Theoretical insights into novel Ba3MX3 (M = P, Sb; X = F, Cl) perovskites for advanced optoelectronics: A first-principles DFT study

Non-toxic halide cubic perovskites set the standard for the commercialization of optoelectronic and photovoltaic devices. Because of their enormous importance, a comprehensive analysis of the physical characteristics of cubic Ba₃MX₃ (M = P, Sb; X = F, Cl) perovskites was analyzed in this study utilizing ab initio Density Functional Theory. The thermodynamic stability of the explored materials was validated by negative formation energies, while the simulated XRD spectra firmly solidified that all the perovskites exhibit cubic structures. The GGA-PBE functional unveiled direct band gaps of 0.95 eV, 0.96 eV, 1.07 eV, and 0.99 eV for the semiconducting perovskites Ba₃PF₃, Ba₃PCl₃, Ba₃SbF₃, and Ba₃SbCl₃, respectively. The HSE06 potential unveiled refined band gaps of 1.42 eV, 1.50 eV, 1.96 eV, and 1.89 eV for the respective perovskites, emphasizing their potential as viable options for solar cell technologies. Moreover, the explored materials exhibited excellent absorption, high photoconductivity, an ideal refractive index, lower reflectivity, and minimal loss function in the visible spectrum, rendering them outstanding contenders for solar cell applications. The Born stability benchmarks validated the mechanical stability of all the explored perovskites. Additionally, their inherent stiffness, hardness, toughness, brittleness, and anisotropic behavior are vital for long-term durability in engineering applications. Thermodynamic assessments validated the thermal stability of these perovskites at wide temperature ranges. The study's findings revealed that Ba₃MX₃ (M = P, Sb; X = F, Cl) perovskites could emerge as promising optical materials, and their synthesis in the upcoming days is highly anticipated.