Quinoxaline-based thermally activated delayed fluorescence emitters for highly efficient organic light-emitting diodes

Xiaoning Li; Yi Chen; Shuhui Li; Aisen Li; Liangjing Tu; Dongdong Zhang; Lian Duan; Yujun Xie; Ben Zhong Tang; Zhen Li

doi:10.1039/D2TC04403J

Quinoxaline-based thermally activated delayed fluorescence emitters for highly efficient organic light-emitting diodes†

Xiaoning Li,^a Yi Chen,^a Shuhui Li,^d Aisen Li,^e Liangjing Tu,^a Dongdong Zhang,*^b Lian Duan,

^b Yujun Xie,

*^a Ben Zhong Tang*^ac and Zhen Li

*^adef

Author affiliations

* Corresponding authors

^a Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China
E-mail: xieyujun@tju.edu.cn

^b Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University Beijing, Beijing 100084, China
E-mail: ddzhang@mail.tsinghua.edu.cn

^c Shenzhen Institute of Molecular Aggregate Science and Engineering, School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 2001 Longxiang Boulevard, Longgang District, 518172 Shenzhen City, Guangdong, China
E-mail: tangbenz@cuhk.edu.cn

^d Department of Chemistry, Wuhan University, Wuhan, Hubei, China
E-mail: lizhen@whu.edu.cn

^e Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University Binhai New City, Fuzhou, Fujian, China

^f Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China

Abstract

Thermally activated delayed fluorescence (TADF) materials are regarded as the most promising next-generation emitters in organic light-emitting diodes (OLEDs). In this work, three TADF compounds were designed and synthesized based on 1,2,3,4-tetrahydrophenazine as acceptor and 9,9-dimethyl-9,10-dihydroacridine (DMAC-TTPZ), phenoxazine (PXZ-TTPZ), and phenothiazine (PTZ-TTPZ) as donors. Wherein, cyclohexane was introduced to the acceptor segment to improve solubility and weaken the conjugate degree to realize blue-shifted emission. Due to the twisted conformation, the frontier molecular orbital (FMO) overlap was largely minimized, resulting in small singlet-triplet energy splitting (ΔE_ST) of 0.15, 0.09, and 0.07 eV for DMAC-TTPZ, PXZ-TTPZ, and PTZ-TTPZ, respectively. Taking these compounds as emitters for OLEDs, maximum brightness, power efficiency (PE), and external quantum efficiency (EQE) of up to 36 480 cd m⁻², 41.0 lm W⁻¹, and 15.3% were achieved, demonstrating their potential in OLEDs.

Journal of Materials Chemistry C

Quinoxaline-based thermally activated delayed fluorescence emitters for highly efficient organic light-emitting diodes†

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Quinoxaline-based thermally activated delayed fluorescence emitters for highly efficient organic light-emitting diodes

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