Hydrothermal Etching Treatment to Rutile TiO(2) Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO(2) Solar Cells

Highly ordered TiO(2) nanorod arrays (NRAs) were directly grown on an F:SnO(2) (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO(2) NRAs. The results showed that the center portion of the TiO(2) nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO(2) NRAs. The TiO(2) films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO(2) films with TiCl(4), a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-016-1236-9) contains supplementary material, which is available to authorized users.