Tunable and enhanced luminescence of Ba2−xCaxSiO4−yN2/3y:Eu2+ phosphors for white light-emitting diodes

Color tuning and luminescence enhancement are predominant challenges for improving the performance of white light emitting diodes (LEDs) toward commercial application. In this paper, a novel promising Ba2−xCaxSiO4−yN2/3y:Eu2+ phosphors with tunable and enhanced luminescence for phosphors converted LEDs (pc-LEDs) have been successfully synthesized by a direct gas-reduction nitridation method. The effects of Ca and N doping on the phase purity, morphology and optical properties of Ba2−xCaxSiO4−yN2/3y:Eu2+ phosphors were also systematically investigated. The optical results show that Ba2−xCaxSiO4−yN2/3y:Eu2+ phosphors can be actively excited over a broad range from 250 to 430 nm. With the adding of different concentrations of Ca2+ ions in phosphors, the emission color wavelength can be tailored from 501 to 441 nm by a 375 nm NUV LED excitation source. Furthermore, it has been found that the emission and absorption of Ba2−xCaxSiO4:Eu2+ phosphor can be significantly improved when N3− ions were introduced into the host lattices. The intensity of Ba1.5Ca0.5SiO4−yN2/3y:Eu2+ phosphor was 3.4 times higher than the phosphor without N doping. The fabrication and characterization of pc-LEDs using Ba2−xCaxSiO4−yN2/3y:Eu2+ phosphors-silica gel as the coating layer onto 375 nm-emitting InGaN LED caps demonstrated the superior optical and current tolerant properties, making it a promising and competitive candidate for commercial utilization in white LED applications.