Thermally robust Al2O3–La3Si6N11:Ce3+ composite phosphor-in-glass (PiG) films for high-power and high-brightness laser-driven lighting

Abstract

The key to developing laser-driven solid-state lighting lies in high-performance color converters, which must be thermally robust under the high-power density excitation of a laser. Phosphor-in-glass (PiG) films are considered as a kind of promising color converter for laser lighting, but the poor thermal dissipation of the glass matrix will cause large thermal quenching of the PiG films and hence low luminous flux of lighting sources. In this work, Al₂O₃ particles, acting as a heat transfer medium, are introduced into the La₃Si₆N₁₁:Ce³⁺ (LSN:Ce³⁺) PiG film to form a composite color converter for realizing high-brightness laser lighting. By optimizing the ratio of glass frits to Al₂O₃ as well as the film thickness, the Al₂O₃–LSN:Ce³⁺ composite PiG film shows a luminance saturation threshold of 23.08 W mm⁻², which is 26.3% higher than that of the Al₂O₃-free LSN:Ce³⁺ PiG film (18.27 W mm⁻²). The luminous flux of the composite PiG film under blue laser excitation is improved by 51.4% and reaches 3120 lm, and the luminous flux of the laser-driven white light can reach up to 2886 lm. It indicates that the Al₂O₃–LSN:Ce³⁺ composite PiG film would be an interesting color converter for producing high-brightness laser-driven white light.