Band gap and optical property modulation under pressure in vacancy-ordered double perovskite Cs[formula omitted]SeCl[formula omitted

Abstract

This paper presents a comprehensive study on the effect of pressure on the structural, elastic, electronic, thermoelectric, and optical properties of vacancy ordered double perovskite Cs2SeCl6, using first principle calculations. Results show that the lattice constant and band gap of Cs2SeCl6 decrease with increasing hydrostatic pressure from 0 to 140 GPa. The band gap value decreases from 2.94 eV to 1.62 eV and the electronic structure analysis reveals an indirect band gap nature. The elastic constants, Poisson’s ratio, and Pugh’s ratio indicate the mechanical stability and ductile behavior of Cs2SeCl6. Furthermore, due to its suitable band gap and enhanced light absorption with increasing pressure, Cs2SeCl6 exhibits potential as a photoelectric absorption layer material for high-pressure solar cell applications. Moreover, Cs2SeCl6 exhibits high electrical conductivity and low thermal conductivity, resulting in a high figure of merit and promising thermoelectric applications.