Cobalt/molybdenum ternary hybrid with hierarchical architecture used as high efficient counter electrode for dye-sensitized solar cells

Cobalt selenide/molybdenum selenide/molybdenum oxide (Co0.85Se/MoSe2/MoO3) ternary hybrid is synthesized by a facile hydrothermal method and used as efficient Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). Field emission scanning electron microscopy observes that Co0.85Se/MoSe2/MoO3 possesses hierarchical architecture with one-dimensional (1D) nanorods, two-dimensional (2D) nanosheet and three-dimensional (3D) nanoparticle. Cyclic voltammogram indicates that Co0.85Se/MoSe2/MoO3 hybrid have larger current density than sputtered Pt electrode. Electrochemical impedance spectroscopy shows that cooperation among Co0.85Se, MoSe2 and MoO3 reduces series resistance and charge transfer resistance. The DSSC based on Co0.85Se/MoSe2/MoO3 CE achieves a power conversion efficiency of 7.10%, which is higher than that of the DSSC based on sputtered Pt CE (6.03%).