Erlangen 2022 – scientific programme
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MO: Fachverband Molekülphysik
MO 14: Photochemistry II
MO 14.6: Talk
Wednesday, March 16, 2022, 15:45–16:00, MO-H6
Exciton Diffusion in Perylene Derivative Microcrystals — •Chris Rehhagen1, Alexander Villinger2, and Stefan Lochbrunner1 — 1Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany — 2Institute for Chemistry, University of Rostock, 18051 Rostock, Germany
Improving light harvesting and opto-electronic organic devices relays on our knowledge about the transport mechanism of electronic excitations. The transport efficiency of excitons in molecular systems is strongly influenced by the order of the molecules. Amorphous and crystalline structure represent two extreme cases. In this work, we investigate the exciton dynamics in single organic microcrystals consisting of Perylene Red, a member of the perylene bisimide dye class and exploited already in many applications. We characterize the absorption, emission and geometric properties of single crystals in order to get a detailed view of the intermolecular coupling and the exciton distribution inside an irradiated crystalline sample. X-ray structure analysis reveals an orthorhombic unit cell with a volume of 12 nm3 consisting of eight dye molecules. Spatially resolved time-correlated single photon counting at high excitation powers is used to extract the diffusion properties of the excitons from two-exciton interaction. We find, that the excitons are indeed mobile within the sample and their motion can be described by an incoherent ’hopping’ process. The diffusion length is about 12 nm.