|AVS 55th International Symposium & Exhibition|
|Thin Film||Thursday Sessions|
|Session:||Aspects of Thin Films|
|Presenter:||K. Tanaka, Kogakuin University, Japan|
|Authors:||K. Tanaka, Kogakuin University, Japan
I. Takano, Kogakuin University, Japan
|Correspondent:||Click to Email|
TiO2 is anticipated as one of materials which are alternative for existing solar cell technology based on silicon. TiO2 shows relatively high reactivity and chemical stability under UV light whose energy exceeds the band gap of 3.2 eV in the anatase crystalline phase. The sun can provide an abundant source of photons. however, UV light accounts for the only small fraction (～5 %) of the sun’s energy compared to the visible region (45 %). Many techniques have been examined to achieve this purpose, including the doping of TiO2 with transition metals (such as Cr, Fe, Ni, V), but these doped materials suffer from thermal instability and an increased number of carrier recombination centers. Many research groups proposed to replace Oxygen by another anionic species (such as C, P, S, N, F) rather than incorporating transition metals into TiO2. Especially, Nitrogen-doped TiO2 is often used to improve the photocatalytic properties of TiO2 in order to achieve visible light response.1 In this study, the Nitrogen-doped TiO2 film has been prepared by reactive magnetron sputtering using a Ti target in an Ar/N2+O2 gas mixture. Composition and microstructure of these films were investigated by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. Chromatic change of a methylene blue solution was applied to a photocatalytic property. Light irradiation to the TiO2 film in a methylene blue solution was carried out using a commercial sterilizing lamp as ultraviolet light and a commercial fluorescent lamp as visible light. Transmittance of a methylene blue solution was measured by a spectro photometer. Furthermore, photocurrent between the TiO2 film and a platinum electrode was measured by a volt-ampere characteristic using an unresisted ammeter in a KCl solution of 0.5 mol/ℓ. In the case of the Nitrogen-doped TiO2 film, the higher photocatalytic property and photocurrent under a sterilization lamp were obtained at N2 gas flow rate of 0.6 sccm and 0.4-0.5 sccm, respectively. In the case of a fluorescent lamp, the photocatalytic property showed lower transmittance and photocurrent as compared with that of a sterilization lamp. But transmittance and photo current showed the maximum value at N2 gas flow rate around 0.5 sccm, so Nitrogen-dope effect was confirmed under a fluorescent lamp.
1 R.Asahi, et al.; Science, 293(2001)269.