Blue excitable green emitting Ce(3+) doped CaS phosphor for w-LEDs

CaS:Ce(3+) is an efficient green-emitting (535 nm) phosphor, excitable with blue light (450-470 nm) and was synthesized via a solid-state reaction method by heating under a reducing atmosphere. The luminescent properties, photoluminescent (PL) excitation and emission of the phosphor were analyzed by spectrofluorophotometry. The excitation and emission peaks of the CaS:Ce(3+) phosphor lay in the visible region, which made them relevant for light-emitting diode (LED) application for the generation of white light. Judd-Oflet parameters were calculated and revealed that green light emitted upon blue illumination. The prepared phosphor had strong blue absorption at 470 nm and a broad green emission band range from 490-590 nm with the peak at 537 nm. The characteristics of the CaS:Ce(3+) phosphor make it suitable for use as a wavelength tunable green emitting phosphor for three band white LEDs pumped by a blue LED (470 nm). The Commission International de l'Eclairage co-ordinates were calculated by a spectrophotometric method using the spectral energy distribution (0.304, 0.526) and confirm the green emission. The potential application of this phosphor is as a phosphor-converted white light-emitting diode.