Design and Simulation of CdS-Free Sb₂(S, Se)₃ Solar Cells with Efficiency Exceeding 20%

Sb₂(S, Se)₃ is a technologically intriguing material for the next generation of flexible and lightweight photovoltaic (PV) devices. Recently, photoelectric conversion efficiency (PCE) values of 10.75 and 11.66% have been reported in Sb₂(S, Se)₃ (single-junction) and Sb₂(S, Se)₃/Si (tandem) solar cells, respectively. However, all the high-performing Sb₂(S, Se)₃ solar cells (PCE >10%) employ toxic CdS and expensive Spiro-OMeTAD as electron and hole transport layers (ETL and HTL), respectively. Exploring eco-friendly and economical alternatives to the aforementioned layers is imperative for the sustainable advancement in this emerging PV technology. In this context, we investigated different ETL and HTL materials for Sb₂(S, Se)₃ solar cells via Solar Cell and Capacitance Simulator (SCAPS). Our study endorses ZnSe and CuSbS₂ as the potential replacement of CdS and Spiro-OMeTAD, respectively. The ameliorated optimized device demonstrated a PCE of 20.01%, outperforming a (CdS- and Spiro-OMeTAD-based) baseline device (PCE of 10.65%). This work presents judicious recommendations for the fabrication of economical, sustainable, and highly efficient Sb₂(S, Se)₃ solar cells.