JP2982699B2 - Material for forming electron injection layer of multilayer organic electroluminescence device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an organic electroluminescence (EL) device used for a flat light source and a display, and to a high-luminance light-emitting device.

[0002]

2. Description of the Related Art An EL device using an organic substance is expected to be used as an inexpensive, large-area, full-color display device of a solid light emitting type, and many developments have been made. Generally EL
The device is composed of a light emitting layer and a pair of counter electrodes sandwiching the light emitting layer. In light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode side, holes are injected from the anode side , and the electrons recombine with holes in the light emitting layer, and the energy level is changed to the conduction band. This is a phenomenon in which energy is emitted as light when returning to the valence band from.

[0003] Conventional organic EL elements are compared with inorganic EL elements.
In all, the driving voltage was high, and the light emission luminance and light emission efficiency were low.
In addition, the characteristic deterioration was remarkable, and it had not been put to practical use.
Recently, high fluorescence quantum efficiency that emits light at a low voltage of 10 V or less
EL layered with organic compound-containing thin film
Devices have been reported and are of interest (Applied Field
Zix Letters, 51, 913, 1987
reference). In this method, the metal chelate complex is converted into a phosphor layer,
Amine-based compounds are used for the hole injection layer to create
Light emission was obtained, and the luminance was 1000 at a DC voltage of 6 to 7 V.
cd / m ^Two, Achieves maximum luminous efficiency of 1.5lm / W
It has performance close to the practical range. However,
Organic EL devices up to now have improved emission
Has been improved, but does not yet have sufficient emission brightness.
No. In addition, it is inferior in stability when used repeatedly.
There's a problem. Also, sufficient emission of blue-emitting materials
There are few materials that have light luminance and luminous efficiency.
The development of materials was desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic electroluminescent device having a high emission luminance and excellent stability when used repeatedly.
L element. As a result of intensive studies by the present inventors,
An organic EL device material of the compound represented by the general formula [1] is charged.
The present inventors have found that the organic EL device used for the electron injection layer has a high emission luminance and has excellent stability during repeated use, leading to the present invention.

[0005]

That is, the present invention relates to a material for forming an electron injection layer of a multilayer organic electroluminescent device represented by the following general formula [1].

The general formula [1]

Embedded image [Wherein, Q ¹ and Q ² each independently represent a ligand represented by the following general formula [2], and L represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, Or an unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, -OR ¹ (R ¹ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group , A substituted or unsubstituted heterocyclic group.) Or -O-Ga
—Q ³ (Q ⁴ ) (Q ³ and Q ⁴ represent the same meaning as Q ¹ and Q ² ), provided that
L can not be the same as Q ¹ or Q ² . ). General formula [2]

Embedded image [In the formula, rings A ¹ and A ² are a 6-membered aryl ring structure which may have a substituent and are fused to each other. ]

Furthermore, the present invention, L is an electronic injection layer forming material of the multilayer type organic electroluminescent device is -OR ^1.

[0008] Further, the present invention relates to Q ¹ and / or Q ²
Relates to a material for forming an electron injection layer of the multilayer organic electroluminescence element, which is a ligand represented by the following general formula [3]. General formula [3] [Wherein, R ^{2 to} R ⁷ each independently represent a hydrogen atom, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group,
It is a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. ]

Further, the present invention relates to the material for forming an electron injection layer of the multilayer organic electroluminescence device, wherein Q ¹ or Q ² is a ligand represented by the following general formula [4]. General formula [4]

The present invention relates to a material for forming an electron injection layer of the multilayer organic electroluminescence device, wherein the multilayer organic electroluminescence device is a laminate of an anode / a light emitting layer / an electron injection layer / a cathode.

Further, the present invention provides a material for forming an electron injection layer of the above-mentioned multilayer organic electroluminescence element, wherein the multilayer organic electroluminescence element is a laminate of anode / hole injection layer / light-emitting layer / electron injection layer / cathode. About.

[0012]

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

The ligand Q of the compound represented by the general formula [1]
Residues of the general formula [2] represented by ¹ to Q ⁴ is 8-hydroxyquinoline, there is a quinoline residue such as 2-methyl-8-hydroxyquinoline is not limited thereto.

Rings A ¹ and A ^{2 represented by the} general formula [2]
Is a substituted or unsubstituted aryl or heterocyclic structure bonded to each other. The metal complex of the present invention has a strong property as an n-type semiconductor and has a large electron injection ability. Furthermore, since the energy generated during the formation of the complex is low, the bond between the metal and the ligand of the formed metal complex is strengthened, and the fluorescence quantum efficiency as a light emitting material is also increased.

