Berlin 2005 – scientific programme

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SYOO: Organic Optoelectronics and Photonics

SYOO 6: Poster

SYOO 6.20: Poster

Monday, March 7, 2005, 18:00–20:00, Poster TU A

Porous Films from Layer-by-Layer Deposition of TiO₂ Nanoparticles and Polyelectrolytes for Photovoltaic Applications — •Kerstin Schulze^1,2 and Stefan Kirstein¹ — ¹Institut für Physik, Humboldt-Universität zu Berlin — ²Hahn-Meitner Institut, Berlin

Dye-sensitized solar cells (DSSCs) are based on photoinduced charge separation at a TiO₂ surface. Staining of the surface with dye molecules is used to shift the absorption from the UV to the visible spectrum. For sufficient absorption of light a very rough and highly porous TiO₂ surface is desired. In this work we report on the preparation and characterization of thin porous films of TiO₂ by alternate adsorption of TiO₂ nanoparticles and various polyelectrolytes from aqueous solutions. It is demonstrated that the adsorption process is independent of electrostatic forces and due to a sol-gel process. The resulting films are growing linearly with the deposition cycles and show high surface roughness, as analyzed by AFM measurements. The current transport through the films is investigated by measuring the current voltage characteristics of ITO/TiO₂/Au structures. Almost ideal thin film Schottky diodes are obtained whereas the parameters were only slightly affected by annealing of the TiO₂ films at a temperature of 400 C. First demonstration samples of DSSCs made of these films are presented.