Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 44: P9: Crystallization, Nucleation and Self Assembly
CPP 44.11: Poster
Mittwoch, 18. März 2015, 10:00–13:00, Poster A
Optical waveguiding and anisotropic behavior of large single crystal of thiophene-based oligomers — •Sajedeh Motamen1, Yingying Wang1, Jean-Pierre Malval2, Thibaut Jarrosson3, Françoise Serein-Spirau3, Laurent Simon2, and Günter Reiter1 — 1Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany — 2Institut de Sciences des Materiaux de Mulhouse IS2M, 4 rue des freres Lumiere, 68093 Mulhouse, France — 3Institut Charles Gerhardt de Montpellier, 8 Rue de lEcole Normale, 34296 Montpellier cedex 05, France
Unique properties of conjugated organic molecules are responsible for their remarkable potential as active elements in optoelectronic devices such as field-effect transistors or solar cells. For achieving high performance, ordering of these conjugated molecules within the active layer of these devices has been considered as a promising pathway. Single crystals with unique molecular orientation represent ideal model systems for the corresponding systematic studies. Here, we report the formation of large single crystals of 2,5-dialkoxy-phenylene-thienylene-based oligomers (3TBT). Compared to disordered aggregates in spin-coated thin films, single crystals exhibited a pronounced red shift in absorption and photoluminescence spectra, indicating an increase of the conjugation length. As a consequence of high molecular order, an extremely high dichroic ratio was observed. Without any external stimulation, light could travel along the long axis of the crystal over few hundreds of micrometer. We relate structural properties to this observed optical waveguiding effect, which may be of relevance in applications.