Specific examples of the substituents on the rings A ¹ and A ² which form the ligand of the general formula [2] include chlorine, bromine, iodine, a halogen atom of fluorine, a methyl group, an ethyl group, Propyl group, butyl group, sec-butyl group, ter
t-butyl group, pentyl group, hexyl group, heptyl group,
Octyl group, stearyl group, substituted or unsubstituted alkyl group such as trichloromethyl group, phenyl group, naphthyl group, 3-methylphenyl group, 3-methoxyphenyl group,
Substituted or unsubstituted aryl groups such as 3-fluorophenyl group, 3-trichloromethylphenyl group, 3-trifluoromethylphenyl group, 3-nitrophenyl group, methoxy group, n-butoxy group, tert-butoxy group, trichloro Methoxy, trifluoroethoxy, pentafluoropropoxy, 2,2,3,3-tetrafluoropropoxy, 1,1,1,3,3,3-hexafluoro-2-propoxy, 6- (per Substituted or unsubstituted alkoxy group such as fluoroethyl) hexyloxy group, phenoxy group, p-nitrophenoxy group, p-te
substituted or unsubstituted aryloxy groups such as rt-butylphenoxy group, 3-fluorophenoxy group, pentafluorophenyl group, 3-trifluoromethylphenoxy group, methylthio group, ethylthio group, tert-butylthio group, hexylthio group, octylthio Group, substituted or unsubstituted alkylthio group such as trifluoromethylthio group, phenylthio group, p-nitrophenylthio group, p-
a substituted or unsubstituted arylthio group such as a tert-butylphenylthio group, a 3-fluorophenylthio group, a pentafluorophenylthio group, a 3-trifluoromethylphenylthio group, a cyano group, a nitro group, an amino group, and a methylamino group Mono- or di-substituted amino groups such as diethylamino group, ethylamino group, diethylamino group, dipropylamino group, dibutylamino group, diphenylamino group, bis (acetoxymethyl) amino group, bis (acetoxyethyl) amino group, bisacetoxy Propyl) amino group, acylamino group such as bis (acetoxybutyl) amino group, hydroxyl group, siloxy group, acyl group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group, butylcarbamo Group, a carbamoyl group such as phenylcarbamoyl group, a carboxylic acid group, sulfonic acid group,
Cycloalkyl groups such as imido group, cyclopentane group and cyclohexyl group, phenyl group, naphthyl group, biphenyl group, anthranyl group, aryl groups such as phenanthryl group, fluorenyl group and pyrenyl group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl Group, triazinyl group, indolinyl group, quinolinyl group, acridinyl group, pyrrolidinyl group, dioxanyl group, piperidinyl group, morpholidinyl group, piperazinyl group, triathinyl group, carbazolyl group, furanyl group, thiophenyl group,
Examples include heterocyclic groups such as oxazolyl group, oxadiazolyl group, benzoxazolyl group, thiazolyl group, thiadiazolyl group, benzothiazolyl group, triazolyl group, imidazolyl group, benzimidazolyl group, and prenyl group. Further, the above substituents may be combined with each other to form a further 6-membered aryl ring or hetero ring.

The compound represented by the general formula [1] is converted to an organic EL
When used in the electron injection layer of the device, it has become possible to produce a high-performance organic EL device. Shown by general formula [1]
When the compound used in the electron injecting layer is used, the element has a high electron transporting property and a high electron injecting property from the cathode, and thus is an extremely advantageous organic EL element material. Furthermore, many of the organic EL device materials of the present invention have a melting point of 300 ° C. or higher, which is extremely advantageous when producing a device having high emission luminance and long life.

