Investigating the effects of hydrostatic pressure on the physical properties of cubic Sr3BCl3 (B = As, Sb) for improved optoelectronic applications: A DFT study

Abstract

This article explores changes in the structural, electronic, elastic, and optical properties of the novel cubic Sr₃BCl₃ (B = As, Sb) with increasing pressure. This research aims to decrease the electronic band gap of Sr₃BCl₃ (B = As, Sb) by applying pressure, with the objective of enhancing the optical properties and evaluating the potential of these compounds for use in optoelectronic applications. It has been revealed that both the lattice parameter and cell volume exhibit a declining pattern as pressure increases. At ambient pressure, analysis of the band structure revealed that both Sr₃AsCl₃ and Sr₃SbCl₃ are direct band gap semiconductors. With increasing pressure up to 25 GPa the electronic band gap of Sr₃AsCl₃ (Sr₃SbCl₃) reduces from 1.70 (1.72) eV to 0.35 (0.10) eV. However, applying hydrostatic pressure enables the attainment of optimal bandgaps for Sr₃AsCl₃ and Sr₃SbCl₃, offering theoretical backing for the adjustment of Sr₃BCl₃ (B = As, Sb) perovskite's bandgaps. The electron and hole effective masses in this perovskite exhibit a gradual decrease as pressure rises from 0 to 25 GPa, promoting the conductivity of both electrons and holes. The elastic properties are calculated using the Thermo-PW tool, revealing that they are anisotropic, ductile, mechanically stable, and resistant to plastic deformation. Importantly, these mechanical properties of both compounds are significantly enhanced under pressure. Optical properties, including the absorption and extinction coefficients, dielectric function, refractive index, reflectivity, and loss function, were calculated within the 0-20 eV range under different pressure conditions. The calculated optical properties highlight the versatility and suitability of Sr₃AsCl₃ and Sr₃SbCl₃ perovskites for pressure-tunable optoelectronic devices.