What is it about?
In this paper, we show that efficient TADF can be achieved by enhancing the localization of HOMO and LUMO in carbazole-pyrimidine compounds with rather flat molecular structure. Due to the rather flat molecular geometry, TADF compounds showed remarkable radiative decay rate reaching 4.6 × 107 s−1 for the most efficient TADF-active carbazole-pyrimidine compound dCbz-pPYR, followed by high emission yield of 0.75. Efficient green electroluminescence with peak EQE of 18.3%. was shown for OLED device with dCbz-pPYR emitter.
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Why is it important?
The introduction of phenyl spacer units between diphenylamino and carbazole fragments, enhancing the localization of LUMO only over the acceptor unit, was shown to further minimize the ΔEST and enable efficient TADF. Remarkable radiative decay rate of 4.6 × 107 s−1 was achieved due to sufficient HOMO-LUMO coupling in weakly distorted D-A compound, leading to high prompt fluorescence yield of 0.55.
Perspectives
Construction of rather flat donor-acceptor compounds with enhanced HOMO-LUMO localization could be used for further advance in design of TADF emitters with pronounced prompt and delayed fluorescence yield and rates.
Dr. Sigitas Tumkevicius
Vilnius University
Read the Original
This page is a summary of: Tuning of HOMO-LUMO localization for achieving thermally activated delayed fluorescence, Journal of Luminescence, January 2022, Elsevier,
DOI: 10.1016/j.jlumin.2021.118473.
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