A Thermally Robust La3Si6N11:Ce-in-Glass Film for High-Brightness Blue-Laser-Driven Solid State Lighting

Color converter is a key luminescent material in the laser-driven solid state lighting, which must bear high-density excitation and serious thermal attack from the incident laser. Here, a thermally robust yellow-emitting La3Si6N11:Ce-in-glass (LSN:Ce-PiG) film for laser lighting is reported by co-firing the LSN:Ce and glass powders on a thermally conductive sapphire substrate. No detectable interfacial reaction occurs between the LSN:Ce particle and glass matrix, enabling the film to fully inherit the original thermal robustness and high quantum efficiency. The optical performance of LSN:Ce-PiG-converted white laser light has been effectively optimized by changing the phosphor-to-glass (PtG) ratio and the film thickness. The highest light conversion efficiency is respectively achieved at PtG = 2:3 and the thickness of 70 mu m, and the saturation threshold is found to decrease with either a higher PtG ratio or a thicker film. The optimized LSN:Ce-PiG film (P2G3-50) can withstand a maximum laser power density of 12.91 W mm(-2) and produce a cool white light with a high luminous flux of 1076 lm (luminance of 773 Mcd m(-2)), a luminous efficiency of 166.05 lm W-1, a color rendering index of 70. These results make the LSN:Ce-PiG film a considerably promising color converter for laser lighting.