Insights from computational analysis on novel Lead-Free FrGeCl3 perovskite solar cell using DFT and SCAPS-1D

Although inorganic metal-halide perovskite solar cells (PSCs) have acquired major strides, the reliance on lead (Pb)-based materials remains a major drawback due to Pb’s toxicity. To explore safer alternatives, this study examines the opto-electronic characteristics of lead-free cubic perovskite FrGeCl₃ using first-principles density functional theory (DFT) to appraise its suitability for photovoltaic (PV) applications. The cubic FrGeCl₃ demonstrated thermodynamic stability with a negative formation energy. Using Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation (GGA), key properties were derived and incorporated into the SCAPS-1D simulation framework. Various configurations were tested using SnS₂ and ZnSe as electron transport layers (ETLs) and V₂O₅, CuSCN, and SrCu₂O₂ as hole transport layers (HTLs). The most favorable performance came from the Back Contact/CuSCN/FrGeCl₃/ZnSe/FTO configuration, resulting in a power conversion efficiency (PCE) of 29.39 %. Further optimizations on thickness, interface defect density, doping concentration, and defect concentration led to substantial performance improvements. The role of parasitic resistance in PSC performance was also evaluated. Carbon (C) was proposed as the back contact material. Simulation results yielded promising metrics, including an open-circuit voltage (V_OC) of 0.859 V, a short-circuit current density (J_SC) of 42.401 mA/cm², a fill factor (FF) of 82.06 %, and a notable PCE of 29.88 %. This research may contribute significant understanding toward the experimental advancement of FrGeCl₃-based PSCs, aiming to improve performance and efficacy in PV technologies.