Heidelberg 2015 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 21: Posters 4: Novelties in Molecular Physics

MO 21.5: Poster

Donnerstag, 26. März 2015, 17:00–19:00, C/Foyer

Excitonic spectral diffusion investigated by collinear 2D-VIS spectroscopy — •Merle Ohlsen, Steffen Wolter, Franziska Fennel, and Stefan Lochbrunner — Institut für Physik, Universität Rostock, 18051 Rostock

Large exciton diffusion lengths are desirable for many organic optoelectronic applications like solar cells. However, the migration distance is often limited by trapping of the excitons due to energetic disorder. A model system consisting of a polymer matrix doped with the perylene bisimide dye Perylene Red has proven to be suitable to investigate the influence of energetic disorder on the mobility of the excitons since its system parameters controlling the relevant processes are well understood [1]. It was shown, that the exciton dynamics in these films are determined by dispersive energy migration on the picosecond timescale. The dynamics can be described by a model based on Förster theory that takes inhomogeneous broadening and energetic disorder of the donor and acceptor states into account [1]. To study the influence of the donor energy on the migration steps, we now focus on the dependence of the dynamics on the optical excitation frequency. To this end a newly implemented collinear 2D-VIS spectrometer based on a pulse shaper is applied. This allows for femtosecond absorption measurements with a site-selective excitation within the inhomogeneously broadened energetic distribution of the Perylene Red molecules.

[1] Fennel F., Lochbrunner, S., Phys. Rev. B, 85, 094203 (2012)