A comparative evaluation of the efficiency of CTX (X = S, Se) solar cells with a p⁺-CTS as back surface field

Thin-film solar cells based on CTX (X = S, Se) are gaining interest due to their excellent optoelectronic qualities, as well as the affordability and non-toxicity of their constituent elements. In this work, a novel CTX-based solar cell structure with a p + -CTS back surface field (BSF) layer was numerically investigated using the SCAPS-1D program. A comparison was conducted between CTX solar cells with and without the BSF layer. A thin p + -CTS layer between the molybdenum (Mo) back contact and the CTX absorber layer significantly reduced recombination losses while increasing open-circuit voltage, enhancing a solar cell's overall efficiency. Further tuning of numerous material properties, including bandgap energy, thickness, and doping concentration, for both absorbers CTX and BSF resulted in an enhancement in overall photovoltaic performance. The optimum efficiencies for Mo/p + -CTS/CTS/CdS/ZnO/Al:ZnO/Al and Mo/p + -CTS/CTSe/CdS/ZnO/Al:ZnO/Al solar cells were 6.74% and 7.45%, respectively. These findings offer a potential basis for the development of high-performance, low-cost CTX solar cells.