Enhanced photoelectrochemical performance of CdSe/CdS/TiO_2 nanorod arrays solar cell with a PbS underlayer

摘要

Vertically oriented single-crystalline one-dimensional (1D) TiO_2 nanorod arrays film with high aspect ratio was synthesized directly on transparent fluorine-doped tin oxide conducting glass substrate by a facile two-step hydrothermal process. When used in CdSe/CdS/ PbS quantum dots sensitized solar cells (QDSSCs), the 1D ordered TiO_2 nanorods with the increased internal surface areas can adsorb more QDs, which enhanced the ability of light absorption. Moreover, ID ordered TiO_2 nanorods can also offer a direct electrical pathway for photogenerated electrons, accelerating the electrons transfer rate. In addition, the introduction of PbS as underlayer in CdSe/CdS/ TiO_2 system can extend the optical absorption range, which greatly raised the utilization of the solar energy. The incident photon to current conversion efficiency of the CdSe/CdS/PbS/TiO_2 nanorods solar cell reached to 52 %, which is higher than that of CdSe/CdS/TiO_2 nanorods solar cell, indicating that the better light harvesting ability could be obtained by the introduction of PbS QDs. The power conversion efficiency of CdSe/CdS/PbS/TiO_2 nanorods solar cell can reach to 2.56 % under one sun illumination (AM 1.5 G, 100 mW/cm~2), which is greatly higher than that of CdSe/CdS/TiO_2 nanorods solar cell (1.73 %).