Structural, electronic, optical, mechanical, and thermal properties of A3MCl3 (A = Mg, Ca; M = N, Bi) halide perovskites: A first-principles study

The study examines the structural, electronic, optical, mechanical and thermal properties of halide perovskites A₃MCl₃ (A = Mg, Ca; M = N, Bi) using Density Functional Theory (DFT). The structure was optimized using the Generalized Gradient Approximation – Perdew–Burke–Ernzerhof (GGA-PBE) method, while the electronic and optical properties were calculated using the HSE06 hybrid method. The electronic properties indicate that Mg₃NF₃ exhibits a wide band gap and behaves as an insulator, while Ca₃BiCl₃ and Mg₃BiCl₃ display semiconducting behavior. According to electronic band structure simulations, Mg₃NF₃ act as insulators, while Mg₃BiCl₃ and Ca₃BiCl₃ exhibits semiconductor behavior. Studies of optical properties demonstrate that compounds with Bi absorb strongly within the UV–visible range and reflect very little throughout the spectrum. The compounds show brittle behavior. Mg₃NF₃ being the stiffest and having the lowest level of anisotropy with wide band gap insulator. According to thermal analysis, Mg₃NF₃ melts at a high temperature and is a good thermal conductor, which showed promising for applied as heat sink materials. Mg₃BiCl₃ and Ca₃BiCl₃ compounds showed low thermal conductivity and are therefore suitable for use in thermal barrier coatings. The combined findings identify A₃MCl₃ compounds as promising candidates for multifunctional electronic, optoelectronic, photovoltaic, and thermal management devices.