Dresden 2011 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Poster: Organic Semiconductors

CPP 8.40: Poster

Monday, March 14, 2011, 17:30–19:30, P2

Excitonic coupling in poly(3-hexylthiophene)s - molecular weight and polydispersity effects. — Christina Scharsich¹, Anna Köhler¹, •René Kalbitz², Dieter Neher², Ruth Lohwasser³, Mukundan Thelakkat³, Michael Forster⁴, Sybille Allard⁴, and Ullrich Scherf⁴ — ¹Universität Bayreuth, Experimentalphysik II, 95447 Bayreuth, Germany — ²Universität Potsdam, Physik weicher Materie, 14476 Potsdam-Golm, Germany — ³Universität Bayreuth, Makromolekulare Chemie I, 95447 Bayreuth, Germany — ⁴Universität Wuppertal, Makromolekulare Chemie, 42119 Wuppertal, Germany

The photophysical and electronic properties of regioregular poly(3-hexylthiophene) (P3HT) are of great interest for many applications in the field of organic semiconducting materials such as solar cells and field-effect transistors. Recent research has shown that the charge carrier mobility in P3HT depends not only on the molecular weight, but also on the conformation of the polymer backbone. This was attributed to differences in the intermolecular coupling that exists in weakly aggregated P3HT chains.

By means of absorption and photoluminescence measurements in solution in combination with a Franck-Condon analysis, we determine quantitatively how the coupling strength between the chains and the fraction of aggregated chains formed depend on molecular weight, polydispersity and solvent quality. We use these data to determine the chain conformation in solution. For thin films, we show that we can control the resulting film morphology by pre-aggregates formed in solution.