High Luminescence Saturation Y₃Al₅O₁₂: Ce³⁺‐Diamond Composite Color Converter for High‐Brightness Laser‐Driven White Lighting

Abstract

Phosphor‐converted laser lighting confronts enormous challenges in the development of color converters with high luminescence saturation owing to the thermal issues from laser irradiation and phosphor conversion. Herein, a high luminescence saturation Y3Al5O12: Ce3+‐diamond (YAG‐diamond) composite color converter by introducing diamond particles in phosphor‐in‐glass film (PiGF) coated on transparent sapphire substrate is proposed for high‐brightness laser‐driven white lighting. By optimizing the diamond content to 6 wt.%, the YAG‐diamond converter shows a thermal conductivity (TC) of 14.7 W·m−1·K−1 and displays higher luminescence intensity at 175 °C (1.15 times that at 25 °C). Under laser excitation, the YAG‐diamond converter achieves a luminous flux (LF) of 1990 lm at the laser power density (LPD) saturation threshold (ST) of 24.82 W·mm−2, which is far better than the PiGF@sapphire converter with a LF of 1364 lm@17.64 W·mm−2. The laser‐driven converter yields stable white laser light with a correlated color temperature (CCT) of 5714 K and a chromaticity coordinate of (0.3278, 0.3372) at the ST of 24.82 W·mm−2. Furthermore, the working temperature of the converter is decreased by 59 °C (26.6%) under LPD of 10.89 W·mm−2. These results indicate that the proposed YAG‐diamond composite converter displays excellent opto‐thermal performances, which may be a promising luminescence material in high‐brightness white laser lighting.