Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 2: Focus Session: Structural Ordering and Electronic Transport I (jointly with CPP)
HL 2.4: Vortrag
Montag, 26. März 2012, 10:30–10:45, ER 270
Formation of Single Crystals of Conjugated Polymers — •Khosrow Rahimi1, Ioan Botiz1,2, Natalie Stingelin2,3, and Günter Reiter1,2 — 1Institute of Physics, University of Freiburg — 2Freiburg Research Institute for Advanced Studies (FRIAS) — 3Imperial College London
In order to improve optoelectronic properties of conjugated polymers, a profound understanding of the excitonic and electronic transport with respect to structure is crucial. By gaining a precise control over both molecular conformations and morphology we aim to obtain a correlation between orders at a macromolecular level to charge transport properties. The best controlled system for such a study is a single crystal which is free of grain boundaries and molecular disorder/defects.
Here, we report the preparation and structural properties of Poly(3-hexylthiophene) single-crystal grown by crystallization in dilute solutions. By employing a self-seeding approach, we were able to circumvent the nucleation process. To this end, we first dissolved all but a few small thermodynamically stable crystals, which then act as nuclei (seed crystals) for the subsequent crystallization step at higher polymer concentrations or at lower temperatures. This approach extends the accessible range for crystallization to lower degrees of supersaturation or supercooling. Using such conditions, we could control crystal size in all three dimensions as well as aspect ratio.