Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Organic-Inorganic Hybrid Systems and Organic Films I
O 5.10: Vortrag
Montag, 20. März 2017, 12:45–13:00, WIL A317
Work function tuning by electron irradiation of aromatic self-assembled monolayers — •Eric Sauter1, Can Yildirim1, Andreas Terfort2, and Michael Zharnikov1 — 1Applied Physical Chemistry, Heidelberg University, 69120 Heidelberg, Germany — 2Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
Self-assembled monolayers are frequently used to manipulate injection barriers in organic electronics by introduction of a specific dipole moment at the interfaces between the electrodes and adjacent organic layers. This is usually achieved by the selection of a proper dipolar terminal tail group comprising the SAM-ambient interface, which was recently complemented by embedding such a group into the molecular backbone. Here we demonstrate that the work function of SAMs can also be adjusted by electron irradiation in a quite broad range and in controlled fashion, as far as these films contain pyridine or pyrimidine group. This effect is demonstrated by the example of several representative aromatic SAMs with either embedded pyrimidine group or terminal pyridine group. The observed behavior is presumably related to specific chemical transformations involving the nitrogen atom in these moieties. The SAMs with the embedded pyrimidine group are then especially attractive since this moiety is decoupled from the SAM-ambient interface. The effect is especially pronounced as far as it is monitored in situ but is partly quenched upon exposure of the irradiated films to ambient which is attributed to the enhanced reactivity of these films to airborne molecules, above all water.