JPH01186591A - Electroluminescence element - Google Patents

Abstract

PURPOSE:To make brightness deterioration and film peeling etc., difficult to arise and improve the reliability of an EL element by making a hygroscopic powder to be included in a resistant body layer. CONSTITUTION:A transference electrode 2 having a thickness of approximately 400nm is formed on a glass substrate 1 by a sputtering method. Next a luminous layer 3 of approximately 1mum thickness is formed on the electrode 2 by vacuum evaporation with the substrate 1 heated to about 250 deg.C. And MnO2 as A conductive material is ground in which its particle diameter becomes as small as about 1mum. Then a fine powder having a particle diameter of approximately 0.8mum is made with at least one kind of a hygroscopic material; which is selected from groups composed of silicagel, activated alumina sulfuric anhydride sodium, magnesium perchlorate, barium oxide, and active carbon; ground. A resistance layer 4 of the sickness of about 20mum is formed with a conductive fine powder and a hygroscopic fine powder mixed together with a binder material, applied on the layer 3, and then dried. Then Al having the thickness of about 200mum is formed on the layer 4 by a vacuum evaporation method as an upper electrode. Finally a glass cap 6 is adhered with a seal material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electroluminescent device that emits light by applying an electric field, and particularly relates to an electroluminescent device that has a moisture absorbing effect on a resistor to prevent deterioration of the light emitting layer due to moisture. It is related to the element.

[Prior art] Conventionally, electroluminescence/sense elements (hereinafter referred to as E
(abbreviated as L element) is known.

These Group 1 sulfides are extremely sensitive to moisture and are a cause of brightness deterioration or film peeling during driving.

Conventionally, as a moisture-proofing measure for an EL element containing a resistor layer made of conductive fine powder hardened with a binder, an envelope such as a glass cap is provided, and the inside of the glass cap is degassed and evacuated, or a dry gas A method of substitution was used.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional moisture-proofing measures, it is not possible to make the inside of the glass cabinet completely moisture-free, and the EL
Moisture may enter the envelope from the seal between the substrate glass and the envelope, or moisture may be released from the resistor layer, making it impossible to obtain a sufficient moisture-proofing effect.
There was a big problem with the lifespan of LXe.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and includes a transparent electrode, a light-emitting layer, a resistor layer, and a back electrode that are sequentially laminated on a transparent insulating substrate. In the electroluminescent device, the resistor layer contains a hygroscopic powder. □As the hygroscopic powder, any material can be used as long as it has hygroscopic properties, but among them, the group consisting of hygroscopic gel, anhydrous calcium sulfate, magnesium perchlorate, barium oxide, calcium oxide, and activated carbon can be used. Using at least one powder or mixed powder selected from
This is preferable because the material after absorbing moisture is unlikely to have an adverse effect on the EL element f.

If the amount of hygroscopic powder contained in the resistor layer is small, the effect of the present invention will not be apparent (and if it is too large, the electrical properties will be impaired, so the amount of hygroscopic powder contained in the resistor layer is 2 to 10 vol
It is preferable that it is added in a range of %.

In addition, if the size of the hygroscopic powder is too large compared to the main powder (usually 1 to several μm in diameter) of the resistor layer that produces conductive or semiconducting characteristics, it will easily affect the electrical characteristics; If it is too large, it will be difficult to handle, so use a diameter of 0.
The size of the intestine is preferably 5 to 1.0 microns.

The hygroscopic powder may be mixed uniformly into the resistor layer, or may be mixed so as to exhibit a maximum concentration at a position away from the light emitting layer.

[Function] According to the present invention, a moisture absorbing mechanism is provided inside the EL element, so moisture that enters due to leakage in the envelope of the glass camp or the like or that is generated from the inside is absorbed before it is taken into the light emitting layer. However, a decrease in luminous efficiency can be prevented.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of an EL element according to the present invention. A transparent electrode (2) with a thickness of about 400 nm is formed on a transparent glass substrate (1) by sputtering. Next, the glass substrate is heated to about 250°C, and the light emitting layer (3
) is formed to a thickness of about 1 μI on the transparent electrode (2) by vacuum evaporation. Thereafter, the glass substrate (1) is taken out from a vacuum apparatus and a resistance layer (4) is formed thereon. Resistance layer (4)
An example of a method for forming is as follows. First, N M n O 2 as a conductive substance is pulverized by a pulverizer to a particle size of about 1 μm to produce a conductive fine powder. Next, the hygroscopic material is pulverized in the same manner as above to produce a hygroscopic fine powder having a particle size of about 0.8 μm. (The particle size of the hygroscopic fine powder is preferably smaller than that of the conductive fine powder.

The reason for this is that when the particle size of the hygroscopic fine powder becomes larger than that of the conductive fine powder, the contact area between the conductive fine powders becomes smaller, the resistance of the resistive layer increases, and the luminous efficiency decreases. This is because the non-light-emitting portion within the area increases.

) Such conductive fine powder and hygroscopic fine powder are mixed together with a binder material. The amount of hygroscopic fine powder was 5% based on the conductive fine powder. (If this ratio becomes too large, it will cause a decrease in luminous efficiency and an increase in non-luminous areas.) The mixed conductive a powder, hygroscopic fine powder, and binder are sprayed onto the luminescent layer (3 ), [-, and then dried to form a resistor layer (4) with a thickness of about 20 μm. next,
AI is formed as an upper electrode on the low antibody layer (4) to a thickness of about 200 nm by vacuum evaporation. Finally, the glass camp (6) is adhered with a sealant.

The EL element in this example has about 30
Approximately 50% of the samples showed performance degradation after 00 hours, while about 50% of samples showed performance degradation after about 10,000 hours.

In the above embodiment, external shielding is applied to the IEL element,
This device is equipped with an envelope for the purpose of protecting against external injuries, etc., but if the above purpose is achieved, one envelope is provided for multiple EL elements.
There is no need to provide an envelope or an envelope having the above shape.

[Effects of the Invention] According to the present invention, a portion of the EL element that does not affect light emission has a moisture absorbing function, so that, for example, leakage from the envelope and the adverse effects of moisture generated from the inside can be prevented. can do. Also, since the luminescent layer does not deteriorate due to moisture,
Brightness deterioration, film peeling, etc. are less likely to occur, and the reliability of the EL element can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing an electroluminescent device produced in an example. (1) Glass substrate (4) Resistor layer containing hygroscopic powder (
2) Transparent conductive film (5) Az electrode (3) Light emitting layer (6) Pack cap Figure 1

Claims (2)

[Claims] (1) An electroluminescent device in which a transparent electrode, a light emitting layer, a resistor layer, and a back electrode are sequentially laminated on a transparent insulating substrate, characterized in that the resistor layer contains a hygroscopic powder. electroluminescent element. (2) Claim 1, wherein the hygroscopic powder is at least one powder or mixed powder selected from the group consisting of silica gel, activated alumina, anhydrous sodium sulfate, magnesium perchlorate, barium oxide, and activated carbon. The electroluminescent device described.