With the help of electronic structure calculations, the project aims at a comprehensive theoretical understanding at the microscopic level of the adsorbate-substrate and adsorbate-adsorbate interactions of functionalized organic molecules on structured oxide surfaces, which eventually shall enable a controlled formation of organic films with specific structural, electronic and optical properties. The first basic interaction, the adsorbate-substrate interaction, is the bonding of organic molecules to pristine oxide surfaces or to low-coordinated sites on structured oxide substrates and the variation of this binding by different linker groups that modify the bonding geometry and strength, which, subsequently, may influence the second important interaction, the adsorbate-adsorbate interaction, as well as the diffusion kinetics and structure formation. The different interactions shall be calculated and analyzed with density-functional methods supplemented by Van-der-Waals corrections and, where necessary, by Hubbard-U approaches. For the investigation of structure formation also semi-empirical methods shall be employed, which enable the treatment of large molecular assemblies on structured oxide surfaces. Adsorbed organic molecules may show new photo-physical and electronic properties originating from the interaction of their frontier states with the substrate electronic structure. Another aim of the project is to analyze and understand these modifications of the molecules and to unravel possible charge transfer processes between the adsorbate and the substrate that are pivotal for applications encompassing photovoltaics, sensing, illumination, and photo-chemistry. To that end, based on density-functional calculations, time-dependent density-functional methods and many-body perturbation-theory methods shall be applied.
