D-A类共轭聚合物晶界内部tie molecule构象调控

Enhancing the coplanar conformation of tie molecule in grain boundary of donor-acceptor conjugated copolymer is an important strategy to elevate the carrier mobility. Better understanding the parameter of affecting the conformation of tie molecule in grain boundary of donor-acceptor conjugated copolymer, developing the effective physical methods to tune the tie molecular conformation and correlating the condensed state structures and the device performance are helpful to guide the optimization of morphology and electric properties for conjugated polymers. Therefore, our works will focus on the following aspects: (1) The effect of stiffness in the backbones and steric hinder in the side chains of donor-acceptor conjugated copolymer on the tie molecular coplanar conformation will be investigated(2) The effect of the entanglement degree of molecular chains on the tie molecular conformation will be realized by adjusting the solution state. (3) Aligning the crystals will be used to induce the tie molecular coplanar conformation. The optimization of tie molecular conformation and alignment of crystalls will be simultaneously tuned by the solution state and film forming process. (4) The relationship between morphology and carrier mobility will be established, which will provide the theoretical guidelines for optimizing the morphology and performance of conjugated polymer films.

增强D-A共轭聚合物晶界内部tie molecule共平面构象是提高薄膜载流子迁移率的重要手段。理解影响D-A共轭聚合物体系tie molecule构象的物理参数，掌握调控tie molecule构象的方法及手段，对进一步优化薄膜凝聚态结构并提高器件性能具有指导意义。本项目主要内容包括：(1)研究具有不同主链刚性及侧链位阻的D-A共轭聚合物分子的tie molecule共平面程度，总结影响tie molecule构象的相关参数。(2)研究分子链缠结程度对tie molecule构象的影响，通过调节溶液状态降低分子链缠结程度实现tie molecule共平面构象的调节并阐述相关机制。(3)将溶液状态与成膜方法相结合，利用晶区长程有序排列诱导tie molecule采取共平面构象，实现tie molecule构象及晶体排列的同时优化。(4)构建溶液状态-薄膜形貌-载流子迁移率间的关系。

共轭聚合物由于具有独特的结构特征(π电子共轭体系)、本征柔性、可大面积溶液加工及光电性质可调等优势，在有机太阳能电池、场效应晶体管等领域具有很大的应用前景。作为化学结构和器件性能之间的纽带，薄膜中共轭聚合物的凝聚态结构是决定载流子传输性能的关键因素。研究表明如何实现长程有序排列诱导tie-molecule共平面构象基础上实现分子共平面性的提高以增强聚合物薄膜结晶度减少晶界、及增加数量的基础上的基础上实现tie-molecule共平面构象是提高载流子迁移率的有效手段。主要研究进展包括：（1）通过控制三相线的后退速率与临界取向速率相匹配时获得高取向薄膜、添加剂增强聚合物tie-molecule共平面性及晶区间引入强刚性共平面高分子量聚合物，增强晶区间tie-molecule共平面构象。（2）通过烷烃类添加剂降低侧链位阻增强聚合物分子刚性、调节聚合物-溶剂间的相互作用实现解缠结，在此基础上调节辅溶剂的含量与组成调控溶液中分子间聚集，同时结合溶剂挥发动力学，控制成核与生长过程，实现了共轭聚合物纳米线的制备，显著提高了共轭聚合物薄膜结晶性，大幅度减少了晶界。（3）在上述工作的基础上，在共混体系中通过调节溶液聚集状态及分子量和热退火处理匹配组分间的结晶速率和结晶程度，促进实现了共混体系中tie-molecule增强晶区间的连通性，构建更完善的互穿网络结构，建立了薄膜形态与器件性能间关联。