Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 38: Organic Molecules on Inorganic Substrates II: Electronic Properties and Charge Transfer

O 38.7: Vortrag

Dienstag, 2. April 2019, 15:30–15:45, H24

Reliable Modeling of the Charge Transfer Mechanism at Inorganic/Organic Interfaces — •Elisabeth Wruss, Egbert Zojer, and Oliver T. Hofmann — Institute of Solid State Physics, Graz University of Technology, Graz, Austria

Charge transfer between substrate and adsorbate is one of the determining factors for the electronic structure at inorganic/organic interfaces. In this work we raise the question how well this property can be simulated using DFT and how the results are influenced by the chosen methodology as well as by assumptions regarding the interface structure. We focus on hybrid functionals, elucidating the interplay between the charge transfer mechanism (integer vs. fractional charge transfer) and the applied amount of Hartee-Fock-like exchange. As an exemplary system, we use tetrafluoro-1,4-benzoquinone adsorbed on Cu and Cu2O. We find that the simulated charge transfer mechanism is determined by a delicate interplay of the DFT functional and the physical properties of the system, such as hybridization strength, the size of the adsorbed molecule, and the surface polarizability. As a next step, we go beyond the simplified idea of perfect metallic or insulating substrates and include surface defects. By acting as reaction centers, such defects strongly impact the interaction between substrate and adsorbate and lead to charge transfer even in situations in which this would not be expected for idealized systems. Our results highlight that not only a proper choice of the DFT functional, but also the consideration of realistic, defect-afflicted surfaces is crucial for reliably modeling charge transfer at interfaces.