Synthesis and Properties of Nitrogen-Linked Poly(2,7-carbazole)s as Hole-Transport Material for Organic Light Emitting Diodes
Synthesis and Properties of Nitrogen-Linked Poly(2,7-carbazole)s as Hole-Transport Material for Organic Light Emitting Diodes
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DOI：
10.1002/pola.23454
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发表时间：
2009-08-01
影响因子：
--
通讯作者：
Shigehara, Kiyotaka
中科院分区：
文献类型：
--
作者：
Michinobu, Tsuyoshi;Kumazawa, Hiroe;Shigehara, Kiyotaka
利用钯催化的胺化反应，通过两种双官能团单体之间的缩聚反应，合成了一类新型咔唑聚合物--氮连接的聚（2，7-咔唑）。通过（1）H NMR、红外、凝胶渗透色谱和MALDI-TOF MS对聚合物进行了表征，并揭示了单体结构的组合对于制备高分子量聚合物是重要的。热分析表明具有高玻璃化转变温度的良好热稳定性，例如，对于较高分子量聚合物P2，温度为138 ℃。为了探索这些聚合物的应用可能性，通过紫外-可见吸收光谱和荧光光谱以及它们的电化学特性来研究它们的光学性质和能级。尽管在溶液中确实观察到所有聚合物的蓝光发射，但量子产率非常低，并且固体膜没有荧光。另一方面，由固体薄膜中第一次氧化的起始电位估计的聚合物的HOMO能级在-5.12至-5.20 eV的范围内相对较高。因此，制造了使用这些聚合物作为空穴传输层和铱（III）络合物作为三重态发射体的发光二极管。含对，对′-联苯基的氮连接聚（2，7-咔唑）P3具有更高的HOMO能级和更高的分子量，比含间苯基的P2具有更好的性能。(C)2009 Wiley Periodicals，Inc.聚合物科学杂志A部分：聚合物化学47：3880-3891，2009
A novel class of carbazole polymers, nitrogen-linked poly(2,7-carbazole)s, was synthesized by polycondensation between two bifunctional monomers using the palladium-catalyzed amination reaction. The polymers were characterized by (1)H NMR, Infrared, Gel permeation chromatography, and MALDI-TOF MS and it was revealed that the combination of the monomer structures is important for producing high molecular weight polymers. Thermal analysis indicated a good thermal stability with high glass transition temperatures, e.g., 138 degrees C for the higher molecular weight polymer P2. To pursue the application possibilities of these polymers, their optical properties and energy levels were investigated by UV-Vis absorption and fluorescence spectra as well as their electrochemical characteristics. Although the blue light emission was indeed observed for all polymers in solution, the quantum yields were very low and the solid films were not fluorescent. On the other hand, the HOMO levels of the polymers estimated from the onset potentials for the first oxidation in the solid thin films were relatively high in the range of -5.12 to -5.20 eV Therefore, light emitting diodes employing these polymers as a hole-transport layer and iridium(III) complex as a triplet emitter were fabricated. The device of the nitrogen-linked poly(2,7-carbazole) P3 with p,p'-biphenyl spacer, which has a higher HOMO level and a higher molecular weight, showed a much better performance than the device of P2 with m-phenylene spacer. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3880-3891, 2009