Thermally Robust Orange‐Red‐Emitting Color Converters for Laser‐Driven Warm White Light with High Overall Optical Properties
Taoli Deng, Linhui Huang, Shuxing Li, Qiangqiang Zhu, Le Wang, Takashi Takeda, Naoto Hirosaki, Rong‐Jun Xie
Abstract
Abstract 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.