JPH0547474A - Electroluminescence element - Google Patents

Abstract

PURPOSE:To provide an electroluminescence element of excellent brightness and efficiency. CONSTITUTION:A surface process layer including 0.1-10wt.% of palladium in a composition primarily composed of a resin of high dielectric constant, is formed into the thickness of 0.005-0.5mum between an emission layer and a transparent electrode layer, of an electroluminescence element comprising an electrode layer, an insulating layer, the emission layer, the transparent electrode layer, and a moistureproof film. The electroluminescence element is thus provided, in which the airtightness of the emission layer and of the transparent electrode layer is improved, and the efficiency is improved without lowering initial EL emission brightness, while the life span of which is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent device (electroluminescent light emitting device).

More specifically, the present invention relates to an electroluminescent device having good emission brightness / efficiency and excellent durability.

[0003]

2. Description of the Related Art Conventionally, as an electroluminescent device (hereinafter sometimes abbreviated as EL), it is known that an insulating layer, a light emitting layer and a transparent electrode layer are laminated on an electrode layer. Inorganic powders of ferroelectrics such as barium titanate, strontium titanate, and lead titanate are dispersed in a cellulose-based high dielectric constant binder such as cyanoethyl cellulose. As the light emitting layer, a phosphor powder such as zinc sulfide doped with copper or manganese is dispersed in a cellulose-based high dielectric constant binder such as cyanoethyl cellulose. As the transparent electrode layer, a film formed by vacuum deposition or sputtering of an indium oxide / tin compound on a polyester film is used.

[0004]

However, the conventional electroluminescent device has the following problems.

That is, used as a light emitting layer,
Dispersion of phosphor powder such as zinc sulfide doped with copper or manganese in a cellulosic high dielectric constant binder such as cyanoethyl cellulose reduces the emission brightness by adsorbing moisture. However, there is a problem in that the adhesion between the transparent electrode layer and the light emitting layer is poor and uneven light emission occurs.

In order to solve these problems, in order to improve the moisture-proof property, a method of further forming an inorganic moisture-proof layer on the fluorine film (JP-A-2-229032), and on the transparent electrode layer for improving the adhesion, Method for forming a palladium layer or a method for forming a high dielectric constant layer on a substrate (Japanese Patent Laid-Open No. 64-811)
12, JP-A-2-72940, JP-A-2-98436,
JP-A-2-199791, JP-A-2-213992, and JP-A-2-227992) have been proposed.

However, it is difficult to completely reduce the moisture transmittance to zero. On the other hand, the formation of the palladium layer or the high dielectric constant layer reduces the emission luminance of EL. Although it is possible to prevent or improve the adhesion to some extent, the formation of the palladium layer lowers the initial EL emission brightness, and the formation of the high dielectric constant layer increases the power consumption, that is, the efficiency. Cause a decline.

The object of the present invention is to add palladium evenly in the middle of the light emitting layer and the transparent electrode layer through the high dielectric constant resin, and thereby to improve both the life and the adhesion without lowering the efficiency. To improve.

[0009]

That is, the present invention provides an electroluminescent device comprising an electrode layer, an insulating layer, a light emitting layer, a transparent electrode layer, and a moisture-proof film, in which a high dielectric constant resin is provided between the light emitting layer and the transparent electrode layer. A surface treatment layer containing 0.1 to 10% by weight of palladium in a composition mainly containing
The electroluminescent device is characterized by being provided with a thickness of 0.5 μm.

Aluminum foil of 10 to 50 μm is mainly used for the electrode layer of the present invention, but the electrode layer is not limited to this. For example, an electrode may be formed by applying a silver paste or the like to a plastic film such as a copper foil or a polyester film having a thickness of 10 to 50 μm.

The insulating layer is made of ferroelectric powder of barium titanate, lead titanate, strontium titanate, etc., together with a solvent such as dimethylformamide, cyanoethyl cellulose, cyanoethyl sucrose, cyanoethylated pullulan, cellulose acetate. − High dielectric constant binder such as
10 to 5 of the paint dispersed in the aluminum electrode layer
It is formed by applying and drying to a thickness of 0 μm.

For the light emitting layer, zinc sulfide doped with copper, aluminum or the like is used together with a solvent such as dimethylformamide to form cyanoethyl cellulose or cyanoethyl sucrose.
Of the coating material dispersed in a high dielectric constant binder such as bismuth, cyanoethylated pullulan, or cellulose acetate on the insulating layer.
It is formed by coating and drying to a thickness of ˜50 μm.

