Oxygen in SrS phosphor powder and its effects on performance of thin film electroluminescent devices

This paper reports on oxygen and oxidation effects in SrS powder that were investigated in order to improve luminance of SrS-based thin-film electroluminescent devices, XPS analysis revealed that the SrS powder surface was oxidized by the adsorption of water, giving the surface products SrSO3 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 H2S atmosphere