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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/51351

Title: Highly Twisted Carbazole–Oxadiazole Hybrids as Universal Bipolar Hosts for High Efficiency PhOLEDs
Authors: Shuo-Hsien Cheng
Wen-Yi Hung
Ming-Hung Cheng
Hsiao-Fan Chen
Gene-Hsiang Lee
Chin-Lung Chung
Tzu-Chin Yeh
Wei-Chieh Tang
Shou-Ling Huang
Ken-Tsung Wong
Contributors: 國立臺灣海洋大學:光電與材料科技學士學位學程(學系)
Date: 2015-11
Issue Date: 2018-11-23T06:17:01Z
Publisher: ADVANCED ELECTRONIC MATERIALS
Abstract: Abstract: Four bipolar molecules oDOXA, mDOXA, oOXA, and mOXA composed of a hole‐transport carbazole (donor, D) and an electron‐transport 1,3,4‐oxadiazole (acceptor, A) bridged with different π‐spacers (biphenyl or o‐terphenyl) are synthesized, characterized, and used as host materials for various colored phosphorescent OLEDs (PhOLEDs). The highly twisted geometry established via multiple ortho/meta‐connections effectively inhibits direct electronic D–A coupling and gives these bipolar molecules similar high triplet energies (≈2.70 eV). In addition, distinctive bipolar transport capabilities are observed by time‐of‐flight technique (μh ≈ μe ≈ 10−5–10−6 cm2 V−1 s−1). The D/A connection topology is found to subtly govern the physical properties, rendering these new molecules suitable for serving as bipolar host materials. Among the four host materials, oOXA using the tandem ortho‐linkage terphenyl as a linker outperforms the other three hosts in terms of the device efficiency, in which the maximum external quantum efficiencies (ηext) of the corresponding PhOLEDs are as high as 19.4%, 21.3%, 20.9%, 20.1%, and 19.0% for blue, green, yellow, orange, and red PhOLEDs, respectively. Moreover, a single‐host multilayered warm‐white OLED based on oOXA also shows remarkable efficiency (19.8%, 42.4 cd A−1, and 38.6 lm W−1) with high color‐rendering index of 86.8 and stable chromaticity.
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/51351
Appears in Collections:[光電科學研究所] 期刊論文

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