An oligomer approach for blue thermally activated delayed fluorescent emitters based on twisted donor-acceptor units
Date
14/03/2023Author
Grant ID
RPG-2016-047
SRF\R1\201089
812872
838885
Metadata
Show full item recordAbstract
The development of efficient blue donor–acceptor thermally activated delayed fluorescence (TADF) emitters remains a challenge. To enhance the efficiency of TADF-related processes of the emitter, we targeted a molecular design that would introduce a large number of intermediate triplet states between the lowest energy excited triplet (T1) and singlet (S1) excited states. Here, we introduce an oligomer approach using repetitive donor–acceptor units to gradually increase the number of quasi-degenerate states. In our design, benzonitrile (BN) moieties were selected as acceptors that are connected together via the amine donors, acting as bridges to adjacent BN acceptors. To preserve the photoluminescence emission wavelength across the series, we employed a design based on an ortho substitution pattern of the donors about the BN acceptor that induces a highly twisted conformation of the emitters, limiting the conjugation. Via a systematic photophysical study, we show that increasing the oligomer size allows for enhancement of the intersystem crossing and reverse intersystem crossing rates. We attribute the increasing intersystem crossing rate to the increasing number of intermediate triplet states along the series, confirmed by the time-dependent density functional theory. Overall, we reportan approach to enhance the efficiency of TADF-related processes without changing the blue photoluminescence color.
Citation
Duda , E , Madayanad Suresh , S , Hall , D , Bagnich , S , Saxena , R , Cordes , D B , Slawin , A M Z , Beljonne , D , Olivier , Y , Köhler , A & Zysman-Colman , E 2023 , ' An oligomer approach for blue thermally activated delayed fluorescent emitters based on twisted donor-acceptor units ' , Chemistry of Materials , vol. 35 , no. 5 , pp. 2027-2037 . https://doi.org/10.1021/acs.chemmater.2c03438
Publication
Chemistry of Materials
Status
Peer reviewed
ISSN
0897-4756Type
Journal article
Description
Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 812872 (TADFlife) and Grant Agreement No. 838885 (NarrowbandSSL). S.B. acknowledges support from the German Science Foundation (392306670/HU2362). The St Andrews team would like to thank the Leverhulme Trust (RPG-2016-047) for financial support. E.Z.-C. is a Royal Society Leverhulme Trust Senior Research fellow (SRF\R1\201089). S.M.S. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship. Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifiques de Belgique (F.R.S.-FNRS) under Grant No. 2.5020.11, as well as the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles, infrastructure funded by the Walloon Region under the grant agreement n1117545. Y.O. acknowledges funding by the Fonds de la Recherche Scientifique-FNRS under grant no. F.4534.21 (MIS-IMAGINE). D.B. is an FNRS Research Director.Collections
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