Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 22: POSTER: INTERNAL SYMPOSIUM Optical Spectrosopy
CPP 22.2: Poster
Mittwoch, 28. März 2007, 16:00–18:30, Poster B
Revealing the Electron-Phonon Coupling in a Conjugated Polymer by Single-Molecule Spectroscopy — •Richard Hildner1, Ulrich Lemmer2, Ullrich Scherf3, Marin van Heel4, and Jürgen Köhler1 — 1Experimentalphysik IV, Universität Bayreuth, 95440 Bayreuth, Germany — 2Lichttechnisches Institut, Universität Karlsruhe (TH), 76131 Karlsruhe, Germany — 3Fachbereich C, Universität Wuppertal, 42097 Wuppertal, Germany — 4Department of Biological Sciences, Imperial College London, London SW7 2AY, United Kingdom
The efficiency of charge- and energy-transfer processes in π-conjugated polymers is strongly determined by their electron-phonon coupling strength. However, the inherent pronounced structural disorder as well as the strong spectral diffusion in this class of functional materials prevented a direct determination of this parameter as yet. Here we employ single-molecule spectroscopy in combination with pattern recognition techniques which allows us to retrieve the profile of the electronic spectrum and concomitantly the electron-phonon coupling strength in a methyl-substituted ladder-type poly(para-phenylene) (MeLPPP). From these data we find a weak electron-phonon coupling for this polymer at low temperatures consistent with the fast excitation energy transfer processes that have been observed for this polymer. Moreover, we find strong evidence that the low-frequency vibrational modes, which are coupled to the electronic transitions, stem from vibrations of the surrounding host matrix indicating an even weaker intra-chain electron-phonon coupling in MeLPPP.