Issue 5, 2024

Liquid-crystalline circularly polarised TADF emitters for high-efficiency, solution-processable organic light-emitting diodes

Abstract

Achieving a high emission efficiency and a large luminescence asymmetry factor (glum) in a single molecule exhibiting circularly polarised thermally activated delayed fluorescence (CP-TADF) remains a formidable challenge. In this work, a proof-of-concept, liquid-crystalline CP-TADF molecule is proposed to realise high glum by taking advantage of the order inherent in liquid crystals. Employing a chiral dinaphthol-based CP-TADF molecule as the emissive unit, a pair of liquid-crystalline CP-TADF molecules (R/S-4) is synthesised via the introduction of six mesogenic moieties. The enantiomers show intense emission at about 520 nm which has clear TADF and liquid-crystalline characteristics. Both enantiomers display symmetrical electronic circular dichroism (CD) and circular polarisation luminescence (CPL) signals as thin films. Impressively, relatively large glum values of 0.11 are realised for the films. Solution-processed devices were fabricated using R/S-4 as the dopants, with the TADF molecule CzAcSF as the sensitiser. The OLEDs so prepared show a very high maximum external quantum efficiency of 21.2%, revealing a novel strategy for realising large glum values in CP-TADF.

Graphical abstract: Liquid-crystalline circularly polarised TADF emitters for high-efficiency, solution-processable organic light-emitting diodes

  • This article is part of the themed collection: #MyFirstMH

Supplementary files

Article information

Article type
Communication
Submitted
19 okt 2023
Accepted
13 dec 2023
First published
13 dec 2023
This article is Open Access
Creative Commons BY license

Mater. Horiz., 2024,11, 1251-1260

Liquid-crystalline circularly polarised TADF emitters for high-efficiency, solution-processable organic light-emitting diodes

B. He, Q. Zhong, Q. Dong, X. Yang, S. J. Cowling, W. Qiao, D. W. Bruce, W. Zhu, P. Duan and Y. Wang, Mater. Horiz., 2024, 11, 1251 DOI: 10.1039/D3MH01736B

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