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O: Fachverband Oberflächenphysik

O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory

O 36.2: Poster

Dienstag, 1. April 2014, 18:30–22:00, P1

Self organization driven structure formation of DIP molecules on Cu(111) — Hazem Aldahhak, •Wolf Gero Schmidt, and Eva Rauls — Theoretische Physik, Universität Paderborn

Thin films of organic molecules like diindenoperylene (DIP) on metal substrates are of great interest for the further miniaturization of organic optoelectronic devices. DIP molecules show an interesting behavior on different terraces. While step edges have rare influence on the azimuthal molecular orientation of DIP-molecules on Cu(100) [1], they control the molecular crystallographic directions on Au(111) independently of the underlying surface symmetry [2]. On Cu(111), the self-assembly depends on the terrace width. On narrow terraces (<15 nm), the DIP molecules assemble in a co-directionally oriented adsorption pattern, the symmetry of which is not dictated by the hexagonal substrate symmetry [3]. On wider terraces, in contrast, completely different adsorption patterns with a short-range order determined by the underlying substrate are observed. We performed first principles calculations and investigated the balance between intermolecular and molecule-substrate interactions. Special focus is put on the role of step-edges to initiate the molecular self-assembly depending on the terrace width. Based on our investigations, we deduced a model which explains the experimental observations.

[1] Zhang et al., Surface Science, 603(2009) 3179. [2] De Oteyza et al., Journal of Physical Chemistry C 112, 18 (2008) 7168. [3] De Oteyza et al., Phys. Chem. Chem. Phys. 11, 8741 (2009).