Analysis of the role of A-cations in lead-free A₃SbI₃ (A = Ba, Sr, Ca) perovskite solar cells

Recently, the solar energy sector has been greatly interested in lead (Pb)-free inorganic halide perovskites due to their remarkable mechanical, optical, electronic, and structural characteristics. Our study comprehensively assessed these attributes in cubic A₃SbI₃(A = Ba, Sr, Ca) perovskite materials via first principles density functional theory (FP-DFT) and SCAPS-1D simulation. These materials, similar to lead-free inorganic metal halide perovskites, demonstrated favorable tolerance factors, direct bandgaps, mechanical robustness, minimal losses, and high absorption coefficients. We aimed to explore how A-cation size influences their properties and solar cell performance, enabling effective comparisons. We systematically investigated novel A₃SbI₃-based structures with tin (IV) sulfide (SnS₂) buffers, varying layer thickness, doping density, and defect density to evaluate photovoltaic (PV) capabilities. The Ba₃SbI₃ absorber exhibited the highest power conversion efficiency (PCE) at 30.26% with J_SC of 44.24 mA/cm², FF of 85.65%, and V_OC of 0.80 V, while Sr₃SbI₃ and Ca₃SbI₃ absorbers achieved PCE of 26.93% and 20.87%, respectively, with corresponding J_SC of 34.5 and 21.87 mA/cm², FF of 86.90% and 85.85%, and V_OC of 0.90 and 1.11 V. Our A₃SbI₃-based solar cell structures offer innovative alternatives to conventional designs.