Correlations Between Morphology and Photoelectrical Properties of Single-Crystal Rutile TiO2 Nanorods

Oriented single-crystal rutile TiO2 nanorod arrays were grown directly on transparent conductive fluorine-doped tin oxide (FTO) substrates through a facile hydrothermal method with different growth times and temperatures. It was found that reaction temperature significantly affected morphology, crystallinity, and photoelectrical performance of TiO2, while growth time demonstrated less influence. Under the irradiation, short-circuit photocurrent density of TiO2 increased along with the reaction temperature until nanorod aggregation arose and the optimal value reached to 0.91 mA/cm(2) at 180 degrees C. In UV-visible diffuse reflectance spectrum and external quantum efficiency (EQE) measurements, red shifts appeared with the increase of growth time and temperature, which can be ascribed to the improvement of rutile crystallinity. Furthermore, it was for the first time proved that sintering treatment didn't improve the crystallinity of TiO2 on FTO substrata. The highest photocurrent density of 3.36 mA/cm(2) and EQE value of 22.2% appeared after sintering at 300 degrees C, while the decay at high temperatures may be caused by the aggregation and fracture of the nanorods, consistent with the effects of reaction temperature. In summary, long, oriented, and separated TiO2 nanorods with the elimination of organic titanium precursor on their surface demonstrate highly efficient photoelectrical characteristics.