Performance optimization of Ce:YAG sapphire films for high power density white laser-driven lighting applications

To withstand higher power density (PD), exhibit higher luminous efficiency (LE), use in smaller size and lower cost has become the direction of solid-state lighting technology. In the face of high-density laser irradiation and strong thermal shock, improving the performance of color conversion materials related to laser illumination has become a research hotspot. In this study, The Y3Al5O12:Ce3+ phosphor-in-glass film (Ce:YAG-PiF) was obtained by scraping method. The optimized Ce: YAG-PiF external quantum efficiency (EQE) reaches 74.7%, closing to the phosphor (EQE = 78.47%). Excitingly, at 573 K, the thermal conductivity of sample remains at 9.47 W m-1 K-1. Besides, the sample has an ultra-high LE of 256 lm/W @ 32.47 W/mm2. After recombining with the red phosphor CaAlSiN3:Eu2+ (CASN), the color rendering index (CRI) is 84.6, the correlation color temperature (CCT) is 5594 K, and the LE is 192.91 lm/W @ 39.87 W/mm2. More importantly, the relative intensity of laser module packaged by Ce:YAG & CASN-PiF decreased by 15% when tested at 4 W for 24 h. Besides, the packaged laser flashlight has good collimation within a visible illuminance. All the results show that the prepared sample can maintain high emission intensity at high laser PD and have a good heat resistance, which is a promising color conversion material in the field of solid-state laser illumination.