Lookup NU author(s): Dr Julien Eng,
Dr Thomas Penfold
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
By inverting the common structural motif of thermally activated delayed fluorescence materials to a rigid donor core and multiple peripheral acceptors, reverse intersystem crossing (rISC) rates are demonstrated in an organic material that enables utilization of triplet excited states at faster rates than Ir-based phosphorescent materials. A combination of the inverted structure and multiple donor–acceptor interactions yields up to 30 vibronically coupled singlet and triplet states within 0.2 eV that are involved in rISC. This gives a significant enhancement to the rISC rate, leading to delayed fluorescence decay times as low as 103.9 ns. This new material also has an emission quantum yield ≈ 1 and a very small singlet–triplet gap. This work shows that it is possible to achieve both high photoluminescence quantum yield and fast rISC in the same molecule. Green organic light-emitting diode devices with external quantum efficiency > 30% are demonstrated at 76 cd m−2 .
Author(s): dos Santos PL, Ward JS, Congrave DG, Batsanov AS, Eng J, Stacey JE, Penfold TJ, Monkman AP, Bryce MR
Publication type: Article
Publication status: Published
Journal: Advanced Science
Pages: epub ahead of print
Online publication date: 16/04/2018
Acceptance date: 01/02/2018
ISSN (electronic): 2198-3844
Data Source Location: http://dx.doi.org/10.17634/162036-2
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