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Excited State Dynamics of Thermally Activated Delayed Fluorescence from an Excited State Intramolecular Proton Transfer System

Long, Yun; Mamada, Masashi; Li, Chunyong; dos Santos, Paloma Lays; Colella, Marco; Danos, Andrew; Adachi, Chihaya; Monkman, Andrew

Excited State Dynamics of Thermally Activated Delayed Fluorescence from an Excited State Intramolecular Proton Transfer System Thumbnail


Authors

Yun Long

Masashi Mamada

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Dr Chunyong Li chunyong.li@durham.ac.uk
Laser Science Experimental Officer

Paloma Lays dos Santos

Marco Colella

Chihaya Adachi



Abstract

We describe the photophysical processes that give rise to thermally activated delayed fluorescence in the excited state intramolecular proton transfer (ESIPT) molecule, triquinolonobenzene (TQB). Using transient absorption and time-resolved photoluminescence spectroscopy, we fully characterize prompt and delayed emission, phosphorescence, and oxygen quenching to reveal the reverse intersystem crossing mechanism (rISC). After photoexcitation and rapid ESIPT to the TQB-TB tautomer, emission from S1 is found to compete with thermally activated ISC to an upper triplet state, T2, very close in energy to S1 and limiting photoluminescence quantum yield. T2 slowly decays to the lowest triplet state, T1, via internal conversion. In the presence of oxygen, T2 is quenched to the ground state of the double proton transferred TQB-TC tautomer. Our measurements demonstrate that rISC in TQB occurs from T2 to S1 driven by thermally activated reverse internal conversion from T1 to T2 and support recent calculations by Cao et al. (Cao, Y.; Eng, J.; Penfold, T. J. Excited State Intramolecular Proton Transfer Dynamics for Triplet Harvesting in Organic Molecules.

Journal Article Type Article
Acceptance Date Apr 3, 2020
Online Publication Date Apr 15, 2020
Publication Date May 7, 2020
Deposit Date Apr 20, 2020
Publicly Available Date Apr 21, 2020
Journal Journal of Physical Chemistry Letters
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 11
Issue 9
Pages 3305-3312
DOI https://doi.org/10.1021/acs.jpclett.0c00498
Public URL https://durham-repository.worktribe.com/output/1272669

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http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Advance online version This is an open access article published under a Creative Commons Attribution (CC-BY)
License, which permits unrestricted use, distribution and reproduction in any medium,
provided the author and source are cited.






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