Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Inorganic/Organic Interfaces: Electronic Properties II
O 55.3: Vortrag
Mittwoch, 18. März 2015, 15:45–16:00, HE 101
Charge Transport through Molecular Monolayers: Impact of Collective Effects and Docking Groups — •Veronika Obersteiner1, David Egger1,2, Georg Heimel3, and Egbert Zojer1 — 1Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Graz, Austria. — 2Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth, Israel. — 3Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany.
For advancing the exciting field of molecular electronics, a microscopic understanding of charge transport through molecule-based systems is essential. Over the past years, the fundamental physical differences between devices comprising an individual molecule or a homogeneous monolayer have been increasingly acknowledged. Here, we relate those differences to collective electrostatic effects arising from the combined electric fields of all molecules within a monolayer. Employing density functional theory in conjunction with a Green's function approach, we theoretically investigate current-voltage characteristics of metal-molecule-metal systems that comprise either single molecules or an assembly.We show that, depending on the chemical nature of the molecular backbones and the used docking groups, collective effects either significantly increase or decrease the current at a given voltage. As a consequence, the 'ideal' docking group is clearly different for monolayer and single-molecule devices. These insights are also used to design molecules in which collective effects cancel, and thus transport characteristics remain largely unaffected by environmental effects.