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標題: | 以咔唑及芴為核心之雙極性磷光主體材料之合成、性質與元件應用 Syntheses, Properties, and Applications of Carbazole/Fluorene-Based Bipolar Host Materials |
作者: | Shu-Hua Chou 周書華 |
指導教授: | 汪根欉(Ken-Tsung Wong) |
關鍵字: | 有機發光二極體,雙極性分子,磷光主體材料,?唑,芴, OLED,Bipolar Molecules,Phosphorescence Host Materials,Carbazole,Fluorene, |
出版年 : | 2010 |
學位: | 碩士 |
摘要: | 本論文於同一分子上加入予體、受體基團,開發具有雙極性或雙偶極性之磷光主體材料,在具有高電洞傳輸特性的咔唑核心之 3、6 位置上,引入具有電子傳輸特性之基團,包括苯並咪唑或噁二唑 (o-Cz2B, m-Cz2B, o-Cz2O);於芴環核心之9號位上引入兩個相同之高電洞傳輸特性之基團,包含咔唑或三苯胺,2號位則加入一具有電子傳輸特性之基團,為苯並咪唑或噁二唑(F2Cz1B, F2Cz1O, F2TPA1O)。
分子設計將予體與受體基團之間以芴環或苯環為阻隔,利用鄰、間位的連接方式產生扭曲的結構:(1)以理論計算證實能有效增加 HOMO、LUMO 上予體與受體之電子分布差異;(2)增加立障提高材料之熱穩定性;(3)減少分子內予體與受體間之電荷轉移以維持高三重態能量。元件應用上,咔唑為核心的分子中,以m-Cz2B之電洞電子傳輸最為平衡,為一雙偶極性之主體材料,搭配綠色磷光材料Ir(pbi)2(acac)之三層元件的效率最高(ηext=21.7%,ηp= 72lm/W,Lmax=195000 cd/m 2);而以芴為核心的分子中,F2Cz1B 可搭配黃綠紅三色的磷光材料,元件表現搶眼 (ηext > 16 %),其中以紅色磷光材料 Ir(NTHU)元件效率最佳 (ηext=19.6%,ηp=14.4 lm/W),為一深紅色 (CIE =0.66,0.33)磷光元件。 We have designed and synthesized a series of twisted bipolar molecules, o-Cz2B, m-Cz2B, o-Cz2O, F2Cz1B, F2Cz1O, and F2TPA1O, which incorporate hole-transporting unit (D) such as carbazole or triphenylamine and benzimidazole/oxa- diazole as electron-transporting unit (A). The ortho/meta linkages between donor and acceptor and the existence of saturated carbon on fluorene obstruct the conjugation between D and A. DFT calculations show that spatial distributions of the HOMO and LUMO are nearly fully localized at the D and A units, respectively. The result indicates the bipolar hosts possess less intramolecular charge-transfer and improved charge transporting properties. Efficient performance (ηext=19.6%) of a deep-red (CIE=0.66, 0.33) PhOLED is obtained by using F2Cz1B doped with Ir(NTHU). In addition, m-Cz2B exhibits great balance in charge mobility, the green device with Ir(pbi)2acac as dopant shows an extremely high maximum external quantum efficiency, power efficiency and maximum luminance of 21.7%, 72 lm/W, and 195000 cd/m2, respectively. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/22307 |
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顯示於系所單位: | 化學系 |
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