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

TY - JOUR

T1 - Liquid-crystalline circularly polarised TADF emitters for high-efficiency, solution-processable organic light-emitting diodes

AU - He, Binghong

AU - Zhong, Qihang

AU - Dong, Qiwei

AU - Yang, Xuefeng

AU - Cowling, Stephen J.

AU - Qiao, Wenjian

AU - Bruce, Duncan W.

AU - Zhu, Weiguo

AU - Duan, Pengfei

AU - Wang, Yafei

N1 - Funding Information: Financial support was from the National Natural Science Foundation of China (no. 22371020, 52073035, U1663229), the Special Programme for foreign talents in Changzhou City (CQ20224052) and the University of York. The authors also would like to thank the Analysis and Testing Center, NERC Biomass of Changzhou University, for their help on NMR measurements and Professor Youxan Zheng of Nanjing University for measurements of CPEL spectra. Publisher Copyright: © 2024 The Royal Society of Chemistry.

PY - 2023/12/22

Y1 - 2023/12/22

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85180613510&partnerID=8YFLogxK

U2 - 10.1039/d3mh01736b

DO - 10.1039/d3mh01736b

M3 - Article

AN - SCOPUS:85180613510

SN - 2051-6347

JO - Materials Horizons

JF - Materials Horizons

ER -