Numerical Simulation of Low Cost Gold Alternatives for Performance Improvement in Lead Free Perovskite Solar Cells

Abstract

Lead-free perovskites such as CsSnI₃ are promising absorbers for sustainable solar energy; however, their performance is highly dependent on the choice of back contact layer. In this work, SCAPS-1D simulations (calibrated with experimental data) were employed to investigate a wide range of materials (Al, Cr, Mo, Cu, Ag, Fe, rGO, C, Ni, W) as alternatives to gold. Results indicate that the short-circuit current density (Jsc) remains nearly constant at 31.8 mA/cm² for most cases, while the open-circuit voltage (Voc) and fill factor (FF) vary depending on the material work function. Gold exhibited a power conversion efficiency (PCE ≈ 17.4%), (Voc ≈ 0.886 V), (FF ≈ 61%), whereas tungsten (WF = 5.22 eV) achieved the highest efficiency (PCE ≈ 20.16%), (Voc ≈ 0.91 V), (FF ≈ 70%), followed by nickel with (PCE ≈ 18.78%), (Voc ≈ 0.90 V), (FF ≈ 65%). Carbon-based electrodes also demonstrated competitive performance with an efficiency of (14.5%), making them a stable and low-cost alternative. This study confirms that selecting of the back contact layer, based on energy level alignment and interfacial properties, is a critical factor in enhancing the performance of lead-free CsSnI₃ solar cells.