A promising vanadium sulfide counter electrode for efficient dye-sensitized solar cells

In this study, we demonstrated the synthesis of vanadium sulfide (VS2) via an in situ hydrothermal route, which was subsequently employed as a counter electrode (CE) for Pt-free dye-sensitized solar cells (DSSCs) for the first time. It was demonstrated from scanning electron microscopy that the size of VS2 increased with the increasing temperature, and the morphology was also affected by temperature. Extensive electrochemical performance analysis, including cyclic voltammetry, electrochemical impedance, and Tafel polarization, revealed that the VS2 CE possesses a high electrocatalytic activity for the reduction of triiodide to iodide and a low charge-transfer resistance at the electrolyte/CE interface. The DSSC based on the VS2 CE exhibited a conversion efficiency of 6.24% under an illumination of 100 mW cm(-2) as compared to the DSSC based on the Pt CE.