SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Poster Session VII: Organic molecules on inorganic substrates: electronic, optical and other properties III
O 89.4: Poster
Donnerstag, 4. März 2021, 10:30–12:30, P
Excited state dynamics of terrylene — •Boubacar Tanda Bonkano1,2, Samuel Palato1,2, Sergey Kovalenko1, Lukas Gierster1,2, Bjoern Kobin1, Stefan Hecht1,3, and Julia Staehler1,2 — 1Institut für Chemie, Humboldt-Universität zu Berlin — 2Fritz-Haber-Institut der MPG, Berlin — 3Leibniz-Institut für Interaktive Materialien, RWTH Aachen
In hybrid solar cells, the separation of the electron-hole pairs after photogeneration is a key aspect of the light harvesting functionality. This requires, in hybrid inorganic/organic systems, the use of molecules that have excited states with sufficiently long lifetime to allow charge separation. In order to investigate terrylene molecules, we performed two types of time-resolved spectroscopy, time-correlated single photon counting (TCSPC) and broadband transient absorption (TA) using a white light continuum probe. The steady state absorption and emission spectra of terrylene monomers in solution show mirrored lineshapes. Both the TCSPC and TA consistently show a decay of 3.7 ns for the excited state S1. Thin terrylene film shows absorption bands strongly (> 0.5 eV) blue-shifted due to H-aggregation. Photoexcitation of the H-aggregate leads to the formation of an induced absorption band at 2.3 eV, indicating the presence of transient terrylene monomers. A phenomenological fit model allows for the disentanglement of the participating elementary processes. The determination of the relaxation pathways is challenging but yet necessary for a better understanding and control of terrylene-based systems, beneficial for applications.