Skip to main content

Research Repository

Advanced Search

TADF dendronized polymer with vibrationally enhanced direct spin-flip between charge-transfer states for efficient non-doped solution-processed OLEDs

Li, Chensen; Harrison, Alastair K.; Liu, Yuchao; Zhao, Zhennan; Dias, Fernando B.; Zeng, Cheng; Yan, Shouke; Bryce, Martin R.; Ren, Zhongjie

TADF dendronized polymer with vibrationally enhanced direct spin-flip between charge-transfer states for efficient non-doped solution-processed OLEDs Thumbnail


Authors

Chensen Li

Alastair K. Harrison

Yuchao Liu

Zhennan Zhao

Cheng Zeng

Shouke Yan

Zhongjie Ren



Abstract

A novel type of thermally activated delayed fluorescence (TADF) dendronized polymer was designed and synthesized. Firstly, one side of the asymmetric TADF unit was encapsulated by 3,6-di-tert-butylcarbazole via a conjugated linkage with strong twisted intramolecular charge transfer (TICT) to minimize the energy gap between 1CT and 3CT, and then the peripheral dicarbazole connects in a non-conjugated way on the other side, showing weak TICT and high-lying 3LE&3CT state; finally, a linear dendronized polymer, PDCDC, was obtained by introducing the alkyl polymer backbone as main chains. As far as we know, this is the first blue or greenish-blue-emitting TADF dendronized polymer. For PDCDC, the spin-forbidden 1CT ↔ 3CT transitions are activated by molecular vibrations, which combine with a small energy gap and reorganization energy to enable 1CT ↔ 3CT spin-flip transition rates reaching 106 s−1 with negligible role of a second triplet state. Films of PDCDC show a double exponential decay (prompt fluorescence and delayed fluorescence) in the presence of oxygen due to a low oxygen permeability ascribed to the entangled polymeric backbone which increases film density. Besides, obvious aggregation-enhanced emission (AEE) property can minimize the exciton quenching in aggregated states. A maximum external quantum efficiency of 9.0% for non-doped PDCDC-based organic light-emitting diodes (OLEDs) can be obtained. To the best of our knowledge, these are the most efficient dendronized polymer devices with blue or greenish-blue emission.

Citation

Li, C., Harrison, A. K., Liu, Y., Zhao, Z., Dias, F. B., Zeng, C., …Ren, Z. (2022). TADF dendronized polymer with vibrationally enhanced direct spin-flip between charge-transfer states for efficient non-doped solution-processed OLEDs. Chemical Engineering Journal, 435, Article 134924. https://doi.org/10.1016/j.cej.2022.134924

Journal Article Type Article
Acceptance Date Jan 22, 2022
Online Publication Date Feb 11, 2022
Publication Date 2022-05
Deposit Date May 26, 2022
Publicly Available Date May 26, 2022
Journal Chemical Engineering Journal
Print ISSN 1385-8947
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 435
Article Number 134924
DOI https://doi.org/10.1016/j.cej.2022.134924
Public URL https://durham-repository.worktribe.com/output/1205683

Files

Published Journal Article (3.9 Mb)
PDF

Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

You are not required to obtain permission to reuse this article.






You might also like



Downloadable Citations