) -N-phenyl-amino] biphenyl, 4,4'-bis [N- (2-perylenyl) -N-phenyl-amino] biphenyl, 4,4'-bis [N-
(1-colonenyl) -N-phenyl-amino] biphenyl, 2,6-bis (di-p-tolylamino) naphthalene, 2,6-bis [di- (1-naphthyl) amino] naphthalene, 2,6-bis [N- (1-naphthyl) -N-
(2-naphthyl) amino] naphthalene, 4,4 ″ -bis [N, N-di (2-naphthyl) amino] terphenyl,
4,4'-bis {N-phenyl-N- [4- (1-naphthyl) phenyl] amino} biphenyl, 4,4'-bis [N-phenyl-N- (2-pyrenyl) -amino] biphenyl, 2,6-bis [N, N-di (2-naphthyl) amino] fluorene, 4,4 ″ -bis (N, N-di-p-
Tolylamino) terphenyl, bis (N-1-naphthyl) (N-2-naphthyl) amine and the like. further,
In addition, a known device conventionally used for manufacturing an organic EL element can be appropriately used.

Further, the hole injection layer, the hole transport layer,
As the hole transporting light emitting layer, a layer in which the above-mentioned organic compound is dispersed in a polymer or a layer in which a polymer is formed can be used. A so-called π-conjugated polymer such as polyparaphenylenevinylene or a derivative thereof, a hole-transporting non-conjugated polymer represented by poly (N-vinylcarbazole), and a sigma-conjugated polymer of polysilanes can also be used.

The hole injection layer formed on the ITO electrode is not particularly limited, but metal phthalocyanines such as copper phthalocyanine and non-metal phthalocyanines, carbon films, and conductive polymers such as polyaniline can be suitably used. Further, the arylamines described above can be reacted with a Lewis acid as an oxidizing agent to form radical cations and be used as a hole injection layer.

[0040]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by this.

For the deposition of organic compounds and metals, a VPC-400 vacuum evaporator manufactured by Vacuum Kiko Co., Ltd. was used.
An ST stylus type step meter was used.

For the evaluation of the characteristics of the device, Kikusui PBX 40-
A 2.5 DC power supply, a Iwatsu VOAC-7510 multimeter, and a Topcon BM-8 luminance meter were used. Element ITO
Was applied as an anode and Mg: Ag was used as a cathode, and a DC voltage was applied in a stepwise manner at a rate of 1 V / 2 seconds, and the luminance and current value one second after the voltage rise were measured. The EL spectrum was measured with a constant current drive using a Hamamatsu Photonics PMA-10 optical multi-channel analyzer.

Example 1 The following formula [II]

Embedded image The synthesis of tris (4-methyl-8-quinolinolato) aluminum (Almq ₃ ) represented by the following formula was performed according to the following procedure.

Aluminum trichloride hexahydrate (AlCl ₃
・ 6H ₂ O) Dissolve 0.21 mmol in water and add 7
The following formula (III) dissolved in ml of tetrahydrofuran

Embedded image 4-methyl-8-hydroxyquinoline 0.6 represented by
3 mmol was added dropwise. After stirring for 30 minutes, 1N NaOH
Was added dropwise in an equivalent amount to 4-methyl-8-hydroxyquinoline. After stirring for 30 minutes, tetrahydrofuran was distilled off using a rotary evaporator, and the precipitated crude tris (4-methyl-8-quinolinolato) aluminum [II
I] (hereinafter sometimes abbreviated as Almq ₃ ) was filtered off and dried under reduced pressure. Purification was performed by a train sublimation method to obtain yellow powdery Almq ₃ . Yield 29
%, Elemental analysis value, theoretical value C = 71.85%, H = 4.8
3%, N = 8.38%, analysis value C = 71.70%, H =
4.80%, N = 8.28%.

Fabrication of Two-Layer Type Organic EL Device A two-layer type organic EL device was fabricated using this Almq ₃ as a light emitting layer. The hole transport layer has the following formula (IV)

Embedded image Is formed on an ITO substrate at a deposition rate of 3 ° / sec at a deposition rate of 3 ° / sec, and Almq ₃ is formed thereon as a light emitting layer and an electron transport layer at a deposition rate of 3 ° / sec.
It formed 600 ° in seconds. The Mg: Ag alloy electrode serving as the cathode was vapor-deposited at 1500 ° from a separate vapor deposition source while controlling the vapor deposition rate so that the Mg: Ag weight ratio became 10: 1, to produce a two-layer organic EL device.

When a DC voltage was applied to the device using ITO as an anode and Mg: Ag as a cathode, green light emission was observed from the device through the glass substrate. Fig. 1 shows the emission spectrum.
Shown in This is the same as the fluorescence spectrum of Almq _3, are those emitting from elements from Almq ₃ layers,
It was confirmed that Almq ₃ functions as a light emitting layer.

