Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 12: Organic Molecules at Surfaces 2: Characterization of Organic Monolayers
O 12.6: Talk
Monday, September 5, 2022, 16:15–16:30, S051
Surface Chemical Bond and Molecular Topology of Polycyclic Aromatic Systems — •Lukas Ruppenthal1, Florian Münster1, Benedikt P. Klein1, Jan Herritsch1, Leonard Neuhaus1, Stefan R. Kachel1, Pengcai Liu2, Xing-Yu Chen2, Jiawen Cao2, Lars E. Sattler3, Sebastian M. Weber3, Qitang Fan1, Gerhard Hilt3, Xiao-Ye Wang2, and J. Michael Gottfried1 — 1Department of Chemistry, Philipps-University Marburg, Germany — 2College of Chemistry, Nankai University Tianjin, China — 3Institute of Chemistry, Carl von Ossietzky University Oldenburg, Germany
Metal/organic interfaces have a large impact on the performance of organic (opto-)electronic devices. Therefore, the detailed understanding of their chemical, electronic and geometric structure is important for the further technological development. Many common organic semiconductors contain π-electron systems with alternant topologies, whereas non-alternant alternatives have only recently found increasing attention due to their unusual electronic properties. Here, we compare the alternant polycyclic aromatic molecule pyrene with its non-alternant isomers acepleiadylene and azupyrene regarding their interaction with Cu(111) surface, using PES, NEXAFS, TPD and STM. The non-alternant isomers are also interesting as molecular models of graphene defects, e.g. azupyrene for the Stone-Wales defects. In all cases, the non-alternant isomers show increased metal/molecule-interaction due to their reduced HOMO-LUMO gap, which brings the LUMO energetically closer to the Fermi energy of the metal, causing stronger hybridization with electronic states of the metal surfaces.