共轭聚合物定向阵列的构筑及性能研究

The optoelectronic properties of conjugated materials are intimately related to the organization of the polymer chains. The transport processes of the electronic excitations and the charge carriers are very strongly affected by the degree of order in the thin films and the chain orientation. Many methods have been devoted to assemble the conjugated polymers. However, there are limitations of expensive equipment, orientation layer, supporting materials, etc. to these methods. This application plans to use the array structures fabricated with colloidal crystals as platforms and templates for the assembly of moleculars. Template constraints and internal driving force synergetic induce polymer molecules to align along the template direction. Ultimately horizontally and vertically aligned conjugated polymer films would be obtained. Array fabrication technique is simple and flexible, which facilitates the regulation of the template period, height and other parameters. And then it can improve the degree of ordering of the molecular assembly and optoelectronic anisotropy. Characterization and properties of molecular arrangement in the film provide scientific basis for the controlling of fabrication technology. This technology not only achieves the controlled assembly of molecules in the film, but also fabricates ordered crystal array structures on the film surface. We expect the perfect combination of these two can be applied to the high efficiency of directional charge transporting thin-film transistor device.

共轭高分子材料的光电特性与聚合物分子链的组装密切相关，其结构有序和链取向程度的控制是提高光电传输性能的关键参数。基于现有组装方法存在设备昂贵、需定向层、支撑材料等的局限，本申请计划采用胶体晶体制备的阵列结构作为构筑分子组装的模板和平台，利用模板限制效应和共轭聚合物内在驱动力协同作用，诱导聚合物分子沿模板方向定向排列，得到相对基底水平和垂直排列的有序分子组装。阵列结构加工的简单灵活便于模板周期、高度等参数的调控，进而改善分子组装的有序程度及光电各向异性；膜层内分子排列的表征及性能研究可以作为模板加工调控的依据。该技术在膜内分子可控组装的同时，在膜层表面也构筑了有序晶体阵列结构，并有望应用于高效率定向电荷迁移的薄膜晶体管器件。

在光电领域广泛应用的有机半导体材料，其特性与聚合物分子组成和分子链的组装密切相关，结构有序和链取向程度的控制是提高光电传输性能的关键因素。本项目基于课题组聚芴类共轭高分子材料的合成基础，通过功能基团的二价钯配合物催化芴单体发生缩聚反应时的链式聚合特征，将橙光基团与不同配体钯(0)组成催化体系，得到端基为橙光基团，分子量为7.48×10~4的聚芴。实现纯白光发射，国际色坐标CIE为(0.31，0.32)。芴侧链引入磷氧根合成的小分子量橙光均聚芴，在橙光基团比例为1.9%时，实现白光发射。端基为并三噻吩单元bt-DTT的聚芴，bt-DTT平面基团与主链芴单元形成共轭体系。这些为后期聚合物阵列结构的构筑提供材料基础。进一步将延迟荧光材料作为客体发光材料，合成主链中心含延迟荧光单元的共轭聚合物。通过控制吸收峰与发射峰的重叠，调控两者之间的能量转移效率，最终得到白光发射。最后将胶体晶体软模板作为构筑分子组装的平台，在一定温度压力下的热运动过程中，分子链在驱动力和模板限制的双重作用下有序排列。椭圆阵列的聚合物膜层掠入射X射线衍射峰与平整膜层对比，衍射峰的缺失表明分子间作用的减少，也表明分子链为完全平行于基底排列的单一结构。溶剂调控分子链组装，当不良溶剂DMF含量低时，加强π-π堆积和烷基侧链的范德华相互作用，分子链排列紧密；当达到一定量时，不良溶剂的相分离作用出现，大量DMF插入相邻侧链的空隙，增加晶面间距，从而调控能量转移情况和色坐标。本项目研究表明优异的分子组成结合分子的有序排列决定了膜层的光学特性，并辅以膜层表面精细的纳米阵列结构可以有效提高整体性能，可以应用到需要定向电荷迁移率的薄膜晶体管器件设备，达到了预期研究目标。