Regensburg 2002 – wissenschaftliches Programm
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SYOH: Organische Halbleiter
SYOH 6: Organic Photovoltaic Cells
SYOH 6.1: Vortrag
Montag, 11. März 2002, 17:15–17:30, H37
Ultrafast spectroscopy of excitons and polaron pairs in conjugated polymer solar cells — •U. Lemmer1, J. G. Müller1, J. Feldmann1, U. Scherf2, M. Scharber3, C. Brabec3, and S. Sariciftci3 — 1Lehrstuhl für Photonik und Optoelektronik, Ludwig-Maximilians-Universität München, 80799 München — 2Institut für Physikalische und Theoretische Chemie, Universität Potsdam, 14476 Golm — 3Christian Doppler Laboratory for Plastic Solar Cells, Johannes Kepler University, A-4040 Linz
Recently, organic solar cells with a power-efficiency of more than 2.5% have been developed. Such devices utilize the photoinduced electron transfer in a composite system comprising a conjugated PPV-type polymer and a functionalized C60 (PCBM). After dissociation of the neutral photoexcitation a spatially separated electron-hole pair (polaron pair) is formed. Depending on the distance of the charges and the electric field the pair will either recombine geminately or fully dissociate. Only the latter process contributes to the photovoltaic response. Using a femtosecond photocurrent correlation technique, we time-resolve the generation of polaron pairs and their recombination dynamics. The experiments are performed on two different conjugated polymer/PCBM samples, MeLPPP/PCBM and MDMOPPV/PCBM. The comparison of the experimental data allows to clarify the role of geminate recombination of polaron pairs and its effect on the performance of organic solar cells and photodetectors.