Microstructured interface modification of laser-driven phosphor-in-glass-film for ultra-high-efficiency white lighting

Abstract

Phosphor-converted white laser lighting has been regarded as a potential high-brightness light source in lighting and display. Nevertheless, the traditional phosphor-in-glass-film (PiGF) converter suffers the roadblock of low luminous efficiency owing to the low phosphor conversion from small laser spot and the light scattering loss from film-substrate interface. Herein, a laser-driven PiGF with microstructured interface modification was proposed for ultra-high-efficiency white lighting. The effects of PiGF thickness and laser power on the optical performance of PiGF-MS based laser lighting were assessed and compared with the conventional PiGF based laser lighting. The PiGF-MS converter has higher phosphor conversion efficiency and suitable thermal stability originating from the light field strengthening effect of microstructured interface and the outstanding thermal conductivity of sapphire. At the PiGF thickness of 80 µm, the luminous efficacy of PiGF-MS based laser lighting is enhanced by 11% compared with that of PiGF based laser lighting. At this thin PiGF thickness, the PiGF-MS converter adequately emits a cold white light while the PiGF converter still yields a blue light due to its insufficient blue-yellow light conversion. The PiGF-MS converter enables an ultra-high luminous efficacy of 249.1 lm/W and a suitable correlated color temperature (CCT) of 6500 K under a laser power of 3.15 W. The results indicate that the presence of microstructure interface in the PiGF significantly reduces the blue intensity and enhances yellow intensity in the emitted light . The PiGF-MS converter provides a promising roadmap to enhance the light conversion and efficiency of white laser lighting.