FWF - Computergestützte Nanow - Computational Nanotechnology

Computational Nanoscience: Interfaces between Self Assembled Organic Semiconductors and Metals

The fields of nanotechnology and organic semiconducting materials are of enormous interest both from a scientific as well as from a technological point of view. The present project aims at linking those two areas by investigating possibilities for tuning the electronic properties of organic/inorganic interfaces making use of covalently bound self-assembled monolayers (SAMs). These form central building blocks in numerous nanoscopic devices and new functionalities can be expected making use of the huge variety of conjugated organic compounds. The investigated aspects are of significant relevance for all types of organic electronic or optoelectronic devices as well as for the nascent field of single-molecule electronics. The work will focus on a computational approach based on quantum-mechanical electronic-structure calculations using so called slab-geometries. Additionally, it will rely on very close collaboration with numerous national as well as international collaboration partners engaged in experimental investigations.
Two aspects of particular interest will be how tuning the chemical structure of the adsoprbed molecules affects the alignment between the electronic states inside the semi-conducting SAM and the metal and how SAMs can be used to tune the work functions of metal electrodes.
The central topics will be
to develop general relationships between the chemical structure of the molecules comprising a SAM and the resulting modifications of the properties of the metal/organic interface; here, going beyond our previous research, we will study SAMs with varying polarizabilities of their backbones, SAMs consisting of quinoidal molecules, and in particular the impact of the surrounding molecules, e.g., in mixed monolayers.
We will gain a profound understanding how the detailed nature of the substrate surface affects the properties of the metal/SAM interface; beyond elucidating the detailed bonding chemistry of common docking groups on various metals, we will study the impact of the substrate morphology (including the role of ad-atoms, surface vacancies, and disorder).
Finally, we aim at understanding the electronic properties of organic semiconducting layers grown on top of SAMs bonded to metal substrates. Such multi-layer systems are of particular importance for practical applications.
The eventual goal of this research is to propose a versatile toolbox for tuning the properties of metal/organic interfaces, which is based on the gained fundamental insight generated within the current project. The latter is highly multidisciplinary at the borderline between semiconductor physics, computational physics, organic chemistry and advanced materials design and this combination of different disciplines will help boosting the generated added value.