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 > GaCaI_3, 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.