Pressure-Induced Structural Evolution and Optical Properties of Metal-Halide Perovskite CsPbCl₃

Abstract

Metal-halide perovskites have emerged as the most promising semiconductor materials for advanced photovoltaic and optoelectronic applications. Herein, we comprehensively investigate the optical response and structural evolution of metal-halide perovskite CsPbCl₃ (ABX₃) upon compression. Band gap realized a pronounced narrowing under mild pressure followed by a sharp increase, which could be ascribed to Pb–Cl bond contraction and inorganic framework distortion, respectively. The transformation of the crystal structure is confirmed and analyzed through in situ high-pressure X-ray diffraction and Raman experiments, consistent with the evolution of optical properties. Combining with the first-principles calculations, we understand the electronic band structure changes and phase transition mechanism, which are ascribed to severe PbCl₆ octahedral titling and twisting. Our results demonstrate that the high-pressure technique can be used as a practical tool to modify the optical properties of metal-halide perovskites and maps an innovative strategy for better photovoltaic and optoelectronic device design