JP2000299187A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an element drivable at low voltage, obtaining optional luminescent color and excellent in luminous efficiency, luminance and life stability by containing metal chelate with a cycloheptatoluene devivative as a ligand, as luminescent materail in at least one organic layer laminated between a positive electrode and a negative electrode on a base. SOLUTION: This organic electroluminescent element contains metal chelate with a cycloheptatoluene derivative expressed by formula I, concretely a compound expressed by formula II, as a ligand. As the central metal of metal chelate, metal of valence 2 or 3 such as aluminum, gallium and beryllium is preferable. In the formula I, R1, R2 and R3 are each a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a heterocyclic group; X is a residual group condensed with a cycloheptatoluene ring to form an aromatic ring or a hetero-ring. R1 and R2, R2 and X, and R3 and X are bonded to form a ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an organic electroluminescent device. More specifically, the present invention relates to a thin-film type device that emits light by applying an electric field to a light-emitting layer made of an organic compound, that is, an organic electroluminescent element that can be used for a flat light source or display.

[0002]

2. Description of the Related Art Conventionally, as an electroluminescent element, an inorganic electroluminescent element using an inorganic compound obtained by doping a luminescent center Mn or a rare earth element with ZnS, CaS or SrS as a II-IV compound semiconductor is known. Was common. However, the inorganic electroluminescent element has a problem that it requires AC driving, has a high driving voltage, and is difficult to achieve full color.

On the other hand, an organic electroluminescent device using an organic compound has problems that the driving voltage is higher, the luminous brightness and the luminous efficiency are lower, and the characteristics are significantly deteriorated as compared with the inorganic electroluminescent device. Was not reached. However, in recent years,
Research has been conducted on organic compounds for electroluminescent devices that can lower the driving voltage (for example, CW Tang and SA).
VanSlyke, Appl. Phys. Lett., 51, 913 (1987)).

[0004] Generally, an electroluminescent element is composed of a pair of opposing electrodes (anode and cathode) sandwiching a light emitting layer. Then, light is emitted by applying an electric field between the opposed electrodes,
Electrons injected from the cathode side and holes injected from the anode side are recombined in the light emitting layer, and are generated by emitting energy as light when the energy level returns from the conduction band to the valence band. .

[0005] Therefore, in the case of an organic electroluminescent device, an arbitrary luminescent color can be easily obtained by changing the molecular structure of an organic compound used in the light emitting layer, and therefore, the application as a full color display device is promising. Have been. In addition, the organic electroluminescent device has a clear self-luminous type display, and research on its practical use has been actively made (for example, see Japanese Patent Publication No. 2555771).

[0006] However, organic light-emitting devices to date have been improved in light emission intensity due to the improved structure, but do not yet have sufficient light emission luminance. In addition, when a low-molecular organic compound is used, there is a major problem that stability during repeated use is poor, such as the organic compound being crystallized due to Joule heat during driving and the layer being separated. Therefore, development of a light emitting substance, a charge transporting substance, and an organic electroluminescent element having higher emission luminance and excellent stability upon repeated use is desired.

An invention close to the present invention is disclosed in Japanese Patent Application Laid-Open No. 9-157.
Japanese Patent No. 642 discloses a light emitting device containing a chelate compound of a tropolone derivative, but does not disclose the metal chelate of the present invention at all. Further, the light-emitting element described in this publication has a relatively low light-emitting intensity.

[0008]

SUMMARY OF THE INVENTION According to the present invention, light-emitting efficiency,
An object of the present invention is to provide an organic electroluminescent device having excellent light emission luminance and lifetime stability.

[0009]

The present inventors have conducted intensive studies to develop an organic electroluminescent device having the above-mentioned excellent characteristics. As a result, a specific cycloheptatriene derivative was used as a luminescent material. The present inventors have found that an organic electroluminescent device using a metal chelate as a ligand has high emission intensity and excellent stability even when repeatedly used, and has completed the present invention.

Thus, according to the present invention, there is provided an organic electroluminescent device in which an anode, at least one organic layer and a cathode are stacked in this order on a substrate, wherein the organic layer is a general formula represented by the following general formula: (I):

[0011]

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(Wherein R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group X is a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group; X is a substituted or unsubstituted group which can be condensed with a cycloheptatriene ring to form an aromatic ring or a heterocyclic ring. R ¹ and R ² , R ² and X, and R ³ and X may be bonded to each other to form a substituted or unsubstituted ring. An organic electroluminescent device comprising a metal chelate as a ligand is provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The cycloheptatriene derivative which is a ligand of the metal chelate of the present invention is represented by the general formula (I) and can be synthesized by a known method.

