JPH0541285A - Electroluminescence element - Google Patents

Abstract

PURPOSE:To provide an electric field luminescent element less in deterioration but high in brightness by selecting material in which carriers can be easily implanted into a transport layer, and thereby combining electrons with holes efficiently. CONSTITUTION:An electric field luminescent element is so constituted that a carrier transport layer 3 composed of an inorganic semitransistor made by a Sol-Gel method, is formed on a glass substrate on which ITO2 is disposed, and an organic luminescent layer 4 and a cathode 5 are then formed thereon by means of deposition. In this case, if the luminescent layer 4 is made of electron transport material, a hole transport layer is combined with the transport layer 3, and if the luminescent layer 4 is the hole transport layer, an electron transport layer is combined with the transport layer 3. By this constitution, the electric field luminescent element can be obtained, which can efficiently combine electrons with holes while being high in brightness but less in deterioration.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a display, a backlight,
The present invention relates to an electroluminescent element used for an optical functional element or the like.

[0002]

2. Description of the Related Art Since the discovery of a phenomenon in which a certain organic compound exhibits electroluminescence (EL) by carrier injection, research on organic EL devices has started, and a layer structure of a hole transport layer and / or an electron transport layer and a light emitting layer. There have been various studies on. Unlike the electroluminescence type inorganic EL element, the organic EL element has a low driving voltage, high brightness, and is promising for colorization, but the repeated stability of each layer is not sufficient, and the carrier transport layer material However, there is a problem that it is difficult to inject carriers because the reduction potential of is high. In order to solve this, a material having a small work function, for example, a Mg-Ag alloy has been used as an injection electrode for the transport layer. However, since these electrodes have a small work function, they are easily oxidized and their stability is insufficient. An object of the present invention is to solve the above-mentioned problems by selecting a material that can reduce deterioration and can easily inject carriers into the transport layer, unlike the conventional carrier transport layer.

[0003]

It is an object of the present invention to provide an electroluminescent device including at least a carrier transport layer for efficiently injecting carriers adjacent to a light emitting layer, the electroluminescent device including at least an inorganic oxide semiconductor, an organic electroluminescent body and an electrode. ..

[0004]

[First Structure] A first aspect of the present invention relates to an electroluminescent device comprising at least a carrier transport layer made of an inorganic oxide semiconductor, a light emitting layer made of an organic electroluminescent body, and an electrode. The second aspect of the present invention relates to a carrier transport layer using the Sol-Gel method and a method for producing the same.

Since EL in an organic compound is developed by the combination of electrons and holes injected into the light emitting layer, a transport layer for efficiently injecting carriers is provided next to the light emitting layer to enhance the emission brightness and to provide excellent light emission. The device is obtained. If the light emitting layer is an electron transporting substance, a hole transporting layer,
If the light emitting layer has a hole transporting property, it is combined with an electron transporting layer. Examples of the electron-transporting light emitting layer in the present invention include:

[Chemical 1]

[Chemical 2]

[Chemical 3] Etc. Examples of the hole-transporting light emitting layer in the present invention include:

[Chemical 4] Is mentioned. A p-type inorganic oxide semiconductor is used for the hole transport layer. Specifically, Cu ₂ O, Cr
₂ O ₃ , Mn ₂ O ₃ , FeOx (x to 0.1), NiO, C
If the light emitting layer such as oO, Pr ₂ O ₃ , Ag ₂ O, MoO ₂ and Bi ₂ O ₃ has a hole transporting property, an electron transporting layer, that is, an n-type inorganic oxide semiconductor is used. Specifically, Zn
O, TiO ₂ , SnO ₂ , ThO ₂ , V ₂ O ₅ , Nb ₂ O ₅ ,
_{Ta 2 O 5, MoO 3,} WO 3, MnO 2 , and the like.
The carrier transport layer made of these inorganic oxides is Sol-G.
It is manufactured by the EL method. The Sol-Gel method is a method for producing an inorganic oxide which is completed by hydrolyzing and polycondensing a metal organic compound such as a metal alkoxide in a solution system to grow a metal-oxygen-metal bond and finally sintering it. Is. A feature of the Sol-Gel method is that a uniform and large-area film can be obtained at a low substrate temperature. Further, since the film is formed from the solution, it has excellent adhesion to the substrate. Specifically, a solution containing a metal organic compound is applied onto a substrate, and a thick film made of an inorganic oxide is laminated and then sintered. Examples of the metal organic compound used include alkoxides such as methoxides, ethoxides, propoxides, butoxides, etc., of metals constituting an inorganic oxide, and acetate compounds. Inorganic salts such as nitrates, oxalates and perchlorates may be used. In order to produce an inorganic oxide from these compounds, it is necessary to proceed with hydrolysis and polycondensation reactions, and therefore it is necessary to add water to the coating solution. The amount of addition varies depending on the system, but if it is too large, the reaction proceeds rapidly and the quality of the film obtained tends to be non-uniform, and it is difficult to control the reaction rate. If the amount of water added is too small, it is difficult to control the reaction, and there is an appropriate amount. Generally, 0.5 equivalent mole to 5 times equivalent mole is preferable with respect to the number of bonds to be hydrolyzed. When a hydrolysis catalyst is further added, the reaction rate and reaction form can be controlled. As the catalyst, acids and bases usually used as hydrolysis catalysts are used. As the solvent for addition, a solvent in which the above materials do not precipitate, that is, a solvent having excellent compatibility is desirable. The solution concentration depends on the coating method, but in the case of spin coating,
It is advisable to adjust the solution viscosity to be several cP to several tens of cP. Further, a chelating agent or the like may be added.

