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 38.10: Vortrag
Dienstag, 2. April 2019, 16:15–16:30, H24
Mixed monomolecular films with embedded dipolar groups on Ag(111) — Eric Sauter1, Charles-Olivier Gilbert2, Jean-François Morin2, Andreas Terfort3, and •Michael Zharnikov1 — 1Applied Physical Chemistry, Heidelberg University, 69120 Heidelberg, Germany — 2Département de Chimie and Centre de Recherche sur les Matériaux Avancés,Université Laval, Québec, Canada G1V 0A6 — 3Institut für Anorganische und Analytische Chemie, Universität Frankfurt, 60438 Frankfurt, Germany
We studied the application of the concept of embedded dipole in monomolecular self-assembly to the Ag(111) substrate, using two different types of molecules with either pyrimidine groups embedded into aromatic backbones or ester groups embedded into aliphatic backbones as test systems. The orientation of the embedded group was varied and the molecules with the oppositely oriented dipoles were combined together as mixed self-assembled monolayers (SAMs). Pronounced electrostatic effects of the dipolar groups were observed, reflected, in a consistent manner, by the electrostatic shift in photoemission and by work function variation. The character and extent of these effects could be explained in context of molecular orientation. The pyrimidine-substituted SAMs were found to be especially useful for the electrostatic interface engineering, allowing, in the case of Ag, a flexible tuning of the work function in the ca. 0.85 eV range without changing the character of the SAM-substrate and SAM-ambient interfaces. An analogous behavior can also be expected for other substrates.