Template-Free Synthesis of Hierarchical TiO2 Structures and Their Application in Dye-Sensitized Solar Cells

We demonstrate here the synthesis of a hierarchical TiO2 architecture without any surfactants or templates. Two kinds of structure existed simultaneously, the ordered nanoarrays at bottom provided direct conduction pathway for photo generated electrons, while the upper micro-flowers consisted of nanobelt as building units increased the light harvesting ability as the scattering part. The formation mechanism of the hierarchical architecture has been proposed by studying the morphology evolution processes upon reaction time. The performance of dye-sensitized solar cells based on the obtained hierarchical anatase TiO2 has been also studied, giving a J(SC) = 12.44 mA cm(-2), V-OC = 0.64 V, FF = 69.05%, and n = 5.53%, which is superior than commercial TiO2 (P25). The UV-vis results prove that the obtained morphology is beneficial to light-scattering and thus increases the light harvesting ability. This hierarchical TiO2 structure offers great potential for the development of high-efficiency DSSCs.