Efficient control of band gap energy and optical properties of titania thin films for solar cell applications

Abstract

Titanium dioxide, also known as titania is an important semiconducting oxide that has gained prominence in recent years for applications in photoelectrochemical/dye-sensitized solar cells. TiO2 is at present preferred over oxides such as ZnO or SnO2 for applications in dye-sensitized solar cell, because of its mesoporous structure, which offers high surface area for efficient dye loading. It is also important that the band gap of the metal oxide can be adjusted for efficient electron injection from most available commercial dyes since the generation of voltage in the device depends mainly on the band edge matching. Herein, TiO2 thin films were deposited in a polyvinyl pyrolidon medium by the chemical bath deposition technique at 65 °C. The inclusion of lead ions during the film formation process led to structural modification of the thin films of titania – anatase (TiO2) and subsequent formation of structurally disordered Pb-doped TiO2 thin films. The resulting films retain the high band gap energy of crystalline anatase and substantially tuned in the range, 2.85–3.26 ± 0.05 eV by the Pb2+ inclusion.