MOF-derived CuS double-faced-decorated carbon nanosheets as high-performance and stable counter electrodes for quantum dots solar cells.

The development of highly-catalytic counter electrode (CE) materials is vital to the construction of quantum dot-sensitized solar cells (QDSCs) but is still challenging. Here, a novel self-assembly double-faced decorated carbon nanosheets with MOF-derived CuS nanospheres (DF-CuS/C NSs) were prepared as high-performance hybrid CEs for improving the catalytic activity towards polysulfide electrolytes and enhancing the performance of QDSCs. It is shown that the MOF-derived CuS nanospheres disperse well on the surface of the carbon NSs in the obtained DF-CuS/C NSs hybrids. Electrochemical characterization demonstrated that the DF-CuS/C NSs with moderate mass ratio exhibited enhanced electrocatalytic activity towards the reduction of the polysulfide redox couple (S/S) and decreased charge transfer resistance at the interface of the CE/electrolyte. Benefitting from the merits of this novel hybrid CE, the power conversion efficiency (PCE) of the CdSeTe QDs-based QDSCs is increased to 9.39%, which is higher than the pristine carrageenan (CA)-derived CEs (5.84%) and Cu-BTC-derived CEs (7.74%). With the further optimization of the substrate, the highest PCE of 11.36% was achieved based on the Ti mesh substrate supported hybrid CE.