Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Poster: Organic Semiconductors
CPP 24.19: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
Organic Heteroepitaxy of RGB Nanoneedles — •Martin Oehzelt1, Clemens Simbrunner2, Günther Schwabegger2, Francesco Quochi3, Ingo Salzmann4, Antje Vollmer1, Norbert Koch1,4, and Helmut Sitter2 — 1HZB-BESSY II, Berlin, Germany — 2Inst. Semincond. and Solid State Physics, JKU Linz, Austria — 3Dipartimento di Fisica, Universita di Calgiary, Italy — 4Institut für Physik, HU-Berlin, Germany
Self-assembly processes and organic-organic heteroepitaxy are powerful techniques to obtain highly ordered molecular aggregates. Here we demonstrate that combining both methods allows not only to fabricate highly crystalline and uniaxially oriented self-assembled nanofibers but also to tune their polarized emission. We show that submonolayer coverage of sexithiophene on top of para-sexiphenyl nanofibers is sufficient to change their emission color from blue to green. Triband emission in the red, green, and blue is generated in nanofibers with thicker sexithiophene coverage, where layers of co-oriented crystals are separated by green-emitting molecular sheets. The nanofibers were grown on a dielectric substrate mica and therefore the study of the electronic structure with photoemission is hampered due to sample charging. To solve this problem the same organic heterostructures were grown on HOPG (highly oriented pyrolytic graphite), as evidenced by x-ray diffraction as well as fluorescence measurements. The main difference, however, is that the fibers are not uniaxially oriented any more. Nevertheless, the color-tuning ability and also the crystal plane that makes contact to the substrate surface are preserved on HOPG when compared to mica.