In situ fabrication of 2D SnS₂ nanosheets as a new electron transport layer for perovskite solar cells

To promote commercialization of perovskite solar cells (PSCs), low-temperature processed electron transport layer (ETL) with high carrier mobility still needs to be further developed. Here, we reported two-dimensional (2D) tin disulfide (SnS₂) nanosheets as ETL in PSCs for the first time. The morphologies of the 2D SnS₂ material can be easy controlled by the in situ synthesized method on the conductive fluorine-doped tin oxide (FTO) substrate. We achieved a champion power conversion efficiency (PCE) of 13.63%, with the short-circuit current density (J_SC) of 23.70 mA/cm², open-circuit voltage (V_OC) of 0.95 V, and fill factor (FF) of 0.61. The high J_SC of PSCs results from effective electron collection of the 2D SnS₂ nanosheets from perovskite layer and fast electron transport to the FTO. The low V_OC and FF are the results of the lower conduction band of 2D SnS₂ (4.23 eV) than that of TiO₂ (4.0 eV). These results demonstrate that 2D material is a promising candidate for ETL in PSCs.