Growth of NiS/graphene nanocomposites for enhanced performance of dye sensitized solar cells

One dimensional (1D) NiS/2D graphene nanocomposites were synthesized via a simple, facile, and low-temperature hydrothermal method and used as cocatalysts for triiodide reduction in dye sensitized solar cell (DSSCs). The influence of the graphene content on the microstructure and morphology of the NiS/graphene hybrid was investigated. Catalytic activities of the composite catalysts for reduction of I₃ ⁻ were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. It was found that the content of graphene played an important role in the structure and the quality of the formed NiS/graphene hybrid counter-electrode (CE) and the photovoltaic performance of the resultant DSSC as well. The mechanisms for the NiS/graphene hybrid formation and electrocatalytic performance improvement are discussed. The NiS/graphene hybrid CE exhibits the best catalytic property when the mass ratio of graphene to NiS is 0.4 %. The DSSC with the optimized NiS/graphene hybrid CE produces an energy conversion efficiency of 8.26 %, which is significantly higher than that of the device with pure graphene or bare NiS CE, and also superior to that (8.12 %) for the DSSC with the Pt CE under the same conditions.