A facile method to produce TiO₂ nanorods for high-efficiency dye solar cells

Highly ordered TiO₂ nanorods are considered promising for photoanodes in dye-sensitized solar cells due to their high charge transfer rate of photo-generated electrons, but they often suffer from low specific area, which may lead to a low conversion efficiency. Here, we produce long vertical single-crystalline rutile TiO₂-nanorod arrays on fluorine-doped tin oxide conductive glass substrates(FTO)by the hydrothermal method. To further increase the specific area, the TiO2-nanorod arrays are etched in a secondary hydrothermal process by hydrochloric acid. The etching time have a major effect on the nanorod microstructure and on the dye-sensitized solar cells efficiency. The best result is reached with 8 h of etching, which results in a record high conversion efficiency of 11.14 ± 0.12% (certified efficiency 10.3%) under full sunlight illumination (AM 1.5 G, 100 mW/cm²). The record cell has an open voltage of 0.79 V and a short current density of 21.59 mA/cm². The proposed manufacturing approach of TiO₂ nanorods is highly potential for producing high-efficiency dye-sensitized solar cells.