Addressing thermal challenges in laser-assisted perovskite crystallization

Hybrid lead halide perovskites such as methylammonium lead bromide (MAPbBr 3 ) exhibit strong light-matter interaction, making them suitable model systems for investigating laser-assisted crystallization and localized thermal effects under optical trapping. A key challenge in laser trapping-induced crystallization is uncontrolled local heating at the laser focus, which can influence crystal growth and stability. In this study, we present a practical, indirect approach to estimate local temperature elevation at the focal spot of a continuous-wave 1064 nm near-infrared trapping laser during MAPbBr 3 crystallization. Crystals were grown using laser trapping-induced crystallization and solvent evaporation, followed by focused laser irradiation in isopropanol, a solvent with a boiling point of 82 °C. Morphological and optical responses of the trapped crystals were monitored as a function of laser power. Stable green photoluminescence was observed at 1.0 W, whereas spontaneous bubble formation occurred at 1.1 W, indicating that the local temperature exceeded the solvent boiling point. This observation provides a threshold-based, lower-bound estimate of laser-induced heating near the focal region. The localized thermal effect is attributed to non-radiative energy dissipation associated with nonlinear optical absorption in the perovskite crystal. These findings highlight the importance of thermal management during laser trapping-assisted crystallization and provide experimental insight into laser-induced heating in perovskite systems relevant to laser-based photonic material processing.