The ligand L forming the metal complex compound of the general formula [1] is an alkyl group, a cycloalkyl group, an aryl group, a heterocyclic group, -OR ¹ (R ¹ is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heterocyclic group), -. a ligand represented by ^{O-Ga-Q 3 (Q} 4). ( However, L must be the same as Q ¹ or Q ²
There is no. ). Specific examples of the groups or substituents represented by L or R ^{1 to} R ⁷ are the same as the specific examples of the substituents described for the ring A ¹ and the ring A ² . Further, -O-Ga
A ligand or a residue represented by -Q ³ (Q ⁴ );

An example of a method for synthesizing the compound represented by the general formula [1] of the present invention is shown below. The gallium metal complex of the present invention can be synthesized by using gallium metal or a gallium compound and a compound having a ligand residue of Q or L as a raw material in order to form a ligand of the complex. Examples of gallium compounds include alkyl gallium, gallium halide, gallium acetate, gallium nitrate, gallium sulfate, gallium arsenide, gallium nitride, gallium phosphide, gallium sulfide, gallium selenide, gallium telluride, gallium hydroxide, gallium oxide, and tritium. It may be a gallium alkoxide such as methoxygallium, triethoxygallium, triisopropoxygallium, diethylgallium chloride, or a gallium compound partially substituted with acetylacetonate. In the synthesis, gallium alkoxide is preferred in view of reactivity, safety and the like, but is not limited thereto. The ligand residue represented by Q is 8
Quinoline residues such as -hydroxyquinoline and 2-methyl-8-hydroxyquinoline.

The solvents used in the synthesis are methanol, ethanol, isopropyl alcohol, ethyl acetate, acetonitrile, 1,4-dioxane, tetrahydrofuran,
Benzene, toluene, xylene, n- hexane, Jimechiruhoru arm amide, quinoline, sulfolane, are selected such water. The reaction temperature is determined by the metal complex formation rate of the ligand. Between 0 ° C and 250 ° C, and even between 20 ° C and
80 ° C. is preferred. The reaction is performed for 10 minutes to 24 hours. The synthesis conditions are determined by conditions such as a metal compound, a ligand, a solvent, and a catalyst, and are not limited thereto.

The gallium complex represented by the general formula [1] is a compound for forming a ligand residue represented by Q in a gallium compound such as alkyl gallium or gallium alkoxide, and is a steric compound such as 2-methyl-8-hydroxyquinoline. A highly hindered ligand compound is reacted to bind two ligand residues to one gallium atom. Ligand L
Form the gallium complex of the present invention by bonding to the necessary residues. Gallium metal has a strong bond with an alkyl group, an oxygen atom, and a halogen atom, and can form a stable metal complex. Furthermore, 2-methyl-8
It is difficult to form a stable aluminum metal complex with 8-hydroxyquinoline having an alkyl substituent at the 2-position such as -hydroxyquinoline, but gallium can form a stable metal complex. Are also more advantageous than other metal complexes.

Representative examples of the compound of the general formula [1] of the present invention are specifically shown in Table 1, but are not limited thereto.

[0023]

[Table 1]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

The gallium metal complex may be washed with water or an organic solvent, recrystallized from an appropriate solvent, purified by sublimation, or the like.
Alternatively, the required purity can be obtained by combining them.

[0031] The organic EL element, Ri Oh the element forming the multi-layered organic compound thin film between the anode and the cathode is provided with a light emitting layer between an anode and a cathode. The light emitting layer contains a light emitting material,
In addition, a hole-injection material or an electron-injection material may be contained in order to transport holes injected from the anode or electrons injected from the cathode to the light-emitting material. Multi-layer type,
There is an organic EL device having a multilayer structure of (anode / light-emitting layer / electron injection layer / cathode) and (anode / hole injection layer / light-emitting layer / electron injection layer / cathode). The compound of the general formula [1] can transport carriers such as holes or electrons.
Since it has better electron transportability, it can be used for an electron injection layer of an organic EL device .

The organic EL element has a multi-layer structure, so that a decrease in luminance and life due to quenching can be prevented. If necessary, a combination of two or more kinds of light emitting materials, doping materials, hole injection materials for transporting carriers, and electron injection materials can be used. Also,
The hole injection layer, the light-emitting layer, and the electron injection layer may each be formed in a layer structure of two or more layers, and an element structure in which holes or electrons are efficiently injected from the electrode and transported in the layer is selected. You.

When the metal complex compound of the present invention is used as an electron injecting material, known light emitting materials or doping materials that can be used include naphthalene,
Anthracene, phenanthrene, pyrene, tetracene,
Coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole,
Aldazine, bisbenzoxazoline, bisstyryl, diamine, pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, imine, diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, imidazole Examples include, but are not limited to, chelated oxinoid compounds, quinacridone, rubrene, and derivatives thereof.
Compounds particularly suitable as a light emitting material include metal complex compounds, bisstyryl compounds, conjugated polymers, and arylamine derivatives.