R ¹ , R ² and R in the general formula (I)
The “halogen atom” in ³ includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

R ¹ , R ² and R in the general formula (I)
The “substituted amino group” in ³ includes a dialkylamino group, an alkylarylamino group and a diarylamino group. Examples of the substituted “alkyl” and “aryl” include the “alkyl group” and “aryl group” described below. More specifically, examples include a methylamino group, a dimethylamino group, a methylphenylamino group, a diphenylamino group, and the like.

R ¹ , R ² and R in the general formula (I)
³ "substituted or unsubstituted alkyl group" is a straight-chain,
It may be either branched or cyclic. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, ter
Examples include t-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, n-hexyl group, isohexyl group, cyclohexyl group, chloromethyl and chloroethyl.

R ¹ , R ² and R in the general formula (I)
^{As the 3} `` substituted or unsubstituted alkoxy group '',
For example, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-
Butoxy group, tert-butoxy group, n-pentyloxy group,
Examples include an isopentyloxy group, a tert-pentyloxy group, a neopentyloxy group, an n-hexyloxy group, an isohexyloxy group, a chloromethoxy group, and a chloroethoxy group.

R ¹ , R ² and R in the general formula (I)
Examples of the ³ "substituted or unsubstituted aryl group" include a phenyl group, a (1- or 2-) naphthyl group,
(1-, 2- or 9-) anthryl group, (1-, 2
-, 3-, 4- or 9-) phenanthryl group, (1-
Or 2-) pyrenyl group, (2-, 3- or 4-) biphenylyl group, terphenyl group, methylphenyl group, dimethylphenyl group, ethylphenyl group, diethylphenyl group and the like.

R ¹ , R ² and R in the general formula (I)
Examples of the ³ "substituted or unsubstituted heterocyclic group" include a furyl group, a pyridyl group, a pyrimidyl group, a pyridinyl group, an indolyl group, an indazonyl group, a quinolyl group, a methylfuryl group and a methylpyridyl group.

R ¹ , R ² and R in the general formula (I)
As the substituent ³ , among the above substituents, a hydrogen atom, a halogen atom (particularly, a bromine atom) and an alkyl group (particularly, an isopropyl group) are preferable, and a hydrogen atom is particularly preferable.

The combination of the substituents R ¹ , R ² and R ^{3 in} the general formula (I) includes the following (R ¹ ,
R ^2, referred to in the order of R ³⁾ are preferred, particularly preferred. Hydrogen atom, hydrogen atom, hydrogen atom hydrogen atom, hydrogen atom, bromine atom bromine atom, hydrogen atom, bromine atom hydrogen atom, hydrogen atom, isopropyl group

X in the general formula (I) is a substituted or unsubstituted residue which can be condensed with a cycloheptatriene ring to form an aromatic ring or a heterocyclic ring. Specifically, along with the two carbon atoms of the cycloheptatriene skeleton to which X is bonded, a benzene ring, a naphthalene ring, a pyridine ring, (2
—, 3- or 4-) substituted or unsubstituted residues capable of forming an aromatic or heterocyclic ring such as a picoline ring (= methylpyridine ring), a quinoline ring, a methylbenzene ring and an ethylbenzene ring. Among them, benzene ring,
Pyridine ring and picoline ring (especially 2-picoline ring)
Are particularly preferred.

As the cycloheptatriene derivative represented by the general formula (I), those represented by the following structural formulas are particularly preferred.

[0024]

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The central metal of the metal chelate of the present invention is not particularly limited as long as the metal is formed by coordinating the cycloheptatriene derivative represented by the general formula (I) as a ligand. , A metal having a valence of 2 or 3 is preferred. Specific examples include aluminum, gallium, boron, beryllium, zinc, magnesium, and strontium, with aluminum, gallium and beryllium being preferred.

The metal chelate of the present invention is characterized in that the central metal M ₂ having a valence of ₂ is used as a ligand for the cycloheptatriene derivative 2
Bonding to form a 5-membered ring with the molecule, or bonding the central metal M ₃ having a valence of 3 to form a 5-membered ring with 3 molecules of the cycloheptatriene derivative as a ligand,
It is considered that a complex having the following structural formula was formed.

