Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 29: Organic/bio Molecules on Metal Surfaces III
O 29.10: Talk
Tuesday, March 12, 2013, 12:45–13:00, H38
Trimesic acid-assisted self-assembly of oligoethynylene-thiophene macrocycles: A donor-acceptor rectifier bilayer — •Jose D. Cojal1, Masahiko Iyoda2, and Jürgen P. Rabe1 — 1Department of Physics, Humboldt-Universität zu Berlin, Berlin, Germany — 2Department of Chemistry, Tokyo Metropolitan University, Tokyo, Japan
Fully conjugated π-expanded macrocyclic oligothiophenes [1] have attracted considerable interest due to their structural and optoelectronic properties. They have been envisaged for photovoltaic applications, host-guest systems and as building blocks of supramolecular nanostructures. Here, a self-assembled monolayer of trimesic acid (TMA) at the interface between its heptanoic acid solution and highly oriented pyrolytic graphite (HOPG) provided a way to template the 2D self-assembly of oligoethynylene-thiophene macrocycles. The so-formed bilayer was confirmed using STM tomography [2], i.e. discrete bias set-point imaging of each layer. Scanning Tunneling Spectroscopy of the macrocycle layer allowed us to determine the HOMO-LUMO gap of the bilayer and the position of the combined frontier orbitals, The I-V characteristics revealed an underneath TMA layer with acceptor (A) characteristics and an upper donor (D) macrocycle layer, forming a D-A rectifier bilayer.
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