Electrocatalytic activity of chemically deposited CuxS thin film for counter electrode in quantum dots-sensitized solar cells

The compact (c-CuxS) and the porous (p-CuxS) with particle decorated films of coppers-ulfidearesynthesized using a chemical bath deposition technique, and the films are characterized using electrochemical techniques. In addition, the chemically deposited CuxS films are investigated as a counter electrode in quantum dots-sensitized solar cells (QSSCs). The available redox active reaction sites of the p-CuxS film are found to be 57.9% higher than those available in the c-CuxS film. From the electrochemical impedance spectroscopy, the effective diffusion coefficients of the polysulfide electrolyte in the c-CuxS and p-CuxS films are estimated to be 3.67 × 10−5 and 6.35 × 10−5 cm2 s−1, respectively. These results can be ascribed to the improvement in the available redox active reaction sites and the electrocatalytic activity of the CuxS counter electrode. As compared to the c-CuxS film, the p-CuxS film as a counter electrode exhibits an enhanced photovoltaic performance of the QSSCs with the power conversion efficiency of 3.17%, short-circuit current of 11.89 mA c−m2, open-circuit voltage of 0.50 V, and fill factor of 53.29. The improved performance of the QSSCs is ascribed to the improvements on the available redox active reaction sites, electrocatalytic activity and the diffusion coefficients, which are directly related to the surface morphology of the sulfide films.