TY - JOUR
T1 - Substitution Effects on a New Pyridylbenzimidazole Acceptor for Thermally Activated Delayed Fluorescence and Their Use in Organic Light-Emitting Diodes
AU - Hall, David
AU - Rajamalli, Pachaiyappan
AU - Duda, Eimantas
AU - Suresh, Subeesh Madayanad
AU - Rodella, Francesco
AU - Bagnich, Sergey
AU - Carpenter-Warren, Cameron L.
AU - Cordes, David B.
AU - Slawin, Alexandra M.Z.
AU - Strohriegl, Peter
AU - Beljonne, David
AU - Köhler, Anna
AU - Olivier, Yoann
AU - Zysman-Colman, Eli
N1 - Funding Information:
The St Andrews team would like to thank the Leverhulme Trust (RPG-2016-047) for financial support. P.R. acknowledges support from a Marie Skłodowska-Curie Individual Fellowship (MCIF; No. 749557). S.M.S. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship, Grant Agreement No. 838885 (NarrowbandSSL). 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 No. 1117545. The authors acknowledge support from the European Union's Horizon 2020 research and innovation programme under the Innovative Training Network TADFlife (No. 812872). 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.
Funding Information:
The St Andrews team would like to thank the Leverhulme Trust (RPG‐2016‐047) for financial support. P.R. acknowledges support from a Marie Skłodowska‐Curie Individual Fellowship (MCIF; No. 749557). S.M.S. acknowledges support from the Marie Skłodowska‐Curie Individual Fellowship, Grant Agreement No. 838885 (NarrowbandSSL). 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 No. 1117545. The authors acknowledge support from the European Union's Horizon 2020 research and innovation programme under the Innovative Training Network TADFlife (No. 812872). 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.
Publisher Copyright:
© 2021 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH
PY - 2021/10/18
Y1 - 2021/10/18
N2 - In this work a new acceptor is used for use in thermally activated delayed fluorescence (TADF) emitters, pyridylbenzimidazole, which when coupled with phenoxazine allows efficient TADF to occur. N-functionalization of the benzimidazole using methyl, phenyl, and tert-butyl groups permits color tuning and suppression of aggregation-caused quenching (ACQ) with minimal impact on the TADF efficiency. The functionalized derivatives support a higher doping of 7 wt% before a fall-off in photoluminescence quantum yields is observed, in contrast with the parent compound, which undergoes ACQ at doping concentrations greater than 1 wt%. Complex conformational dynamics, reflected in the time-resolved decay profile, is found. The singlet−triplet energy gap, ΔEST, is modulated by N-substituents of the benzimidazole and ranges of between 0.22 and 0.32 eV in doped films. Vacuum-deposited organic light-emitting diodes, prepared using three of the four analogs, show maximum external quantum efficiencies, EQEmax, of 23.9%, 22.2%, and 18.6% for BIm(Me)PyPXZ, BIm(Ph)PyPXZ, and BImPyPXZ, respectively, with a correlated and modest efficiency roll-off at 100 cd m–2 of 19% 13%, and 24% of the EQEmax, respectively.
AB - In this work a new acceptor is used for use in thermally activated delayed fluorescence (TADF) emitters, pyridylbenzimidazole, which when coupled with phenoxazine allows efficient TADF to occur. N-functionalization of the benzimidazole using methyl, phenyl, and tert-butyl groups permits color tuning and suppression of aggregation-caused quenching (ACQ) with minimal impact on the TADF efficiency. The functionalized derivatives support a higher doping of 7 wt% before a fall-off in photoluminescence quantum yields is observed, in contrast with the parent compound, which undergoes ACQ at doping concentrations greater than 1 wt%. Complex conformational dynamics, reflected in the time-resolved decay profile, is found. The singlet−triplet energy gap, ΔEST, is modulated by N-substituents of the benzimidazole and ranges of between 0.22 and 0.32 eV in doped films. Vacuum-deposited organic light-emitting diodes, prepared using three of the four analogs, show maximum external quantum efficiencies, EQEmax, of 23.9%, 22.2%, and 18.6% for BIm(Me)PyPXZ, BIm(Ph)PyPXZ, and BImPyPXZ, respectively, with a correlated and modest efficiency roll-off at 100 cd m–2 of 19% 13%, and 24% of the EQEmax, respectively.
KW - DFT calculations
KW - organic light-emitting diodes
KW - photophysics
KW - pyridylbenzimidazole
KW - thermally activated delayed fluorescence
UR - http://www.scopus.com/inward/record.url?scp=85111656464&partnerID=8YFLogxK
U2 - 10.1002/adom.202100846
DO - 10.1002/adom.202100846
M3 - Article
AN - SCOPUS:85111656464
SN - 2195-1071
VL - 9
JO - Advanced Optical Materials
JF - Advanced Optical Materials
IS - 20
M1 - 2100846
ER -