Impact of pressure on perovskite MSnX3 (M = Li, Na; X = Cl, Br, I): A density functional theory study

Abstract

This study explores the structural, electronic, and optical properties of tin-based halide perovskites, MSnX₃ (M = Li, Na; X = Cl, Br, I), under varying pressure conditions. Using volume optimization and the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) method, it analyzes these perovskites in their cubic Pm \(Pm\ \bar{3}\ m\) phase. The findings reveal that the lattice constants of these compounds decrease as pressure increases, with more pronounced changes observed when anions are substituted from Cl to I. The electronic analysis shows that these materials maintain their direct band gap nature under pressures, although the band gaps narrow with increasing pressure and larger anion sizes. Notably, Li/NaSnCl₃, Li/NaSnBr₃, and Li/NaSnI₃ may exhibit metallic behavior at pressures exceeding 5 GPa. Optical studies reveal significant pressure-induced enhancements in static dielectric constant and optical absorption, especially in the visible spectrum, highlighting the potential of these perovskites for solar cell applications. The refractive index increases with pressure, indicating a higher material density and enhanced optical performance. Additionally, the extinction coefficient and electron energy loss function provide insights into the energy absorption and scattering characteristics, which are crucial for improving the efficiency of optoelectronic devices. This comprehensive analysis underscores the potential of these tin-based halide perovskites for advanced optoelectronic and photovoltaic technologies.