Room-temperature synthesis of Cu2−xE (E=S, Se) nanotubes with hierarchical architecture as high-performance counter electrodes of quantum-dot-sensitized solar cells

Copper chalcogenide nanostructures (e.g. one- dimensional nanotubes) have been the focus of interest because of their unique properties and great potential in various applications. Their current fabrications mainly rely on high-temperature or complicated processes. Here, with the assistance of theoretical prediction, we prepared Cu2−xE (E=S, Se) micro-/nanotubes (NTs) with a hierarchical architecture by using copper nanowires (Cu NWs), stable sulfur and selenium powder as precursors at room temperature. The influence of reaction parameters (e.g. precursor ratio, ligands, ligand ratio, and reaction time) on the formation of nanotubes was comprehensively investigated. The resultant Cu2−xE (E=S, Se) NTs were used as counter electrodes (CE) of quantum-dot-sensitized solar cells (QDSSCs) to achieve a conversion efficiency (η) of 5.02 and 6.25 %, respectively, much higher than that of QDSSCs made with Au CE (η=2.94 %).