Tailoring thermal behavior and luminous performance in LuAG:Ce films via thickness control for high‐power laser lighting applications

Abstract

Abstract Lutetium aluminum garnet doped with cerium (LuAG:Ce) thin films have been identified as a promising material for high‐power laser‐driven lighting applications. In this study, spray pyrolysis we employed to fabricate LuAG:Ce films on sapphire substrates and the impact of film thickness on thermal management and light emission efficiency was investigated. Our results show that, regardless of thickness, LuAG:Ce films exhibit impressive internal quantum efficiencies (IQE) exceeding 83.2% and external quantum efficiencies (EQE) surpassing 56.4%, with minimal alteration of luminescent color. Notably, thinner films facilitate more efficient heat dissipation to the underlying sapphire substrate, resulting in superior thermal management and outstanding luminous performance under high‐power laser excitation. Specifically, the thinnest LuAG:Ce film (15.79 μm) exhibited rapid thermal stabilization (~ 130 °C within 30 s) and maintained stability during continuous irradiation lasting 30 min, with a corresponding decrease in luminous flux to 87.9% of its initial value within the first 60 s. This film also demonstrated relatively high and stable conversion efficiency and luminous efficiency, achieving higher saturation thresholds (15 W·mm −2 ) and luminous flux (1070 lm). In contrast, thicker films exhibited a shift in the saturation point toward lower power densities. These findings provide valuable insights for the practical implementation of LuAG:Ce films in advanced lighting technologies.