Highly reflective interface design for phosphor-in-glass converter enabling ultrahigh efficiency laser-driven white lighting

To address the problems of low luminous efficacy and poor thermal stability of reflective phosphor-in-glass (PiG) converter, a thermally robust and highly reflective PiG-boron nitride (BN)-aluminum nitride (AlN) converter was designed for enabling ultrahigh efficiency laser-driven white lighting. Benefiting from the ingenious sandwich design with the thermally conductive AlN substrate and highly reflective BN-glass interface, a La₃Si₆N₁₁:Ce³⁺ (LSN) PiG-BN-AlN converter achieves white light emission with a high luminous efficacy of 214.2 lm/W under the 3.15 W blue laser excitation, which is the best recorded value for the reflective PiG-based converters thus far, and the surface temperature of LSN PiG is low to 126 °C. Furthermore, the LSN PiG-BN-AlN converter incorporates CaAlSiN3:Eu²⁺ (CASN) red phosphor to enable high-quality white light emission with high luminous flux and good color quality. The results reveal that the designed PiG-BN-AlN converter provides a promising strategy for achieving ultrahigh efficiency laser-driven white lighting.