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Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems

Kelly, Daniel; Gomes Franca, Larissa; Stavrou, Kleitos; Danos, Andrew; Monkman, Andrew P.

Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems Thumbnail


Authors

Daniel Kelly

Larissa Franca larissa.gomes-franca@durham.ac.uk
PGR Student Doctor of Philosophy



Abstract

Donor–acceptor (D–A) thermally activated delayed fluorescence (TADF) molecules are exquisitely sensitive to D–A dihedral angle. Although commonly simplified to an average value, these D–A angles nonetheless exist as distributions across the individual molecules embedded in films. The presence of these angle distributions translates to distributions in the rates of reverse intersystem crossing (krISC), observed as time dependent spectral shifts and multiexponential components in the emission decay, which are difficult to directly quantify. Here we apply inverse Laplace transform fitting of delayed fluorescence to directly reveal these distributions. Rather than a single average value, the crucial krISC rate is instead extracted as a density of rates. The modes and widths of these distributions vary with temperature, host environment, and intrinsic D–A torsional rigidity of different TADF molecules. This method gives new insights and deeper understanding of TADF host–guest interactions, as well as verifies future design strategies that target D–A bond rigidity.

Citation

Kelly, D., Gomes Franca, L., Stavrou, K., Danos, A., & Monkman, A. P. (2022). Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems. Journal of Physical Chemistry Letters, 13(30), 6981-6986. https://doi.org/10.1021/acs.jpclett.2c01864

Journal Article Type Article
Acceptance Date Jul 18, 2022
Online Publication Date Jul 26, 2022
Publication Date Aug 4, 2022
Deposit Date Aug 16, 2022
Publicly Available Date Mar 29, 2024
Journal The Journal of Physical Chemistry Letters
Electronic ISSN 1948-7185
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 13
Issue 30
Pages 6981-6986
DOI https://doi.org/10.1021/acs.jpclett.2c01864

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