Toward highly efficient CdS/CdSe quantum dot-sensitized solar cells incorporating a fullerene hybrid-nanostructure counter electrode on transparent conductive substrates

Abstract

At present, the performance of quantum dot-sensitized solar cells (QDSCs) is still much lower than that of conventional dye-sensitized solar cells. Besides efforts on the development of photoanodes, a new generation of materials for counter electrodes is also urgently needed to optimize the structure of QDSCs and improve their power conversion efficiency (PCE). Here, fullerene (C₆₀) films on transparent conductive substrates have been prepared through a cost-effective doctor blade process, which were subsequently applied as counter electrodes in QDSCs. Compared to conventional counter electrodes composed of Pt or activated carbon (AC) electrodes, the C₆₀-based counter electrodes exhibit better electrocatalytic activity, lower charge-transfer resistance and higher exchange current density. Based on these merits, the QDSC with C₆₀-based counter electrode and a polysulfide electrolyte shows an improved PCE of 4.18% under simulated 100 mW cm⁻² AM 1.5 illumination. In contrast, the PCEs of the QDSC using Pt or activated carbon as counter electrode under the same conditions are only 1.17% and 3.48%, respectively. Stability test reveals that the C₆₀-based counter electrode has good stability at room temperature.