Phosphor converters for laser driven light sources

Due to the “efficiency droop” effect of light-emitting diodes (LEDs) under high drive currents, laser diode (LD) driven light sources are considered to replace LED lighting for the next-generation solid-state-lighting technology. In this Perspective, the history of lighting technology and the intrinsic advantages of LDs lighting are outlined. We provide a comparative overview of several typical LD phosphors, such as single crystal, transparent ceramic, phosphor-in-glass, and film thereof, as well as surface texture modification of film-type phosphor plates. The relationship between the illumination characterizations (luminance saturation, conversion efficiency, extraction efficiency, illuminating directionality, and color spatial uniformity) with thermal conductivity, pores, defects, second phases, and surface roughing or patterning is discussed. Finally, the current challenges and prospects are highlighted to provide guidelines for future research on LD phosphors.