title: The Metal/Organic Interface - Binding, Adsorption Geometry, and Electronic Structure
creator: Maaß, Friedrich
subject: ddc-530
subject: 530 Physics
subject: ddc-540
subject: 540 Chemistry and allied sciences
description: Metal/organic interfaces as they appear between electrodes and organic semiconductors in organic electronics decisively determine device properties of transistors, light emitting diodes, or photovoltaic cells. The interactions within the organic semiconductor and between organic adsorbate and metallic substrate lead to characteristic properties of the particular interface. These properties, namely the binding strength, the adsorption geometry, and the electronic structure, have been studied with comprehensive surface sensitive experimental methods like high-resolution electron energy-loss spectroscopy (HREELS) and temperature-programmed desorption (TPD). The use of single crystal metal surfaces as substrates and self-assembling small organic molecules as adsorbates lead to insights into structure-property relationships that will contribute to the further development of materials and devices.    The first part of this work investigates the bonding strength between metal substrates and organic adsorbates. With the quantification of binding energies of simple aromatic molecules on coinage metal surfaces by means of TPD, this part enters questions of basic surface science. Besides the delivery of benchmarks of unrivalled accuracy for the further development of computational methods to model binding properties of adsorbate-covered surfaces the focus of this part also lays on the first investigation of the extraordinary coverage dependency of the binding energy of such systems.   The second part is about the self-assembly of small-molecule organic semiconductors on metal surfaces, and how this arrangement is influenced by the molecular structure. This part covers the elucidation of adsorption geometries of N-heteropolycyclic aromatic molecules on the Au(111) surface by means of vibrational HREELS. Moreover, electronic HREELS enabled us to get insight into the electronic structure of these interfaces. To maximize the interaction between metal bands and the pi-system of the adsorbate the planar molecules prefer a planar adsorption geometry. This presetting of a flat geometry works subsequently as a template for further layers which leads to a growth mechanism and therefore film structure significantly different from that of the bulk crystal.  The last part of this work studies the influence of organic adsorbate films on collective electronic properties of the metal surface with angle-resolved HREELS. Characteristic collective excitations of a two-dimensional electron gas present on the pristine gold surface are strongly influenced in their properties by adsorbate layers, e.g., they show a strongly enhanced intensity and a varied dispersion relation.
date: 2018
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/25641/1/Diss_FMaass.pdf
identifier: DOI:10.11588/heidok.00025641
identifier: urn:nbn:de:bsz:16-heidok-256413
identifier:   Maaß, Friedrich  (2018) The Metal/Organic Interface - Binding, Adsorption Geometry, and Electronic Structure.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/25641/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng