Reflective PiGF@AlN converter with heat-conducting intermediate MgO layer for high-brightness laser lighting

Phosphor-in-glass (PiG) materials have been widely fabricated into various types of luminescent films due to their simple fabrication process, high color purity, and adjustable luminescence. However, existing reflective PiG films (PiGFs) still face significant challenges in serving as reliable color converters, mainly stemming from inadequate thermal management capabilities and limited optical efficiency. Herein, magnesium oxide (MgO) with a high thermal conductivity of 47–53.5 W/(m·K) was selected to form a MgO-in-glass (MiG) layer aimed at simultaneously enhancing heat dissipation and light extraction. A reflective PiGF@AlN converter with a sandwich structure—Y 3 Al 5 O 12 :Ce 3 + (YAG) PiGF and MiG layer on AlN substrate (YAG@MiG@AlN, YMA)—was developed. This structure effectively leverages the high thermal conductivities of AlN and MgO to improve heat dissipation. The optimized YMA converter with 60 wt% YAG and 4 wt% MgO achieves a high saturation threshold of 29 W/mm 2 and a luminous flux (LF) of 3682 lm, which exhibits a 24 % enhancement in maximum LF over the YAG@TiO 2 @AlN (YTA) converter and a 39 % improvement over the YAG@AlN converter (2649 lm@31 W/ mm 2 ). These results highlight the potential of the YMA converter in high-brightness and efficiency laser-driven lighting.