In order to get a fundamental understanding of the primary processes in organic photovoltaics or light harvesting processes, controlled, isolated aggregates are attached to the surface of large solid rare-gas clusters. Acenes or perylene derivatives as well as donor-acceptor complexes are probed in order to study collective effects. Laser-induced fluorescence excitation and emission spectra will be recorded for a detailed understanding of the vibronic structure of excited aggregates. The use of nanosecond lasers allows both to resolve vibrational levels in high resolution, as well as lifetime measurements and dynamics down to ~1ns by means of time-correlated single-photon counting. In this way, we are able to identify intermolecular collective effects like superradiance, singlet fission and triplet-triplet annihilation. The generation of UV radiation around 200 nm will be implemented in order to get access to dark states via REMPI schemes and photoion or photoelectron detection. (F. Stienkemeier)

Research group of Prof. Stienkemeier