A novel mesogen‐jacketed liquid crystalline electroluminescent polymer with both thiophene and oxadiazole in conjugated side chain
A novel mesogen‐jacketed liquid crystalline electroluminescent polymer with both thiophene and oxadiazole in conjugated side chain
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DOI：
10.1002/pola.23908
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发表时间：
2010-04
期刊：
影响因子：
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通讯作者：
Qian Yang;Yiding Xu;Hao Jin;Zhihao Shen;Xiaofang Chen;Dechun Zou;Xinghe Fan;Qifeng Zhou
中科院分区：
文献类型：
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作者：
Qian Yang;Yiding Xu;Hao Jin;Zhihao Shen;Xiaofang Chen;Dechun Zou;Xinghe Fan;Qifeng Zhou
据报道，侧链上同时具有电子传输恶二唑和空穴传输噻吩的介晶夹套液晶聚合物（MJLCP）具有良好的电致发光性能。合成了2,5-双{5-[(4-烷氧基苯基)-1,3,4-恶二唑]噻吩-2-基}苯乙烯单体（M-Cm，m为烷氧基中的碳原子数，m=8,10），并通过 1 H-NMR、质谱和元素分析进行了确认。成功获得了相应的聚合物，并通过热分析、光谱、循环伏安法、电致发光分析、偏光显微镜（PLM）和广角X射线衍射（WAXD）进行了表征。该聚合物表现出高达 382 °C 的高分解温度和高达 184 °C 的高 Tg。吸收光谱表明，单体和聚合物在薄膜中的聚集程度均低于溶液中的聚集程度，并且聚合物的吸收光谱较单体呈现明显的蓝移。单体和聚合物均具有蓝绿光发射，薄膜中聚合物的光致发光光谱表明形成了准分子或激基复合物。该聚合物表现出比之前报道的含有恶二唑单元的MJLCP更低的HOMO能级和LUMO能级。 ITO/PEDOT/PVK/polymer/TPBI/Ca/Ag器件结构的电致发光研究显示最大亮度和电流效率分别为541 cd/m 2 和0.10 cd/A，证明直接连接的电子和空穴传输单元的引入可以极大地提高侧链共轭聚合物的EL性能。通过PLM和WAXD结果证实聚合物的相结构为近晶A相。退火后的样品在室温下发出偏振光致发光，这表明其在显示领域的实际应用具有潜在的实用性。
Mesogen-jacketed liquid crystalline polymers (MJLCPs) with both electron-transport oxadiazole and hole-transport thiophene in the side chain were reported for their promising electroluminescent property. Monomers of 2,5-bis{5-[(4-alkoxyphenyl)-1,3,4-oxadiazole]thiophen-2-yl}styrene (M-Cm, m is the number of the carbons in the alkoxy groups, m = 8,10) were synthesized and confirmed by 1 H-NMR, mass spectrometry, and elemental analysis. The corresponding polymers were successfully obtained and characterized by thermal analysis, optical spectroscopy, cyclic voltammetry, electroluminescent analysis, polarized light microscopy (PLM), and wide-angle X-ray diffraction (WAXD). The polymers exhibited high decomposition temperatures reaching 382 °C and high Tg's reaching 184 °C. The absorption spectra indicated that both the monomers and polymers had little aggregation in film than that in solution, and the absorption spectra of the polymers showed an obvious blue-shift compared with those of the monomers. Both the monomers and the polymers had blue-green emission, and the photoluminescence spectra of the polymers in film suggested the formation of excimer or exciplex. The polymers showed lower HOMO energy levels and LUMO energy levels than those of the MJLCPs containing oxadiazole unit reported before. Electroluminescence study with the device configuration of ITO/PEDOT/PVK/polymer/TPBI/Ca/Ag showed maximum brightness and current efficiency of 541 cd/m 2 and 0.10 cd/A, which proved that the introduction of directly connected electron- and hole-transport units could greatly improve the EL property of side-chain conjugated polymers. The phase structures of the polymers were confirmed to be smectic A phase through the results of PLM and WAXD. The annealed samples emitted polarized photoluminescence at room temperature, which indicated potential utility for practical applications in display.