Hierarchical or one-dimensional architectures are among the most exciting developments in material science these recent years We present a nanostructured TiO2 assembly combining these two concepts and resembling a forest composed of individual, high aspect-ratio, treelike nanostructures We propose to use these structures for the photoanode in dye-sensitized solar cells, and we achieved 4 9% conversion efficiency in combination with C101 dye We demonstrate this morphology beneficial to hamper the electron recombination and also mass transport control in the mesopores when solvent-free ionic liquid electrolyte is used