Thermally Conductive AlN‐Based Bicolor Phosphor‐in‐Glass Films for High‐Brightness Laser Lighting

High‐brightness laser‐driven lighting requires color converters that simultaneously deliver efficient light extraction, rapid heat dissipation, and stable spectral output under intense local irradiation. Here, reflective phosphor‐in‐glass film (PiGF) converters on AlN substrates, denoted PiTA, are fabricated by screen printing and low‐temperature co‐sintering. A TiO 2 reflective interlayer and a lithium‐aluminum‐silicate (LAS) glass matrix are integrated with Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) or Lu 3 Al 5 O 12 :Ce 3+ (LuAG:Ce) phosphors to construct Y‐PiTA and Lu‐PiTA. Interlocking lithium disilicate crystallization within the glass matrix, together with the thermally conductive AlN support, enables thermal conductivities of 74.3 and 69.9 W m −1 K −1 for Y‐PiTA and Lu‐PiTA, respectively. Under blue‐laser excitation, Y‐PiTA and Lu‐PiTA deliver maximum luminous fluxes of 2 658 and 4 004 lm and peak luminous efficiencies of 236.6 and 247.5 lm W −1 , respectively. Furthermore, a spatially spliced bicolor PiTA color wheel suppresses photon reabsorption during dynamic operation, producing 4 528 lm white light with a color rendering index of 71.3 under 62 W excitation. These results establish a practical structure‐property‐performance design strategy for thermally robust color converters in next‐generation high‐power laser‐lighting systems.