Optimal-Temperature-Based Highly Efficient NiS Counter Electrode for Quantum-Dot-Sensitized Solar Cells

Metal sulfide electrodes were compared to a conventional platinum (Pt) counter electrode (CE) in quantum-dot-sensitized solar cells (QDSSCs), in which they were used to improve the short circuit current, fill factor, and conversion efficiency (eta). We deposited optimal-temperature-based nickel sulfide (NiS) thin films on a fluorine-doped tin oxide (FTO) substrate by a facile chemical bath deposition method and successfully employed them as a highly efficient CE for QDSSCs. The obtained NiS thin-film nanoparticles exhibit high electrocatalytic performance and fast mass transfer rates toward the polysulfide electrolyte. Under the illumination of one sun (100 mWcm(-2)), the QDSSC with a NiS CE produces a higher eta of 3.30%, which is much higher than that of a Pt CE (1.89%). Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization measurements were performed to investigate the electrocatalytic activity of the NiS CE toward polysulfide electrolyte.