Synthesis and luminescence properties of CaS:Eu2+,Si4+,Ga3+ for a white LED

Abstract

The luminescence intensity of calcium sulfide codoped with Eu2+, Si4+ and Ga3+ was investigated as a function of the dopant concentration. An enhancement of the red luminescence resulted from the incorporation of Si4+ and Ga3+ into CaS:Eu2+. The non-codoped CaS:Eu2+ converted only 3.0% of the absorbed blue light into luminescence. As the Si4+ and Ga3+ were embedded into the host lattice, the luminescence intensity increased and reached a maximum of Q = 10.0% at optimized concentrations of the codopants in CaS. Optimized CaS:Eu2+,Si4+,Ga3+ phosphors were fabricated with blue GaN LED and the chromaticity index of the phosphor-formulated GaN LED was investigated as a function of the wt% of the optimized phosphor.