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O: Fachverband Oberflächenphysik
O 40: Organic Molecules on Inorganic Substrates III: Electronic, Optical and other Properties
O 40.7: Vortrag
Dienstag, 17. März 2020, 12:00–12:15, REC C 213
Organic alkali salt layer formation as surface decoupling strategy in metal organic thin films: K and TCNQ on Ag(111) — •Billal Sohail1, Luke Rochford1, Phil Blowey1,3, Phil Woodruff2, Giovanni Costantini1, and Reinhard J. Maurer1 — 1Department of Chemistry, University of Warwick, UK — 2Department of Physics, University of Warwick, UK — 3Department of Chemistry, University of Leeds, UK
A detailed characterisation of structure and electronic properties at metal-organic interfaces is crucial for the design of novel molecular electronics devices such as organic photovoltaics (OPVs) and organic field effect transistors (OFETs). In these devices, strong donors such as alkaliatoms and acceptor molecules, such as TCNQ (7,7,8,8-tetracyanoquinodimethane), are often added to organic electronics devices to tune the charge injection properties at the metal-organic interface. We present a joint computational and experimental study to examine the intricate coupling of geometry and electronic structure for TCNQ coadsorbed with potassium atoms on a Ag(111) surface. By combining dispersion-inclusive Density-Functional Theory calculations, x-ray standing wave (XSW), LEED, and STM measurements, we find that K and TCNQ form a strongly interacting organic salt. This stands in contrast to TCNQ on Ag(111), which forms strongly surface-bound adlayers containing silver adatoms. We identify the energetic driving force for organic salt formation and discuss the intricate competition between donor, acceptor, and metal surface.