Dresden 2009 – wissenschaftliches Programm
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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices
SYOP 4: Organic Photovoltaics: from Single Molecules to Devices
SYOP 4.21: Poster
Donnerstag, 26. März 2009, 16:30–19:00, P1A
Temperature induced structural changes of P3HT thin films — •Souren Grigorian1, Siddharth Joshi1, Patrick Pingel2, Tobias Panzner1, Ullrich Pietsch1, Achmad Zen3, Dieter Neher2, Michael Forster4, and Ullrich Scherf4 — 1Solid State Physics, Universität Siegen — 2Institute of Physics and Astronomy, University of Potsdam — 3Inst. of Mat. Res.&Eng., Research Link, Singapore — 4Macromolecular Chemistry, University of Wuppertal
Current study is focus on the temperature dependent crystalline structure of spin coated thin films of high molecular weight regioregular poly(3-hexylthiophene) (P3HT) (Mn ~ 30000) and its correlation with charge carrier mobility [1]. Crystalline structure reveal temperature-dependent anisotropy: interlayer lattice spacing (100) along the film normal continuously increases up to a temperature of about 180 ° C and in opposite the in-pane p-p distance becomes smaller compared to the values measured at room temperature. These structural changes are reversible and can be repeated several times. Regarding the electrical properties we find a rather constant mobility up to a temperature of ca. 100-120 °C, followed by a continuous decrease. Upon cooling back to room temperature, the electrical properties almost recover. The drop of the charge carrier mobility at higher temperatures is explained by the creation of numerous small crystallites at the film-substrate interface reducing the number of long polymer chains bridging crystalline domains.
1.S. Joshi, S. Grigorian, P. Pingel, T. Panzner, U. Pietsch, A. Zen, D. Neher, M. Forster, U. Scherf, Macromolecules, 2008, (submitted)