From theoretical analysis to device simulation: First-principles and SCAPS-1D insights into A3MI3 anti-perovskites for high-efficiency solar cells

The quest for high-efficiency, stable solar absorbers has driven exploration beyond silicon-based photovoltaics. This study presents a computational and device-level investigation of cubic A 3 MI 3 anti-perovskites (A = Sr, Ba; M = As, Sb, Bi) as promising absorber layers for thin-film solar cells. First-principles Density Functional Theory (DFT) calculations using CASTEP, combined with SCAPS-1D device simulations, were employed to evaluate structural, electronic, optical, and mechanical properties. Sr 3 MI 3 compounds exhibit direct bandgaps of 1.25–1.33 eV, optimal for single-junction solar cells, whereas Ba 3 MI 3 analogues possess narrower gaps (0.74–0.83 eV) suitable for infrared or tandem applications. Mechanical analysis shows Sr-based halides are stiff and brittle, favoring thermal stability, while Ba-based compounds are ductile and flexible, advantageous for flexible photovoltaics. Electronic and optical analyses reveal efficient visible-light absorption, low non-radiative losses, and strong light trapping (refractive index ∼2.55). Device simulations indicate that absorber thickness, defect density (∼10 14 cm −3 ), and acceptor concentration (∼10 19 cm −3 ) critically determine performance. Ba 3 MI 3 cells achieve higher short-circuit currents (J sc ∼52–57 mA/cm 2 ) but lower open-circuit voltages (V oc ∼0.61–0.70 V), whereas Sr 3 MI 3 devices show higher V oc (0.97–1.20 V) with moderate J sc (∼34–36 mA/cm 2 ). Optimized configurations deliver power conversion efficiencies of 27.6% for Ba 3 SbI 3 and 31.8% for Sr 3 BiI 3 . These results highlight Sr 3 BiI 3 as a high-efficiency, defect-tolerant absorber and Ba 3 MI 3 as a flexible infrared-harvesting candidate. Overall, A 3 MI 3 anti-perovskites represent a tunable, mechanically robust platform for next-generation high-performance photovoltaic devices.