Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 104: Focus Session: Ultrafast Processes in Organic Semiconductors and Perovskites III (joint session O/CPP)
O 104.3: Vortrag
Freitag, 22. März 2024, 11:00–11:15, MA 004
The effect of the acceptor strength on intramolecular charge separation in quadrupolar dye — •Somayeh Souri1, Katrin WInte1, Daniel Luenemann1, Fulu Zheng2, Mohamed Madjet2, Teresa Kraus3, Elena Mena-Osteritz3, Peter Baeuerle3, Sergei Tretiak4, Antonietta De Sio1, and Christoph Lienau1 — 1Oldenburg University, Germany — 2Bremen University, Germany — 3Ulm University, Germany — 4Los Alamos National Laboratory, USA
Quadrupolar dyes, consisting of two terminal acceptors (A) linked to a central donor (D) are of high relevance for applications in nonlinear optics and photovoltaics. They recently demonstrated exceptional nonadiabatic quantum dynamics. In A-D-A thin films, we have uncovered the existence of intermolecular conical intersections, funneling energy into a lower-lying electronic state within less than 50 fs [1]. This raises the question how the strength of the acceptor group affects the quantum dynamics. Chemical intuition suggests that an increase in acceptor strength may accelerate charge transfer and increase its yield. We synthesize three A-D-A molecules with different acceptor strength and study them in polar solvents using ultrafast spectroscopy with 10fs time resolution. Even though we can distinguish between vibronic coupling-induced charge separation on a sub-100 fs scale and slower solvatochromism, we observe only weak effects of the acceptor group on the dynamics. The results suggest that vibronic coupling-induced excited state symmetry breaking plays a major role in quantum dynamics. [1] A. De Sio et al., Nature Nano 16, 63 (2021).
Keywords: Nonadiabatic dynamics; Quadrupolar dyes; Vibronic coupling; Charge transfer; Ultrafast spectroscopy