High quality germanate phosphor La(2-x-y)Ge2O7: Tb3+, Eu3+for WLED applications

Abstract

White light emitting diodes (WLEDs), as the fourth generation of new light source, has the advantages of light weight, small size, low energy consumption, fast response speed and convenient use, but their poor thermal stability, high correlation color temperature (CCT) and low color rendering (Ra) limit their large-scale application of high-power WLED. In this work, we report the preparation of WLEDs by combining rare earth ions Tb3+-Eu3+ with La2Ge2O7, which exhibits tunable photoluminescence properties and excellent thermal stability. The detailed study shows that the layered structure of the material is conducive to efficient energy transfer (ET) between Tb3+ (sensitizer) and Eu3+ (activator), and effectively inhibits the luminescence attenuation caused by concentration quenching. Based on this, the doping ratio of Tb3+/Eu3+ in the phosphor is controlled and the phosphor is combined with blue chip to obtain excellent white light (CCT = 3955 K). The light efficiency (87 lm w−1) is comparable to that of commercial phosphors, and there is no significant decrease after continuous operation for 1000 h, which provides a good candidate material for the preparation of high-power WLED.