Blue CuxS coated ZnS:Ag,Cl phosphor as potential field emission display material

Abstract

The ZnS:Ag,Cl phosphor shows a blue luminescence due to electron–hole recombination at donor–acceptor pairs. Ag dopant acts as the acceptor and Cl co-dopant acts as the donor. For conductivity treatment, the CuxS conductive layer is coated on the particle’s surface of ZnS:Ag,Cl by a wet chemical reaction. The low voltage phosphor film is prepared by sedimentation. Analyses by x-ray diffraction patterns and scanning electron microscopy photographs observe a preferential orientation phenomenon of the phosphor film. Electron probe microanalysis reveals that the Cu ions in the CuxS coated ZnS:Ag,Cl are homogeneously distributed. For CuxS coated at room temperature, the luminance intensity of the phosphor film is increased with the coating time and coating solution concentration. However, the luminance of phosphor film will degrade due to the oxidized phosphor’s surface. A proper heat treatment enhances the luminance of the phosphor film. A high luminance is observed from the CuxS coated ZnS:Ag,Cl phosphor and it is compatible for field emission display applications.