As the transparent electrode layer, a transparent conductive layer made of an indium oxide-tin oxide composite oxide (hereinafter sometimes abbreviated as ITO) is formed on one surface of a transparent substrate such as a polyester film by vacuum deposition, sputtering or the like. Method 1
It is formed to a thickness of 0 to 100 nm.

In the present invention, a thickness of 0.005 containing 0.1 to 10% by weight of palladium between the light emitting layer and the transparent electrode layer.
A surface treatment layer made of a composition mainly containing a high dielectric constant resin having a thickness of 0.5 μm is provided. Here, the high dielectric constant resin has a dielectric constant of 5 or more, preferably 10 or more, more preferably 15
The above resins are referred to. A thermoplastic resin having a small dielectric loss tangent and transparent to visible light is desirable, but a thermosetting resin may be used. Further, other substances having a low dielectric constant may be added to the composition mainly composed of a high dielectric constant resin, but the dielectric constant of the composition as a whole is at least 5 or more, preferably 10 or more.
As described above, more preferably 15 or more.

Examples of the method for forming a surface treatment layer containing 0.1 to 10% by weight of palladium in a composition mainly composed of a high dielectric constant resin include cyanoethyl cellulose, cyanoethyl sucrose and cyanoethylated pullulan. , A high dielectric constant resin such as cellulose acetate and the like are dissolved in an organic solvent such as dimethylformamide and decomposed at a high temperature such as palladium acetylacetonate or palladium acetate to release palladium, and an organopalladium compound or palladium Examples thereof include a method in which a coating material to which a powder or the like is added is applied onto the transparent electrode or the light emitting layer and then dried. As a method of adding palladium, it is preferable to use an organopalladium compound that decomposes to release palladium at a high temperature in terms of dispersibility, but in this case, at least palladium must be released before completion of the electroluminescent element. There is. It is preferable to liberate palladium during drying after coating the surface treatment layer.

The coating thickness of this surface treatment layer is 0.00 in order to maintain sufficient adhesiveness between the transparent conductive layer and the light emitting layer.
It is necessary to be 5 to 0.5 μm, preferably 0.01
.About.0.2 .mu.m, most preferably 0.02 to 0.1 .mu.m. The palladium contained in this thin film plays an important role in the brightness, efficiency and life of electroluminescence, and when converted to the thickness of palladium, it is preferably 0.05
To 5 nm, more preferably 0.1 to 2 nm, and most preferably 0.2 to 1 nm in the high dielectric constant resin. If the amount of palladium added is small, the life will be shortened,
If it is too large, the brightness and efficiency will be reduced.

This surface treatment layer is preferably formed first on the transparent electrode layer side in the manufacturing process of the light emitting device of the present invention, but may be formed on the light emitting layer side.

The moisture-proof film wraps the entire surface of the back electrode, the insulating layer, the light-emitting layer and the transparent electrode layer, and is mainly made of polyethylene, which has excellent moisture-proof properties and can be heat-sealed to trifluoroethylene chloride.
Films laminated with vinyl acetate resin are generally used, but are not necessarily limited thereto. Also,
If necessary, a water catching layer such as a polyamide film may be included between the transparent electrode, the back electrode layer and the protective sheet.

[0019]

【Example】

Examples 1 to 9 40 μm of an insulating layer having the following coating composition was formed on 50 μm aluminum foil (manufactured by Showa Aluminum Co., Ltd.) washed with acetone.
m thickness was formed.

Barium titanate (ELMIC BT-300 manufactured by Rhone Plan Co., Ltd.): 10 g. Cyanoethylated pullulan (CR-S manufactured by Shin-Etsu Chemical Co., Ltd.)
: 5 g N, N-dimethylformamide: 5 g Acetone: 5 g Then, a light emitting layer having a coating composition shown below was formed to a thickness of 35 μm on the insulating layer.

ZnS phosphor (manufactured by SYLVANIA)
ELPHOSPHOR 830): 10 g-Cyanoethylated pullulan (CR-S manufactured by Shin-Etsu Chemical Co., Ltd.)
: 5 g N, N-dimethylformamide: 5 g Acetone: 5 g Next, an ITO transparent conductive film (surface resistance value of 20 was formed on a 75 μm polyester film by a sputtering method.
A surface treatment layer of a high dielectric constant resin containing palladium having the composition shown in Table 1 was applied to 0 Ω / □ in a thickness of 30 nm.

