Carbazole/Benzimidazole-Based Bipolar Molecules as the Hosts for Phosphorescent and Thermally Activated Delayed Fluorescence Emitters for Efficient OLEDs
學年 108
學期 2
出版（發表）日期 2020-05-03
作品名稱 Carbazole/Benzimidazole-Based Bipolar Molecules as the Hosts for Phosphorescent and Thermally Activated Delayed Fluorescence Emitters for Efficient OLEDs
作品名稱（其他語言）
著者 Gao, Z.-J.; Yeh, T.-H.; Xu, J.-J.; Lee, C.-C.; Chowdhury, A.; Wang, B.-C.; Liu, S.-W.; Chen, C.-H.
單位
出版者
著錄名稱、卷期、頁數 ACS Omega 5(18), 10553–10561
摘要 A series of carbazole/benzimidazole-based molecules, namely, o-CbzBiz, m-CbzBiz, and p-CbzBiz, were readily synthesized in three steps by integrating carbazole with benzimidazole via the ortho-, meta-, and para-positions of phenyl linked to N-phenyl carbazole. These bipolar molecules exhibited a maximum UV absorption band ranging from 310 to 327 nm and a maximum emission band ranging from 380 to 400 nm. Density functional theory calculations showed that the twist angles between the donor and acceptor moieties of these molecules were from 54.9 to 67.1°. Such a twisted structure hampered the π-electron conjugation within the molecule and resulted in high-lying LUMO levels and triplet energies, which make them suitable to be applied as host materials in OLED devices. Our results showed that a maximum external quantum efficiency (EQE) of OLED reached 21.8% when p-CbzBiz was applied as the host of a green phosphorescent emitter, i.e., Ir(ppy)2(acac). In addition, a maximum EQE of OLED reached 16.7% when o-CbzBiz with the host of a green TADF emitter, i.e., 4CzIPN. Moreover, these devices exhibited lower efficiency roll-off than the CBP-hosted device using the same emitters, which demonstrated the bipolar charge carrier property of carbazole/benzimidazole-based molecules.
關鍵字
語言 en_US
ISSN 2470-1343
期刊性質 國外
收錄於 SCI
產學合作
通訊作者
審稿制度 是
國別 USA
公開徵稿
出版型式 ,電子版,紙本
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