Issue 26, 2018

A simple and broadly applicable synthesis of fluorene-coupled D–σ–A type molecules: towards high-triplet-energy bipolar hosts for efficient blue thermally-activated delayed fluorescence

Abstract

An effective two-step synthesis of high-triplet-energy (ET) bipolar hosts that is simple and broadly applicable is introduced. Electron-donating (D = (9-phenyl-9H-carbazol-3-yl/4-(9H-carbazol-9-yl)phenyl)) and -accepting (A = (tetrafluoropyridin-4-yl/4,6-diphenyl-1,3,5-triazin-2-yl)) units have been coupled to the C9 atom of fluorene to afford the four hosts 3CzFTFP, 9PhFTFP, 3CzFDPhTz, and 9PhFDPhTz with sp3 C9-centered bulky ternary structures, excellent thermal/morphological stabilities, tunable abilities for bipolar charge carrier injection/transport, and identical high ET (2.87 eV). Blue thermally-activated delayed fluorescence (TADF) devices using these new hosts and 2CzPN as the host–guest system exhibited efficient electroluminescence efficiencies of 38 cd A−1/30 lm W−1/17%, which are among the best for 2CzPN-based TADF devices. The generality of this synthetic strategy to high-ET fluorene-coupled D–σ–A type hosts was confirmed by successfully appending other D/A groups ((diphenylamino)phenyl/phenylsulfonyl) to fluorene, affording TPAFBSO.

Graphical abstract: A simple and broadly applicable synthesis of fluorene-coupled D–σ–A type molecules: towards high-triplet-energy bipolar hosts for efficient blue thermally-activated delayed fluorescence

Supplementary files

Article information

Article type
Paper
Submitted
18 Mar 2018
Accepted
10 May 2018
First published
12 May 2018

J. Mater. Chem. C, 2018,6, 6949-6957

A simple and broadly applicable synthesis of fluorene-coupled D–σ–A type molecules: towards high-triplet-energy bipolar hosts for efficient blue thermally-activated delayed fluorescence

C. Li, X. Du, Y. Zhou, J. Ye, L. Fu, M. G. Humphrey, C. Wu, J. Zhao, Y. Du, S. Tao, J. Wu and C. Zhang, J. Mater. Chem. C, 2018, 6, 6949 DOI: 10.1039/C8TC01309H

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