FIG. 2 shows the relationship between the luminance and the voltage (○ plot) and the current density and the voltage (△ plot) of the device. The brightness reached a maximum at 12 V, and a brightness of 27,000 cd / m ² was obtained. It was observed when the luminous efficiency of 2.8% was 11 V, and the luminance at that time was 14,700 cd / m ^2.
Met.

When the device was continuously driven in a dry nitrogen atmosphere, the half-life of luminance was as long as 5000 hours.
A film formed on ITO using surface level meter DekTak
FIG. 3 shows the cross-sectional profile of the lmq ₃ film. As expected, the surface of the Almq ₃ film was extremely smooth, and was smoother than the ITO surface used for the substrate. This is the ligand 8-
This demonstrates that the introduction of a methyl group at the 4-position of quinolinolato reduced the crystallinity and improved the film formability.

Comparative Example 1 A device was manufactured under the same conditions as in Example 1, except that the light-emitting layer used was Alq (shown by the above formula (A)), which was conventionally used. This NPD / Alq two-layer type device exhibited a maximum luminance of 13,000 cd / m ² (about half that of Example 1) and an external quantum efficiency of only 1.3%. From this result, it can be seen that the device using Almq ₃ of Example 1 of the present invention is superior in terms of luminance and efficiency to Alq which is a conventional light emitting material. In addition, the luminance half-life in continuous driving is as short as 20 hours (1/250 of Example 1).
It was found that the device of Example 1 was much better in terms of device life.

Comparative Example 2 In the device structure of Example 1, Almq ₃ having a methyl group at the 4-position was used in the light emitting layer.
The following formula (B) is used for the light emitting layer.

Embedded image Using the Tris having a methyl group (2-methyl-8-quinolinolato) aluminum (Al2mq ₃₎ in the 2-position represented An element was prepared in the same conditions as in Example 1. In addition,
Al2mq ₃ having a methyl group at the 2-position is obtained by Matsu
Mura et al. [M. Matsum
ura, Jpn. J. Appl. Phys. , V
ol. 35, P5357. (1996)]. This NP
D / but Al2mq blue green emission having a peak 500nm from ₃ two-layer element was observed at the maximum luminance 9,0
It was as low as 00 cd / m ² (one third of Example 1), and the external quantum efficiency was 0.9%. In addition, the half-life of luminance in continuous driving was as short as 10 hours (1/500 of Example 1). From the above results, the Almq ₃ substituted with a methyl group at the 4-position used in Example 1 of the present invention is superior to Al2mq ₃ having a methyl group at the 2-position in terms of luminance and efficiency, and It can be seen that the position of the substituent is very important.

Example 2 By a method similar to that of Example 1, the following formula [V]

Embedded image (Bis- (4-methyl-8-quinolinolato) mono (8-quinolinolato) aluminum (Almq ₂ q ₁ ) represented by the following formula was synthesized. (This compound is a compound having two ligands according to the present invention. The two ligands are conventional). After train sublimation, a yellow powdery compound was obtained. Yield 25%, elemental analysis value, theoretical value C = 71.4
5%, H = 4.55%, N = 8.62%, analytical value C = 7
1.42%, H = 4.36%, N = 8.58%.

[0052] Using the NPD in the same device structure as in Example 1 with the Almq ₂ q ₁ and a hole transport layer, and the element of. The element configuration is ITO / NPD (400 °) / Almq ₂ q
₁ (600 °) / Mg: Ag. Green light emission from the complex was also observed from this device by applying a DC voltage, the maximum luminance was 19,000 cd / m ² , and the external quantum efficiency was 2.3%.
It was high with. The luminance half-life was as long as 2000 hours.

Example 3 In a manner similar to that of Example 1, the following formula [VI]

Embedded image Mono (4-methyl-8-quinolinolato) bis (8-quinolinolato) aluminum (Almq ₁ q ₂ ) represented by the following formula was synthesized. (This compound has one ligand according to the present invention. The ligand is conventional).
After train sublimation, a yellow powdery compound was obtained. Yield 25%, elemental analysis value, theoretical value C = 71.03
%, H = 4.26%, N = 8.87%, analytical value C = 7
1.20%, H = 4.21%, N = 8.78%.

Next, the synthesized Almq ₁ q ₂ was made into an element by using NPD as a hole transport layer in the same element configuration as in Example 1. Element structure is ITO / NPD (400Å) / Alm
q ₁ q ₂ (600 °) / Mg: Ag. Green light emission from the complex was also observed from this device. From this device, a maximum luminance of 18,000 cd / m ² and an external quantum efficiency of 2.6 were obtained.
%was gotten. Further, the luminance half life was as long as 2200 hours.

Example 4 The following formula [VII] was prepared according to the method described in Example 1.

