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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices

SYOE 8: Poster Session SYOE

SYOE 8.63: Poster

Dienstag, 27. März 2007, 18:00–20:00, Poster B

Investigation of organic heterojunction solar cells by photo-induced absorption — •Toni Müller, Rico Schüppel, Bert Männig, Michael Hoffmann, and Karl Leo — Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden

Investigations on organic heterojunction solar cells have shown an increase of the open-circuit voltage when a spacer is inserted between the photoactive interface of an acceptor and a donor. To improve the understanding of these acceptor/spacer/donor-systems, we have investigated three of these systems. For all three systems, we find an increasing open-circuit voltage with increasing spacer thickness. As a first explanation this increase can be caused by an increased charge carrier density. To test this assumption the systems were analyzed by the means of photo-induced absorption spectroscopy (PIA).

N-N'-dimethylperylene-3,4:9,10-dicarboximide (MePTCDI) was used as absorbing acceptor material. For this material we found a charge carrier signal at a wavelength of 830nm of the probe light. With 4,4',4"Tri(N-carbazolyl)triphenylamine (TCTA) as spacer material a decrease of the charge carrier density with increasing spacer thickness was found. We study and discuss a decrease of lifetimes and a decreased charge carrier generation due to smaller energy differences of the HOMO- and LUMO-levels as possible explanations for that behaviour.