[0027]

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[0028]

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Tables 1 to 3 show specific examples of the metal chelate of the present invention in which a cycloheptatriene derivative represented by the general formula (I) as a ligand is combined with a central metal. However, the present invention is not limited by these examples. The compound numbers in the table represent the numbers of metal chelates.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

The metal chelate of the present invention comprises a ligand, a cycloheptatriene derivative represented by the general formula (I):
It can be obtained by reacting a metal ion to be a central metal in a suitable solvent, and drying the solid obtained by filtration. If necessary, an alkali may be added to the reaction solution to make the pH of the reaction solution alkaline, followed by filtration. Examples of the alkali include hydroxides such as sodium hydroxide and potassium hydroxide.

Examples of the solvent used for the metal chelate formation reaction include alcohols such as methanol and ethanol, water, and a mixed solvent of alcohol and water.

Examples of the compound for supplying a metal ion include halides, alkoxides, and the like containing the central metal described above.
Compounds such as nitrates, sulfates, perchlorates, acetates and oxalates and hydrates thereof are included. Metal ions can be obtained by dissolving these compounds in a suitable solvent. For example, an ethanol solution of aluminum isopropoxide or gallium (III) chloride
Aqueous solution and the like.

FIGS. 1 to 3 show an example of a laminated structure of the organic electroluminescent device of the present invention. The organic electroluminescent device of the present invention,
An anode 2, at least one organic layer 7 and a cathode 6 are laminated on a substrate 1 in this order. Examples of the organic layer 7 include a hole transport layer 3, a light emitting layer 4, and an electron transport layer 5. When the organic electroluminescent element has a multilayer structure, it is possible to prevent a decrease in luminance and life due to quenching.

In the organic electroluminescent device of the present invention, one of these organic layers 7 contains the metal chelate of the present invention as a luminescent substance. Since the metal chelate of the present invention has a strong luminous intensity, it may be contained in any organic layer, but it is particularly preferred that it is contained in the luminescent layer.

A preferred configuration of the organic electroluminescent device of the present invention is one in which the organic layer 7 comprises the light emitting layer 4 and the light emitting layer 4 contains a metal chelate (see FIG. 1).

In another preferred configuration of the organic electroluminescent device of the present invention, the organic layer 7 includes at least one hole transport layer 3 and the light emitting layer 4, and any one of the organic layers 7 may be used. One in which the layer contains a metal chelate (see FIG. 2).

Further, as another preferred configuration of the organic electroluminescent device of the present invention, the organic layer 7 has at least one organic layer.
A layer comprising a hole transporting layer 3, a light emitting layer 4, and at least one electron transporting layer 5, and wherein any one of the organic layers 7 contains a metal chelate (FIG. 3).
reference).

The substrate 1 is not particularly limited as long as it is a transparent substrate usually used for an organic electroluminescent device. Examples of the material include glass, quartz, transparent plastic (polyester, polymethacrylate, polycarbonate, polysulfone, and the like). Further, an element, a circuit, a desired insulating layer, and the like may be formed over these substrates.

The anode 2 in the present invention preferably has a large work function (4 eV or more). In particular,
Metals such as aluminum, vanadium, cobalt, nickel, tungsten, silver and gold and alloys thereof, metal oxides such as tin oxide, zinc oxide and indium oxide, and mixed oxides thereof are included. Above all, organic electroluminescent elements generally emit light from the anode side, and therefore, for example, a transparent conductive compound such as indium-tin oxide (ITO) is preferable.

The anode can be formed into a thin film by a method such as vapor deposition or sputtering of the above electrode material.
The thickness of the anode varies depending on the electrode material used, but is preferably, for example, about 10 nm to 1 μm.

The various organic layers in the present invention can be formed by any of dry film forming methods such as vacuum evaporation and sputtering, and wet film forming methods such as spin coating and dipping. There is no particular limitation on the film thickness of each layer, but it is necessary to set an appropriate film thickness depending on the situation. If the film thickness is too large, a large applied voltage is required to obtain a constant light output, and the efficiency is reduced. On the other hand, if the film thickness is too small, a pinhole or the like is generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. For this reason, the film thickness is usually preferably selected in the range of about 5 nm to 5 μm.

