Efficient Ternary CdSSe Quantum-Dot-Sensitized Solar Cells based on MgO-coated TiO₂ Nanoparticles

The high rate of charge recombination in quantum‐dot‐sensitized solar cells (QDSCs) limits their power conversion efficiency. Here we address a facile way to reduce back electron transfer of QDSCs by introducing a thin MgO bridge layer between the TiO₂ film and quantum dots. The ternary CdSSe QDs were used as our model system, and the MgO‐coated TiO₂‐based ternary QDSCs showed a fill factor 41 % larger and efficiency 29 % higher than non‐coated ones. The enhanced performance is owing to the reduced recombination induced by the MgO bridge layer, which has been confirmed by electrochemical impedance spectroscopy (EIS) and intensity‐modulated photovoltage spectroscopy (IMVS) analysis.