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*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
6 Downloads (Pure)

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. The LEC shows a λEL at 551 nm and FWHM of 60 nm with luminance of 300 cd m−2 and a fast turn-on time of less than 2 s to 100 cd m−2.
Original languageEnglish
Pages (from-to)8263-8273
Number of pages11
JournalJournal of Materials Chemistry C
Volume11
Issue number24
Early online date2 May 2023
DOIs
Publication statusPublished - 28 Jun 2023

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