As the metal complex compound, (8-hydroxyquinolinonato) lithium, bis (8-hydroxyquinolinonato) zinc, bis (8-hydroxyquinolinonato)
Manganese, bis (8-hydroxyquinolinonato) copper, tris (8-hydroxyquinolinonato) aluminum, tris (8-hydroxyquinolinonato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis ( 10-hydroxybenzo [h] quinolinato)
Zinc, bis (10-hydroxybenzo [h] quinolinato) magnesium, tris (10-hydroxybenzo [h] quinolinato) aluminum, bis (2-methyl-
8-quinolinato) chlorogallium, bis (2-methyl-
8-quinolinato) (o-cresolate) gallium, bis (2-methyl-8-quinolinato) (1-phenolate)
Aluminum, bis (2-methyl-8-quinolinato)
(1-Phenolate) gallium, bis (2-methyl-8)
-Quinolinato) (1-naphtholate) aluminum, bis (2-methyl-8-quinolinato) (1-naphtholate) gallium, bis (2- [2-benzoxazolinato] phenolate) zinc, bis (2- [2- [Benzothiazolinato] phenolate) zinc. These compounds may be used alone or as a mixture of two or more.

Examples of the bisstyryl compound include a phenylene group, a naphthylene group and a phenylene group which may have a substituent as a linking group.
Bisstyryl compounds such as biphenylene group, anthranylene group, pyrenylene group, thiophenylene group, and divalent residue of triphenylamine and N-ethylcarbazole are exemplified. Specifically, diphenylamino-1,4-bisstyrylbenzene, ditolylamino-1,4-bisstyrylbenzene, diphenylamino-4,4′-bisstyrylbiphenyl, 3- (N-ethylcarbazole)-
4,4′-bisstyrylbiphenyl, bis (4,4′-
[2,2-diphenylvinyl]) biphenyl and the like.
These compounds may be used alone or as a mixture of two or more.

The conjugated polymer includes an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom alone, or a polymer having 2 to 10,000 repeating units polymerized together with a conjugate group such as a vinyl group. Specifically, poly (p-phenylene), poly (p-thiophene), poly (p-phenylenevinylene), poly (2,5
-Dipentyl-p-phenylenevinylene), poly (2,
5-dipentyl-m-phenylenevinylene), poly (2,5-dioctyl-p-phenylenevinylene), poly (2,5-dihexyloxy-p-phenylenevinylene), poly (2,5-dihexyloxy-m-) Phenylenevinylene), poly (2,5-dihexylthio-p-phenylenevinylene), poly (2,5-didecyloxy-
p-phenylenevinylene), poly (2-methoxy-5-
Hexyloxy-p-phenylenevinylene), poly (2,5-thienylenevinylene), poly (3-n-octyl-2,5-thienylenevinylene), poly (1,4-
Naphthalenevinylene), poly (9,10-anthracenevinylene), and the like, and copolymers thereof. These compounds may be used alone or as a mixture of two or more.

As the arylamine derivative, there is a compound in which a substituted diamino group is substituted for an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. Specifically, N, N, N ', N'-(4-methylphenyl)
-1,4-phenyl-4,4′-diamine, N, N,
N ′, N ′-(4-methylphenyl) -1,3-phenyl-4,4′-diamine, N, N′-diphenyl-N,
N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine, N, N'-(4-methylphenyl) -N, N '-(4-n-butylphenyl)- Phenanthrene-9,10-diamine, N, N′-diphenyl-N, N′-dinaphthyl-1,1′-biphenyl-4,
4′-diamine, N, N, N ′, N ′-(4-methylphenyl) -1,4-naphthyl-4,4′-diamine,
N, N, N ', N'-(4-n-octylphenyl)-
9,10-anthranyl-4,4′-diamine, N,
N, N ′, N ′-[4- (α, α′-dimethylbenzyl) phenyl] -anthranyl-9,10-diamine and the like. These compounds may be used alone or as a mixture of two or more.

The hole injecting material has the ability to transport holes, has the effect of injecting holes from the anode, and has an excellent hole injecting effect on the light emitting layer or the light emitting material. Compounds that prevent excitons from migrating to the electron injection layer or the electron injection material and have excellent thin film forming ability are exemplified.
Specifically, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, Stilbene, butadiene, benzidine-type triphenylamine,
Examples include, but are not limited to, styrylamine-type triphenylamine, diamine-type triphenylamine, and derivatives thereof, and polymer materials such as polyvinyl carbazole, polysilane, and conductive polymers.

