Degradation processes in encapsulated ZnS: Cu powder electroluminescent phosphors

摘要

In this paper we present experimental results of the studying degradationudprocesses in electroluminescent panels, prepared from encapsulated ZnS:Cu powderudphosphors and theoretical simulation of energy parameters for the phosphor. Energy banduddiagrams ZnS, Cu₂S, ZnS-Cu₂₋xS heterojunction and Cu-ZnS metal-semiconductorudjunction have been constructed and cohesive energies for Zn-S, Cu-S, Zn-O, Cu-O andudZn-Cu bonds have been calculated by the method based on a linear combination ofudatomic orbitals and pseudo-potential. Time dependences of brightness have been found toudadequately fit a two-component exponential dependence. The first part of the exponentialudcurve has been attributed to the diffusion processes taking place in Cu₂₋xS, and the secondudone to the diffusion of Cu in ZnS matrix.