Photostriction of CH₃NH₃PbBr₃ Perovskite Crystals

Abstract

Organic–inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light–matter interactions. The photoinduced strain of CH 3 NH 3 PbBr 3 is investigated using high‐resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH 3 NH 3 PbBr 3 is calculated as 2.08 × 10 −8 m 2 W −1 at room temperature under visible light illumination. The significant photostriction of CH 3 NH 3 PbBr 3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling. Unlike CH 3 NH 3 PbI 3 , it is noted that the photostriction of CH 3 NH 3 PbBr 3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH 3 NH 3 PbBr 3 for applications in next‐generation optical micro‐electromechanical devices.