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

TITLE=Saturated Red Electroluminescence From Thermally Activated Delayed Fluorescence Conjugated Polymers

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 8 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00332

DOI=10.3389/fchem.2020.00332

ISSN=2296-2646

ABSTRACT=Two sets of conjugated polymers PFSOTAQx and PCzSOTAQx with anthraquinone groups as pendant acceptors were designed and synthesized. The acceptor is tethered to an diphenylamine group via a phenylene bridge, constructing a TADF unit (TAQ), which is embedded into the polymer backbone through its donor fragment, while the backbone is composed of dibenzothiophene-S,S-dioxide (SO) and 2,7-fluorene (F) or 2,7-carbazole (Cz) groups. The polymers show distinct TADF characteristics, confirmed by transient photoluminescence spectra and theoretical calculations. The carbazole-based polymers PCzSOTAQx exhibit shorter delay lifetimes and lower energy emission relative to the fluorene-based polymers PFSOTAQx. The non-doped organic light-emitting diodes fabricated via solution processing approach produce efficient red emissions with the wavelengths of 625-646 nm. PCzSOTAQ2 with 2% molar content of the TAQ 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).