多苯基苯单元构建防聚集高分子及其在聚合物蓝光二极管中的应用

Polyphenylbenzene as a platform to fabricated blue-emitting polymers: The effect of aggregation inhibition and application in PLED

改善聚芴的性能具有重要意义.本文针对2种影响聚芴蓝光发射的作用,设计并合成了以多苯基苯和芴单元以及多苯基苯和咔唑为构筑单元的聚合物.热重分析结果证实,多苯基苯单元的引入可以赋予聚合物良好的热稳定性.另外,多苯基苯单元能够极大地改善聚合物的溶解性,并有效抑制聚合物链间的相互作用,防止固态时聚合物发射光谱的红移.理论计算结果表明,在其最优化构型中,多苯基苯-芴共聚物中共聚单元间二面角为61.1°,较多苯基苯-苯二面角(36.9°)更大,进一步说明多苯基苯单元的引入能够增加高分子链的扭曲程度,减小共轭程度,更加有利于获得蓝光发射,减少激基缔合物的形成.将聚合物作为高分子发光二极管中的发光层,多苯基苯-咔唑共聚物表现出较好的深蓝光发射,其色坐标为(0.19,0.13).结果表明,多苯基苯单元能作为有效的构筑单元应用于深蓝光聚合物的合成.

The modification of polyfluorene is of significance. Here according to the two factors that influence the blue emission, we design and synthesize two copolymers which contain polyphenylbenzene and fluorene, polyphenylbenzene and carbazole, respectively. Thermogravimetric analysis （TGA） results conforms that the introducing of polyphenylbenzene unit can improve thermal stability of the polymer. Through the research of photophysical data and comparing with copolymers contain benzene unit, we get that the polyphenylbenzene unit can not only largely improve the solubility, but also effectively inhibit the contaction between polymer chains. This can guarantee the original blue emission even in solid state. Theoretical calculation results show that in the optimized structures, the dihedral angle between polyphenylbenzene and fluorene unit is 61.1 °, bigger than that in the polyphenylbenzene and benzene copolymer （36.9°）. This further conform that the introducing of polyphenylbenzene unit can make polymers twisted and reduce conjugation. Also, the formation of excimers can be inhibited which can guarantee blue emission. Based on their good emission efficiency and stability, we fabricated polymer light emission diodes using them as light emission layers. Devices results show that polyphenylbenzene and carbazole copolymer can exhibit better deep-blue emission, the CIE can stay at （0.19, 0.13）. All these results show that the polyphenylbenzene unit can be used as an effective building block to fabricate polymer with deep-blue emission.