[0039]

[0040]

As the conductive material used for the anode of the organic EL device, those having a work function of more than 4 eV are suitable, and include carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, and platinum. , Palladium and their alloys, tin oxide used for ITO substrate, NESA substrate, metal oxide such as indium oxide,
Further, an organic conductive resin such as polythiophene or polypyrrole is 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 the like and alloys thereof are used, but not limited thereto. Representative examples of the alloy include magnesium / silver, magnesium / indium, and lithium / aluminum, but are not limited thereto. The ratio of the alloy is controlled by the temperature, atmosphere, degree of vacuum, etc. of the heating source, and an appropriate ratio is selected. The anode and the cathode may be formed by two or more layers if necessary.

In the organic EL device, at least one of them is desirably sufficiently transparent in the emission wavelength region of the device in order to emit light efficiently. Further, it is desirable that the substrate is also transparent. The transparent electrode is set so as to secure a predetermined translucency by a method such as vapor deposition or sputtering using the above conductive material. The electrode on the light emitting surface desirably has a light transmittance of 10% or more. The substrate is not limited as long as it has mechanical and thermal strength and has transparency, but examples thereof include a glass substrate, a polyethylene plate, a polyethylene terephthalate plate, a polyether sulfone plate, and a polypropylene plate. And the like.

The layers of the organic EL device according to the present invention can be formed by any of dry film forming methods such as vacuum deposition, sputtering, plasma, and ion plating, and wet film forming methods such as spin coating, dipping, and flow coating. Can be applied. The film thickness is not particularly limited, but needs to be set to an appropriate film thickness. If the film thickness is too large, a large applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too small, 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, but is more preferably in the range of 10 nm to 0.2 μm.

In the case of the wet film forming method, the material forming each layer is made of ethanol, chloroform, tetrahydrofuran,
Organic and suitable dissolved or dispersed in a solvent such as dioxane
A compound thin film is formed, and any solvent may be used. In any of the organic compound thin film layers, a suitable resin or additive may be used for improving film forming properties, preventing pinholes in the film, and the like. Possible resins include:
Insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, cellulose and copolymers thereof, poly-N-vinylcarbazole, photoconductive resins such as polysilane, polythiophene, A conductive resin such as polypyrrole can be used. Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

In order to improve the stability of the organic EL device obtained according to the present invention with respect to temperature, humidity, atmosphere, etc., a protective layer is provided on the surface of the device or silicon oil is sealed to protect the entire device. It is also possible.

As described above, in the present invention, since the compound of the general formula [1] was used in the electron injection layer of the organic EL device, the characteristics of the organic EL device such as light emission luminance and light emission efficiency could be improved. In addition, this device is extremely stable against heat and current, and furthermore, it can emit light that can be practically used at a low voltage. I was able to.

The organic EL device of the present invention can be used as a flat panel display such as a wall-mounted television or a flat luminous body.
It can be applied to light sources such as copiers and printers, light sources such as liquid crystal displays and instruments, display boards, and sign lamps, and its industrial value is extremely large.

[0048]

The present invention will be described below in more detail with reference to examples. In this example, an organic EL element was manufactured using a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □).

[0049]

(Synthesis Example 1 ) 5.0 g of trimethoxygallium and 100 g of absolute ethanol were placed in a flask and stirred. Further, a solution in which 9.0 g of 8-hydroxyquinaldine is dissolved in 140 g of absolute ethanol is added dropwise, and the mixture is stirred at 60 ° C. for 30 minutes.
Further, 2.9 g of phenol was added and the mixture was stirred at 70 ° C. for 30 minutes. Thereafter, 4.9 g of 8-hydroxyquinaldine was added and the mixture was stirred at 70 ° C. for 5 hours. The precipitated solid was filtered and washed with anhydrous ethanol. 6.3 g
Was obtained as a pale yellow powder. Elemental analysis, mass spectrometry, infrared absorption spectrum and NMR spectrum of the yellowish white powder were measured, and it was found that the powder was Compound (7). FIG. 1 shows an infrared absorption spectrum of the compound (7).

