Highly Efficient Inverted Type-I CdS/CdSe Core/Shell Structure QD-Sensitized Solar Cells

Presynthesized high-quality CdS/CdSe inverted type-I core/shell structure QDs have been deposited onto TiO2 electrodes after first coating with bifunctional linker molecules, mercaptopropionic acid (MPA), and the resulting quantum dot sensitized solar cells (QDSCs) exhibited record conversion efficiency of 5.32% (Voc = 0.527 V, Jsc = 18.02 mA/cm2, FF = 0.56) under simulated AM 1.5, 100 mW cm–2 illumination. CdS/CdSe QDs with different CdSe shell thicknesses and different corresponding absorption onsets were prepared via the well-developed organometallic high-temperature injection method. MPA-capped water-dispersible QDs were then obtained via ligand exchange from the initial organic ligand capped oil-dispersible QDs. The QD-sensitized TiO2 electrodes were facilely prepared by pipetting the MPA-capped CdS/CdSe QD aqueous solution onto the TiO2 film, followed by a covering process with a ZnS layer and a postsintering process at 300 °C. Polysulfide electrolyte and Cu2S counterelectrode were used to provide h...