In the case of the wet film forming method, a liquid in which a substance forming each layer is dissolved or dispersed in an appropriate solvent such as chloroform, dichloromethane, tetrahydrofuran, and dioxane is used. In addition, a polymer compound or an additive may be used as needed for improving the film forming property, preventing pinholes in the film, and the like.

Hereinafter, each organic layer will be described. The hole transport layer 3 in the present invention is a layer made of a hole transport material, and has a function of transmitting holes injected from the anode 2 to a light emitting layer 4 described later. With such a function, the efficiency of hole transport from the anode 2 to the light emitting layer 4 is improved, and the light emission luminance and light emission efficiency can be increased. In addition, the hole transport layer may contain a luminescent material described below.

The hole transporting substance may be either an organic compound or an inorganic compound, and is conventionally used as a hole transporting substance in a photoconductive material, or a hole transporting substance of an electroluminescent element. Any known ones can be selected from known ones to be used.

Examples of the organic compound include a triazole derivative, an oxadiazole derivative, an imidazole derivative, a polyarylalkane derivative, a pyrazoline derivative,
Examples include pyrazolone derivatives, phenylenediamine derivatives, biphenylenediamine derivatives, arylamine derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, and stilbene derivatives, and high molecular substances such as polyvinylcarbazole and polysilane.

Examples of the inorganic compound include p-type hydrogenated amorphous silicon, p-type hydrogenated amorphous silicon carbide, p-type hydrogenated microcrystalline silicon carbide, p-type zinc sulfide and p-type zinc selenide. Is mentioned. The thickness of the hole transport layer is usually 5 nm regardless of the type of the hole transport substance used.
It is preferable to select within a range of about 5 μm.

The light emitting layer 4 in the present invention is made of a light emitting substance having a light emitting property in a solid state, and at least (1) an injection function capable of injecting holes from an anode or a hole transport layer when an electric field is applied; An injection function capable of injecting electrons from the cathode or the electron transport layer; (2) a transport function for moving injected charges (electrons or holes, usually holes) by the force of an electric field; and (3) an electron and positive It provides a field of recombination of the pores, thereby having any one, preferably all, of the functions that result in emission. Note that there may be a difference between the ease of hole injection and the ease of electron injection, and the transport function represented by the mobility of electrons and holes may be large or small. It is preferable that the charge can be transferred. It is preferable that the thickness of the light emitting layer is usually selected in the range of about 5 nm to 5 μm. As for the light emitting function of the above (3), it is desirable that the light emitting property in the solid state is strong.

The luminescent material constituting the above-mentioned luminescent layer is preferably the metal chelate of the present invention capable of achieving high luminescent characteristics, and may be mixed with a known luminescent material, the above-described hole transport material and the electron transport material described below. May be used. Further, the metal chelate of the present invention may be used as a host material of the light emitting layer or a dopant material of the light emitting layer.

Examples of known luminescent substances include metal oxinoid compounds (8-hydroxyquinoline metal complex), butadiene derivatives, coumarin derivatives, benzoxazole derivatives, oxadiazole derivatives, oxazole derivatives, thiadiazole derivatives, styrylamine derivatives, Examples include a styrylbenzene derivative, a tristilbenzene derivative, a perinone derivative, and an aminopyrene derivative.

The electron transport layer 5 in the present invention is a layer made of an electron transport material, and has a function of transmitting electrons injected from the cathode 6 to the light emitting layer 4. With such a function, the efficiency of transporting electrons from the cathode 6 to the light emitting layer 4 is improved, and the light emission luminance and the light emission efficiency can be increased. Further, the electron transport layer may contain the above-mentioned light emitting substance.

The electron transporting substance may be either an organic compound or an inorganic compound, and is conventionally used as an electron transporting substance in a photoconductive material or a known electron transporting substance used in an electroluminescent element. Any of these can be selected and used.

Examples of the organic compound include oxadiazole derivatives, triazole derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, tetracyanoanthraquinodimethane derivatives, diphenoquinone derivatives, fluorenone derivatives, metal oxinoid compounds (8-hydroxy Quinoline metal complex). Above all, metal oxinoid compounds (8-hydroxyquinoline metal complexes) and oxadiazole derivatives 2-
(4-tert-butylphenyl) -5- (biphenyl) -1,3,4-oxadiazole (Bu-PBD,
Example 6) is particularly preferred.

