New bipolar host materials for high power efficiency green thermally activated delayed fluorescence OLEDs

被引：23

作者：

Chen, Chia-Hsun ^{[1
]}

Lin, Shih-Chun ^{[1
]}

Lin, Bo-Yen ^{[2
]}

Li, Che-Yu ^{[3
]}

Kong, Yu-Cheng ^{[4
]}

Chen, Yi-Sheng ^{[1
]}

Fang, Shao-Cheng ^{[1
]}

Chiu, Ching-Huang ^{[5
,6
]}

Lee, Jiun-Haw ^{[5
,6
]}

Wong, Ken-Tsung ^{[1
,7
]}

Lin, Chi-Feng ^{[3
]}

Hung, Wen-Yi ^{[4
]}

Chiu, Tien-Lung ^{[2
]}

机构：

[1] Natl Taiwan Univ, Dept Chem, Taipei 10617, Taiwan

[2] Yuan Ze Univ, Dept Elect Engn, Taoyuan, Taiwan

[3] Natl United Univ, Dept Electroopt Engn, 2 Lienda, Miaoli 36063, Miaoli County, Taiwan

[4] Natl Taiwan Ocean Univ, Inst Optoelect Sci, Keelung 202, Taiwan

[5] Natl Taiwan Univ, Grad Inst Photon & Optoelect, Taipei 10617, Taiwan

[6] Natl Taiwan Univ, Dept Elect Engn, Taipei 10617, Taiwan

[7] Acad Sinica, Inst Atom & Mol Sci, Taipei 10617, Taiwan

来源：

CHEMICAL ENGINEERING JOURNAL | 2022年 / 442卷

关键词：

Thermally activated delayed fluorescence (TADF); Power efficiency; Organic light emitting diode (OLED); EXTERNAL QUANTUM EFFICIENCY; LIGHT-EMITTING-DIODES; UNIVERSAL HOST; 25-PERCENT; DONOR;

D O I：

10.1016/j.cej.2022.136292

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

Four bipolar molecules, namely m-CzPym, p-CzPym, m-CzTrz, and p-CzTrz, with carbazole (Cz) donor and a benzonitrile-substituted pyrimidine (Pym) or triazine (Trz) acceptor core were synthesized and characterized. The electron deficiency of heteroaryl cores together with the substitution pattern of benzonitrile were employed to tune the energy levels as well as the thermally activated delayed fluorescence (TADF) characteristics. The four molecules exhibited TADF behavior with inferior photoluminescent quantum yields (PLQYs) that limit their applications as emitters. These bipolar molecules were employed as TADF host materials for the benchmark TADF emitter 4CzIPN to achieve high-performing green TADF organic light-emitting diodes (OLEDs). Among the molecules, m-CzPym-hosted TADF-OLEDs achieved a maximum external quantum efficiency (EQE(max)) of 31.5%, maximum power efficiency (PEmax) of 95.6 lm/W, and maximum current efficiency (CEmax) of 100.2 c4/A. Notably, p-CzPym-hosted TADF-OLEDs also achieved a PEmax of 116.5 lm/W, turn-on voltage of 2.5 V, and impressive low efficiency roll-off performance (>89% of EQE(max) at 5000 cd/m(2)), representing one of the highest efficiencies ever reported in 4CzIPN-doped devices. The high device efficiency can be ascribed to the balanced ambipolar carrier-transporting character of the host materials and high PLQY as well as the outstanding light outcoupling efficiency of the emitting layer.

引用

页数：11

共 35 条

[1] Tuning of HOMO levels of carbazole derivatives: New molecules for blue OLED [J].