JPS5986194A - Thin film electroluminescent element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film electroluminescent device formed by laminating a large number of thin films including a light emitting layer, an electrode layer and an insulating layer on one surface of a transparent insulating substrate.

Conventionally, this type of thin film electroluminescent device generally has 11 layers, a transparent electrode, an insulating layer, 9 light-emitting layers, and an insulating layer on a glass substrate as a transparent insulating substrate.

It has a basic configuration of laminated back electrodes. A zinc sulfide film doped with manganese or terbium heptadide as a luminescent center is usually used as the luminescent layer, and after the film is formed, heat treatment is performed for crystallization and activation of the luminescent center.

The brightness of the thin film electroluminescent device obtained in this way strongly depends on the temperature during the heat treatment, and
As shown in the figure, the higher the temperature, the higher the brightness. (
FIG. 1 shows the measurement results when an AC pulse of 100 Hz and 50 μB was applied. ) However, the above temperature is limited because the glass substrate warps due to heat. For example, the maximum heat treatment temperature for Corning's S7O59 glass substrate, which is commonly used as a glass substrate for thin-film electroluminescent devices, is 590'C, and at higher temperatures, warping occurs and the quality of the electroluminescent device is compromised. and performance deteriorates.

The present invention was made in view of the above circumstances, and its purpose is to provide a thin film electroluminescent element that can suppress the occurrence of scratches on the substrate, increase the heat treatment temperature, and obtain high brightness. .

In order to achieve such an object, the present invention aims to reduce the stress exerted on the substrate by an insulating layer formed on the substrate through at least a transparent electrode of a multilayer film formed on one side of the other surface of the substrate. A transparent thin film having approximately the same stress as that is deposited.

In other words, the above-mentioned warping of the glass substrate is mainly caused by thin films formed by vacuum evaporation or sputtering, especially silicon nitride films and aluminum oxide films formed on the glass substrate via transparent electrodes. It was found that this was caused by the insulating layer.

For example, in the case of a silicon nitride film, the thickness of the glass substrate is 1.2 mm, and the thickness of the silicon nitride film is 0.3 AWL.
As a result, a compressive stress of 5 x 10' dyn/crn is generated.

Therefore, by forming a thin film having at least the same film stress as the insulating layer on the other surface of the substrate, it is possible to substantially cancel out the stress and effectively prevent warpage of the substrate.

In this case, since the substrate side is the display surface side, the thin film needs to be transparent.

Hereinafter, the present invention will be explained in detail using examples.

Second FIG. 1 is a sectional view showing an embodiment of the present invention.

In the figure, on a glass substrate (Corning Shrine 7059) 1 as a transparent insulating substrate, an insulating layer 3 consisting of a striped transparent ITO electrode 2.5i3NJ, a light emitting layer 3 consisting of ZnS@Mn Layer 4.81
．． N.

The structure in which the insulating layer 5 made of a film and the striped back electrode 6 made of an AL film are sequentially laminated is the same as the basic structure of what is commonly used in the past and is called a double insulation structure thin film electroluminescent panel. The striped transparent N-shaped grid 2 and the back electrode 6 are orthogonal to each other, forming a matrix type.

On the other hand, in the figure, SS is further added to the other surface of the glass substrate 1.
, a transparent thin film 7 made of N4 film is provided.

This transparent thin film 7 is made of the same material as the insulating layer 3 and has almost the same film stress as the insulating layer 3, and is formed before the heat treatment process of the light emitting layer 4.

In the thin film electroluminescent element having the above configuration, the film stress of the insulating layer 3 and the transparent thin film 7 is effectively offset during heat treatment of the light emitting layer 4, and heat treatment can be performed at a temperature higher than the conventional maximum heat treatment temperature of 590°C. becomes. As a result, the brightness of the device heat-treated at, for example, 650° C. was able to be significantly improved to 1.4 times that of the conventional device.

As explained above, according to the present invention, an insulating layer that is substantially the same as the insulating layer formed on the substrate through at least the transparent electrode of the multilayer film is provided on the other surface of the transparent insulating substrate on which the multilayer film is formed. By depositing and forming a transparent thin film having a stress of Become.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the dependence of brightness on heat treatment temperature, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1...-glass substrate (transparent insulating substrate), 2e... fist transparent electrode, 3... insulating layer, 7 fist...-transparent thin film. Patent applicant: Ise 1T, Kokogyo Co., Ltd. agent: Kazuko Yamakawa (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] In a thin-film electroluminescent element formed by laminating a transparent insulating substrate and a number of thin films including an emitting layer, an electrode layer, and an insulating layer on one side, the insulating substrate is coated on the other side of the insulating substrate through at least a transparent aA electrode. 1. A thin film electroluminescent device comprising a transparent thin film having approximately the same stress as that applied to an insulating substrate by the formed insulating layer.