A transparent cobalt sulfide/reduced graphene oxide nanostructure counter electrode for high efficient dye-sensitized solar cells

• CoS/rGO CE was synthesized by a simple hydrothermal method.
• The nanostructured CoS/rGO CE has a high transparency.
• This CE shows high conducticity and good electrocatalytic activity.
• The DSSCs with CoS/rGO CE shows a high PCE of 9.82%.
• The DSSCs with this CE shows a PCE (8.38%) with back illumination.

A transparent nanostructured cobalt sulfide/reduced graphene oxide (CoS/rGO) hybrid film is prepared by a simple hydrothermal method in alkaline solution and is used as counter electrode (CE) for dye-sensitized solar cell (DSSC). The surface morphology and micro structures of film are characterized by field emission scanning electron microscopy and Raman spectroscopy. The electrochemical properties of the CEs are measured by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel tests. The photovoltaic performance of the DSSCs with CoS/rGO CEs is investigated. Owing to good transmission conductivity and electrocatalytic activity for CoS/rGO film, the DSSC based on CoS/rGO CE with the thickness of 72 nm achieves power conversion efficiency (PCE) of 9.82% and 8.38% under white light irradiation of 100 mW cm−2 (AM 1.5 G) from the front and back illumination, which are higher than the PCE of DSSC with Pt CE. The results indicate that CoS/rGO hybrid film is a low-cost, Pt-free and high efficient CE for DSSCs.

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