Ultrafast excited state dynamics in 9,9′-bifluorenylidene

Conyard, Jamie, Heisler, Ismael A., Browne, Wesley R., Feringa, Ben L., Amirjalayer, Saeed, Buma, Wybren Jan, Woutersen, Sander and Meech, Stephen R. (2014) Ultrafast excited state dynamics in 9,9′-bifluorenylidene. The Journal of Physical Chemistry A, 118 (31). pp. 5961-5968. ISSN 1089-5639

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Abstract

9,9′-Bifluorenylidene has been proposed as an alternative and flexible electron acceptor in organic photovoltaic cells. Here we characterize its excited state properties and photokinetics, combining ultrafast fluorescence and transient IR measurements with quantum chemical calculations. The fluorescence decay is ultrafast (sub-100 fs) and remarkably independent of viscosity. This suggests that large scale structure change is not the primary relaxation mode. The ultrafast decay populates a dark state characterized by distinct vibrational and electronic spectra. This state decays with a 6 ps time constant to a hot ground state that ultimately populates the initial state with a 20 ps time constant; these times are also insensitive to solvent viscosity. No metastable intermediate structures are resolved in the photocycle after population of the dark state. The implications of these results for the operation of 9,9′-bifluorenylidene as an electron acceptor and as a potential molecular switch are discussed.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry (former - to 2024)
UEA Research Groups:	Faculty of Science > Research Groups > Physical and Analytical Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Light and Energy Faculty of Science > Research Groups > Centre for Photonics and Quantum Science
Depositing User:	Pure Connector
Date Deposited:	03 Nov 2014 15:48
Last Modified:	28 Mar 2025 06:13
URI:	https://ueaeprints.uea.ac.uk/id/eprint/50525
DOI:	10.1021/jp504391s

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