Color tuning of multi-resonant thermally activated delayed fluorescence emitters based on fully fused polycyclic amine/carbonyl frameworks

John Marques dos Santos, Chin Yiu Chan, Shi Tang, David Hall, Tomas Matulaitis, David B. Cordes, Alexandra M.Z. Slawin, Youichi Tsuchiya, Ludvig Edman, Chihaya Adachi, Yoann Olivier, Eli Zysman-Colman

Research output: Contribution to journalArticlepeer-review

Abstract

Two novel π-extended amine/carbonyl-based multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters have been designed and synthesized. The two emitters are isomeric, composed of nine fused rings and show green-yellow emission. Sym-DiDiKTa and Asym-DiDiKTa possess tert-butyl groups distributed in a symmetrical and asymmetrical fashion, respectively, which significantly impact the single-crystal packing structure. The two compounds possess similar singlet-triplet energy gaps, ΔEST, of around 0.23 eV, narrowband emission characterized by a full-width at half-maximum, FWHM, of 29 nm and a photoluminescence quantum yield, ΦPL, of 70% and 53% for the symmetric and asymmetric counterparts, respectively, in toluene. Investigation in OLEDs demonstrated that the devices with Sym-DiDiKTa and Asym-DiDiKTa displayed electroluminescence maxima of 543 and 544 nm, and maximum external quantum efficiencies (EQEmax) of 9.8% and 10.5%, respectively. The maximum EQE was further improved to 19.9% by employing a hyperfluorescence strategy. We further present the first example of a neutral MR-TADF emitter incorporated in a LEC device where Sym-DiDiKTa acts as the emitter.

Original languageEnglish
Pages (from-to)8263-8273
Number of pages11
JournalJournal of Materials Chemistry C
Volume11
Issue number24
DOIs
Publication statusPublished - 2 May 2023

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