Dendron-Jacketed Electrophosphorescent Copolymers: Improved Efficiency and Tunable Emission Color by Partial Energy Transfer
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- 作者：Hao Jin ; Wei Zhang ; Dan Wang ; Zengze Chu ; Zhihao Shen ; Dechun Zou ; Xinghe Fan ; Qifeng Zhou
- 刊名：Macromolecules
- 出版年：2011
- 出版时间：December 27, 2011
- 年：2011
- 卷：44
- 期：24
- 页码：9556-9564
- 全文大小：1093K
- 年卷期：v.44,no.24(December 27, 2011)
- ISSN：1520-5835
文摘
A styrene-based phosphorescent monomer VC3DbmIr(ppy)2 with cyclometalated iridium complex was synthesized. It was then copolymerized with the first-generation dendritic carbazole monomer VC3CbzG1 through the conventional free radical polymerization to obtain a series of electrophosphorescent random copolymers. Characteristic vibrational bands in the FT-IR spectra were utilized to determine the compositions of the copolymers. The glass transition temperatures of the copolymers were about 90 掳C, and the 5% weight loss temperatures were all above 346 掳C. All the copolymers exhibited similar absorbing bands of the carbazole units in the UV鈥搗is absorption spectra. In the photoluminescent spectra of the copolymer films, energy transfer was found from the carbazole units to iridium phosphors. No obvious energy transfer was found in the copolymer solutions. Light-emitting diodes were fabricated with two configurations. With increasing iridium content, the electroluminescence of the copolymers shifted from blue to orange and passed through a near-white emission region. After the optimization of the device structure, the device containing the copolymer PCbzG1Ir3 had the best performance with a maximum luminescence of 2441 cd/m2 and a maximum external quantum efficiency of 0.520%.