AG TEGEDER

MOLECULAR PROCESSES AT INTERFACES

Research topics:

Our research aims towards an understanding of the mechanisms of electronically and thermally induced elementary processes in molecular ensembles at surfaces and interfaces. In order to study these processes we use the time- and angle-resolved two-photon photoemission (2PPE) spectroscopy, high-resolution electron energy loss spectroscopy (HREELS), core-level spectroscopy, and non-linear optical methods, namely vibrational sum-frequency generation (SFG) and second harmonic generation (SHG).

The focuses of our research are:

• Molecular switching processes at surfaces: The aim of this project is to realize reversible conformational changes in adsorbed molecular switches via optical or thermal excitation in order to change and control the surface functionality.

• Organic materials for applications in optoelectronic and electronic devices: The energetic position of molecular electronic states, i.e., occupied and unoccupied electronic states, the charge carrier dynamics and energetics at interfaces between organic molecules and metal or semiconducting surfaces will be determined. The influence of these parameters on the efficiency of electronic and optoelectronic processes like in organic solar cell or light emitting diodes will be developed.

• Carbon based materials - Graphene nanoribbons: The energetic position of electronic bands, i.e., valence and conduction bands , the charge carrier dynamics, energetics and dispersions of  atomically precise sub-nanometer wide graphene nanoribbons (GNRs) with different widths, edge shapes and degrees of doping will be investiagted.

• Interaction of pi-conjugated molecules with surfaces: Well-ordered and defect-free films with defined interfaces are needed to improve electronic devices based on organic molecules. The growth of such films is dominated by the adsorption structure of the first molecular layer, i.e. the molecules in direct contact with the substrate which is investigated in this project.