Modulating the Electron-Donating Ability of Acridine Donor Units for Orange-Red Thermally Activated Delayed Fluorescence Emitters

Tianheng Chen; Chen-Han Lu; Zhanxiang Chen; Xu Gong; Chung-Chih Wu; Chuluo Yang

doi:10.1002/chem.202004719

Modulating the Electron-Donating Ability of Acridine Donor Units for Orange-Red Thermally Activated Delayed Fluorescence Emitters

Chemistry. 2021 Feb 10;27(9):3151-3158. doi: 10.1002/chem.202004719. Epub 2020 Dec 30.

Authors

Tianheng Chen^{1

2}, Chen-Han Lu³, Zhanxiang Chen¹, Xu Gong¹, Chung-Chih Wu³, Chuluo Yang^{1

2}

Affiliations

¹ Renmin Hospital of Wuhan University, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, P.R. China.
² College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P.R. China.
³ Department of Electrical Engineering, Graduate Institute of Electronics Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, 10617, Taiwan.

PMID: 33241622
DOI: 10.1002/chem.202004719

Abstract

The development of thermally activated delayed fluorescence (TADF) emitters with orange-red emission still lags behind that of their blue, green, and yellow counterparts. Recent research to address this problem mainly focused on developing new acceptor units. There were few donor units designed especially for orange-red emitters. Herein, with benzothiophene fused to a diphenylacridine donor unit, a new donor moiety, namely, 5,5-diphenyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine (BTDPAc), was designed and synthesized. Benefiting from the strong electron-donating ability of the new donor moiety, a new TADF emitter, 2-[4'-(tert-butyl)(1,1'-biphenyl)-4-yl]-6-[5,5-diphenylbenzo[4,5]thieno[3,2-c]acridin-13(5H)-yl]-1H-benzo[de]isoquinoline-1,3(2H)-dione (BTDPAc-PhNAI), shows an orange-red emission with a maximum at 610 nm in dilute toluene solution. Also, with the help of the diphenyl rings of the donor unit, high photoluminescence quantum yields were achieved for BTDPAc-PhNAI over a wide concentration range. Consequently, an orange-red organic light-emitting diode based on BTDPAc-PhNAI achieved a high external quantum efficiency of nearly 20 %, which was comparable to state-of-the-art device performances with similar emission spectra.

Keywords: donor-acceptor systems; fluorescence; orange-red emitters; organic light-emitting diodes; thermally activated delayed fluorescence.

Abstract

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