Luminescence and Energy Transfer in Eu2 + and Mn2 + Co-doped Ca2P2O7 for White Light-Emitting Diodes

Abstract

and co-doped α- and are prepared by solid-state reaction. An orange emission band originating from the transition of is observed in both phases upon UV excitation through energy transfer from to . Photoluminescence and energy transfer in , are investigated as a function of concentrations. The energy transfer rates are calculated based on the analysis of the luminescence dynamical process as well as fluorescence lifetime measurements. The intensity ratios of the orange to blue band as a function of concentrations are also calculated and the results are in good agreement with that obtained directly from emission spectra. A white light emitting diode (LED) fabricated through the integration of a GaN near-UV chip and two phosphor blends (, blue-orange phosphor and green phosphor) into a single package shows a warm white light of 3797 K correlated color temperature, a good color rendering index (CRI) of 84, and a luminescent efficiency of 11 lm/W with color coordinates of , . Moreover, the CRI can be improved to 94 by using blue phosphor added to the two phosphor blends.