Project A8 in the SFB 951


Adjusting energy levels of hybrid inorganic/organic heterostructures



Develop a fundamental understanding of the processes determining the energy levels at HIOS interfaces and utilizing such knowledge to tune the alignment with organic semiconductors. A first route to tune energy levels is to use strong donor/acceptor molecules as interlayers, that tune the inorganic's work function.

  • Physisorbed strong donor/acceptor molecules on semiconductors.
  • Covalently bond molecules to semiconductors (self-assembled monolayers formation).
  • Tuning the energy levels of organic semiconductors on such modified semiconductor surfaces.
  • Understanding the processes at the multiple interfaces concerning energy levels, morphology, orientation etc.
  • Transfer such information to other groups of the Collaborative Research Center to optimize understanding and device operation


Research Tools

The emphasis of our research is to measure the energetic structure by means of photoelectron spectroscopy, kelvin probe and UV-Vis spectroscopy. However to reach a sustainable understanding structural/morphological information are most useful to complement the discussion of the energy levels. Differences in orientation, islanding, phase seperation etc. to name a few may influence the results of photoelectron spectroscopy being our main analytical tool. This is of utmost importance for our particular HIOS context involving ZnO and GaN, since those materials exhibit a far more complex surface structure than e.g. metals. Hence techniques as atomic force microscopy, scanning tunneling microscopy, NEXAFS, XSW and XRD are within the scope of our project.