Ultra-small TiO₂ nanowire forests on transparent conducting oxide for solid-state semiconductor-sensitized solar cells

One-dimensional TiO₂ nanostructures that have large specific surface area have broadened their applications in solar cells and water splitting, but their synthesis still remains a challenge. In this report, vertically ordered rutile TiO₂ nanowires with an ultra-high coverage density of 2.4 × 10¹¹ cm^-2 and ultra-small width of barely ∼16 nm were synthesized on transparent conducting oxide by a facile solvothermal reaction using methanol and aqueous hydrochloride as solvent. The nanowires were fabricated with Sb₂S₃ into solid-state solar cells, which yielded a power conversion efficiency of 2.03%. Such a photoanode showed reduced electron recombination, due to moderate wire fusion at the bottom.