A transparent electrode layer coated with this surface treatment layer and an aluminum foil in which an insulating layer / a light emitting layer were formed in this order were faced to the surface treatment layer and the light emitting layer, and the electrodes were taken out. Moisture-proof film (Nitoflon N manufactured by Nitto Denko Corporation)
o. 4810) and was laminated with a fast laminator to obtain an electroluminescent device.

[0023]

[Table 1]

Comparative Examples 1 to 4 An insulating layer having the same coating composition as in Example 1 was formed on 50 μm aluminum foil (manufactured by Showa Aluminum Co., Ltd.) washed with acetone.
The thickness was 0 μm.

Next, a light emitting layer having the same coating composition as in Example 1 was formed on the insulating layer to a thickness of 35 μm.

Next, an ITO transparent conductive film (surface resistance value of 200 Ω / □) formed on a 75 μm polyester film by a sputtering method and an insulating layer / light emitting layer formed on an aluminum foil in this order were used as an ITO layer and a light emitting layer. After facing each other and taking out the electrode, the electrode was placed in a fluorine-based moisture-proof film (Nitoflon No. 4810 manufactured by Nitto Denko Corporation) and laminated with a far straminator to obtain an electroluminescent device. This is referred to as Comparative Example 1.

Comparative Example 2 in which palladium was formed to a thickness of 0.5 nm by sputtering on an ITO transparent conductive film (surface resistance value 200 Ω / □) formed on a 75 μm polyester film by sputtering to give a transparent electrode. And

A transparent electrode was prepared by applying 30 nm of cyanoethylated pullulan (CR-S manufactured by Shin-Etsu Chemical Co., Ltd.) on an ITO transparent conductive film (surface resistance value 200 Ω / □) formed on a 75 μm polyester film by a sputtering method. Is referred to as Comparative Example 3.

On an ITO transparent conductive film (surface resistance value 200 Ω / □) formed on a 75 μm polyester film by a sputtering method, palladium was formed to a thickness of 0.5 nm by a sputtering method, and cyanoethylated pullulan (CR manufactured by Shin-Etsu Chemical Co., Ltd. CR Comparative Example 4 is a transparent electrode formed by applying -S) to a thickness of 30 nm.

Table 2 shows the characteristics of the examples and comparative examples.

[0031]

[Table 2]

The following methods were used to measure the properties shown in Table 2.

(A) Adhesiveness The electroluminescent elements produced in Examples and Comparative Examples were disassembled and judged by the degree of peeling when peeled between the transparent electrode and the light emitting layer. (◯: Any of the transparent electrode, the surface treatment layer and the light emitting layer is broken. Δ: No breakage occurs but there is resistance when peeling. ×: Peeling without resistance.)

(B) Luminance The light emitting state when an electric field of 1 kHz and an effective value of 100 V is applied to the electroluminescent element is J16 D manufactured by Tetronicix.
It was measured by IGITAL PHOTOMETER.

(C) Efficiency The efficiency was calculated from the voltage and current applied to the electroluminescent device at a frequency of 1 kHz and a brightness of 200 cd / m ² .

(D) Deterioration test An electric field of 1 kHz and an effective value of 100 V was applied to the electroluminescence device for 100 hours in an atmosphere of 50 ° C. and 90% RH, and a luminescence test was conducted.

[0037]

INDUSTRIAL APPLICABILITY The electroluminescent device of the present invention can be widely used in fields such as planar illumination and display. Among them, it can be used for a liquid crystal display device, a backlight of a liquid crystal television, a curved surface display, or a panel display for automobiles, trains, and the like.

The electroluminescent device of the present invention has good emission brightness and efficiency and excellent durability, and therefore has higher brightness than the conventional EL. Since the efficiency is good, the power consumption is low with the same brightness. Due to its excellent durability, the EL emission brightness is maintained for a long time. And so on.

As described above, the effect is exhibited by the fact that palladium added to the surface-treated layer having a high dielectric constant acts on the moisture that has penetrated into the electroluminescent device, and ZnS in the light-emitting layer is produced.
It is presumed that it is due to the function of preventing the deterioration of the film and that the adhesion between the ITO transparent electrode layer and the light emitting layer is improved. Therefore, for example, a hydrogen storage alloy is considered to have the same effect.

Claims (1)

[Claims] 1. An electrode layer, an insulating layer, a light emitting layer, a transparent electrode layer,
In an electroluminescent device comprising a moisture-proof film, a surface treatment layer containing 0.1 to 10% by weight of palladium in a composition mainly composed of a high dielectric constant resin is provided between 0.005 and 0 between the light emitting layer and the transparent electrode layer. An electroluminescent device having a thickness of 0.5 μm.