Ab <i>initio</i> exploration of structural, electronic, optical, and thermal properties of X3NY3 (<i>X</i> = Mg, Ca; <i>Y</i> = F, Cl, Br, I) halide perovskites for optoelectronic and thermal applications

The present study investigates structural, electronic, optical, and thermal characteristics of new cubic halide perovskites, X3NY3 (X = Mg, Ca; Y = F, Cl, Br, I), with the first-principles density functional theory. The thermodynamic and dynamic stability of all the compounds establishes their feasibility of synthesis. Analysis of electronic band structures indicates that Mg3NF3 is a wide-bandgap insulator, whereas Ca-based halides are semiconductors with bandgaps ranging between Ca3NF3 (4.119 eV) and Ca3NI3 (1.267 eV), indicating optoelectronic potential. The bandgaps have optical correlations, and Ca3NI3 has best visible light absorption and largest dielectric response. Thermal analysis indicates that Mg3NF3 possesses the highest Debye temperature and thermal conductivity, thus making it appropriate in heat dissipation, and Ca3NI3 has low thermal conductivity, which goes in favor of its application as a thermal barrier coating. These have shown that the X3NY3 materials, particularly Ca3NI3, have great potential for use in both optoelectronic applications and thermal management.