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Electroabsorption Spectroscopy as a Tool to Probe Charge-Transfer and State Mixing in Thermally-Activated Delayed Fluorescence Emitters

De Sa Pereira, Daniel; Menelaou, Christopher; Danos, Andrew; Marian, Christel Maria; Monkman, Andrew P.

Electroabsorption Spectroscopy as a Tool to Probe Charge-Transfer and State Mixing in Thermally-Activated Delayed Fluorescence Emitters Thumbnail


Authors

Daniel De Sa Pereira

Christopher Menelaou

Christel Maria Marian



Contributors

Daniel Pereira drhf75@durham.ac.uk
Other

Abstract

Solid-state electroabsorption is demonstrated as a powerful tool to probe the charge-transfer (CT) character and state mixing in the low energy optical transitions of two structurally similar thermally-activated delayed fluorescent (TADF) materials with divergent photophysical and device performances. The Liptay model is used to fit differentials of the low energy absorption bands to the measured electroabsorption spectra, with both emitters showing CT characteristics and large changes of dipole moments on excitation despite the associated absorption bands appearing structured. High electric fields then reveal transfer of oscillator strength to a state close to the CT in the better performing molecule. With supporting TDDFT-TDA and DFT/MRCI calculations, this state showed ππ* characteristics of a local acceptor triplet that strongly mixes with the σπ* of the CT. The emitter with poor TADF performance showed no evidence of such mixing.

Citation

De Sa Pereira, D., Menelaou, C., Danos, A., Marian, C. M., & Monkman, A. P. (2019). Electroabsorption Spectroscopy as a Tool to Probe Charge-Transfer and State Mixing in Thermally-Activated Delayed Fluorescence Emitters. Journal of Physical Chemistry Letters, 10(12), 3205-3211. https://doi.org/10.1021/acs.jpclett.9b00999

Journal Article Type Article
Acceptance Date May 21, 2019
Online Publication Date May 22, 2019
Publication Date Jun 20, 2019
Deposit Date May 24, 2019
Publicly Available Date Mar 28, 2024
Journal Journal of Physical Chemistry Letters
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 10
Issue 12
Pages 3205-3211
DOI https://doi.org/10.1021/acs.jpclett.9b00999

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
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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