Examples of the inorganic compound include n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide. The thickness of the electron transport layer is usually 5 n
It is preferable to select in the range of about m to 5 μm.

The cathode in the present invention preferably has a large work function (4 eV or more). Specific examples include metals such as lithium, magnesium, calcium, titanium, yttrium, ruthenium, and manganese, and alloys thereof, and mixtures thereof. Among them, alloys of magnesium and silver, alloys of aluminum and lithium, and alloys of magnesium and indium are preferable.

The cathode can be formed into a thin film by a method such as vapor deposition or sputtering of the above electrode material.
The thickness of the cathode varies depending on the electrode material used, but is preferably, for example, about 10 nm to 1 μm.

The organic electroluminescent device containing a metal chelate of the present invention has high luminous efficiency and high luminance, is very stable against heat and current, and can be used as various display devices.

[0060]

The present invention will be described in more detail with reference to Synthesis Examples and Examples, but the present invention is not limited by these Synthesis Examples and Examples.

Synthesis Example 1 [Synthesis of metal chelate (1)] (Synthesis of ligand) A ligand (A) of a cycloheptatriene derivative was synthesized according to the following reaction formula.

[0062]

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First, 5.00 g of o-phthalaldehyde and 3.55 g of methoxyacetone were dissolved in 500 ml of water, and 15 ml of a 2.5% aqueous sodium hydroxide solution was added thereto, followed by stirring at room temperature for 24 hours. Subsequently, the reaction solution was acidified by adding dilute hydrochloric acid, and further saturated by adding sodium chloride, and the reaction product was subjected to solvent extraction with dichloromethane. Dichloromethane was removed from the dichloromethane extract by distillation under reduced pressure, and the residue was purified by an alumina column and recrystallized from butyl ether to obtain 1.46 g of a methyl ether compound.

1.46 g of the obtained methyl ether compound and 4
100 ml of 7% hydrobromic acid was heated under reflux for 6 hours.
Next, the reaction solution was cooled to room temperature, diluted with 300 ml of water, and the reaction product was subjected to solvent extraction with dichloromethane. A 5% aqueous potassium hydroxide solution was added to the dichloromethane extract, and the mixture was shaken. The alkali layer was taken out, acidified, and the reaction product was extracted with dichloromethane. The dichloromethane was removed from the dichloromethane extract by distillation under reduced pressure, and the residue was recrystallized from ethanol to obtain 1.21 g of the ligand (A).
(18.8% yield). Melting point was 156-159 ° C.

(Synthesis of Metal Chelate) The obtained ligand (A) 200 mg and aluminum isopropoxide 7
9.1 mg was heated to reflux in 50 ml of ethanol for 6 hours. The resulting precipitate is filtered by suction, and the obtained solid is washed by boiling with ethanol to obtain a metal chelate (1) 1
81 mg were obtained.

Synthesis Example 2 [Synthesis of Metal Chelate (2)] The ligand (A) 2 obtained in (Synthesis of Ligand) of Synthesis Example 1
00 mg and 68.1 mg of gallium (III) chloride in water 10
aqueous solution dissolved in 50 ml of ethanol in 6 ml of ethanol.
Heated to reflux for hours. The generated precipitate was filtered by suction, and the obtained solid was washed by boiling with ethanol to obtain 225 mg of metal chelate (2).

Synthesis Example 3 [Synthesis of Metal Chelate (10)] (Synthesis of Ligand) A ligand (B) of a cycloheptatriene derivative was synthesized by the following reaction formula.

[0068]

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First, 5.00 g of 5-aminotropolone (5-amino-2-hydroxy-2,4,6-cycloheptatrienone), 4.43 g of nitrobenzene, 13.5 g of glycerin, and 7.30 ml of a 70% aqueous sulfuric acid solution Was heated at 160 ° C. for 30 minutes with stirring. Then, the reaction solution was cooled to room temperature, and 5 ml of water was added. Further, concentrated ammonia water was added to make the reaction solution alkaline. Then, acetic acid was added to make the reaction solution weakly acidic, and the reaction product was subjected to solvent extraction with ethyl methyl ketone. Ethyl methyl ketone was distilled off under reduced pressure from the ethyl methyl ketone extract, and the residue was recrystallized from ethanol to obtain 885 mg of the ligand (B) (14.0% yield). Melting point was 165-167 ° C.

