Cu3Se2 nanomeshes constructed by enoki-mushroom-like Cu3Se2 and their application to quantum dot-sensitized solar cells

Abstract Novel copper selenide (Cu3Se2) nanomeshes are synthesized on F-doped SnO2 (FTO) glass substrates via a facile single-step potentiodynamic electrodeposition method for efficient counter electrode (CE) in quantum dot-sensitized solar cells (QD-SSCs). The electrodeposited FTO/Cu3Se2 films consist of vertically standing Cu3Se2 nanomeshes, constructed by vertically and laterally grown enoki-mushroom-like Cu3Se2. The FTO/Cu3Se2 electrodes exhibit excellent electrocatalytic activity and good electrochemical stability for the S2−/Sn2− redox couple, even better than those of FTO/Cu2S and FTO/Pt. This is because the vertically standing Cu3Se2 nanomeshes provide not only high electrochemical active sites but also efficient charge transport pathways. Besides, high crystalline Cu3Se2 phase and widened pores between nanomeshes improve the electronic conduction and make ionic transport more efficient into and out of the film. As a result, the CdSe-based QD-SSC containing the optimized FTO/Cu3Se2 CE achieves a significantly increased power conversion efficiency of 5.5%, compared to those containing FTO/Cu2S and FTO/Pt CEs (4.52 and 2.62%, respectively).