Regensburg 2007 – wissenschaftliches Programm
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.8: Poster
Dienstag, 27. März 2007, 18:00–20:00, Poster B
X-ray studies of structure and crystallinity of Poly(3-hexylthiophene) — •Siddharth Joshi1, Souren Grigorian1, Ullrich Pietsch1, Achmad Zen2, and Dieter Neher2 — 1Festkörperphysik, Universität Siegen, Siegen, Germany — 2Institut für Physik, Universität Potsdam, Potsdam, Germany
Poly (3-hexylthiophene) P3HT is one of the most promising π-conjugated polymers used in polymer-electronics and exhibits relatively high charge carrier mobility. Our studies are focussed on the investigation of the structural order and the degree of crystallinity of semi-crystalline films with thickness ~ 50 nm of low-and high-molecular weights materials. Various x-ray scattering geometries have been used in order to determine the vertical and lateral crystalline structures of P3HT films. Based on additional investigations using AFM and TEM we concluded that the thin film of low molecular weight fraction samples consist of highly ordered crystallites with ribbon- or whiskers- like structures embedded in an amorphous matrix. Further, the small charge-carrier mobility in low-Mw films is mainly due to the charge-carriers scattering in the amorphous region. In contrast, the higher mobility in high-Mw fraction can be explained by the fact that this fraction consists of small partially-ordered domains where the chains either folded back into the disordered phase, or interconnect into neighbouring domains creating an efficient inter-chain transport. Also, we have determined the degree of crystallinity for low-and- high molecular weight fractions utilising Ruland's method indicating an increase of crystallinity with increasing the concentration of polymer samples.