Electrochemical Growth of FeS on Three-dimensional Carbon Scaffold as the High Catalytic and Stable Counter Electrode for Quantum Dot-sensitized Solar Cells

A low-cost, efficient and stable FeS/Carbon (FeS/C) composite counter electrode (CE), combining the excellent electrical conductivity of the carbon material and the superior catalytic activity of FeS, is prepared for quantum dot-sensitized solar cells (QDSCs) by electrochemical deposition of FeS on three-dimensional carbon mesoporous scaffold. The QDSC based on FeS/C CE achieves a rather high power conversion efficiency (PCE) of 4.58% with a fill factor (FF) of 0.51, which is much higher than those based on FeS/FTO CE (0.27) and C/FTO CE (0.11). Moreover, the FeS/C CE exerts excellent stability in photoelectric performance, which still performs high photoelectric conversion properties (PCE = 4.17%, V_oc = 0.42 V, J_sc = 20.25mA·cm^-2 and FF = 0.49) after serving for 8 weeks. Besides, compared with conventional CEs based on conductive fluorine doped tin oxide (FTO) glass, FeS/C not only can work independently but also can be fabricated on various substrate forms (such as conductive or insulative, flexible or non-flexible), which is attributed to the facile preparation procedure and usage of conductive carbon paste. Therefore, the FeS/C has exhibited much promise as the CE in QDSCs. And our works have provided new insight into the material and structure optimization of CE for QDSCs.