First-principles investigation of inorganic antiperovskite A3SbAs (A = Ba, Sr, and Ca): insights into thermoelectric and optoelectronic potential

Abstract

This study presents a comprehensive theoretical investigation of the structural, electronic, optical, thermoelectric, mechanical, phonon, and thermodynamic properties of A₃SbAs (A = Ba, Sr, and Ca) antiperovskites using first-principles density functional theory (DFT). The compounds exhibit stable cubic perovskite structures, with lattice parameters ranging from 5.49 Å for Ca₃SbAs to 6.18 Å for Ba₃SbAs. The electronic properties reveal direct band gaps, with values of 0.372 eV for Sr₃SbAs and 0.596 eV for Ca₃SbAs in the GGA-PBE approximation, increasing significantly up to 0.978 eV for Ba₃SbAs, 1.003 eV for Sr₃SbAs, and 1.195 eV for Ca₃SbAs using the TB-mBJ potential. These band gaps indicate suitability for optoelectronic applications. Optical properties show that Ba₃SbAs performs well in the near-infrared and visible ranges, while Ca₃SbAs excels in the ultraviolet range. Thermoelectric performance is also promising, with ZT values approaching unity at 300 K for all compounds, indicating high potential for energy conversion. Mechanical properties show that Ca₃SbAs is the most robust, while Ba₃SbAs is more flexible. Phonon dispersion confirms the dynamical stability of all compounds, and thermodynamic analysis suggests that these materials are stable under varying temperatures and pressures. The results highlight the potential of A₃SbAs antiperovskites for applications in optoelectronics and thermoelectrics, offering promising candidates for sustainable energy technologies.