Unveiling role of exchange-correlation functions in investigating physical properties of CsMnCl3 perovskite for optoelectronic applications

Metal halide perovskites have garnered significant attention for their transformative applications in photovoltaics, optoelectronics, and photocatalysis. This study pioneers an in-depth examination of the structural, electronic, elastic, mechanical, and optical properties of CsMnCl₃ perovskite using GGA-PBE and GGA + U calculations with diverse exchange-correlation functionals (PBE, RPBE, PW91, WC, and PBEsol) within the CASTEP code. The structural parameters of CsMnCl₃ perovskite are substantially affected by the exchange-correlation function, particularly the lattice constants, which exhibit functional-dependent variations. The material demonstrates metallic properties under GGA-PBE, while it manifests semiconductor behavior with an indirect energy bandgap energy (R→G) under other functionals GGA + U with PBE, RPBE, PW91, WC, and PBEsol. Notably, the calculated energy bandgaps exhibit functional-specific variations: 1.956 eV (GGA + U-PBE), 2.041 eV (GGA + U-RPBE), 1.994 eV (GGA + U-PW91), 1.890 eV (GGA + U-WC), and 1.895 eV (GGA + U-PBEsol). The compound shows low reflectivity, a large absorption coefficient value, and good optical conductivity in the visible region. Moreover, the Born stability criterion suggests that material is mechanically stable, and ductile according to Poisson scale/Pugh's ratio. It has an anisotropic nature according to the anisotropy index. These exceptional results advocate its suitability for flexible optoelectronic applications.