One of these researchers is Frank Ortmann, Professor of Theoretical Methods in Spectroscopy at TUM. He and his colleagues from Dresden focus more than anything on the mutual interaction between light and material – especially the behavior of what are called excitons. "Excitons are something like the fuel of the sun, which has to be used optimally," explains Ortmann, who is also a member of the "e-conversion" Excellence Cluster. "When light energy in the form of a photon collides with the material of a solar cell it is absorbed and buffered as an excited state. This intermediate state is referred to as an exciton." These charges cannot be used as electrical energy until they reach a specially designed interface. Ortmann and his team have now shown that what are referred to as exciton transport highways can be created using organic dyes.