FWF - EMBEDDED - Tuning the electronic properties of SAMs by embedded molecular dipoles

Project: Research project

Description

The present project aims at providing an atomic-level understanding of the electronic and structural properties of
alkylthiolate based self-assembled monolayers that contain embedded (di)polar functional groups. Such systems are
highly interesting both from a fundamental as well as from an application point of view, as the dipolar groups
induce a potential discontinuity inside the monolayer electrostatically shifting the energy levels in the regions
above and below the dipoles relative to each other. Such SAMs also allow tuning the substrate work-function
independent of the docking chemistry and the identity of the SAM-ambient interface in a controlled manner. New
insights are expected from combining a number of experimental surface-science techniques with quantummechanical
and molecular-dynamics modelling.
The former will be used in the group of Michael Zharnikov and include high-resolution X-ray and ultraviolet
photoelectron spectroscopy, near-edge absorption fine structure spectroscopy, and Kelvin probe measurements. The
simulations, which are to be performed in the group of Egbert Zojer, are ideally complementary to those
experiments and include density-functional theory as well as classical force-field based calculations on metal slabs
covered on one side by the organic adsorbate. To understand the relationship between the molecular structure and
the SAM properties, we will systematically vary the length of the aliphatic chains, the positions of the embedded
dipoles, as well as the chemical functionalities giving rise to the dipoles. The molecules will be provided by the
group of David A. Allara, where also the infrared reflection absorption spectroscopy will be performed.
By combining experiments and simulations we expect in-depths insights into the details of the electrostatic
potential shifts between the parts of the SAM above and below the embedded dipoles and how these shifts are
linked to the induced changes of the substrate work-function (where preliminary experiments and calculations
indicate that this link is not straightforward).
StatusFinished
Effective start/end date15/05/1214/05/15