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Lookup NU author(s): Dr Julien EngORCiD, Professor Thomas Penfold
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Intramolecular charge transfer (ICT) occurs when photoexcitation causes electron transfer from an electron donor to an electron acceptor within the same molecule and is usually stabilized by decoupling of the donor and acceptor through an orthogonal twist between them. Thermally activated delayed fluorescence (TADF) exploits such twisted ICT states to harvest triplet excitons in OLEDs. However, the highly twisted conformation of TADF molecules results in limited device lifetimes. Rigid molecules offer increased stability, yet their typical planarity and π-conjugated structures impedes ICT. Herein, we achieve dispersion-free triplet harvesting using fused indolocarbazole-phthalimide molecules that have remarkably stable co-planar ICT states, yielding blue/green-TADF with good photoluminescence quantum yield and small singlet-triplet energy gap < 50meV. ICT formation is dictated by the bonding connectivity and excited-state conjugation breaking between the donor and acceptor fragments, that stabilises the planar ICT excited state, revealing a new criterion for designing efficient TADF materials.
Author(s): Kuila S, Miranda-Salinas H, Eng J, Li C, Bryce MR, Penfold TJ, Monkman AP
Publication type: Article
Publication status: Published
Journal: Nature Communications
Year: 2024
Volume: 15
Online publication date: 07/11/2024
Acceptance date: 21/10/2024
Date deposited: 07/11/2024
ISSN (electronic): 2041-1723
Publisher: Nature Publishing Group
URL: https://doi.org/10.1038/s41467-024-53740-1
DOI: 10.1038/s41467-024-53740-1
Data Access Statement: The data that support the plots and tables and conclusions in this work are given within the paper and supplementary information. The source data is available upon request from the corresponding author.
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