Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 14: Poster I

HL 14.41: Poster

Montag, 24. März 2003, 17:00–19:30, HSZ/P2

P3HT films : Cristalline order, electronic and optical properties — •Stefan Hugger, Ingo Blum, Marcel Lorenz, Thomas Thurn-Albrecht, and Thomas Heinzel — Institut für Physik, Hermann-Herder-Str.3, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg i. Br.

We report about structural and electronic investigations of regioregular Poly(3-hexylthiophene) films. Using x-ray diffraction measurements, we determined the cristalline order and orientation of P3HT films. It is demonstrated that even films of several microns thickness show a bulk orientation with respect to the substrate (SiO₂). DSC and x-ray measurements reveal a phase transition into a liquid crystalline state at 230 degree Celsius, consisting of a layered structure in which the thiophene backbones and the hexyl side chains are microphase separated. Possibly, this preordered state also appears in concentrated solutions and is a crucial prerequisite for fabricating highly ordered films. Furthermore, the lateral structure has been characterized. Cristalline films are birefringent, and in some cases a large scale anisotropy is found, which is not related to molecular orientation, but most likely caused by form birefringence. The films have been integrated in transistor structures as the active medium. Electronic transport measurements at temperatures between 2K and 300K were carried out, and relations between microscopic structure und electronic properties are discussed.