Enhancement of fluorescence by Ce3+ doping in green-emitting Ca15(PO4)2(SiO4)6:Eu2+ phosphor for UV-based w-LEDs

Ca15(PO4)2(SiO4)6:Eu2+,Ce3+ phosphor was synthesized by a solid-state reaction. Doping of Ce3+ into the Ca2+ site of the Ca15(PO4)2(SiO4)6:Eu2+ phosphor enhanced the Eu2+ emission greatly, as observed by measuring the photoluminescence properties and the quantum efficiency levels. The mechanism of the enhancement of the Eu2+ emission by Ce3+ doping was investigated by comparing the normalized photoluminescence (PL) spectra with the normalized photoluminescence excitation (PLE) spectra and analyzing the absorbance and the fluorescence lifetime of the Ca15(PO4)2(SiO4)6:Eu2+,Ce3+ phosphors. Furthermore, the thermoluminescence properties were measured to confirm the thermal stability of the synthesized phosphor when exposed to the high junction temperature of recent high-power LED chips, showing a thermal activation energy barrier of 0.213 eV.