Are the Rates of Dexter Transfer in TADF Hyperfluorescence Systems Optically Accessible?

Haase, Nils; Danos, Andrew; Pflumm, Christof; Stachelek, Patrycja; Brütting, Wolfgang; Monkman, Andrew P.

doi:10.1039/d0mh01666g

Are the Rates of Dexter Transfer in TADF Hyperfluorescence Systems Optically Accessible?

Haase, Nils; Danos, Andrew; Pflumm, Christof; Stachelek, Patrycja; Brütting, Wolfgang; Monkman, Andrew P.

Authors

Nils Haase

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

Christof Pflumm

Dr Patrycja Brook patrycja.stachelek@durham.ac.uk
Royal Society University Research Fellow

Wolfgang Brütting

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

Abstract

Seemingly not, but for unexpected reasons. Combining the triplet harvesting properties of TADF materials with the fast emission rates and colour purity of fluorescent emitters is attractive for developing high performance OLEDs. In this “hyperfluorescence” approach, triplet excitons are converted to singlets on the TADF material and transferred to the fluorescent material by long range Förster energy transfer. The primary loss mechanism is assumed to be Dexter energy transfer from the TADF triplet to the non-emissive triplet of the fluorescent emitter. Here we use optical spectroscopy to investigate energy transfer in representative emissive layers. Despite observing kinetics that at first appear consistent with Dexter quenching of the TADF triplet state, transient absorption, photoluminescence quantum yields, and comparison to phosphor-sensitised “hyperphosphorescent” systems reveal that this is not the case. While Dexter quenching by the fluorescent emitter is likely still a key loss mechanism in devices, we demonstrate that – despite initial appearances - it is inoperative under optical excitation. These results reveal a deep limitation of optical spectroscopy in characterizing hyperfluorescent systems.

Citation

Haase, N., Danos, A., Pflumm, C., Stachelek, P., Brütting, W., & Monkman, A. P. (2021). Are the Rates of Dexter Transfer in TADF Hyperfluorescence Systems Optically Accessible?. Materials Horizons, 8(6), 1805-1815. https://doi.org/10.1039/d0mh01666g

Journal Article Type	Article
Acceptance Date	Apr 8, 2021
Online Publication Date	Apr 8, 2021
Publication Date	Jun 1, 2021
Deposit Date	Apr 8, 2021
Publicly Available Date	Jun 23, 2021
Journal	Materials horizons.
Electronic ISSN	2051-6355
Publisher	Royal Society of Chemistry
Peer Reviewed	Peer Reviewed
Volume	8
Issue	6
Pages	1805-1815
DOI	https://doi.org/10.1039/d0mh01666g
Public URL	https://durham-repository.worktribe.com/output/1250147

Files

Published Journal Article (2.5 Mb)
PDF

Publisher Licence URL
http://creativecommons.org/licenses/by/3.0/

Copyright Statement
This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.