Photon‐Induced Reversible Phase Transition in CsPbBr₃ Perovskite

Abstract Structure reorganization within perovskite materials has attracted much attention due to its assisted appealing features in optoelectronic devices, such as achieving continue‐wave laser and performance enhancement in photovoltaic devices. Unfortunately, the difficulty of controlling reorganization processing and unclear underlying mechanisms impose an impediment for taking advantage of the structural reorganization in pursuit of distinctive functions in perovskite‐based devices. In this work, using above‐bandgap illumination with a small energy threshold (1.6 mW cm⁻²) triggering phase transition from orthorhombic to tetragonal in CsPbBr₃ is first reported. This photon‐induced structure reorganization is reversible and presents a fast and controllable response (<0.5 s) to light on/off. Raman spectroscopy and density functional theory calculations reveal that such a dynamic structure reorganization is caused by the transition of torsion direction in Pb–Br octahedral, while the diffusion potential difference induced local Coulombic field is proved to drive this process. The findings provide a deep understanding for universal structure reorganization under irradiation in perovskite materials and encourage further study of the novel functions associated with structure reorganization inducing temporal behaviors in optoelectronic devices, for example variations in dielectric constant and band edge fluctuation induced Rashba effects, which show a significant influence on perovskite‐based optoelectronic devices.