Tailoring the physical properties of InSnX3 (X = F, Cl) perovskites via pressure: A path toward sustainable optoelectronics

Abstract

The present research employs ab-initio modeling via density functional theory to study the key physical characteristics of non-toxic, lead-free metal-based halide perovskites under pressure, aiming to explore their potential applications as photovoltaic materials and in optoelectronic technology. To demonstrate the compounds' supremacy for practical applications, the structural, dynamical, bonding, optoelectronic, elastic, and mechanical adaptabilities of InSnX₃ (X = F, Cl) are specifically explored under hydrostatic pressures spanning from 0 to 5 GPa. The structures show excellent accuracy in the lattice constants of InSnF₃ (4.728 Å) and InSnCl₃ (5.568 Å), supporting the previously released data. The TB-mBJ functional, along with the GGA-PBE scheme, is utilized to obtain a more accurate band gap. The calculated band gap values from both the GGA-PBE and TB-mBJ methods confirm the indirect semiconducting nature of the materials at 0 GPa pressure. However, as pressure increases, the band gap narrows, enhancing the material's conductivity and initiating a transition from a semiconductor to a metallic state. The application of hydrostatic pressure leads to a notable reduction in the electronic band gap, with InSnF₃ and InSnCl₃ showing initial values of 0.65 eV and 0.69 eV at 0 GPa, respectively, decreasing to 0 eV for both compounds under 5 GPa. Utilizing the TB-mBJ potential improves the precision of the band gap calculation, resulting in values of 1.12 eV for InSnF₃ and 1.45 eV for InSnCl₃ at 0 GPa. The charge concentration mapping reveals the types of ionic and covalent bonds in In−F(Cl) and Sn−F(Cl), respectively, as well as the reduction in bond lengths induced by external pressure. When stress is applied, both the optical absorption and photoconductivity are significantly improved, demonstrating the applicability of the selected perovskites in a variety of visible and ultraviolet optoelectronic components. In a similar vein, hydrostatic pressure has a major effect on mechanical characteristics while preserving mechanical stability. When pressure is exerted, both perovskites exhibit increased ductility and maintain the Born stability criteria.