Efficient CdS/Sb2S3 interfacial modification using sodium borohydride etching for enhanced performance of low-cost full-inorganic antimony-based solar cells

Abstract

Antimony sulfide (Sb₂S₃) is a promising material for photovoltaic applications because of its high absorption coefficient, environmental friendliness and low cost. Nevertheless, the conversion efficiency of Sb₂S₃ solar cells severely deviates from theoretical predictions, and the interface between CdS and Sb₂S₃ is crucial for the overall performance. In this study, we conducted a highly effective sodium borohydride (NaBH₄) etching to modify the CdS/Sb₂S₃ interface, aiming to improve the device performance. The NaBH₄ etching led to a reduction in surface roughness and an enhancement in the hydrophilicity of the CdS layer, creating a more conducive environment for the subsequent deposition of the Sb₂S₃ absorber layer. Simultaneously, the reduction of cadmium oxide serves to optimize interfacial energy alignment and minimize recombination losses. Ultimately, our full-inorganic Sb₂S₃ solar cells, featuring the configuration FTO/CdS/Sb₂S₃/MnS/Carbon, attain a PCE of 6.26%. This marks a significant improvement of 15% compared to cells without NaBH₄ etching. This study presents a feasible and efficient perspective for modifying the CdS/Sb₂S₃ interface, thereby enhancing the performance of Sb-based solar cells.