Single-step fabrication of phase-controllable nanocrystalline TiO2 films for enhanced photoelectrochemical water splitting and dye-sensitized solar cells

► A phase-controllable TiO2 film was directly onto transparent conductive oxide glass. ► Either a single layer or a bilayer-structured TiO2 film can be obtained. ► The bilayer-structured film outperformed the monolayer-structured films by 50%.