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O: Fachverband Oberflächenphysik
O 47: Poster Session IV: Organic molecules on inorganic substrates: networks and overlayers
O 47.1: Poster
Tuesday, March 2, 2021, 13:30–15:30, P
Alkali Doping Leads to Charge-Transfer Salt Formation in a Two-Dimensional Metal Organic Framework — •Billal Sohail1, Phil Blowey1,3, Giovanni Costantini1, Phil Woodruff2, 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 electronic devices such as organic photovoltaics (OPVs). In such devices, strong donors such as alkali atoms and acceptor molecules, such as TCNQ (7,7,8,8,-tetracyanoquinodimethane), are added to organic electronics devices to tune the charge interjection properties at the metal-organic interfaces. We present a joint computational and experimental study to examine the intricate coupling of geometry and electronic structure of TCNQ coadsorbed with potassium atoms on Ag(111), which forms a strongly interacting organic salt. Conversely, pure TCNQ on Ag(111) forms strongly surface-bound adlayers containing silver adatoms. Quantitative agreement between theory and experiment required the rescaling of dispersion coefficients to account for strong charge transfer. We further identify the energetic driving force for organic salt formation and discuss the intricate competition between donor, acceptor and metal substrate.