CALSON:Ce3+ Phosphor Ceramics for Laser-Driven Solid-State Lighting

Laser-driven solid-state lighting is recognized as next-generation high-power and super-brightness lighting sources, but the color temperature of which is greatly limited by scarcity of efficient orange–red color converters. To address this issue, a thermally robust phosphor ceramic of Ca 1- x - y Li x Al 1- x - y Si 1+ x + y N 3- y O y :Ce 3+ (CALSON:Ce is reported, with chromatic coordinates of x = 0.15 and y = 0.1) prepared by spark plasma sintering. Highly efficient CALSON:Ce phosphor powders are first synthesized by “seed” sintering and further treated by acid washing, demonstrating an external quantum efficiency (EQE) as high as 66% and a photoluminescence retention of 91% at 200 °C. The phosphor ceramic fabricated at 1600 °C has the highest EQE of 57% and luminous saturation threshold of 19.58 W mm −2 . By coating the CALSON:Ce ceramic with a La 3 Si 6 N 11 :Ce (LSN:Ce) phosphor layer, white light can be generated under blue laser excitation with a power density of 11.28 W mm −2 , achieving a color temperature of 4943 K, a luminous flux of 675.76 lm, and a luminous efficacy of 119.81 lm W −1 . This work proposes a “seed” sintering method that enables to improve the quantum efficiency of phosphors and ceramics.