Unlocking the lead-free new all inorganic cubic halide perovskites of Ba₃MI₃ (M = P, As, Sb) with efficiency above 29%

The solar industry is increasingly shifting its attention toward lead (Pb)-free inorganic cubic halide perovskite materials due to their outstanding structural, mechanical, electronic, and optoelectronic properties. In our study, we conducted a thorough examination of the structural, mechanical, electronic, and optical properties of Ba₃MI₃ (M = P, As, Sb), and assessed their photovoltaic potential using first-principles density functional theory (FP-DFT) and the SCAPS-1D solar cell simulator. Our results revealed that all the perovskite materials exhibited a direct band gap at the Γ-point, favorable tolerance factors, mechanical durability, minimal energy losses, and excellent absorption coefficients. This makes them promising candidates for use in photovoltaic cells and various optoelectronic devices. Additionally, we employed the SCAPS-1D simulator to perform an in-depth analysis of photovoltaic efficiency in solar cell architectures with Ba₃PI₃, Ba₃AsI₃, and Ba₃SbI₃ as absorber layers, incorporating a SnS₂ electron transport layer (ETL). The study explored the effects of variations in thickness, defect densities, and doping concentrations. The highest power conversion efficiencies (PCE) achieved were 29.50% for Ba₃PI₃, 27.16% for Ba3AsI3, and 21.29% for Ba₃SbI₃, with open-circuit voltages (V_OC) of 1.02, 0.96, and 0.91 V; short-circuit current densities (J_SC) of 32.92, 32.19, and 27.51 mA/cm², and fill factors (FF) of 87.75%, 87.56%, and 85.16%, respectively. We observed that variations in the M-anion size influenced the bandgap energy, band structure, mechanical, and optoelectronic properties, as well as the solar cell performance. This research provides valuable insights into the development of lead-free hybrid solar cells and other optoelectronic applications.