The effect of pressure on the structural, electronic, optical and mechanical properties of lead-free ASnBr3 (A = Na, K, Rb, Cs) perovskites for solar technologies: First principles calculations

This study examines the influence of pressure on the mechanical, electronic, and optical properties of leadfree ASnBr3 perovskites (A = Na, K, Rb, Cs) for applications in photovoltaic technologies, using the density functional theory (DFT) framework. The dependence of the physical properties is evaluated fora range of pressures from 0 GPa to 10 GPa. Bandgaps of 1.71 [2.48] for NaSnBr3, 1.81 [2.62] for KSnBr3, 1.82 [2.63] for RbSnBr3 and 1.83 [2.64] for CsSnBr3 were obtained using the HSE [PBE0] hybrid functionals. With increasing pressure, we observe the semiconductor-metal transition, higher absorption coefficients and advancements in the ductility and stability of the perovskites studied. This makes them suitable for pressurized optoelectronic devices.