(Synthesis Example 2 ) 5.0 g of trimethoxygallium and 100 g of absolute ethanol were placed in a flask and stirred. Further, a solution in which 9.0 g of 8-hydroxyquinaldine is dissolved in 140 g of absolute ethanol is added dropwise, and the mixture is stirred at 60 ° C. for 30 minutes.
Further, 5.3 g of 4-hydroxybiphenyl was added and
After stirring at 0 ° C. for 30 minutes, 4.9 g of 8-hydroxyquinaldine was added, and the mixture was stirred at 70 ° C. for 5 hours. The precipitated solid was filtered, washed with anhydrous ethanol, and dried under vacuum to 7.2 g. Was obtained as a pale yellow powder. Elemental analysis, mass spectrometry, infrared absorption spectrum and NMR spectrum of the yellowish white powder were measured, and it was found that the powder was Compound (9). FIG. 2 shows the infrared absorption spectrum of the compound (9).

(Synthesis Example 3 ) 7.2 g of triisopropoxygallium and 100 g of absolute ethanol were placed in a flask and stirred. Further, 8-
9.0 g of hydroxyquinaldine was added to anhydrous ethanol 140
g), and the mixture is stirred at 60 ° C. for 30 minutes. Further, 5.5 g of 4-cyclohexylphenol
And stirred at 70 ° C. for 30 minutes. Then, 4.9 g of 8-hydroxyquinaldine was added and the mixture was stirred at 70 ° C. for 5 hours. The precipitated solid was filtered, washed with anhydrous ethanol, and dried in vacuo. 7.4 g of a yellow-white powder was obtained. Elemental analysis, mass spectrometry, infrared absorption spectrum and NMR spectrum of this yellowish white powder were measured. As a result, compound (12)
It turned out to be. FIG. 3 shows an infrared absorption spectrum of the compound (12).

(Synthesis Example 4 ) 5.0 g of trimethoxygallium and 100 g of absolute ethanol were put into a flask and stirred. Further, a solution in which 9.0 g of 8-hydroxyquinaldine is dissolved in 140 g of absolute ethanol is added dropwise, and the mixture is stirred at 60 ° C. for 30 minutes.
Further, 4.5 g of 1-naphthol was added and the mixture was heated at 70 ° C. for 30 minutes.
For 8 minutes, followed by 8-hydroxyquinaldine 4.9.
After stirring for 5 hours at 70 ° C., the precipitated solid was filtered, washed with anhydrous ethanol, and dried in vacuo.
5 g of a yellow-white powder was obtained. Elemental analysis of this yellow-white powder,
As a result of measuring mass spectrometry, infrared absorption spectrum and NMR spectrum, it was found to be compound (16).
FIG. 4 shows the infrared absorption spectrum of the compound (16).

(Synthesis Example 5 ) 5.0 g of trimethoxygallium and 100 g of absolute ethanol were placed in a flask and stirred. Further, a solution in which 9.0 g of 8-hydroxyquinaldine is dissolved in 140 g of absolute ethanol is added dropwise, and the mixture is stirred at 60 ° C. for 30 minutes.
Further, 4.5 g of 2-naphthol was added, and 30
For 8 minutes, followed by 8-hydroxyquinaldine 4.9.
After stirring for 5 hours at 70 ° C., the precipitated solid was filtered, washed with anhydrous ethanol, and dried in vacuo.
6 g of a yellowish white powder was obtained. Elemental analysis of this yellow-white powder,
As a result of mass spectrometry, infrared absorption spectrum, and NMR spectrum measurement, the compound was found to be compound (17).
FIG. 5 shows the infrared absorption spectrum of the compound (17).

(Synthesis Example 6 ) In a flask, 9.0 g of 8-hydroxyquinaldine and gallium-di-isopropoxy-acetyl acetate 1 were added.
1.5 g and 200 ml of toluene were added and stirred at room temperature for 20 hours. The obtained solution was distilled at 50 ° C. under reduced pressure under vacuum, and toluene was evaporated to obtain a yellow paste compound. The obtained compound was washed with toluene and dried under vacuum to obtain 8.7 g of a yellowish white powder. Elemental analysis, mass spectrometry, infrared absorption spectrum and NMR spectrum of this yellow-white powder were measured, and it was found that the powder was Compound (26).

