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Highly Efficient TADF OLEDs: How the Emitter–Host Interaction Controls Both the Excited State Species and Electrical Properties of the Devices to Achieve Near 100% Triplet Harvesting and High Efficiency

Jankus, V.; Data, P.; Graves, D.; McGuinness, C.; Santos, J.; Bryce, M.R.; Dias, F.B.; Monkman, A.P.

Highly Efficient TADF OLEDs: How the Emitter–Host Interaction Controls Both the Excited State Species and Electrical Properties of the Devices to Achieve Near 100% Triplet Harvesting and High Efficiency Thumbnail


Authors

V. Jankus

P. Data

D. Graves

C. McGuinness

J. Santos



Abstract

New emitters that can harvest both singlet and triplet excited states to give 100% internal conversion of charge into light, are required to replace Ir based phosphors in organic light emitting diodes (OLEDs). Molecules that have a charge transfer (CT) excited state can potentially achieve this through the mechanism of thermally activated delayed fluorescence (TADF). Here, it is shown that a D–A charge transfer molecule in the solid state, can emit not only via an intramolecular charge transfer (ICT) excited state, but also from exciplex states, formed between the molecule and the host material. OLEDs based on a previously studied D–A–D molecule in a host TAPC achieves >14% external electroluminescence yield and shows nearly 100% efficient triplet harvesting. In these devices, it is unambiguously established that the triplet states are harvested via TADF, but more interestingly, these results are found to be independent of whether the emitter is the ICT state or the D–A–D/host exciplex.

Citation

Jankus, V., Data, P., Graves, D., McGuinness, C., Santos, J., Bryce, M., …Monkman, A. (2014). Highly Efficient TADF OLEDs: How the Emitter–Host Interaction Controls Both the Excited State Species and Electrical Properties of the Devices to Achieve Near 100% Triplet Harvesting and High Efficiency. Advanced Functional Materials, 24(39), 6178-6186. https://doi.org/10.1002/adfm.201400948

Journal Article Type Article
Online Publication Date Aug 8, 2014
Publication Date Oct 22, 2014
Deposit Date Nov 24, 2014
Publicly Available Date Mar 28, 2024
Journal Advanced Functional Materials
Print ISSN 1616-301X
Electronic ISSN 1616-3028
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 24
Issue 39
Pages 6178-6186
DOI https://doi.org/10.1002/adfm.201400948
Keywords Exciplex, TADF, Delayed fluorescence, Charge transfer state, OLED.

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Copyright Statement
This is the peer reviewed version of the following article: FJankus, V., Data, P., Graves, D., McGuinness, C., Santos, J., Bryce, M. R., Dias, F. B. and Monkman, A. P. (2014), Highly Efficient TADF OLEDs: How the Emitter–Host Interaction Controls Both the Excited State Species and Electrical Properties of the Devices to Achieve Near 100% Triplet Harvesting and High Efficiency. Advanced Functional Materials, 24 (39): 6178-6186, which has been published in final form at http://dx.doi.org/10.1002/adfm.201400948. This article may be used for non-commercial purposes in accordance With Wiley-VCH Terms and Conditions for self-archiving.





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