Electronic properties of Nano-porous TiO2- and ZnO-Thin Films-comparison of simulations and experiments

Wilfried Wunderlich, Torsten Oekermann, Lei Miao, Nguyen Thi Hue, Sakae Tanemura, Masaki Tanemura

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The electronic properties of anatase, rutile and ZnO thin films are of interest for many applications such as photocatalysis, or dye-sensitised solar cells. This paper describes the correlation between microstructure and electronic properties of photoactive TiO2 and ZnO thin films, which are based on experimental data and are interpreted by ab-initio simulations. This study considers the influence of three main factors on the optical and electrical properties: Strain of epitaxially grown thin films, nano-particle- and nano-pore- structures, and finally the interface to adsorbed dye molecules. The first part describes the search for a suitable substrate to grow titania layers with a smaller band-gap and ab-initio simulations showed excellent agreement to the experimental data. A narrow band gap is predicted for strained lattice constants in the a-direction and compressed in the c-direction. The second part describes the fabrication of nano-porous thin films by sol-gel processing using appropriate precursor solutions (titanium-tetra-iso-propanol (TTIP), di-ethanol-amine (DEA)) applied on suitable nano-templates. Due to the surface curvatures the nano-porous TiO2 has a narrow band gap, while nano-particles of titania show a larger band-gap. In the third part Dvxα ab-initio simulations were applied to dye-sensitized solar cells (DSSC), based on ZnO and TiO2. The results are compared to experimental data obtained for different dyes on nanoporous electrodeposited ZnO films. The ranking in efficiency found experimentally for the different combinations could be explained by the calculation results. This finding is discussed in the view of further optimization of solar cells.

Original languageEnglish
Pages (from-to)343-354
Number of pages12
JournalJournal of Ceramic Processing Research
Volume5
Issue number4
Publication statusPublished - 2004
Externally publishedYes

Keywords

  • Ab-initio calculations
  • Band gap
  • Dye-sensitized solar cells
  • Electronic orbitals
  • Epitaxial thin films
  • Nano-porous titania
  • Photo-catalyst

ASJC Scopus subject areas

  • Ceramics and Composites

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