Regensburg 2013 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 26: Organic Electronics and Photovoltaics (jointly with CPP, HL, O)
DS 26.10: Vortrag
Mittwoch, 13. März 2013, 18:15–18:30, H33
Bottom-up synthesis of self-aligned conjugated polymers — Sören Krotzky1, •Rico Gutzler1, Vijay Vyas1,2, Bettina Lotsch1,2, and Klaus Kern1,3 — 1Max Planck Institute for Solid State Research, Stuttgart, Germany — 2Department of Chemistry, University of Munich (LMU), Munich, Germany — 3Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, Switzerland
We investigate the synthesis of self-assembled organometallic structures and well-defined long 1D polymers by the surface-supported Ullmann reaction on an Ag(111) surface. The brominated semiconducting precursor molecule (2,7-dibromobenzothieno[3,2-b]benzothiophene) is sublimed under UHV conditions on the crystalline surface where a dehalogenation step is induced at room temperature. STM reveals self-assembly of the dehalogenated ditopic molecule into short organometallic coordination polymers that arrange in a ladder-like monolayer. Annealing to 420 K leads to C-C coupling of the molecules via ejection of the coordinated metal atom. At this temperature the newly formed 1D polymer strands align in a side-by-side manner with three preferred directions with respect to the high-symmetry directions of the surface. DFT calculations show that the length of the synthesized polymers is sufficient to reduce the HOMO-LUMO gap to its value at infinite length of the polymer. Together with the calculated band-structure this suggests possible unidirectional charge mobility within the well-ordered semiconducting polymeric monolayer.