The method of combining the inorganic oxide produced by the Sol-Gel method and the organic light emitting layer is not particularly limited,
Both may be laminated, and it is particularly preferable that the light emitting layer is dispersed in a carrier transport layer produced by the Sol-Gel method to form a composite. In such a composite, if the formation temperature of the inorganic oxide is equal to or lower than the decomposition point of the organic light emitting layer, the organic light emitting layer is dispersed in the solution when the metal organic compound is dissolved in the solvent, and coating and sintering are performed as they are. Just go. Also,
When the organic light emitting layer decomposes at the firing temperature of the metal organic compound, a porous inorganic oxide is prepared by the Sol-Gel method,
After that, the organic light emitting body may be dispersed. In the present invention, the anode is preferably one that injects holes, and the cathode is preferably one that injects electrons, and at least one of them must be transparent. Specific examples will be described below.

Example 1 On a glass substrate 1 on which ITO2 was vapor-deposited, a solution of nickel nitrate refluxed in ethylene glycol was applied by a spinner to form a film 3, which was baked at 450 ° C. for 1 hour. A 500Å-thick film 4 made of a perinone derivative having the structure of formula (1) is formed on this by vapor deposition, and a cathode 5 is formed on the film 4.
As a result, aluminum was vapor-deposited to prepare the device shown in FIG.
The emission spectrum of the obtained device is shown in FIG. No deterioration of the cathode was observed.

[Chemical 4] Example 2 A solution of nickel acetate dissolved in methoxyethanol on a glass substrate on which ITO2 was deposited was applied with a solution of the perinone derivative of the structure of formula (1) decomposed by a spinner to form a film 6, and the film 6 was formed at 350 ° C. It was baked for 1 hour. Aluminum was vapor-deposited on this as a cathode to prepare the device shown in FIG. The emission spectrum of the obtained device is shown in FIG.
No deterioration of the cathode was observed.

[0008]

[Effect] According to the present invention, an electroluminescent device having high brightness with little deterioration can be obtained by efficiently causing the coupling of electrons and holes, which is the cause of light emission.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electroluminescent device of Example 1 in which a perinone derivative is formed on an inorganic oxide semiconductor layer manufactured by a Sol-Gel method.

FIG. 2 is an emission spectrum of the electroluminescent device of FIG.

FIG. 3 is a cross-sectional view of an electroluminescent device of Example 2 in which a perinone derivative is dispersed in an inorganic oxide semiconductor layer manufactured by the Sol-Gel method.

FIG. 4 is an emission spectrum of the electroluminescent device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 ITO 3 Inorganic oxide semiconductor layer 4 Organic light emitting layer 5 Electrode 6 Inorganic oxide semiconductor layer in which a perinone derivative is dispersed

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H05B 33/14 8815-3K (72) Inventor Satoshi Fujimura 1-3-6 Nakamagome, Ota-ku, Tokyo Issue Stock Company Ricoh

Claims (4)

[Claims] 1. An electroluminescent device comprising at least an inorganic oxide semiconductor, an organic electroluminescent body and an electrode. 2. The electroluminescent device according to claim 1, wherein the inorganic oxide semiconductor is manufactured by a Sol-Gel method. 3. The electroluminescent device according to claim 1, wherein an organic electroluminescent body is laminated on the inorganic oxide semiconductor. 4. The electroluminescent device according to claim 1, wherein the organic electroluminescent body is dispersed in the inorganic oxide semiconductor.