CuCo2S4 hollow spherical shell supported by RGO as an efficient counter electrode for QDSSCs: Shortening electron migration paths and promoting electron migration

In recent years, low-cost spinel sulfides as counter electrode materials for quantum dot sensitized solar cells (QDSSCs) have gradually become a research hotspot in this field. In this study, CuCo2S4/reduced graphene oxide (RGO) composite is successfully prepared via a simple and low-cost solvothermal method, which was used as counter electrode (CE) and assembled with CdS/CdSe photoanode to form QDSSCs device. In comparison with other materials, the power conversion efficiency of CuCo2S4/RGO CE reaches 6.59% and is conspicuously superior to that of pure CuCo2S4 and Cu2S/brass CE, benefiting from that the peculiar structure of the CuCo2S4 hollow spherical shell loaded on RGO nanosheets shortens electron migration paths and enables efficient transportation of electrons. Furthermore, the corrosion resistance of CEs has been prominently enhanced compared with Cu2S/brass CE. Thus, CuCo2S4/RGO composite can be primely acknowledged as promising CE materials for competitive high-performance QDSSCs and offer the possibility for high efficiency and energy saving of QDSSCs in the future.