Development of a double-sided heat-conducting BN@PiGF@Al2O3 color converter for high-brightness laser lighting

Abstract

A color converter is a critical component in realizing new-generation laser lighting because it displays thermal-induced luminescence saturation due to substantial heat accumulation. Herein, a multi-channel thermal design was introduced in a phosphor-in-glass film (PiGF) color converter, and a double-sided heat-conducting BN@PiGF@Al₂O₃ converter was proposed for high-brightness laser lighting. The BN@PiGF@Al₂O₃ was prepared via low-temperature sintering of a PiGF on a reflective Al₂O₃ substrate, which was then topped with a BN-in-glass (BiG) layer. The PiGF thickness was adjusted to control the photo-thermal performance of the laser-driven BN@PiGF@Al₂O₃. As the Y₃Al₅O₁₂:Ce³⁺ (YAG) PiGF thickness reached 80 μm, the laser-driven BN@PiGF@Al₂O₃ emitted white light with a correlated color temperature (CCT) of 5823 K and a chromaticity coordinate of (0.3251, 0.3441) under a laser power density (LPD) of 30 W mm⁻². The BN@PiGF@Al₂O₃ yielded a high luminous flux (LF) of 4784 lm@30 W mm⁻², which was 1.39 times that of the traditional PiGF@Al₂O₃ converter with an LF of 3445 lm@18 W mm⁻². Furthermore, the BN@PiGF@Al₂O₃ displayed a working temperature of 232 °C under an LPD of 30 W mm⁻². The results demonstrate that the BN@PiGF@Al₂O₃ displays efficient double-sided heat transfer and improved luminescence saturation, making it a promising reflective color converter for high-brightness laser lighting.