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O: Fachverband Oberflächenphysik

O 28: Organic Molecules at Surfaces 3: Theory

O 28.1: Vortrag

Dienstag, 6. September 2022, 10:30–10:45, S051

Switchable interfaces based on bistable molecules: tetrachloropyrazine on Pt(111) — •Lukas Hörmann, Andreas Jeindl, and Oliver T. Hofmann — Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria

Organic/inorganic interfaces govern the properties of many organic electronic devices. To imbue devices with additional functionality, it would be useful to make these interface properties reversibly switchable by means of easily accessible external parameters, such as the temperature.

In this work, we realize such a switchable interface with tetrachloropyrazine (TCP) on Pt(111). TCP can either chemisorb or physisorb on the Pt(111) surface, forming a double-well potential with strongly differing adsorption geometries. These allow forming diverse interface structures with notably different work functions and coherent fractions (obtained by X-ray standing wave measurements).

We model this switchable interface using a machine learning algorithm, based on Gaussian process regression. This facilitates structure search for commensurate as well as higher-order commensurate adlayers. We find three different classes of interface structures with varying work functions and coherent fractions and demonstrate that external stimuli, such as temperature and pressure, allow to reversibly shift between these different classes. Based on our insights, we discuss how systems need to be constructed so that the switch between different states leads to an even larger change in their properties.