Thermally Robust Orange-Red-Emitting Color Converters for Laser-Driven Warm White Light with High Overall Optical Properties

Laser-driven solid-state lighting with super-brightness and compactness is recognized as a promising alternative to white light-emitting diodes. However, it is quite difficult to achieve laser-driven warm white light with long-term stability due to the shortage of robust orange- or red-emitting laser phosphors. In this work, an efficient and thermally robust orange-red (La,Y) 3 Si 6 N 11 :Ce 3+ (LYSN)-BN phosphor-in-glass (PiG) film is proposed to realize warm white light, where h -BN acts as an optical medium to enhance light scattering, a heat sink to reduce the temperature, and a protective layer to prevent LYSN from oxidation. The “LYSN+15 wt.% BN” PiG film shows an internal quantum efficiency of 70% and a luminance saturation threshold of 12.82 W mm −2 , much higher than those without h -BN (i.e., 57.5% and 7.63 W mm −2 ). A warm white light lamp fabricated by combining “LYSN+15 wt.% BN” PiG film with blue laser diodes, showing tunable correlated color temperatures (2800–5000 K), has a maximal luminous flux of 740 lm and a luminous efficacy of 133.5 lm W −1 , which promises high collimation and penetration lighting in the rainy or foggy weather. By designing a composite orange-red-emitting phosphor converter, this work lays a foundation for realizing high quality laser-driven warm white lighting source.