Enhanced Cyan Emission and Optical Tuning of Ca_3Ga_4O_9:Bi~(3+) for High-Quality Full-Spectrum White Light-Emitting Diodes

摘要

Highly efficient cyan-emitting phosphor materials are indispensable for closing the cyan gap in spectra of the traditional phosphor-converted white light-emitting diodes (WLEDs) to achieve high-quality full-spectrum white lighting. In this work, bright cyan-emitting Ca3Ga4O9(CGO):0.02Bi(3+),0.07Zn(2+)phosphor is developed to bridge the cyan gap. Such a Bi3+,Zn(2+)codoping enhances the cyan emission of CGO:0.02Bi(3+)by 4.1 times due to the influence of morphology and size of phosphor particles, charge compensation and lattice distortion. Interestingly, codoping La(3+)ions into the current system can achieve a photoluminescence tuning of CGO:0.02Bi(3+)from cyan to yellowish-green by crystallographic site engineering. Besides, Bi3+-Eu(3+)energy transfer is successfully realized in CGO:0.02Bi(3+),0.07Zn(2+),nEu(3+)phosphors and the emission color tuning from cyan to orange is observed. The investigation of thermal quenching behaviors reveals that the incorporation of Zn(2+)and La(3+)improves the thermal stability of CGO:0.02Bi(3+). Finally, CGO:0.02Bi(3+),0.07Zn(2+),0.10Eu(3+)phosphor is employed to obtain a single-phased warm WLED device. A full-spectrum WLED device with remarkable color rendering index (Ra) of 97.4 and high luminous efficiency of 69.72 lm W(-1)is generated by utilizing CGO:0.02Bi(3+),0.07Zn(2+)phosphor. This result suggests the important effect of CGO:0.02Bi(3+),0.07Zn(2+)phosphor on closing the cyan gap, providing new insights of cyan-emitting phosphors applied in full-spectrum white lighting.