Saturated Red Electroluminescence From Thermally Activated Delayed Fluorescence Conjugated Polymers

Hongmei Zhan; Yanjie Wang; Kuofei Li; Yuannan Chen; Xiaohu Yi; Keyan Bai; Guohua Xie; Yanxiang Cheng

doi:10.3389/fchem.2020.00332

Saturated Red Electroluminescence From Thermally Activated Delayed Fluorescence Conjugated Polymers

Front Chem. 2020 Apr 24:8:332. doi: 10.3389/fchem.2020.00332. eCollection 2020.

Authors

Hongmei Zhan¹, Yanjie Wang¹, Kuofei Li¹, Yuannan Chen¹, Xiaohu Yi¹, Keyan Bai¹, Guohua Xie^{2

3}, Yanxiang Cheng¹

Affiliations

¹ State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China.
² Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, China.
³ Guangdong Provincial Key Laboratory of Luminescence From Molecular Aggregates (South China University of Technology), Guangzhou, China.

Abstract

Two sets of conjugated polymers with anthraquinone groups as pendant acceptors were designed and synthesized. The acceptor is tethered to an diphenylamine group via a phenylene bridge, constructing a thermally activated delayed fluorescence (TADF) unit, which is embedded into the polymer backbone through its donor fragment, while the backbone is composed of dibenzothiophene-S, S-dioxide and 2, 7-fluorene or 2, 7-carbazole groups. The polymers show distinct TADF characteristics, confirmed by transient photoluminescence spectra and theoretical calculations. The carbazole-based polymers exhibit shorter delay lifetimes and lower energy emission relative to the fluorene-based polymers. The non-doped organic light-emitting diodes fabricated via solution processing approach produce efficient red emissions with the wavelengths of 625-646 nm. The carbazole containing polymer with 2% molar content of the TADF unit exhibits the best maximum external quantum efficiency of 13.6% and saturated red electroluminescence with the Commission Internationale de l'Eclairage coordinates of (0.62, 0.37).

Keywords: anthraquinone; conjugated polymers; electroluminescence; red emission; thermally activated delayed fluorescence.