Boosting Open-Circuit Voltage of AgBiS<sub>2</sub> Quantum Dot Solar Cells through Post-treatment Passivation
Wanpeng Yang, Tianyu Sun, Xiaoting Ma, Haixuan Yu, Haodan Shi, Yong Hu, Junyi Huang, Zhirong Liu, Ying Xu, Xiongjie Li, Yan Shen, Mingkui Wang
Abstract
Silver bismuth disulfide (AgBiS 2 ) colloidal quantum dots (CQDs) have emerged as attractive absorbers in ecofriendly photovoltaics due to their high absorption coefficient and suitable bandgap. However, it is a significant challenge to completely eliminate the numerous defect states on the entire surface of CQDs formed in solid-state ligand exchange. Here, we propose a simple stepwise passivation approach in which AgBiS 2 CQD films are subjected to halide post-treatment after conventional surface passivation with iodide. This approach can compensate for the ligand loss on the surface of AgBiS 2 -CQD under a protic solvent attack. It not only largely reduces the surface trap density but also enhances the dielectric-screening effect, effectively promoting charge transport. Through gradual passivation with chloride ions and optimizing the thickness of the light-absorber layer, AgBiS 2 -CQD-based solar cells achieved a power conversion efficiency of 10.02% with a high open-circuit voltage of 0.581 V, which is among the highest reported values for this type of photovoltaic to date.