Cuprous sulfide counter electrodes prepared by ion exchange for high-efficiency quantum dot-sensitized solar cells

We report a novel method to prepare cuprous sulfide counter electrodes by ion exchange of ZnS. The ZnS film is deposited on a porous ITO electrode beforehand by successive ionic layer adsorption and reaction, and converted into cuprous sulfide upon ion exchange for a short period of time. Using the cuprous sulfide counter electrodes, CdSe-sensitized solar cells exhibit a much higher photovoltaic performance as compared to their platinum counterpart, achieving a power conversion efficiency of 4.78%. Such an ion exchange process is promising to fabricate other sulfide counter electrodes, such as PbS, CoS, etc.