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

Example 1 On a cleaned glass plate with an ITO electrode, the following chemical structure was used.
The compound (29) shown was vacuum-deposited to a film thickness of 30 nm.
Was obtained. Next, the compound (7) was vapor-deposited to form a light-emitting layer having a thickness of 30 nm, and a 20-nm-thick electron injection layer of the compound (25) was obtained by a vacuum vapor deposition method. An electrode having a thickness of 150 nm was formed thereon using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer, the light emitting layer, the electron injection layer and the cathode are
Vapor deposition was performed at a substrate temperature of room temperature in a vacuum of 10 ^-6 Torr. This element has a DC voltage of 12 V and 6300 (cd)
/ M ² ), and a luminous efficiency of 0.68
(Lm / W). Compound (29)

Example 2 A compound (31) represented by the following chemical structure was vacuum-deposited on a washed glass plate with an ITO electrode to form a film having a thickness of 30 nm.
Was obtained. Next, the compound (7) was vapor-deposited to form a light-emitting layer having a thickness of 40 nm, and a 20 nm-thick electron injection layer of the compound (17) was obtained by a vacuum vapor deposition method. An electrode having a thickness of 150 nm was formed thereon using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer, the light emitting layer, the electron injection layer and the cathode are
Vapor deposition was performed at a substrate temperature of room temperature in a vacuum of 10 ^-6 Torr. This device has a DC voltage of 8 V and 16000 (cd)
/ M ² ), and a luminous efficiency of 2.04
(Lm / W).

[0065]

Embedded image Compound (31)

[0066]

Example 3 Compound (31) was placed on a washed glass plate with an ITO electrode.
Was vacuum deposited to obtain a hole injection layer having a thickness of 30 nm. Next, a compound (32) represented by the following chemical structure was vapor-deposited to form a 40-nm-thick light-emitting layer, and a 20-nm-thick electron injection layer of compound (9) was obtained by vacuum vapor deposition. An electrode having a thickness of 150 nm was formed thereon with an alloy of aluminum and lithium mixed at a ratio of 100: 3 to obtain an organic EL device. The hole injection layer, the light emitting layer, the electron injection layer and the cathode were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This element has a DC voltage of 8V and 13500
A yellow-green emission of (cd / m ² ) was obtained.

[0068]

Embedded image Compound (32)

Example 4 Compound (31) was placed on a washed glass plate with an ITO electrode.
Was vacuum deposited to obtain a hole injection layer having a thickness of 30 nm. Next, a compound (33) represented by the following chemical structure was vapor-deposited to form a light-emitting layer having a thickness of 40 nm, and an electron injection layer of compound (9) having a film thickness of 20 nm was obtained by vacuum vapor deposition. An electrode having a thickness of 150 nm was formed thereon with an alloy of aluminum and lithium mixed at a ratio of 100: 3 to obtain an organic EL device. The hole injection layer, the light emitting layer, the electron injection layer and the cathode were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a DC voltage of 8V and 12000
Blue light emission of (cd / m ² ) was obtained.

[0070]

Embedded image Compound (33)

Example 5 Compound (31) was placed on a washed glass plate with an ITO electrode.
Was vacuum deposited to obtain a hole injection layer having a thickness of 30 nm. Next, a solution prepared by dissolving poly (2,5-hexylthio-p-phenylenevinylene) having a number average molecular weight of 25,000 in chloroform was spin-coated on the hole injection layer to form a light emitting layer having a thickness of 40 nm. Then, an electron injection layer having a thickness of 20 nm of the compound (9) was obtained by a vacuum evaporation method. An electrode having a thickness of 150 nm was formed thereon using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer, the electron injection layer, and the cathode are 10 ^-6 T
Vapor deposition was performed at a substrate temperature of room temperature in a vacuum of orr.
This element is 10500 (cd / m ² ) at a DC voltage of 8V.
Yellow light emission was obtained.

Example 6 Compound (31) was placed on a washed glass plate with an ITO electrode.
Was vacuum deposited to obtain a hole injection layer having a thickness of 30 nm. Next, a compound (30) represented by the following chemical structure was vapor-deposited to form a 40-nm-thick light-emitting layer, and a 20-nm-thick electron injection layer of the compound (7) was obtained by vacuum vapor deposition. An electrode having a thickness of 150 nm was formed thereon with an alloy of aluminum and lithium mixed at a ratio of 100: 3 to obtain an organic EL device. The hole injection layer, the light emitting layer, the electron injection layer and the cathode were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a DC voltage of 8V and 12000
(Cd / m ² ), and blue-green light emission with a luminous efficiency of 2.35 (lm / W) was obtained. Compound (30)

[0073]

[0074]

Comparative Examples 1 and 2 An organic EL device was prepared in the same manner as in Example 6 except that the compound shown in Table 2 was used instead of the compound (7) for the electron injection layer, and the emission luminance was measured.

