Improving performance and stability in quantum dot-sensitized solar cell through single layer graphene/Cu 2 S nanocomposite counter electrode

In this work, we presented an effective nanocomposite to modify the Cu 2 S film by employing single layer graphene (SLG) frameworks via chemical vapor deposition, and utilized this nanocomposite as counter electrode (CE) with CdSe/ZnS core/shell quantum dots for highly stable and efficient quantum dot-sensitized solar cell (QDSSC). Furthermore, Cu 2 S film is directly synthesized on SLG framework by electrodeposition method. Using this nanocomposite as CE, we have achieved the high efficiency as high as 3.93% with fill factor of 0.63, which is higher than those with bare Cu 2 S CE (3.40% and 0.57). This remarkable performance is attributed to the surface area enhancement by creating nanoflower-shape, the reduction of charge transfer resistance, improvement of catalytic stability, and the surface smoothness as well as good adhesion. More importantly, no visible color change and detachment from surface for the Cu 2 S@SLG nanocomposite was observed, demonstrating that the SLG framework is critical role in shielding the Cu 2 S structure from sulphur ions into electrolyte, and increasing the adhesion of the Cu 2 S structure on surface, thus preventing its degradation. Consequently, the Cu 2 S@SLG nanocomposite can be utilized as an effective agent to boost up the performance of QDSSCs.