Exploration of structural, mechanical and opto-electronic properties of Mg3PBr3 perovskite: A comparative DFT study

Abstract

We investigated the structural, mechanical, and optoelectronic properties of Mg₃PBr₃ perovskite using density functional theory (DFT) with the generalized gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE), the meta-generalized gradient approximation (Meta-GGA or MGGA), and the hybrid Heyd–Scuseria–Ernzerhof (HSE06) functionals. Our results indicate that Mg₃PBr₃ exhibits an indirect bandgap within the range of 1.53–2.33 eV based on the QE benchmark, making it a promising candidate for solar energy applications. Optical analyses reveal a strong absorption coefficient (1.80 × 10⁵ cm⁻¹ using HSE06) and a refractive index within the optimal range (1.0–2.0). The material also demonstrates low reflectivity (<0.10) and stable dielectric constants, ensuring efficient photon utilization. Furthermore, a strong polarizability of 1.74 × 10⁻³⁹C·m²·V⁻¹ (HSE06) and balanced susceptibility suggest its suitability for tandem solar cell applications. Phonon dispersion analysis confirms the dynamical stability of Mg₃PBr₃, as no imaginary frequencies are observed across the Brillouin zone, while strong optical modes indicate robust lattice interactions.