Cobalt selenide/tin selenide hybrid used as a high efficient counter electrode for dye-sensitized solar cells

Abstract

Cobalt selenide/tin selenide (CoSe/SnSe) hybrid is successfully synthesized via a facile solvothermal method and used as an efficient Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). Field emission scanning electron microscopy observes that CoSe/SnSe hybrid is made up of nanosheets and nanoparticles; the nanosheets are CoSe, while the nanoparticles are SnSe. Cyclic voltammogram measurement indicates that CoSe/SnSe hybrid electrodes have larger current density than CoSe electrode and Pt electrode. Electrochemical impedance spectroscopy shows that the 3CoSe/SnSe hybrid has low charge-transfer resistance of 1.03 Ω cm2. Under simulated solar light irradiation with intensity of 100 mW cm−2 (AM 1.5), the DSSC based on the Co3SnSe4 hybrid CE achieves a power conversion efficiency of 7.71 %, which is higher than that the DSSC based on conventional Pt CE (6.89 %). The DSSCs with all as-prepared CoSe/SnSe hybrid CEs exhibit better photovoltaic performance than the DSSC with conventional Pt CE.