Unique composite architecture of phosphor-in-glass film coated on different heat-conducting substrates for high-brightness laser lighting

Next-generation high-brightness laser lighting confronts a key challenge in developing static luminescent materials with remarkable optical-thermal performances and low cost. Herein, a unique composite architecture of Y₃Al₅O₁₂:Ce³⁺ (YAG) phosphor-in-glass film coated on different heat-conducting substrates (PiGF@HCSs), i.e., PiGF@sapphire, PiGF@Al₂O₃, PiGF@AlN, and PiGF@BN-AlN composites, was designed and prepared by a simple film printing and low-temperature sintering technology. The heat-conducting substrates significantly affect the luminescence saturation and phosphor conversion of PiGF@HCSs, making the substrates with higher thermal conductivity (TC) can bear higher laser power density (LPD) and higher reflectivity can enable higher luminous efficacy (LE). As a consequence, the PiGF@sapphire realizes a luminous flux (LF) of 2076 lm@12 W/mm², which is higher than the PiGF@Al₂O₃ of 1890 lm@15 W/mm² and the PiGF@AlN of 1915 lm@24 W/mm², while the PiGF@BN-AlN enables a maximum LF of 3058 lm@21 W/mm². Furthermore, the LE of PiGF@BN-AlN reaches up to 194 lm/W, which is 1.6 times that of PiGF@AlN, while that of PiGF@sapphire and PiGF@Al₂O₃ are 192 lm/W and 150 lm/W, respectively. The working temperature of PiGF@AlN is only 93.3℃ under the LPD of 9 W/mm², while that of PiGF@sapphire, PiGF@Al₂O₃, and PiGF@BN-AlN rises to 193.8℃, 133.6℃, and 117℃, respectively. These findings will provide the guiding idea for the commercial applications of PiGF@HCS converters in high-brightness laser lighting and display.