In:
Materials Chemistry Frontiers, Royal Society of Chemistry (RSC)
Abstract:
Developing thermally activated delayed fluorescence (TADF) emitters showing high horizontal transition dipole orientation and molecular rigidity is crucial for enhancing the color purity and performance of deep-blue organic light-emitting diodes (OLEDs). Here, we report two linearly expanded TADF emitters, O-tsAC-BAsBP (1) and S-tsAC-BAsBP (2), based on a tri-spiral acridine donor and a spiro-fluorenyl B -heterotriangulene acceptor. These emitters exhibit deep-blue emissions, with peaks centered at 458–467 nm for 1 and 462–469 nm for 2, respectively, in the host films, with high photoluminescence quantum yields, small singlet–triplet energy splitting (Δ E ST 〈 0.05 eV), and short delayed fluorescence lifetimes ( τ d 〈 2 μs). Theoretical studies demonstrate that effective spin–orbit coupling between the charge transfer singlet ( 1 CT) and acceptor-centered local triplet ( 3 LE) excited states accelerates the reverse intersystem crossing (RISC) process, resulting in a high RISC rate constant of ∼10 6 s −1 . Notably, both emitters exhibit very high horizontal dipole orientation ratios ( Θ ‖ ) of ∼93% in their doped host films. Owing to the outstanding TADF characteristics and high Θ ‖ values, TADF-OLEDs incorporating emitters 1 and 2 achieve high maximum external quantum efficiencies of 27.4% and 31.5%, respectively, in the deep-blue region.
Type of Medium:
Online Resource
ISSN:
2052-1537
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2023
detail.hit.zdb_id:
2867881-3
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