(Synthesis of Metal Chelate) The ligand (B) 200 obtained based on the method of (Synthesis of ligand) in Synthesis Example 3
mg and 78.6 mg of aluminum isopropoxide were heated under reflux in 50 ml of ethanol for 6 hours. The resulting precipitate was filtered by suction, and the obtained solid was washed by boiling with ethanol to obtain 220 mg of metal chelate (10).

Synthesis Example 4 [Synthesis of metal chelate (11)] 200 mg of ligand (B) obtained according to the method of (Synthesis of ligand) of Synthesis Example 3 and 67.8 gallium (III) chloride.
mg in 10 ml of water and ethanol 5
Heated to reflux in 0 ml for 6 hours. The resulting precipitate was filtered by suction, and the obtained solid was washed by boiling with ethanol to obtain 205 mg of metal chelate (11).

Synthesis Examples 5 to 17 [Metal chelates (3) to
Synthesis of (9) and (12) to (21)] Synthesis Example 1 except that the ligand and the central metal shown in Table 1 were used.
In the same manner as in (1) to (4), metal chelates (3) to (9) and (12) to (21) were obtained.

Example 1 The production of the following organic electroluminescent device will be described with reference to FIG. A transparent electrode (anode 2) formed by depositing ITO (indium-tin oxide) on a glass substrate 1 of 20 mm × 50 mm × 1.1 mm by vapor deposition to a thickness of 1600 °.
A substrate was used. This was subjected to ultrasonic cleaning in isopropyl alcohol for 10 minutes, and dried by blowing nitrogen gas. Then, metal chelate (1), N, N ′ represented by the following formula:
-Diphenyl-N, N'-bis (1-naphthyl) -1,
1′-biphenyl-4,4′-diamine (α-NP
D) Polyvinylcarbazole was dissolved in dichloromethane at a weight ratio of 1: 1: 4. The obtained mixture is formed into a film by spin coating on an anode 2 made of ITO,
The light emitting layer 4 having a thickness of 500 ° was formed.

[0074]

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Next, each of Mg and Ag was placed in a molybdenum resistance heating boat, and heated at the same time to form the light emitting layer 4.
On the top, Mg and Ag were co-deposited such that the ratio of Mg to Ag was 10: 1 to form a cathode 6 having a thickness of 1000 °. In addition, all of the above-mentioned vapor depositions have a degree of vacuum of 3.
The test was performed at 0 × 10 ⁻⁶ Torr. With respect to the organic electroluminescent device (EL1) manufactured as described above, the luminance (cd / m ² ) and the emission color when emitting light with the ITO electrode biased and the Mg: Ag electrode biased negative were measured. The results obtained are shown in Table 4 together with the voltage (V) and the light emission lifetime (hour).

[0076]

[Table 4]

Examples 2 to 4 Organic electroluminescence was performed in the same manner as in Example 1 except that the metal chelates (2), (10) and (11) were used instead of the metal chelates (1) in the light emitting layer 4. Element (EL2
To 4). In the same manner as in Example 1, the prepared ELs ² to 4 were measured for luminance (cd / m ² ) and emission color. The results obtained are shown in Table 4 together with the voltage (V) and the light emission lifetime (hour).

Example 5 The production of the following organic electroluminescent device will be described with reference to FIG. 20 mm × 50 mm × 1.
A transparent electrode (anode 2) substrate was formed on a 1 mm glass substrate 1 with a thickness of 1600 °. This was subjected to ultrasonic cleaning in isopropyl alcohol for 10 minutes, and dried by blowing nitrogen gas. Next, α-NPD was vacuum-deposited on the anode 2 made of ITO to form a hole transport layer 3 having a thickness of 500 °. Next, the metal chelate (3) and polyvinyl carbazole were dissolved in dichloromethane at a weight ratio of 1: 4. The resulting mixture was spin-coated on the hole transport layer 3 to form a light emitting layer 4 having a thickness of 500 °.

Next, each of Mg and Ag was put into a molybdenum resistance heating boat, and heated at the same time, so that the light emitting layer 4 was heated.
On the top, Mg and Ag were co-deposited such that the ratio of Mg to Ag was 10: 1 to form a cathode 6 having a thickness of 1000 °. In addition, all of the above-mentioned vapor depositions have a degree of vacuum of 3.
The test was performed at 0 × 10 ⁻⁶ Torr. The luminance (cd / m ² ) and emission color of the organic electroluminescent device (EL5) thus manufactured were measured in the same manner as in Example 1. The results obtained are shown in Table 4 together with the voltage (V) and the light emission lifetime (hour).

