Oxygen in SrS Phosphor Powder and Its Effects on Performance of Thin Film Electroluminescent Devices

Abstract

Oxygen and oxidation effects in powder were investigated in order to improve luminance of thin‐film electroluminescent devices. XPS analysis revealed that the powder surface was oxidized by the adsorption of water, giving the surface products and free S. Adsorption of water on the surface proceeded rapidly when exposed to a moist atmosphere, and oxidation of the surface occurred when heated in a nitrogen atmosphere as well as in a vacuum. Higher luminance and a better build‐up characteristic in the luminance‐voltage curve of the EL cells were obtained through heat‐treatment of evaporation sources in an atmosphere.