A first-principles study of dynamically stable non-toxic photovoltaic Mg₃PX₃ (X = Cl and Br) compounds

Inorganic, non-toxic halide perovskites have emerged as photovoltaic field breakthroughs because of their outstanding physical properties, which make them viable for sustainable energy systems. The structural properties along with electronic, mechanical and thermal properties of Mg₃PX₃ (X = Cl, and Br) are evaluated by first-principles density functional theory (DFT) calculations executed via the CASTEP code employing GGA-PBE functional. The phonon dispersion results indicate that these compounds are dynamically stable because positive frequency readings show they would be suitable for experimental production. Structural and bandgap calculations required the dual use of hybrid HSE06 and GGA-PBE functionals to achieve better accuracy and resulted in 5.260 Å for Mg₃PCl₃ and 5.478 Å for Mg₃PBr₃. The calculated bandgap values are 2.297 eV for GGA-PBE and 3.093 eV for HSE06 with Mg₃PCl₃ and 1.506 eV for GGA-PBE and 2.187 eV for HSE06 with Mg₃PBr₃. The positive elastic constant C₄₄ indicates structural stability in addition to unfavorable Cauchy pressure values that create brittle and rigid structural behaviors together with the Paugh's ratio and Poisson's ratio at low levels. The magnetic properties of Mg₃PX₃ (X = Cl and Br) compounds create opportunities in quantum research because these compounds exhibit diamagnetic behavior. High thermal efficiency calculated by thermal analysis enables the materials to expand their functional capabilities. Experimentation demonstrates that Mg₃PX₃ (X = Cl and Br) compounds show their exceptional optical characteristics and potential for superior photodetectors and UV protective materials. This research delivers essential knowledge about Mg₃PX₃ (X = Cl and Br), which prepares the way for the upcoming experimental development of sustainable materials for energy technologies.