Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Metal substrates: Adsorption of organic / bio molecules II
O 14.7: Vortrag
Montag, 22. März 2010, 16:30–16:45, H36
Impact of the backbone on the electronic structure of SAMs on gold — •LinJun Wang1,2, Gerold M. Rangger3, Lorenz Romanner4, Tomas Bučko5, ZhongYun Ma1, QiKai Li1, Zhigang Shuai1,6, Egbert Zojer3, and Georg Heimel7 — 1Institute of Chemistry, Chinese Academy of Sciences, Beijing, PR China — 2Chemistry of Novel Materials, University of Mons Hainaut, Mons, Belgium — 3Institute of Solid State Physics, Graz University of Technology, Graz, Austria — 4Department of Material Physics, University of Leoben, Leoben, Austria — 5Fakultät für Physik and Center for Computational Materials Science, Universität Wien, Wien, Austria — 6Department of Chemistry, Tsinghua University, Beijing, PR China — 7Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
Modifying metal electrodes with self-assembled monolayers (SAMs) has promising applications in organic/molecular electronics. Through a comprehensive DFT study on a series of organic thiols on Au(111) surfaces, the impact of the chemical structure of the molecular backbone on the interface electronic structure is discussed. It is found that the backbone significantly impacts the alignment of the SAM conducting states relative to the metal Fermi level; for molecules with small ionization potentials, Fermi-level pinning is observed. For the work-function modification due to SAM adsorption, the main impact of the backbone arises from its influence on the molecular orientation on the surface. The polarizability is of only minor importance as the larger molecular dipole moments achieved with more polarizable backbones are largely compensated by increased depolarization.