TY - JOUR
T1 - Diindolocarbazole - achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units
AU - Hall, David
AU - Stavrou, Kleitos
AU - Duda, Eimantas
AU - Danos, Andrew
AU - Bagnich, Sergey
AU - Warriner, Stuart
AU - Slawin, Alexandra M.Z.
AU - Beljonne, David
AU - Köhler, Anna
AU - Monkman, Andrew
AU - Olivier, Yoann
AU - Zysman-Colman, Eli
PY - 2022/3/7
Y1 - 2022/3/7
N2 - In this work we present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require the presence of acceptor atoms. Based on an in silico design, the compound DiICzMes4 possesses a red-shifted emission, enhanced photoluminescence quantum yield, and smaller singlet-triplet energy gap, ΔEST, than the parent indolocarbazole that induces MR-TADF properties. Coupled cluster calculations accurately predict the magnitude of the ΔEST when the optimized singlet and triplet geometries are used. Slow yet optically detectable reverse intersystem crossing contributes to low efficiency in organic light-emitting diodes using DiICzMes4 as the emitter. However, when used as a terminal emitter in combination with a TADF assistant dopant within a hyperfluorescence device architecture, maximum external quantum efficiencies of up to 16.5% were achieved at CIE (0.15, 0.11). This represents one of the bluest hyperfluorescent devices reported to date. Simultaneously, recognising that MR-TADF emitters do not require acceptor atoms reveals an unexplored frontier in materials design, where yet greater performance may yet be discovered.
AB - In this work we present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require the presence of acceptor atoms. Based on an in silico design, the compound DiICzMes4 possesses a red-shifted emission, enhanced photoluminescence quantum yield, and smaller singlet-triplet energy gap, ΔEST, than the parent indolocarbazole that induces MR-TADF properties. Coupled cluster calculations accurately predict the magnitude of the ΔEST when the optimized singlet and triplet geometries are used. Slow yet optically detectable reverse intersystem crossing contributes to low efficiency in organic light-emitting diodes using DiICzMes4 as the emitter. However, when used as a terminal emitter in combination with a TADF assistant dopant within a hyperfluorescence device architecture, maximum external quantum efficiencies of up to 16.5% were achieved at CIE (0.15, 0.11). This represents one of the bluest hyperfluorescent devices reported to date. Simultaneously, recognising that MR-TADF emitters do not require acceptor atoms reveals an unexplored frontier in materials design, where yet greater performance may yet be discovered.
UR - http://www.scopus.com/inward/record.url?scp=85125882814&partnerID=8YFLogxK
U2 - 10.1039/d1mh01383a
DO - 10.1039/d1mh01383a
M3 - Article
C2 - 35067689
AN - SCOPUS:85125882814
SN - 2051-6355
VL - 9
SP - 1068
EP - 1080
JO - Materials Horizons
JF - Materials Horizons
IS - 3
ER -