Thin-film luminescence device utilizing Zn.sub.(1-x) Mg.sub.x S host material compound activated by gadolinium or a gadolinium compound

Abstract

The object of the invention is to provide UV light of increased luminous intensity. Layered on one surface of a translucent substrate are a transparent electrode, a first insulating layer, an EL layer, a second insulating layer, and a metal electrode, in that order. A compound of the general formula: Zn.sub.(1-x) Mg.sub.x S is selected as a host material of the EL layer, and Gd or a Gd compound is selected as the luminescence center. The composition ratio x of the compound selected as a host material is selected to be within the range of 0.33.ltoreq.x<1, and preferably within the range of from 0.4-0.8, inclusive. This selection allows the band gap energy of the host material to be higher than the band gap energy of the luminescence center, thus preventing the absorption of the emitted light by the host material and providing UV light of increased luminous intensity.

Dependencies are inferred from the claim text.