Theory of the Luminescence of Sulfide Phosphors

Abstract

Assuming the existence of a killer center with an unoccupied electronic ground state above the Fermi level and explicitly including the metastable emitting state of the activator and the electron traps in the formulation, the dependence of emission intensity on excitation intensity for sulfide phosphors is comprehensively treated. The data of Nail, Urbach, and Pearlman, which demonstrate that over an intensity range the emission intensity of the Zn0.5Cd0.5S:Ag, Ni phosphor is proportional to the 3.5 power of the excitation intensity, are quantitatively reproduced by the theory. The adjustable parameters used to fit the data are shown to be reasonable and to be in accord with other measurements and are used to evaluate the energies of the various electronic states involved. In addition, it is shown that the relation of Klasens and Wise between excitation and emission intensity may be derived as a special case of the general theory.