Preparation of a Highly Efficient PbS Electrode and Its Application in Quantum Dots-Sensitized Solar Cells

To improve the light-to-electric conversion efficiency of quantum dots-sensitized nanocrystalline thin-film solar cells, a PbS electrode with high electrocatalytic activity toward polysulfide electrolyte was prepared by successively treating Pb foil in acid and polysulfide solutions. Electrochemical impedance spectroscopy (EIS) measurements were performed to evaluate the electrocatalytic activity of the prepared PbS electrode. Based on the EIS results, the temperature and time to treat the Pb foil in the acid solution were optimized. The PbS electrode prepared under the optimized conditions was used as a counter electrode to fabricate a quantumdotssensitized solar cell with a CdSe quantum dots-sensitized TiO2 nanocrystalline thin film as the photoanode and polysulfide solution as the electrolyte. Both the electrocatalytic activity and light-to-electric conversion properties of the PbS electrode prepared from acid treatment of Pb foil for the optimized temperature and time are superior to those of electrodes prepared by other reported methods. In our method, the treatment time is considerably less but the PbS counter electrode maintains a superior catalytic activity compared with other methods. X-ray diffraction and scanning electron microscopy were performed to demonstrate the formation process of PbS, and the catalytic enhancement mechanism of the prepared PbS electrode is discussed.