Facile Secondary Deposition for Improving Quantum Dot Loading in Fabricating Quantum Dot Solar Cells

Sufficient loading of presynthesized quantum dots (QDs) on mesoporous TiO₂ electrodes is the prerequisite for the fabrication of high-performance QD-sensitized solar cells (QDSCs). Here, we provide a general approach for increasing QD loading on mesoporous TiO₂ films by surface engineering. It was found that the zeta potential of presensitized TiO₂ can be effectively adjusted by surfactant treatment, on the basis of which additional QDs are successfully introduced onto photoanodes during secondary deposition. The strategy developed, that is, the secondary deposition incorporating surfactant treatment, makes it possible to load various QDs onto photoanodes regardless of the nature of QDs. In standard AM 1.5G sunlight, a certified efficiency of 10.26% for the QDSC with Cu₂S/brass counter electrodes was achieved by the secondary deposition of Zn–Cu–In–Se QDs.