Petal-like cobalt selenide nanosheets used as counter electrode in high efficient dye-sensitized solar cells

摘要

A petal-like cobalt selenide nanosheets (Co_(0.85)Se) is prepared by hydrothermal method and used as an efficient Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). Field emission scanning electron microscopy observes that the petal-like Co_(0.85)Se possess porous and large specific surface area, which benefits the enhancement of electrocatalytic activity. Cyclic voltammogram measurement indicates that Co_(0.85)Se electrode has larger current density than Pt electrode. Electrochemical impedance spectroscopy shows that the Co_(0.85)Se electrode with optimal condition has low charge-transfer resistance of 0.79 Ω cm~2. Under simulated solar light irradiation with intensity of 100 mW cm~(-2) (AM 1.5), the DSSC based on the Co_(0.85)Se CE achieves a power conversion efficiency of 8.00 %, which is slightly higher than the solar cell based on the Pt CE (7.83 %).