A Strategy to Enhance the Efficiency of Quantum Dot-Sensitized Solar Cells by Decreasing Electron Recombination with Polyoxometalate/TiO2 as the Electronic Interface Layer

Graphical Sandwich filling : Polyoxometalate (POM) can act as an electron-transfer medium to decrease electron recombination in a photoelectric device. POM/TiO 2 is prepared as an electronic interface layer by a facile layer-by-layer self-assembly method. This interface layer is added to the photoanode of quantum dot-sensitized solar cells (QDSCs) for improved performance of the QDSCs. Electron recombination occurring at the TiO 2 /quantum dot sensitizer/electrolyte interface is the key reason for hindering further efficiency improvements to quantum dot sensitized solar cells (QDSCs). Polyoxometalate (POM) can act as an electron-transfer medium to decrease electron recombination in a photoelectric device owing to its excellent oxidation/reduction properties and thermostability. A POM/TiO 2 electronic interface layer prepared by a simple layer-by-layer self-assembly method was added between fluorine-doped tin oxide (FTO) and mesoporous TiO 2 in the photoanode of QDSCs, and the effect on the photovoltaic performance was systematically investigated. Photovoltaic experimental results and the electron transmission mechanism show that the POM/TiO 2 electronic interface layer in the QDSCs can clearly suppress electron recombination, increase the electron lifetime, and result in smoother electron transmission. In summary, the best conversion efficiency of QDSCs with POM/TiO 2 electronic interface layers increases to 8.02 %, which is an improvement of 25.1 % compared with QDSCs without POM/TiO 2 . This work first builds an electron-transfer bridge between FTO and the quantum dot sensitizer and paves the way for further improved efficiency of QDSCs.