Preparation of nanorod-like anatase TiO2 nanocrystals and their photovoltaic properties

Anatase TiO₂ nanocrystals with the specific surface area ranged from 100 to 220 m₂/g were prepared by the hydrothermal treatment of anatase TiO₂ sols at the temperature of 110°C and above. When TiO₂ sols with a lower content of TiO₂ and at a relatively high pH value were hydrothermal treated, the dispersible and nanorod-like TiO₂ nanocrystals were formed via the oriented attachment. The nanorod-like TiO₂ nanocrystals mixed with the original sol and were subsequently subjected to a further hydrothermal treatment; the branched and nanoring-like nanostructures in the anatase phase were obtained. The as-prepared TiO₂ nanocrystals were characterized with X-ray diffraction, FT-Raman spectrometry, UV-vis absorption spectrometry and transmission electron microscopy. The TiO₂ nanostructures were deposited on the FTO conductive glass as the anodic electrode for the dye-sensitized solar cell and assembled into solar cells. The derived solar cells showed a conversion efficiency of 6.12 % under 1 sun illumination of simulated sunlight and an external quantum efficiency (EQE) of more than 60% at the wavelength of 550 nm.