DFT insights into multifaceted properties of GaCaX3 (X = Cl, Br, I) inorganic cubic halide perovskites for advanced optoelectronic applications

Halide perovskites, known for their outstanding properties and flexible chemistry, gained considerable attention in diverse fields. This study explores the structural, optoelectronic, thermodynamic, and mechanical characteristics of the inorganic cubic halide perovskites, GaCaX3 (X = Cl, Br and I) using DFT within the CASTEP framework. Electronic analysis determined band gaps of GaCaCl3 (4.67 eV), GaCaBr3 (3.89 eV), and GaCaI3 (2.97 eV) respectively. Bond population analysis indicated that GaCaI3 provides accurate electronic bond description with minimal charge loss (0.15 %). Optically, GaCaI3 shows significant absorption, while GaCaCl3 indicate strong plasmonic behavior, high refractive index and reflectivity. Mechanical stability confirmed through Born-stability condition through elastic constants (C11, C12, and C44). Poisson's ratio (n), Pugh's ratio (B/G), and anisotropic factor further emphasize the ductility and anisotropic behavior for all materials. Also, bulk modulus (B), shear modulus (G), and Young's modulus (E), follow the as GaCaCl3 > GaCaBr3 > GaCaI3 respectively. From thermodynamic characteristics, GaCaCl3 exhibits the maximum enthalpy, free energy, entropy, heat capacity, and Debye temperature indicating superior thermal stability. Confidently, these outstanding properties of GaCaX3 (X = Cl, Br and I) halide perovskites hold significant potential for advanced optoelectronic devices.