First-principles studies on the structural, electronic, elastic and optical properties of CsPbI₂Br under pressure

Abstract This study investigates the structural, electronic, elastic, and optical properties of CsPbI 2 Br under various pressures. The electronic properties, including band structure and density of states, are analyzed, showing a linear decrease in band gap under pressure, ultimately reaching zero at 11.2 GPa. The material’s cohesive energy decreases with pressure, indicating enhanced structural stability. Analysis of the mechanical parameters, including Cauchy pressure, B/G ratio, and Poisson’s ratio, reveals that CsPbI 2 Br maintains significant ductility across the studied pressure range. Optical properties, such as the dielectric function, optical absorption, and reflectivity, are also examined, demonstrating a certain degree of optical anisotropy and a shift in the absorption edge towards lower energies with increasing pressure, suggesting potential improvements in photovoltaic performance. The findings provide valuable insights into the behavior of CsPbI 2 Br under pressure, highlighting its potential for photovoltaic applications.