Embedded image In represented by mono (4-ethyl-8-quinolinolato) mono (4-methyl-8-quinolinolato) mono (8-quinolinolato) were synthesized aluminum _{(Aleq 1 mq 1 q 1)} . After train sublimation, a yellow powdery compound was obtained. Yield 22%, elemental analysis value, theoretical value C = 71.85
%, H = 4.82%, N = 8.38%, analytical value C = 7
1.83%, H = 4.81%, N = 8.32%.

Next, the elements of used in the hole transport layer NPD the aleq ₁ mq ₁ q ₁ which synthesized by the same device structure as in Example 1. The device configuration is ITO / NPD (400Å) /
_{Aleq 1 mq 1 q 1 (600Å} ) / Mg: it was Ag.
Green light emission from the complex was also observed from this device. From this device, a maximum luminance of 19,000 cd / m ² and an external quantum efficiency of 2.5% were obtained. The luminance half-life is 230
It was as long as 0 hours.

[0057] The coumarin 6 was prepared 1 wt% doped element in Example 5 Almq _3. Coumarin 6 was prepared by co-evaporation method
Except for doping in the lmq ₃ layer, the same as in Example 1, and the device configuration was ITO / NPD (400 °) / Almq ₃ (600 °) doped with coumarin 6 / Mg:
Ag. Blue-green light emission of coumarin 6 was observed from this device, and the maximum luminance was 62,000 cd / m at 12V.
^{At 2} and 11 V, the external quantum efficiency showed a very high value of 5.2%. Further, the luminance half-life was as long as 8,000 hours.

The embodiments of the present invention are listed below. (1) The following general formula [I]

Embedded image Wherein R is independently selected from the group consisting of an alkyl group, an alkoxy group, a dialkylamino group, a cyano group, a halogen, a phenyl group which may have a substituent, a diphenyl group, a naphthyl group and a styryl group. A luminescent material, which is a metal complex having at least one 8-quinolinolato derivative having a substituent at the 4-position represented by the formula: (2) A light-emitting material, which is a metal complex having as a ligand two or more compounds contained in an 8-quinolinolato derivative having a substituent at the 4-position represented by the general formula [I]. (3) At least one 8-quinolinolato derivative having a substituent at the 4-position represented by the general formula [I], and another ligand for a light emitting material different from the compound represented by the general formula [I] A light-emitting material, which is a metal complex having at least one kind as a ligand. (4) 8 having a substituent at the 4-position described in the general formula [I].
-An electron transport material, which is a metal complex having at least one quinolinolato derivative as a ligand. (5) An electron transport material, which is a metal complex having, as a ligand, two or more compounds contained in an 8-quinolinolato derivative having a substituent at the 4-position represented by the general formula [I]. (6) At least one 8-quinolinolato derivative having a substituent at the 4-position represented by the general formula [I] and another coordination for an electron transport material different from the compound represented by the general formula [I] An electron transporting material, which is a metal complex having at least one element as a ligand. (7) An organic EL device using the luminescent material according to the above (1), (2) or (3). (8) An organic EL device using the electron transporting material according to (4), (5) or (6). (9) An organic EL device using the electron transporting material according to the above (4), (5) or (6) as a host material and having a light emitting layer doped with a trace amount of a dye as a light emitting center.

[0059]

As described above, according to the present invention, a metal complex having at least one 8-quinolinolato derivative having a substituent at the 4-position as a ligand can be used as an active layer of a high-luminance and high-efficiency organic EL device. Extremely effective.

[Brief description of the drawings]

FIG. 1 shows ITO / NPD (400 °) / Al of Example 1.
FIG. 5 is an emission spectrum diagram of an element having a configuration of mq ₃ (600 °) / Mg: Ag.

FIG. 2 shows ITO / NPD (400 °) / Al of Example 1.
mq ₃ (600Å) / Mg: brightness in the configuration of the elements consisting of Ag - voltage (○ mark), the current density - the voltage diagram plotting the relationship (△ mark).

FIG. 3 is a cross-sectional profile of an ITO film surface and Almq ₃
3 shows a cross-sectional profile of the film surface.

Claims (5)

[Claims] 1. A compound represented by the following general formula [I] Wherein R is an alkyl group, an alkoxy group, a dialkylamino group, a cyano group, a halogen, a phenyl group which may have a substituent, a diphenyl group, a naphthyl group and a styryl group. Which is a metal complex having at least one 8-quinolinolato derivative having a substituent at the 4-position represented by formula (1) as a ligand. 2. An electron transporting material, which is a metal complex having at least one 8-quinolinolato derivative having a substituent at the 4-position according to the general formula [I] as a ligand. 3. Organic E using the luminescent material according to claim 1.
L element. 4. An organic EL device using the electron transporting material according to claim 2. 5. An organic EL device using the electron transporting material according to claim 2 as a host material and having a light emitting layer doped with a trace amount of a dye as a light emitting center.