Preparation of Ti foil-based TiO2 film containing rutile sea urchin-like microspheres covered with anatase nanotubes self-organized layer and its application in dye-sensitized solar cells

Abstract

Ti foil-based TiO2 films containing rutile sea urchin-like hierarchical microspheres covered with self-organized anatase nanotubes layer were fabricated through two-step hydrothermal processes. The first-step hydrothermal treatment of TiCl4 solution caused a thick rutile film on Ti foil, in which the sea urchin-like rutile microspheres (RMS) with mean size of 5–6μm are composed of nanorods with ∼200nm diameter and 1–2μm length. After the second-step hydrothermal treatment, a thin self-organized layer of anatase nanotubes (ANT) with ∼10nm diameter formed on those RMS to form Ti foil-based RMS/ANT composite film. The corresponding dye-sensitized solar cell using the Ti foil-based RMS/ANT film as photoanode achieved an efficiency of 5.42%, much better than that (0.73%) of the single RMS film-based one. The thin ANT layer on the RMS film can not only enhance the dye-loading, but also retard the charge recombination. All these lead to higher photocurrent and better photovoltaic conversion efficiency than the single RMS film-based solar cell. The above results present an efficient approach to improve the photovoltaic performance of the rutile-based solar cells by designing photoanode materials with hierarchical structures to counterbalance rutile’s inherent shortages such as low dye-loading and poor conductivity as compared with anatase.