The Effect of SnS Back Surface Field Layer on the Performance of Cu ₂ Te‐Based Thin‐Film Solar Cells: A Numerical Study Using 1D Solar Cell Capacitance Simulator (SCAPS‐1D)

This study presents a comprehensive numerical analysis of Cu 2 Te‐based thin‐film solar cells using the 1D solar cell capacitance simulator (SCAPS‐1D) tool, focusing on performance enhancement via a SnS back surface field (BSF) layer. Two device configurations are investigated: a baseline structure (Au/Cu 2 Te/TiO 2 /fluorine tin oxide (FTO)) and a modified architecture featuring the SnS BSF layer (Au/SnS/Cu 2 Te/TiO 2 /FTO). The SnS layer forms a built‐in electric field at the SnS/Cu 2 Te interface, which reduces rear surface recombination and improves charge collection. A parametric study evaluates the effects of SnS thickness, carrier concentration, and electron affinity on key photovoltaic parameters. Optimal results are achieved at a SnS thickness of 0.12 μm, carrier concentration of 1 × 10 20 cm −3 , and electron affinity of 4.0 eV. Further simulations examine the effects of interfacial defects, series and shunt resistances, operating temperature, and back contact work function (WF). Increasing the WF above 5.1 eV enhances hole extraction, while high interfacial defects and series resistance reduce performance. Elevated temperatures reduce V oc and FF, though the SnS BSF layer mitigates these losses. Finally, the optimized structure achieves a power conversion efficiency of 28.25% with fill factor = 82.75%, J sc = 43.04 mA cm −2 , and V oc = 0.80 V, representing a 22% improvement over the reference device.