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Institute of Solid State Physics

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Charge Transfer at Mixed Physisorbed/Chemisorbed Interfaces      >> more >>

Inorganic/Organic interfaces are of great relevant to a large variety of applications, ranging from catalysis and corrosion protection to appliances such as large-area OLED-TVs. Of particular interest is the charge-transfer across the interface, which typically governs the overall performance of the system. Depending on the strength of the interaction between substrate and adsorbate, two archetypes for charge-transfer are commonly observed. For strongly interacting, chemisorbed molecules, new bonds are formed and each molecule at the surface becomes fractionally charged. Conversely, if the interaction is weak, i.e. the molecule physisorbs, some molecules acquire an integer electron while others remain neutral.

Some material combinations exhibit two distinct structures, where one is physisorbed and the other chemisorbed. Experimentally, a transition between these can be triggered on a single molecule basis e.g. via voltage pulses STM tips. The main objective of this thesis is to investigate how the electronic structure / charge-transfer mechanism evolves for phases where physisorbed and chemisorbed molecules coexist by using density functional theory calculations. Furthermore, the possibility of using other, more readily available impulses (such as electric fields or optical excitations) to switch between chemisorption and physisorption will be explored.

Oliver Hofmann
Email: o.hofmann@tugraz.at
Tel: 0316 873 8465