Bipolar Molecule as an Excellent Hole-Transporter for Organic-Light Emitting Devices

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• 作者：Silu Tao^† ; ^‡ ; ; Lu Li^† ; ; Junsheng Yu^† ; ; Yadong Jiang^† ; ; Yechun Zhou^‡ ; ; Chun-Sing Lee^‡ ; ; Sh
• 刊名：Chemistry of Materials
• 出版年：2009
• 出版时间：April 14, 2009
• 年：2009
• 卷：21
• 期：7
• 页码：1284-1287
• 全文大小：194K
• 年卷期：v.21,no.7(April 14, 2009)
• ISSN：1520-5002

文摘

A new bipolar molecule containing hole-transporting and electron-transporting moieties has been synthesized and characterized. The compound, 4,4′,4′′-tris(8-quinoline)-triphenylamine (TQTPA) exhibited good thermal stability and luminescence properties. A single-layer TQTPA light-emitting device shows sky blue emission with a low turn-on voltage of 2.8 V, a maximum brightness greater than 7500 cd/m² at 10 V, and a maximum current efficiency of 1.6 cd/A. Bipolar transport properties of TQTPA were investigated via the hole-only and electron-only devices. Using the bipolar molecule as a hole-transporter, a typical bilayer device with a configuration of ITO/TQTPA (60 nm)/Alq₃ (50 nm)/LiF (0.5 nm)/MgAg yields a maximum current efficiency of 5.6 cd/A (with Alq₃ emission), which is much better (50% higher) than that of the prototypical NPB-based device (3.8 cd/A) with a similar device structure.