Luminescence in ZnS: (Cu, Tb) and ZnS: (Ag, Tb) phosphors

The electro-, photo-, thermo-, and photoelectro-properties of luminescence in ZnS: (Cu, Tb) and ZnS: (Ag, Tb) phosphors are studied. EL intensity (B) and ac voltage (U) is found to follow a law given by {article}{empty}{document}B = B₀ exp(- b/√U){document}, where B0 and b are constants. EL and PL spectra of these phosphors are obtained. The phosphorescence decay is found to be in agreement with a monomolecular mechanism. An analysis of the decay curves at different temperatures shows that the trap depth increases slowly with temperature. The trap depth, escape frequency, and capture cross-section of electrons are calculated using thermal glow curves. The PEL emission of these phosphors is also studied and quenching and enhancement are reported.