Structural stability and optical properties of two-dimensional perovskite-like CsPb2Br5 microplates in response to pressure.

Here, we report the structural stability and visible light response of two-dimensional (2D) layered perovskite-like CsPb2Br5 microplates (MPs) under high pressure. In situ high-pressure emission, optical absorption, and angle dispersive synchrotron X-ray diffraction indicated that CsPb2Br5 MPs experienced an isostructural phase transformation at roughly 1.6 GPa. The shrinkage of Pb-Br bond lengths and the marked change of Br-Pb-Br bond angles within the lead-bromide pentahedral motif were responsible for the pressure-induced structural modulation and the sudden band-gap change of CsPb2Br5 MPs.