The preparation and assembly of CdSxSe1−x alloyed quantum dots on TiO2 nanowire arrays for quantum dot-sensitized solar cells

Abstract

Highly ordered TiO2 nanowire (NW) arrays were constructed by hydrothermal process as support materials for quantum dot sensitized solar cells (QDSSCs). The CdSxSe1−x alloyed quantum dots (QDs) with tunable composition have been assembled onto the TiO2 NW arrays via a facile hydrothermal method to form CdSxSe1−x/TiO2 NW photoanodes. The light absorption range of the CdSxSe1−x/TiO2 NW photoanodes can be controlled by changing the atomic ratio of S to Se. Based on CdSxSe1−x/TiO2 NW photoanodes, the photovoltaic performance of these CdSxSe1−x/TiO2 NW solar cells gradually improved as the increase of Se content in CdSxSe1−x alloyed QDs. Among all sample CdSxSe1−x/TiO2 NW solar cells which were prepared with different feed molar ratio of S:Se, the CdS0.27Se0.73/TiO2 NW solar cell (prepared with S:Se = 0:4) produced the highest power conversion efficiency up to 2.46 %. The results of investigation into optical properties and incident photon-to-current conversion efficiency indicates that the enlarged light absorption range and effective photo-to-electrical efficiency can be obtained with Se-rich CdSxSe1−x/TiO2 NW photoanodes, which contribute to the enhanced photovoltaic performance of the CdS0.27Se0.73/TiO2 NW solar cell.