CoS/Nanocarbon Composite as a Catalytic Counter Electrode for Improved Performance of Quantum Dot-Sensitized Solar Cells

Abstract

CoS/nanocarbon (NC) composites were prepared via a one-pot hydrothermal method and were used as counter electrodes (CEs) in quantum dot-sensitized solar cells (QDSCs). The CoS/nanocarbon (NC) composite thin film CE has been prepared via a one-pot hydrothermal method. Addition of NC to the solution before hydrothermal treatment led to a CoS/NC composite with a good dispersion of conducting NC. The nanoscaled CoS in the composite CE provides abundant catalytic sites, and the carbon particle framework also acts as highly conductive paths for fast charge transport from the counter electrode (highly catalytic CoS active sites) to the photoanode. The optimized CoS/NC composite CE showed a two-order decrease in the charge-transfer resistance, compared to the pure CoS CE. The TiO2/CdS/CdSe/ZnS-based QDSC using the optimized CoS/NC composite CE shows enhanced photovoltaic performance with a power conversion efficiency of 4.46% and good stability (94.8% retention after 100 h continuous illumination).