Converted white light emitting diodes from Ce3+ doping of alkali earth sulfide phosphors

Abstract

Polycrystalline CaS:Ce³⁺ and SrS:Ce³⁺ phosphors were successfully synthesized via the carbo-thermal reduction method. The XRD patterns of prepared phosphors were well matched with ICDD files and surface morphology of prepared phosphors were found to be in sub micron range. Photoluminescence emission spectra of CaS:Ce³⁺ and SrS:Ce³⁺ exhibits green and blue broad band emissions centered at 504 nm and 477 nm respectively. The concentration quenching phenomena was observed for prepared phosphors. CIE coordinates of Ce³⁺ doped CaS and SrS phosphors were calculated. The critical transfer distance (Rc) is calculated by equation proposed by Blasse. Thus prepared phosphors are suitable for pc-WLED.