JPS5916399B2 - Method for producing a dispersed EL "phosphor" material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a dispersed EL (electroluminescent) phosphor with high brightness and long life.

Conventionally, dispersed EL phosphors have been prepared by adding Cu as an activator and Al, Cl, Br, and I as co-activators to H2.
It was produced by firing in an atmosphere of S, H2S+H2, N2+S, N2, HCII, etc. 3:.

However, devices fabricated using such phosphors have the drawbacks of low brightness and short lifespan. In order to solve this drawback, re-firing in various atmospheres has been attempted, and it has been found that re-firing in atmospheres such as air, NH3, N2, Co, SO2, etc. increases the lifespan. (U.S. Patent No. 3,082,344, Japanese Patent Publication No. 1137-1973)
) Among them, air has the greatest effect, and the higher the firing temperature and the longer the firing time, the more remarkable the effect. However, when firing in air at a higher firing temperature and longer firing time, the dielectric strength of the manufactured element decreases, making it difficult to produce high brightness.
The present invention is a manufacturing method characterized by re-baking in air and then etching in order to solve the above-mentioned drawbacks of the conventional method for manufacturing dispersed EL phosphors. To obtain the phosphor.

In order to achieve the above object, the present invention provides ZnS dispersion type EL.
A method for producing a dispersed EL phosphor, which is characterized in that after the first firing, the phosphor is fired again in air, and the ZnO produced at that time is removed by etching. This is the gist of the invention.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the spirit of the present invention. Example 1 The phosphor used was ZnS with Cu and Br added to ZnS:
It is a Cu, Br phosphor.

Table 1 shows the conditions for the first firing when an activator and an auxiliary activator were added to this phosphor. Table 1 After firing, the samples were washed with cyan and further dried.

A second firing was then carried out in air. Next, it was etched with acetic acid for 10 minutes in a water bath at 80°C, and then etched with 6N hydrochloric acid for 30 minutes. Thereafter, it was washed with cyanide, washed with water, and then dried.
FIGS. 1 and 2 show the dependence of the luminance and life of a device using this phosphor on re-firing temperature, re-firing time, and re-firing time. For comparison, the dependence of the luminance and lifetime on the firing temperature and firing time of an element using a phosphor without etching treatment is also shown.
A and b are the phosphors of the present invention 9, and C and d are those without etching treatment. The lifetime is expressed as the half-life time when the device is driven at 10 KH2 in a desiccator with an initial brightness of 100 nt.The brightness is the brightness just before dielectric breakdown of the device occurs as the applied voltage is increased. The longer the firing time is, the higher the firing temperature, the longer the life will be regardless of the presence or absence of etching.

In the phosphor of the present invention, the luminance hardly decreases due to air re-firing, whereas in the phosphor without etching treatment, the brightness decreases as the firing temperature is higher and the firing time is shorter.

Etching after air refiring in this way has the effect of greatly extending the lifespan without reducing brightness. Next, Table 2 shows the relationship between etching solution, etching processing time, and brightness.

Etching increases the brightness, but it saturates to a certain value when treated with hydrochloric acid for 30 minutes or more.

From the above results, it is desirable to calcinate in air at 700° C. to 900° C. for 30 minutes or more, then to etch in an 80° C. water bath with acetic acid for 10 minutes, and then to etch with 6N hydrochloric acid for 30 minutes or more.

Note that the improvement in brightness due to etching is due to the conductive ZnO
This is thought to be due to the removal of . The X-ray diffraction patterns before and after etching are shown in FIGS. 3 and 4. It can be seen that ZnO was removed by etching. In the above embodiment, etching was performed using acetic acid and hydrochloric acid, but the same effect can be obtained by using any chemical that dissolves ZnS and ZnO.

Furthermore, the present invention has similar effects on all ZnS dispersed EL phosphors other than ZnS:Cu,Br phosphors. As explained above, according to the present invention, high brightness,
High-performance dispersed EL because long-life phosphors can be created
It has the advantage of being able to realize an element.

[Brief explanation of the drawing]

FIG. 1 shows the dependence of the brightness and lifetime of the etched and unetched phosphors on the firing temperature after air re-firing, and the firing time was 1 hour.

Claims (1)

[Claims] 1. Dispersed EL phosphor characterized in that in producing a ZnS dispersed EL phosphor, after the first firing, it is re-fired in air, and the ZnO generated at that time is removed by etching. How to create the body.