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MO: Fachverband Molekülphysik
MO 16: Femtosecond Spectroscopy II
MO 16.2: Vortrag
Donnerstag, 12. März 2020, 14:15–14:30, f102
Ultrafast Triplet Formation and Molecular Vibrations in Halogenated Tetraazaperopyrenes — •Nikolaus Wollscheid1, Benjamin Benjamin2, Vaishnavi Rao1, Felix Berger1, Jose L.P. Lustres1, Marcus Motzkus1, Sebastian Höfener3, Jana Zaumseil1, Lutz H. Gade2, and Tiago Buckup1 — 1Institute of Physical Chemistry, Ruprecht-Karls University Heidelberg, Germany — 2Institute of Organic Chemistry, Ruprecht-Karls University Heidelberg, Germany — 3Institut für Physikalische Chemie, Karlsruher Institut für Technologie, Germany
Tetraazaperopyrenes are air-stable n-type semiconductors which can be used in organic field effect transistors. By introducing halogen substituents to the aromatic backbone, structure property relationships such as energy levels can be tuned systematically. [1] This allows for a methodical investigation of photodynamics via femtosecond transient absorption in solution and zonecast thin films. In both cases, triplet formation is observed, occurring on vastly different timescales and via two different pathways: In solution, intersystem crossing is observed on the nanosecond timescale, correlating with substituent mass and energy detuning. In thin films, the triplet states are formed by singlet fission in a much faster time scale. Moreover, Raman activity of low frequency vibrational modes during singlet fission is observed and correlated with the formation of the biexcitonic state. Quantum chemical calculations of electronic states energy and spectra are presented. [1] Hahn et al., Chem. Eur. J., 21, 17691, (2015).