Highly efficient Ce: Lu(Mg,Al)₂(Si,Al)₃O₁₂ phosphor ceramics for high-power white LEDs/LDs

Abstract

Lu₃Al₅O₁₂: Ce³⁺ (LuAG: Ce³⁺) phosphor ceramics (PCs) with high quantum efficiency and excellent thermal stability are incredibly promising color converters for high-power white light emitting diodes (LEDs)/ laser diodes (LDs) lighting. However, the greenish emission of LuAG:Ce³⁺ PCs does not allow to reach white light emission upon pumping by a blue LED/ LD without an additional red luminescent material. In this work, a series of (Ce_0.003Lu_0.997)₃(MgxAl_1-2xSix)₅O₁₂ (LCMASG) (x = 0-0.15) PCs were fabricated by solid state reaction method. Impressively, the as-prepared PCs exhibited a distinct red-shift (513→538nm) and a 17% increase of the color index (CRI) of high-power white LED(58.4→70.4). Particularly, Ce: Lu(Mg, Al)₂(Si, Al)₃O₁₂ PC with 15 at.% substitution concentration showed only 8% luminescent intensity loss at 150 °C and high internal quantum efficiency (IQE) of 82%, exhibiting desirable optical thermal stability. By combining with a 460 nm blue chip or a 455 nm laser source, white LED/LD devices based on the LCMASG PCs in a remote excitation mode were constructed. The optimized luminous efficiency of Ce: Lu(Mg, Al)₂(Si, Al)₃O₁₂ PC with 15 at.% Mg²⁺/Si⁴⁺ doping up to 176.4 lm/W was obtained as the power density of the blue laser increased to 6.52 W/mm². Also, a 4053K CCT of the warm white light emission was realized. Therefore, this work proves that the LCMASG PCs are promising to serve as color converters for high power LEDs/LDs lighting in the future.