Improved luminescent properties of red-emitting Ca0.54Sr0.16Eu0.08Gd0.12(MoO4)0.2(WO4)0.8 phosphor for LED application by charge compensation

The red-emitting Ca0.54Sr0.16Eu0.08Gd0.12(MoO4)0.2(WO4)0.8 phosphor is improved in the emission charateristics by charge compensation, of which chromaticity coordinates (CIE) are x=0.66 and y=0.33. Three approaches to charge compensation are investigated, namely (a) 3Ca2+/Sr2+→2Eu3+/Gd3++vacancy, (b) 2Ca2+/Sr2+→Eu3+/Gd3++M+(M+ is a monovalent cation like Li+, Na+ and K+ employed as a charge compensator) and (c) Ca2+/Sr2+→Eu3+/Gd3++N− (N− is a monovalent anion like F−, Cl−, Br− and I− employed as charge compensation ions). Through photoluminescent spectra analyzing the radiative and non-radiative relaxation mechanisms of luminescent system are obtained. Under 20 mA forward-bias current, one red-emitting LED is made by combining 390–405 nm-emitting LED chip and the phosphor. The red-emitting phosphor has broad prospects in LED application field.