Issue 20, 2020

Achievement of high efficiency with extremely low efficiency roll-off in solution-processed thermally activated delayed fluorescence OLEDs manufactured using xanthone-based bipolar host materials

Abstract

The use of soluble host materials and thermally activated delayed fluorescence (TADF) emitters is indispensable for developing high-efficiency organic light-emitting diodes (OLEDs) by cost-effective solution processes. In this study, two bipolar hosts were designed as structural isomers, namely 3-(3,5-di(9H-carbazol-9-yl)phenyl)-9H-xanthen-9-one (Xp-mCP) and 2-(3,5-di(9H-carbazol-9-yl)phenyl)-9H-xanthen-9-one (Xm-mCP). The two host materials were synthesized by combining the unipolar host, 1,3-di(9H-carbazol-9-yl)benzene (mCP) with 9H-xanthen-9-one as an electron-accepting moiety. The two hosts exhibit good solubility in various organic solvents and high triplet energy (ET = 2.67 eV for Xp-mCP and ET = 2.82 eV for Xm-mCP), which renders them suitable for t4CzIPN-containing solution-processable green TADF-OLEDs. The maximum external quantum efficiency (EQE) values were 19.3% and 22.0% for Xp-mCP- and Xm-mCP-based green TADF-OLED, respectively. Among them, the device comprising Xm-mCP showed an excellent efficiency roll-off behavior by displaying only a 4.5% decrease and 11.4% decrease at 1000 cd m−2 and 2000 cd m−2, respectively. These results show the significant potential of xanthone-mCP host materials to develop solution-processable OLED technologies.

Graphical abstract: Achievement of high efficiency with extremely low efficiency roll-off in solution-processed thermally activated delayed fluorescence OLEDs manufactured using xanthone-based bipolar host materials

Supplementary files

Article information

Article type
Paper
Submitted
05 Mar 2020
Accepted
15 Apr 2020
First published
15 Apr 2020

J. Mater. Chem. C, 2020,8, 6780-6787

Achievement of high efficiency with extremely low efficiency roll-off in solution-processed thermally activated delayed fluorescence OLEDs manufactured using xanthone-based bipolar host materials

C. Y. Kim, C. Lee, H. J. Kim, J. Hwang, M. Godumala, J. Jeong, H. Y. Woo, M. J. Cho, S. Park and D. H. Choi, J. Mater. Chem. C, 2020, 8, 6780 DOI: 10.1039/D0TC01144D

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