Influence of seeding and bath conditions in hydrothermal growth of very thin (∼20 nm) single-crystalline rutile TiO₂ nanorod films.

New seeding conditions have been examined for the hydrothermal growth of single-crystalline rutile TiO₂ nanorods. Rutile nanorods of ∼20 nm diameter are grown from seed layers consisting of either (A) TiO₂ or MnOOH nanocrystals deposited from suspension, or (B) a continuous sheet of TiO₂. These seed layers are more effective for seeding the growth of rutile nanorods compared to the use of bare F-SnO₂ substrates. The TiO₂ sheet seeding allows lower concentration of titanium alkoxide precursor relative to previously reported procedures, but fusion of the resulting TiO₂ nanorods into bundles occurs at higher precursor concentration and/or longer growth duration. Performance of polymer-oxide solar cells prepared using these nanorods shows a dependence on the extent of bundling as well as rod height.