Main Content

Materials

The range of available material systems is diverse and the University of Marburg offers excellent conditions for collaboration with various experts in the field of preparation of semiconductor materials. In addition to various modifications of organic systems, we are particularly interested in the behavior of mixed systems, where for example molecules with donor character are combined with molecules acting as electron acceptors. Moreover, in combined organic/inorganic semiconductor systems, many questions regarding the excitation dynamics and the influence of the interface are still unresolved. In such mixed systems the transfer of charges or excitons from one component to the other may occur. These transfer processes and various influences on the transfer dynamics can be traced by time-resolved photoluminescence spectroscopy. Furthermore, in some mixed systems, depending on the strength of the coupling between donor and acceptor, special states, so called "charge-transfer excitons", also arise at internal interfaces, and their luminescence provides insights into the nature of the interface.

Example of the formation of an interfacial exciton at an organic/inorganic interface. Organic semiconductors of interest include tetracene or metal phthalocyanines. As an inorganic representative, the structure of a transition metal dichalcogenide is shown in the example.

In addition to molecular systems, we are also interested in solution-processed thin-film semiconductor systems, such as polymer solar cells or hybrid perovskites. The latter have received remarkable research interest in recent years, as they deliver surprisingly high efficiencies as solar cells despite the simplicity of the fabrication process. To further optimize the materials, the nature of the underlying defects must be better understood. Optical spectroscopy makes an important contribution here.