Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 26: Organic-inorganic hybrid systems and organic films III
O 26.8: Vortrag
Dienstag, 13. März 2018, 12:15–12:30, MA 042
Structure and Property Prediction of Tetracene and Pentacene at H:Si(111): A Conceptual Picture for Hybrid Inorganic/Organic Systems — •Svenja Janke1,2, Haiyuan Wang1, Volker Blum2, Sergey Levchenko1, Mariana Rossi1, and Matthias Scheffler1 — 1Fritz Haber Institute of the Max Planck Society, Berlin, Germany — 2Duke University, Durham, USA
Hybrid organic inorganic systems allow to combine the properties of organic and inorganic substances and hence open up a wide field for new materials with tunable properties. In particular, the organic compound offers a large range of functionalities and can be designed to be environmentally benign. As a key example of aromatic molecule-interface systems, we present a first-principles structure search and electronic-property investigation of pentacene (Pc) and tetracene (Tc) adsorbed at the hydrogenated Si(111) surface. The adsorption of single molecules is explored at different thin film coverage conditions with a structure search routine that includes grid- and random-structure search elements. This enables us to identify the most favorable orientation of the acene molecules and, using hybrid functionals, to investigate the level alignment between the organic and inorganic compounds with respect to the possibility of charge transfer: Single Tc and Pc molecules prefer to lie flat on the surface. For both organic molecules, the HOMO lies at the top of the valence band maximum allowing at best little charge transfer. For increasing coverage, we expect a transition to a dense geometry of standing molecules. This work is part of SFB-951 (HIOS).