Example 6 The production of the following organic electroluminescent device will be described with reference to FIG. 20 mm × 50 mm × 1.
A transparent electrode (anode 2) substrate was formed on a 1 mm glass substrate 1 with a thickness of 1600 °. This was subjected to ultrasonic cleaning in isopropyl alcohol for 10 minutes, and dried by blowing nitrogen gas. Next, α-NPD was vacuum-deposited on the anode 2 made of ITO to form a hole transport layer 3 having a thickness of 500 °. Next, the metal chelate (3) and polyvinyl carbazole were dissolved in dichloromethane at a weight ratio of 1: 4. The resulting mixture was spin-coated on the hole transport layer 3 to form a light emitting layer 4 having a thickness of 500 °.

Further, on the light emitting layer 4, 2- (4-tert-butylphenyl) -5- (biphenyl) -1,3,4-oxadiazole (Bu-PB) represented by the following formula:
D) was vacuum-deposited to form an electron transport layer 5 having a thickness of 300 °.

[0082]

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Finally, each of Mg and Ag was put into a molybdenum resistance heating boat and heated at the same time, so that the light emitting layer 4 was heated.
On the top, Mg and Ag were co-deposited such that the ratio of Mg to Ag was 10: 1 to form a cathode 6 having a thickness of 1000 °. In addition, all of the above-mentioned vapor depositions have a degree of vacuum of 3.
The test was performed at 0 × 10 ⁻⁶ Torr. The luminance (cd / m ² ) and emission color of the organic electroluminescent device (EL6) thus manufactured were measured in the same manner as in Example 1. The results obtained are shown in Table 4 together with the voltage (V) and the light emission lifetime (hour).

[0084]

According to the organic electroluminescent device of the present invention, a metal chelate having a ligand of a cycloheptatriene derivative represented by the general formula (I) is used as a light-emitting substance, so that the light-emitting efficiency and luminance are excellent. In addition, it is possible to provide an organic electroluminescent device which is stable against heat and current.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an organic electroluminescent device of the present invention (Examples 1 to 4).

FIG. 2 is a schematic sectional view of an organic electroluminescent device of the present invention (Example 5).

FIG. 3 is a schematic sectional view of an organic electroluminescent device of the present invention (Example 6).

[Description of Signs] 1 substrate 2 anode 3 hole transport layer 4 light emitting layer 5 electron transport layer 6 cathode 7 organic layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB00 AB02 AB03 AB04 AB06 CA01 CA02 CA05 CB01 DA00 DB03 EB00 FA01 5C080 AA06 BB09 DD29 JJ06 5C094 AA08 AA10 AA24 AA37 AA60 BA27 EA05 EB02 FB01

Claims (6)

[Claims] 1. An organic electroluminescent device in which an anode, at least one organic layer, and a cathode are laminated in this order on a substrate, wherein the organic layer is a luminescent substance represented by the general formula (I): 1) (Wherein R ¹ , R ² and R ³ are the same or different,
Hydrogen atom, halogen atom, cyano group, nitro group, hydroxyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group,
A substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group; X is condensed with cycloheptatriene ring, a substituted or unsubstituted residues may form an aromatic ring or a heterocyclic ring; R ¹ And R ² , R ² and X, and R ³ and X may be bonded to each other to form a substituted or unsubstituted ring). An organic electroluminescent device, comprising: 2. The organic electroluminescent device according to claim ¹ , wherein in the general formula (I), R ¹ , R ² and R ³ are hydrogen atoms. 3. The organic electroluminescent device according to claim 1, wherein the central metal of the metal chelate is a metal having a valence of 2 or 3. 4. The method according to claim 1, wherein the organic layer comprises a light emitting layer, and the light emitting layer contains a metal chelate.
3. The organic electroluminescent device according to any one of 3. 5. An organic layer comprising at least one hole transport layer and at least one light-emitting layer, or at least one hole transport layer, at least one light-emitting layer, and at least one electron transport layer; The organic electroluminescent device according to any one of claims 1 to 3, wherein one layer contains a metal chelate. 6. The organic electroluminescent device according to claim 5, wherein the light emitting layer contains a metal chelate.