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Atomic/molecular layer deposition of azobenzene-containing hybrid thin films with reversible photoresponsive behaviour

Wednesday (26.09.2018)
17:00 - 17:15 S1/03 - 226
Part of:

We demonstrate the fabrication of high-quality photoresponsive inorganic-organic thin films of the (Zn-O-C12H10N2-O-)k type prepared by the currently strongly emerging combined atomic/molecular layer deposition (ALD/MLD) technique using azobenzene-4,4’-dicarboxylic acid and diethyl zinc as the organic and inorganic precursors. We moreover fabricate superlattice structures by combining the ALD/MLD process for the hybrid films with the well-known diethylzinc/H2O ALD process for ZnO; in these superlattice thin films crystalline ZnO layers are interspersed with monomolecular layers of azobenzene-4,4’-dicarboxylic acid. The ratio of the ZnO and azobenzene-4,4’-dicarboxylic acid deposition cycles is varied between 199:1 and 1:1, and the structure of the resultant thin films is verified with X-ray diffraction and reflectivity techniques. The reversible photoresponsive behaviour of the films and the effect of films structure on the photoisomerization kinetics are investigated with UV-vis spectroscopy after alternate irradiation with UV and visible light (λ ˃ 450 nm). Inorganic–organic azobenzene-based hybrid and superlattice structures were found to be photoreactive upon 360 nm irradiation. This observation confirms that ALD/MLD technique can be applied for implementation of a photoactive moiety such as azobenzene within the inorganic matrix and provides an attractive and feasible methodology for creating novel light-sensitive materials.

Additional Authors:
  • Prof. Maarit Karppinen
    Aalto University