Modifying back contact by silver to Enhance the performance of carbon-based Sb 2 S 3 solar cells

Antimony sulfide (Sb 2 S 3 ) has drawn significant attention due to its excellent photoelectric properties. However, the photon conversion efficiency of Sb 2 S 3 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 Sb 2 S 3 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/SnO 2 /CdS/Sb 2 S 3 /Carbon structure achieved the power conversion efficiency (PCE) of 5.51 %, representing a 16 % improvement compared to the device without Ag treatment.