Diindolocarbazole – achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units
David Hall, Kleitos Stavrou, Eimantas Du̅da, Andrew Danos, Sergey Bagnich, Stuart L. Warriner, Alexandra M. Z. Slawin, David Beljonne, Anna Köhler, Andrew P. Monkman, Yoann Olivier, Eli Zysman‐Colman
Abstract
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.