Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 34: Organic Electronics and Photovoltaics: Simulations and Optics I (jointly with DS, CPP, O)
HL 34.3: Vortrag
Dienstag, 27. März 2012, 10:00–10:15, H 2032
Migration of singlet excitons in thin films of oligothiophene molecules — •Jens Ludwig, Susanne Hintschich, Hannah Ziehlke, Karl Leo, and Moritz Riede — Institut für Angewandte Photophysik, Technische Universität Dresden, 01069 Dresden, Germany
In organic materials, such as thin amorphous films of oligothiophenes, localized singlet excitons constitute the primary photoexcitations. Via Förster Resonant Energy Transfer (FRET) they migrate between different molecular sites, represented by an inhomogeneously broadened density of states (DOS).
Dispersive exciton migration in thin films of dicyano-substituted terthiophenes is probed by time resolved spectroscopy using a streak camera and simulated with a Monte-Carlo program based on thermally activated hopping of excitons. The time-resolved spectral relaxation and its temperature dependence, as well as the energy dependent decay curves are consistently described within this picture. Side chains appended to the backbone of the oligothiophenes impact the morphology and average intermolecular distance and hence significantly influence the efficiency of exciton migration. In this presentation, oligothiophene derivates with different side chains are compared regarding their exciton dynamics in thin films. We also consider energy transfer to C60 in blend layers with the terthiophene derivatives, leading to a very fast quenching of luminescence from the terthiophene molecules.