Table 2--------------------------Examples Examples of electron-injection materials Luminance Luminous efficiency (cd / m ² ) (lm / W)-----------------------Example 6 Compound (7) 12000 2 .35 Comparative Example 1 Compound (32) 9500 1.25 Comparative Example 2 Compound (34) 6500 0.80 ---------------------------------------------------------------------------------------------------------- −−−−−−− Compound (34)

The organic EL device shown in this embodiment has a light emission color of blue to blue-green and a light emission luminance of 5000 (cd / m ² ) or more in a two-layer or more device structure, and has a high light emission efficiency. I got it. Furthermore, for all the organic EL elements shown in this example, 3 (mA / c
m ² ), continuous emission of more than half of the initial emission luminance could be observed for 10,000 hours or more. Comparative Example 1 prepared under the same conditions, while the organic EL element of Example 6 had stable emission luminance for 10,000 hours or more and almost no dark spot was observed.
In the organic EL devices of Nos. 2 and 3 , the emission luminance was less than half of the initial luminance in the light emission time of 500 hours or less, and the number of dark spots was large. This is because, compared to the compound of the present invention, the adhesion between the light-emitting layer and the cathode layer, poor film formability,
It is considered that the difference in work function between the light emitting layer and the cathode is large. From the above results , the organic EL device using the organic EL device material of the present invention for the layer between the light emitting layer and the cathode was able to achieve high luminous efficiency and long life of the light emitting device.

The organic EL device of the present invention achieves an improvement in luminous efficiency, luminous luminance, and a long life, and is used together with a luminescent material, a doping material, a hole injection material, an electron injection material, and a sensitizer. It does not limit the agent, resin, electrode material and the like, and the element manufacturing method.

[0079]

Layer in said formula between the onset optical layer and the cathode, according to the present invention
The organic EL device using the compound represented by [1] exhibited higher luminous efficiency than the conventional one, and a long-life organic EL device was obtained. As described above, by using the compound shown in the present invention in the layer between the light-emitting layer and the cathode of an organic EL device, an organic EL device having high emission luminance, high luminous efficiency, and long life can be easily produced. It has become possible.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of compound (7).

FIG. 2 is an infrared absorption spectrum of compound (9).

FIG. 3 is an infrared absorption spectrum of compound (12).

FIG. 4 is an infrared absorption spectrum of compound (16).

FIG. 5 is an infrared absorption spectrum of compound (17).

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-145146 (JP, A) JP-A-5-331460 (JP, A) JP-A-7-62526 (JP, A) 503878 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09K 11/06 CA (STN) REGISTRY (STN)

Claims (6)

(57) [Claims] 1. A material for forming an electron injection layer of a multilayer organic electroluminescence device represented by the following general formula [1]. General formula [1] [Wherein, Q ¹ and Q ² each independently represent a ligand represented by the following general formula [2], and L represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, Or an unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, -OR ¹ (R ¹ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group , A substituted or unsubstituted heterocyclic group.) Or -O-Ga-Q
³ (Q ⁴ ) (Q ³ and Q ⁴ represent the same meaning as Q ¹ and Q ² ) (provided that L is not the same as Q ¹ or Q ²⁾ .). General formula [2] [In the formula, rings A ¹ and A ² are a 6-membered aryl ring structure which may have a substituent and are fused to each other. ] 2. The material for forming an electron injection layer of a multilayer organic electroluminescence device according to claim ¹ , wherein L is -OR1. 3. The material for forming an electron injection layer of a multilayer organic electroluminescence device according to claim 1, wherein Q ¹ and / or Q ² is a ligand represented by the following general formula [3]. General formula [3] [Wherein, R ^{2 to} R ⁷ each independently represent a hydrogen atom, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group,
It is a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. ] 4. The material for forming an electron injection layer of a multilayer organic electroluminescence device according to claim 3, wherein Q ¹ or Q ² is a ligand represented by the following general formula [4]. General formula [4] 5. The material for forming an electron injection layer of a multilayer organic electroluminescence device according to claim 1, wherein the multilayer organic electroluminescence device is a laminate of an anode / a light emitting layer / an electron injection layer / a cathode. 6. The electron injection of the multilayer organic electroluminescence device according to claim 1, wherein the multilayer organic electroluminescence device is a laminate of anode / hole injection layer / light emitting layer / electron injection layer / cathode. Layer forming material.