Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

Etherington, Marc K.; Kukhta, Nadzeya A.; Higginbotham, Heather F.; Danos, Andrew; Bismillah, Aisha N.; Graves, David R.; McGonigal, Paul R.; Haase, Nils; Morherr, Antonia; Batsanov, Andrei S.; Pflumm, Christof; Bhalla, Vandana; Bryce, Martin R.; Monkman, Andrew P.

doi:10.1021/acs.jpcc.9b01458

Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

Etherington, Marc K.; Kukhta, Nadzeya A.; Higginbotham, Heather F.; Danos, Andrew; Bismillah, Aisha N.; Graves, David R.; McGonigal, Paul R.; Haase, Nils; Morherr, Antonia; Batsanov, Andrei S.; Pflumm, Christof; Bhalla, Vandana; Bryce, Martin R.; Monkman, Andrew P.

Authors

Marc K. Etherington

Nadzeya A. Kukhta

Heather F. Higginbotham

Dr Andrew Danos andrew.danos@durham.ac.uk
Senior Experimental Officer

Aisha N. Bismillah

Mr David Richard Graves d.r.graves@durham.ac.uk
PGR Student Doctor of Philosophy

Dr Paul Mcgonigal paul.mcgonigal@durham.ac.uk
Academic Visitor

Nils Haase

Antonia Morherr

Dr Andrei Batsanov a.s.batsanov@durham.ac.uk
Academic Visitor

Christof Pflumm

Vandana Bhalla

Professor Martin Bryce m.r.bryce@durham.ac.uk
Professor

Professor Andrew Monkman a.p.monkman@durham.ac.uk
Professor

Abstract

We expose significant changes in emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise through the presence of persistent dimer states in thin films and organic light-emitting diodes(OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electroluminescence. The dimer species is sensitive to the sample preparation method and its enduring presence contributes to the widely reported concentration-mediated redshift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has significant implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The significant dimerization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consideration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.

Citation

Etherington, M. K., Kukhta, N. A., Higginbotham, H. F., Danos, A., Bismillah, A. N., Graves, D. R., …Monkman, A. P. (2019). Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials. Journal of Physical Chemistry C, 123(17), 11109-11117. https://doi.org/10.1021/acs.jpcc.9b01458

Journal Article Type	Article
Acceptance Date	Apr 3, 2019
Online Publication Date	Apr 3, 2019
Publication Date	May 2, 2019
Deposit Date	Apr 3, 2019
Publicly Available Date	May 2, 2019
Journal	Journal of Physical Chemistry C
Print ISSN	1932-7447
Electronic ISSN	1932-7455
Publisher	American Chemical Society
Peer Reviewed	Peer Reviewed
Volume	123
Issue	17
Pages	11109-11117
DOI	https://doi.org/10.1021/acs.jpcc.9b01458

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