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Method for accurate experimental determination of singlet and triplet exciton diffusion between thermally activated delayed fluorescence molecules

Jakoby, Marius; Heidrich, Shahriar; Graf von Reventlow, Lorenz; Degitz, Carl; Suresh, Subeesh Madayanad; Zysman-Colman, Eli; Wenzel, Wolfgang; Richards, Bryce S.; Howard, Ian A.

Abstract:
Understanding triplet exciton diffusion between organic thermally activated delayed fluorescence (TADF) molecules is a challenge due to the unique cycling between singlet and triplet states in these molecules. Although prompt emission quenching allows the singlet exciton diffusion properties to be determined, analogous analysis of the delayed emission quenching does not yield accurate estimations of the triplet diffusion length (because the diffusion of singlet excitons regenerated after reverse-intersystem crossing needs to be accounted for). Herein, we demonstrate how singlet and triplet diffusion lengths can be accurately determined from accessible experimental data, namely the integral prompt and delayed fluorescence. In the benchmark materials 4CzIPN and 4TCzBN, we show that the singlet diffusion lengths are (9.1 ± 0.2) and (12.8 ± 0.3) nm, whereas the triplet diffusion lengths are negligible, and certainly less than 1.0 and 1.2 nm, respectively. Theory confirms that the lack of overlap between the shielded lowest unoccupied molecular orbitals (LUMOs) hinders triplet motion between TADF chromophores in such molecular architectures. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000130949
Veröffentlicht am 25.03.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Mikrostrukturtechnik (IMT)
Institut für Funktionelle Grenzflächen (IFG)
Lichttechnisches Institut (LTI)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 21.01.2021
Sprache Englisch
Identifikator ISSN: 2041-6520, 2041-6539
KITopen-ID: 1000130949
Erschienen in Chemical science
Verlag Royal Society of Chemistry (RSC)
Band 12
Heft 3
Seiten 1121–1125
Vorab online veröffentlicht am 16.11.2020
Nachgewiesen in Web of Science
Scopus
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