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 104.2: Vortrag
Freitag, 22. März 2024, 10:45–11:00, MA 004
Ultrafast Charge-Transfer in Spiro-Bridged Triphenylamine Derivatives Investigated by Broadband Transient Absorption Spectroscopy — •Danyellen Galindo1, Angelina Jocic2, Anna Weidlich Weidlich3, Frank Rominger2, Thomas Oeser2, Jonathan Zerhoch1, Felix Deschler1, Andreas Drew3, Milan Kivala2, and Tiago Buckup1 — 1PCI, Universität Heidelberg, Heidelberg — 2OCI, Universität Heidelberg, Heidelberg — 3IWR, Universität Heidelberg, Heidelberg
Triphenylamine compounds (TPA) are studied in order to understand their photochemical processes such as charge transfer (CT). This investigation is motivated by their ability in stabilizing positive charges through a delocalize π-system, thereby facilitating hole transport. This work aimed to study the optical properties of Spiro-bridged Fluorene N-heterotriangulenes (FTN-H) and FTN-(CN)6. Both compounds, dissolved in dichloromethane (DCM), underwent transient absorption experiments with 300 nm excitation. Initial findings suggest that the solvent does not play a significant role in the CT process. The non-subsituted compound upon excitation simultaneously displayed S1 electronic band for the molecule core and fluorene side group, succeeded by a 2 ns inter-system crossing (ISC) transition, thus forming a triplet state T*1 that decays to S0 with time constant of 16 *s. FTN-(CN)6 exhibited overall comparable dynamics, but also displayed an ultrafast CT between S1 and T*1 states. Such CT, which can be observed in various donor-acceptor materials, hints at potential applications in solar energy conversion and storage systems.
Keywords: triphenylamine; hole transport; charge transfer; transient absorption; energy conversion