Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 38: Organic Molecules on Inorganic Substrates II: Electronic Properties and Charge Transfer
O 38.8: Vortrag
Dienstag, 2. April 2019, 15:45–16:00, H24
Modifying the tunneling decay coefficients of self-assembled monolayer junctions — Xiaoping Chen1, Harshini Annadata1, •Bernhard Kretz2, David Alexander Egger2, and Christian Nijhuis1,3,4 — 1Department of Chemistry, National University of Singapore, Singapore — 2Institute of Theoretical Physics, University of Regensburg, Regensburg, Germany — 3Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore — 4NUSNNI-Nanocore, National University of Singapore, Singapore
The development and improvement of molecular electronic devices requires insight into charge transport across organic-inorganic interfaces. Charge transfer rates in the quantum tunneling transport regime strongly depend on the tunneling decay coefficient β, which determines the decline of the current across the junction as a function of the length and the barrier height. It is well-known that the value of β of self-assembled monolayer (SAM) junctions depends on the specific electronic structure of the molecular backbone. Combining experiments and computer simulations, we demonstrate that β of a non-conjugated SAM junction can be altered by using different halogens as termination on one side of the molecular backbone. Our experiments indicate that this modification of the tunneling coefficient is correlated with a change in the dielectric constant. Furthermore, our calculations shed some light on how the frontier orbitals and transmission channels are affected by the change of the end-group.