FeS/nickel foam as stable and efficient counter electrode material for quantum dot sensitized solar cells

•FeS/NF CE is fabricated by electrochemical deposition.•FeS/NF exhibits excellent electrocatalytic activity in polysulfide electrolyte.•The QDSC based on FeS/NF CE achieves a high fill factor of 0.58.•The electrode can transform between FeS/NF and Fe2O3/NF spontaneously.•The FeS/NF CE shows excellent stability in photoelectric performance.

A stable and efficient FeS/nickel foam (NF) counter electrode for quantum dots-sensitized solar cells (QDSCs) is first fabricated by electrochemistry deposition and characterized with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), current voltage and impedance spectroscopy. The QDSC based on FeS/NF CE achieves a power conversion efficiency (PCE) of 4.39% attributing to the high fill factor (FF) of 0.58, and the PCE is much higher than that of based on FeS/FTO CE (2.76%) and other reported FeS CEs (1.76% and 3.34%). The phenomenon that the electrode can transform between FeS/NF (in the polysulfide electrolyte) and Fe2O3/NF (in the air) spontaneously is first reported. And the excellent stability in photoelectric performance of the CE is also demonstrated in the present work. Therefore, the FeS/NF is very promising as a stable and efficient CE for QDSCs.

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