Modifying back contact by silver to Enhance the performance of carbon-based Sb2S3 solar cells

Abstract

Antimony sulfide (Sb2S3) has drawn significant attention due to its excellent photoelectric properties. However, the photon conversion efficiency of Sb2S3 solar cell is limited by its magnificent value band offset between absorber layer and carbon electrode. Herein, a back surface optimization strategy is developed to reduce the barrier at the back contact. By introducing Ag at back contact before post-selenization process, the Valence-Band Maximum (VBM) of Sb2S3 is elevated under the action of spin–orbit interaction between Sb-5 s orbit and Ag-d orbit, leading to improve the extraction of holes. Consequently, the electrical conductivity of the film undergoes a significant improvement, rising from 1.20 × 10-5 to 1.59 × 10-5 S/cm. Additionally, the film surface morphology is refined, exhibiting a reduction in roughness from 17.1 nm to 13.6 nm, which leads to less leak current generated. Finally, the device based on FTO/SnO2/CdS/Sb2S3/Carbon structure achieved the power conversion efficiency (PCE) of 5.51 %, representing a 16 % improvement compared to the device without Ag treatment.