Facile synthesis of rare earth ions doped LiSr4(BN2)3 phosphors for white light-emitting diodes

Abstract

Rare earth ions doped nitride is a kind of excellent phosphor for phosphor-converted white light-emitting diodes (WLEDs). However, the critical synthesis condition limits the application of nitrides in WLEDs. In this work, we develop a modified carbothermal reduction and nitridation method to synthesize rare earth ions doped LiSr₄(BN₂)₃ phosphors. The crystal structure, morphology and photoluminescence properties of the obtained phosphors were systematically investigated. Intense blue emitting is achieved in Ce³⁺ doped LSBN with internal quantum efficiency (IQE) of 85.7 % and external quantum efficiency (EQE) of 45.5 %. The emitting color can be tuned from blue to green by co-doping with different amounts of Tb³⁺ ions. Near unit IQE is achieved in LSBN:Ce 0.5 mol%, Tb 5 mol%. The obtained phosphors exhibit excellent thermal and color stability at temperature range of 300–523 K. A WLED is fabricated by coating LSBN:Ce 0.5 mol%, Tb 5 mol% and commercial CaAlSiN₃:Eu²⁺ on a 370-nm chip. The rare earth ions doped LSBN phosphors with high QE and excellent thermal stability in this work are promising candidates for WLEDs