Preparation of nickel selenide by pulsed-voltage electrodeposition and its application as a highly-efficient electrocatalyst at counter electrodes of quantum-dot sensitized solar cells

Abstract We fabricate the nickel selenide thin films on fluorine-doped tin oxide conducting glass subtract using pulsed-voltage electrodeposition method for counter electrodes in quantum-dot-sensitized solar cells. The novelty of this work is nickel selenides are prepared by PVE significantly differs from the traditional continuous-voltage electrodeposition in morphology, compositions, and electrocatalytic activities. In general, NiSe 2 -PVE films consist of clusters with crystalline NiSe 2 nanoparticles which remain nanoporous because application of anodic bias during pulsed electrodeposition enables diffusion layer of H 2 SeO 3 recover from the deposition. The subsequent short cathodic bias not only facilitates new nucleation of nickel selenide but also hinders grain growth. In contrast, Ni 3 Se 2 -CVE film consists dense larger Ni 3 Se 2 grains with surface microcracks attributed to continuous grain growth and accumulated film stress. Hence, NiSe 2 -PVE enhances electrocatalytic activity in polysulfide electrolyte in an effective manner when compare to Ni 3 Se 2 -CVE, owing to significantly more electrocatalytic active sites and enhance charge and mass transports. As an outcome, QDSSC with NiSe 2 -PVE CE achieve significantly higher power conversion efficiency of 4.46% than those of cells with Pt (2.62%) and Ni 3 Se 2 -CVE (2.63%) CEs. Furthermore, electrochemical stability in polysulfide electrolyte medium is reasonably high.