Surface Modified TiO₂ Nanostructure with 3D Urchin-Like Morphology for Dye-Sensitized Solar Cell Application

Three-dimensional (3D) urchin-like rutile TiO₂ powders were synthesized by a mild hydrothermal method without any templates. An individual urchin-like TiO₂ powder consists of self-assembled nanorods with a length of about 150 nm and width of about 10 nm. Additionally, the urchin-like TiO₂ nanopowders were coated with an ultra-thin ZnO layer in order to modify the surface properties of the nanopowders, and the ZnO layer was confirmed by high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis. The ZnO-modified TiO2 was used as a photoelectrode of a dye-sensitized solar cell (DSSC) and the solar cell performances were investigated. In comparison with bare TiO₂, ZnO-modified TiO₂ improved the photovoltaic performances, i.e., energy conversion efficiency, open circuit voltage, and short circuit current were increased. The higher DSSC performance of ZnO-modified TiO₂ was attributed to its higher dye loading and lower charge recombination rate.