Pore-existing phosphor-in-glass film realizing ultra-efficient and uniform laser lighting

The development of phosphor-converted laser lighting has encountered a significant problem: the difficulty of homogeneously mixing the laser light with the luminescent light. Previous studies reveal that enhancing the scattering of the phosphor can improve color mixing but often sacrifices luminous efficacy and limits the peak luminance. To address this, a pore-existing YAG:Ce-based phosphor-in-glass film is prepared using the screen-printing technique. Interestingly, it is found that the pore size is highly correlated with the thickness, with thicker samples having larger pores. When excited by blue laser, a typical sample with a thickness of 60 μm exhibits an ultra-high luminous efficacy of 261 lm/W and a high saturation threshold of 20.5 W (9.1 W/mm2), resulting in a peak luminous exitance of 1244 lm/mm2@3839 lm. Furthermore, the color mixing was evaluated via angular color temperature distribution, showing uniform light emission with a maximum correlated color temperature (CCT) variation of only ∼800 K. •Film thickness dependent uniformly-distributed pores were formed in PiG-F samples.•An ultra-high luminous efficacy of 268 lm/W at CCT of 4537 K was achieved in 4-layered PiG-F sample.•A high luminous exitance of 1244 lm/mm2 with relatively low angular CCT variation was obtained.