Hierarchical Cu7S4 nanotubes assembled by hexagonal nanoplates with high catalytic performance for quantum dot-sensitized solar cells

As a kind of promising generation solar cells, the catalytic properties of counter electrodes (CEs) play a key factor on the performance of QDSSCs (quantum dot-sensitized solar cells) at present. Here, hierarchical Cu7S4 nanotubes (Cu7S4-HNT) assembled by hexagonal nanoplates have been prepared by an in-situ growth route and etching process at room temperature. The formation mechanism of the unique morphology is also proposed. Because of the rapid diffusion of electrons and electrolyte, abundant catalytic sites and high stability, the as-prepared Cu7S4-HNT combined the characteristics of nanotube and hierarchical structure can improve the catalytic performance of CEs. QDSSCs based on the Cu7S4-HNT CEs possess a high power conversion efficiency of 4.53%, superior to those with the commonly used Cu2S/brass (3.3%) or the referenced Pt (1.79%) CEs. What's more, the Cu7S4-HNT CE still shows excellent stability in electrolyte after 1000 CV cycles.