Hydrothermal growth of double-layer TiO2 nanostructure film for quantum dot sensitized solar cells

► A two-step hydrothermal deposition method was used to deposit TiO2 films. ► Double-layer TiO2 films were synthesized on transparent FTO substrate. ► The bi-functional character of the electrode were confirmed. ► Photocurrent density of DL-film electrode was enhanced 5 times than a single film.