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Preparation of photocatalytically active TiOO2R layers on polycarbonate by reactive magnetron sputtering

: Neubert, T.; Werner, O.; Neumann, F.; Vergöhl, M.

Society of Vacuum Coaters -SVC-, Albuquerque/NM:
Society of Vacuum Coaters. 51st Annual Technical Conference 2008. Proceedings : April 19 - 24, 2008, Chicago, IL, USA
Albuquerque: SVC, 2008
Society of Vacuum Coaters (Annual Technical Conference) <51, 2008, Chicago/Ill.>
Conference Paper
Fraunhofer IST ()

The term photocatalysis describes chemical reactions on the surface ofsuitable semiconductors like titanium dioxide (TiO2) or zinc oxide (ZnO) during the irradiation of light with higher photon energies than the optical band gap. These photons generate electron-hole pairs which can diffuse to the surface of the photocatalytically active material where they effect the oxidation of water molecules to hydroxyl radicals (·OH) and the dissociation of molecular oxygen to oxygen radicals (·O). Both types of radicals have an oxidzing effect on organic molecules, like fatty acids. Typical applications for photocatalytik materials are self cleaning, antibacterial and antifogging coatings. To achieve a good photocatalytic activity of the TiO2 polycrystalline material the anatase phase is required. For TiO2 layers made by sputter deposition that means a high energy flux or an additional substrate heating, which will usally lead to the damaging of plastic substrates. In this paper we present a method for the deposition of TiO2 based layers on polycarbonate with a high photoanalytic activity and a good adhesion by reactive magnetron sputter deposition. The photocatalytic decomposition rate of these layers on glass substrates was found to be significantly higher than the rate of commercial photocatalytical glasses. On plastic substrates the same photocatalytic activity like commercial photocatalytic glasses was achieved. Another problem to be solved was the unintended photocatalytic decomposition of the plastic substrate by the TiO2 layer which destabilizes the coating after a short period of UV-irradiation. This effect was avoided by an inorganic layer.