Thermally activated delayed fluorescence materialsensitized helicene enantiomer-based OLEDs:a new strategy for improving the efficiency of circularly polarized electroluminescence  

热激活延迟荧光材料敏化的螺烯对映体有机发光二极管:一种提高电致圆偏振发光效率的新策略

作　　者：Meng Li Yin-Feng Wang Da-Wei Zhang Dongdong Zhang Zhi-Qiang Hu Lian Duan Chuan-Feng Chen 李猛;王银凤;张大伟;张东东;胡志强;段炼;陈传峰(Beijing National Laboratory for Molecular Sciences,CAS Key Laboratory of Molecular Recognition and Function,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Department of Chemistry,Tsinghua University,Beijing 100084,China;College of Chemistry and Molecular Engineering,Qingdao University of Science and Technology,Qingdao 266042,China)

机构地区：[1]Beijing National Laboratory for Molecular Sciences,CAS Key Laboratory of Molecular Recognition and Function,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Chemistry,Tsinghua University,Beijing 100084,China [4]College of Chemistry and Molecular Engineering,Qingdao University of Science and Technology,Qingdao 266042,China

出　　处：《Science China Materials》2021年第4期899-908,共10页中国科学（材料科学（英文版）

基　　金：the National Natural Science Foundation of China(21871272,91956119 and 21521002);the Youth Innovation Promotion Association CAS(2019034);Qingdao University of Science and Technology(QUSTHX201929)。

摘　　要：A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic lightemitting diodes(OLEDs)(CP-OLEDs).Consequently,a pair of helicene enantiomers,(P)-HAI and(M)-HAI,were synthesized.The helicene enantiomers with the rigid helicalπ-skeleton had highly thermal and enantiomeric stabilities,and they also showed excellent photophysical properties,especially,intense mirror-image CPL activities with large luminescence dissymmetry factor(|g_(lum)|)values of about 6×10^(-3).Notably,the CP-OLEDs with the helicene enantiomers as emitters and a TADF molecule as sensitizer not only displayed better performance of lower turn-on voltage(V_(T))of 2.6 V,four-fold maxmium-external quantum efficiency(EQE_(max))of 5.3%,and lower efficiencies roll-off of 1.9%at 1000 cd m^(-2),than those of the devices without TADF sensitizer,but also exhibited intense circularly polarized electroluminescence(CPEL)with the electroluminescence dissymmetry factor(g_(EL))values of-2.3×10^(-3)and+3.0×10^(-3).Meanwhile,this study also represents the first thermally activated sensitized fluorescent CP-OLEDs with markedly enhanced efficiencies and intense CPEL.为了提高基于手性荧光分子的有机圆偏振发光二极管(CPOLED)器件效率,本文提出了一种全新的热激活延迟荧光材料敏化圆偏振发光(TAS-CPL)的策略.设计合成了一对具有刚性骨架的螺烯对映体(P)-HAI和(M)-HAI作为器件的手性发光客体,研究发现螺烯对映体具有高的热稳定性、手性构型稳定性、良好的光物理性质,尤其是具有强的CPL性质,其荧光不对称因子(|g_(lum)|)约为6×10^(-3).与直接以螺烯对映体作为发光客体的CP-OLED相比,通过TADF敏化剂热激活敏化螺烯对映体的CP-OLED表现出更低的启动电压(2.6 V)、更低的效率滚降(1.9%,亮度为1000 cd m^(-2))以及增加四倍的最大外量子效率(EQEmax,5.3%),螺烯对映体的电致发光不对称因子分别为-2.3×10^(-3)和+3.0×10^(-3).这是首例基于热激活延迟荧光材料敏化圆偏振发光的CP-OLED,为提高手性荧光分子的电致圆偏振发光效率提供了有效策略.

关 键 词：thermally activated sensitized emission HELICENE ELECTROLUMINESCENCE circularly polarized light organic lightemitting diodes 

分 类 号：TN383.1[电子电信—物理电子学]