Characterization of sputtered triple layer photoactive coating with a glass-like appearance

Photocatalytic activity of sputtered TiO₂ single layer was investigated. From the results on the optical constants analyses and dark- and photo-conductivity measurements, it is revealed that the photocatalytic activities of TiO₂ films depend on the defect density of the TiO₂ films; the atomic defects act as recombination sites for photo-generated carriers diffusing to the TiO₂ surface. A three-layer system with a layer construction of SnO₂/TiO₂/Si₃N₄/Glass was designed for realizing the glass-like appearance, namely almost the same transmission and reflection spectra in visible wavelength region as those of glass, and its photocatalytic activity was investigated. The experimental results indicate that the interface between TiO₂ and SnO₂ acts as a potential barrier for the carriers photo-generated in the TiO₂ and the photo-generated species pass through the SnO₂ overlayer depending on the SnO₂ film characteristics.