Optical and structural properties of nanocrystalline anatase (TiO2) thin films prepared by non-aqueous sol-gel dip-coating

E. Haimi (Corresponding Author), H. Lipsonen, J. Larismaa, Markku Kapulainen, J. Krzak-Ros, S-P. Hannula

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    Abstract

    Anatase (TiO2) thin films were grown by non-aqueous sol-gel dip-coating using titanium (IV) n-butoxide as precursor and 1-butanol as solvent. High withdrawal speed of 4.7 mm/s in dip-coating resulted in defect free films of 100 nm average film thickness after subsequent heat treatments. According to scanning electron microscope and X-ray diffraction measurements, the films consisted of nanocrystalline anatase with 30 nm mean crystallite size. Refractive index n(λ) and extinction coefficient k(λ) were determined over the wavelength range from 200 to 1650 nm. The optical band gap of the film material was approximately 3.2 eV. The results showed very similar optical characteristics to those that are accomplished with chemically more reactive aqueous sol-gel processes. Furthermore, it was found that in addition to porosity, coordination number of Ti atoms to nearest oxygen neighbors is likely to have a significant role in explaining differences of optical properties between bulk anatase and thin film materials of the present work.
    Original languageEnglish
    Pages (from-to)5882-5886
    Number of pages5
    JournalThin Solid Films
    Volume519
    Issue number18
    DOIs
    Publication statusPublished - 2011
    MoE publication typeA1 Journal article-refereed

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    Keywords

    • anatase
    • non-aqueous sol-gel
    • optical properties
    • thin film
    • Titanium dioxide
    • Wemple-DiDomenico model

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