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Enhancing Thermally Activated Delayed Fluorescence by Fine-Tuning the Dendron Donor Strength

Title data

Duda, Eimantas ; Hall, David ; Bagnich, Sergey ; Carpenter-Warren, Cameron L. ; Saxena, Rishabh ; Wong, Michael Y. ; Cordes, David B. ; Slawin, Alexandra M. Z. ; Beljonne, David ; Olivier, Yoann ; Zysman-Colman, Eli ; Köhler, Anna:
Enhancing Thermally Activated Delayed Fluorescence by Fine-Tuning the Dendron Donor Strength.
In: The Journal of Physical Chemistry B. Vol. 126 (2022) Issue 2 . - pp. 552-562.
ISSN 1520-5207
DOI: https://doi.org/10.1021/acs.jpcb.1c05749

Abstract in another language

Thermally activated delayed fluorescence (TADF) relies on a small energy gap between the emissive singlet and the non-emissive triplet state, obtained by reducing the wavefunction overlap between donor and acceptor moieties. Efficient emission, however, requires maintaining a good oscillator strength, which is itself based on sufficient overlap of the wavefunctions between donor and acceptor moieties. We demonstrate an approach to subtly fine-tune the required wavefunction overlap by employing donor-dendrons of changing functionality. We use a carbazolyl-phthalonitrile based donor-acceptor core, 2CzPN, as a reference emitter, and progressively localize the hole density through substitution at the 3,6-positions of the carbazole donors (Cz) with further carbazole, (4-tert-butylphenyl)amine (tBuDPA) and phenoxazine (PXZ). Using detailed photoluminescence studies, complemented with Density Functional Theory (DFT) calculations, we show that this approach permits a gradual decrease of the singlet-triplet gap, ΔEST, from 300 meV to around 10 meV in toluene, yet we also demonstrate why a small ΔEST alone is not enough. While sufficient oscillator strength is maintained with the Cz- and tBuDPA-based donor dendrons, this is not the case for the PXZ-based donor dendron, where the wavefunction overlap is reduced too strongly. Overall, we find the donor-dendron extension approach allows successful fine-tuning of the emitter photoluminescence properties.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: PMID: 34995068
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics II - Optoelectronics of Soft Matter
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics II - Optoelectronics of Soft Matter > Chair Experimental Physics II - Optoelectronics of Soft Matter - Univ.-Prof. Dr. Anna Köhler
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 17 Jan 2022 08:44
Last Modified: 08 Feb 2022 12:54
URI: https://eref.uni-bayreuth.de/id/eprint/68363