Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 85: Poster Session II
HL 85.11: Poster
Donnerstag, 17. März 2011, 18:00–21:00, P4
Optical properties of crystalline and amorphous TiO2 modifications — •Marc Landmann1, Thomas Köhler2, Eva Rauls1, Thomas Frauenheim2, and Wolf Gero Schmidt1 — 1Lehrstuhl für Theoretische Physik, Universität Paderborn, Germany — 2Bremen Center for Computational Materials Science, Germany
In its crystalline form TiO2, is traditionally used as a pigment in industrial applications. Moreover, TiO2 surfaces are among the most studied substrates in catalysis and used as a template for crystalline organic film growth for both light-emitting diodes and field-effect transistor applications [1]. TiO2 also offers the possibility of low cost dye-sensitized solar cells based on optically transparent films of nanocrystalline TiO2. To fully exploit the technological potential of TiO2, a detailed understanding of the bulk and surface optical properties is required. Here, we have calculated the optical response of ordered rutile, anatase and brookite bulk material as well as of the the rutile (110)(1x1) surface. The calculations have been done on the density-functional theory (RPA), quasiparticle (GW) and Bethe-Salpeter equation (BSE) level of theory [2]. The results are interpreted in terms of self-energy and excitonic contributions to the optical spectra and compared with the available experimental data and previous calculations [3]. We find characteristic differences between the various bulk phases as well as between the crystalline and amorphous material.
[1] G. Koller et al. Adv. Mater. 16, 2159 (2004).
[2] W. G. Schmidt et al. Phys. Rev. B 67, 085307 (2003).
[3] H. Sano et al. Phys. Rev. B 70, 125411 (2004)