The improvement of sunlight utilization is a fundamental approach for the construction of high-efficiency quantum-dot-based solar cells (QDSCs). To boost light harvesting, cosensitized photoanodes are fabricated in this work by a sequential deposition of presynthesized Zn-Cu-In-Se (ZCISe) and CdSe quantum dots (QDs) on mesoporous TiO films via the control of the interactions between QDs and TiO films using 3-mercaptopropionic acid bifunctional linkers. By the synergistic effect of ZCISe-alloyed QDs with a wide light absorption range and CdSe QDs with a high extinction coefficient, the incident photon-to-electron conversion efficiency is significantly improved over single QD-based QDSCs. It is found that the performance of cosensitized photoanodes can be optimized by adjusting the size of CdSe QDs introduced. In combination with titanium mesh supported mesoporous carbon as a counterelectrode and a modified polysulfide solution as an electrolyte, a champion power conversion efficiency up to 12.75% (V = 0.752 V, J = 27.39 mA cm , FF = 0.619) is achieved, which is, as far as it is known, the highest efficiency for liquid-junction QD-based solar cells reported.

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Benefiting from the suppressed charge recombination occurring at the photoanode/electrolyte interfaces with the introduction of TEOS additive in the polysulfide electrolyte, a remarkable PCE of over 12% was obtained for ZCISe QDSCs.

Sufficient loading of presynthesized quantum dots (QDs) on mesoporous TiO 2 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 TiO 2 films by surface engineering. It was found that the zeta potential of presensitized TiO 2 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 Cu 2 S/brass counter electrodes was achieved by the secondary deposition of Zn−Cu−In−Se QDs.

A facile method for synthesizing high-quality Cu–In–Se quantum dots (QDs) was developed by Al/Zn co-incorporation. Benefiting from the reduction of trap-state defects in QDs, the efficiency of solar cells basing prepared QDs is obviously improved.