Phase transitions in metal halide perovskites triggered by external provocations produce significantly different material properties, providing a prodigious opportunity for a comprehensive applications. In the present study, the first principles calculation has been performed with the help of density functional theory (DFT) using CASTEP code to investigate the physical properties of lead-free CsSnBr3 metal halide under various hydrostatic pressures. The pressure effect is determined in the range of 0-16 GPa. Subsequently, a significant change is observed in lattice constant and volume with increasing pressure. The electronic band structure show semiconductor to metal phase transition under elevated pressure. The investigation of optical functions displays that the absorption edge of CsSnBr3 perovskite is shifted remarkably toward the low energy region (red shift) with improved pressure up to 16 GPa. In addition, the absorptivity and dielectric constant also upsurges with the applied hydrostatic pressure. Finally, the mechanical properties reveal that CsSnBr3 perovskite is mechanically stable and highly ductile; the ductility is increased with raising pressure. This type of semiconductor to metal phase transition may inspire a wide range of potential applications. Graphical diagram FIG. 1. A pristine cubic crystal structure of CsSnBr3 perovskite compound

Inorganic double halide perovskites have a wide range of applications in low-cost photovoltaic and optoelectronic devices.

The antiperovskites based on metal halides have emerged as potential materials for advanced photovoltaic and electronic device applications. But the wide bandgap of non-toxic CsSnCl 3 reduces its photovoltaic efficiency. Here, we report the change of electronic structure of CsSnCl 3 at different pressure by using GGA-rPBE and GGA-PBEsol functionals and the GW method. We have shown that the prediction of electronic structure transition (semiconducting to metallic state) strongly depends on the exchange-correlation and the GW method gives the most reasonable values of the bandgap under pressure. The pressure increases the electronic density of states close to the Fermi level by pushing the valence electrons upward and thus, reduces the bandgap linearly. Afterward, we have also investigated the influence of pressure on absorption coefficient, and mechanical properties meticulously. Although the pressure shifts the absorption peak to lower photon energies, the absorption coefficient is slightly improved.

In the present study, we propose a novel type of lead-free double halide perovskite Cs2AgAsCl6 material exhibiting exceptional photovoltaic and photocatalytic properties. The density functional theory (DFT) is employed to...

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