Introducing an Intermediate Band into Dye-Sensitized Solar Cells by W6+ Doping into TiO2 Nanocrystalline Photoanodes

The novel concept of introducing intermediate band into the mesoporous TiO2 backbone of dye-sensitized solar cells (DSSCs) is proposed to take full advantage of the sunlight and enhance the power conversion efficiency. Nominal trace amount W-doped TiO2 nanocrystralline films were prepared with the purpose of forming intermediate band in the bandgap of TiO2. A notable improvement of the device performance was obtained when N-type W-doped TiO2 films were applied as the photoanode of DSSCs. The short-circuit current density (Jsc) increased from 12.40 mA cm–2 to 15.10 mA cm–2, and the conversion efficiency increased from 6.64 to 7.42% when nominal 50 ppm (ppm) W-doped TiO2 was adopted.