Ordered RTᵢO₂@ATᵢO₂ architecture for dye-sensitized solar cell applications

Herein, we report a green and convenient method to prepare a compact layer for better construction of hierarchical TiO₂ architectures to serve as photoanodes, in which one-dimensional (1D) rutile TiO₂ (RTᵢO₂) arrays are grown hydrothermally on a compact layer for fast electron transport, and branched anatase TiO₂ (ATᵢO₂) particles are deposited orderly on RTᵢO₂ backbones for high efficiency dye harvesting. Characteristic tests indicate that the 1D RTᵢO₂ arrays are tetragonal in shape with a square top surface, whereas the branched ATᵢO₂ particles are nanoconic in shape with exposed {001} facets. As a result, the RTᵢO₂@ATᵢO₂ photoanode, sensitized by the N719 dye, harvests a solar energy conversion efficiency of 5.68%, which is nearly 3 times higher than that found in the RTᵢO₂ array-based dye-sensitized solar cell (DSSC), which demonstrates that the RTᵢO₂ nanorods decorated by ATᵢO₂ nanocones are helpful in enhancing the solar energy conversion efficiency.