Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.1: Poster

Montag, 8. März 2004, 18:00–21:00, Bereich C

Adsorption properties of Ru-dyes on TiO₂ — •M. Dürr, A. Schmid, S. Rosselli, A. Yasuda, and G. Nelles — Materials Science Laboratories, Sony Int. (Europe) GmbH, D - 70327 Stuttgart

Photosensitization of wide band-gap semiconductor surfaces with organic dye molecules has led to the development of high-efficiency solar cells [1]. Within these cells, which are mainly based on nano-crystalline TiO₂, fast electron transfer from the photo-excited dye to the conduction band of the TiO₂ takes place and the dye molecule is regenerated from a redox couple in electrolyte. Therefore the number of dye molecules adsorbed, the type of binding to the surface as well as the evolution of the dye at the interface are crucial for the solar cell’s operation.

For a better understanding of degradation processes of the cell based on dye desorption into the electrolyte, we have investigated the adsorption properties of Ru-dyes on nano-porous TiO₂ by means of FTIR spectroscopy under ambient conditions. The type of binding of the dye molecule via its carboxylic acid groups on the TiO₂ has been determined. The influence of the number of established bonds per molecule on the desorption properties in ethanol was studied as a model system for the desorption process. For comparison, dye molecules with a reduced number of COOH groups have been investigated.

[1] B. O’Regan and M. Grätzel, Nature 353, 737 (1991).