全聚合物共混薄膜相区尺寸及给受体结晶度匹配关系调控与机理研究

全聚合物光伏电池具有稳定性高、机械性能好且易大面积溶液加工等突出优点，应用潜能巨大。然而，由于共轭聚合物玻璃化转变温度低、共混过程中混合熵小，导致活性层相区尺寸大，不利于激子分离；另外，由于分子本征性质差异大，给受体结晶度不匹配，导致载流子传输不平衡。针对上述问题，本项目将以共轭聚合物成核及分子扩散为切入点，提出改变共混体系结晶动力学途径诱导给受体在不同阶段结晶的策略。该策略不仅能够降低相分离驱动力，而且能够独立控制给受体结晶过程，从而实现活性层相区尺寸及给受体结晶度匹配关系的可控调节。本项目将探究成核势垒及分子扩散速率与共混体系单一组分结晶间的关联，揭示结晶动力学途径对相分离驱动力及给受体结晶竞争耦合关系的影响规律，实现高性能器件活性层多层次结构的构筑。在此基础上，拓展结晶动力学调控凝聚态结构的相关原理，并建立活性层结构与器件光物理过程间的构效关系，为制备高性能器件提供理论及技术支持。

All-polymer solar cells have attracted increasing attention due to their various virtues including environmental stability, excellent mechanical endurance and large-area solution processing. However, it is challenging to achieve a fine phase separation structure due to the low glass transition temperature and negligible mixing entropy of polymers. In addition, a huge difference in crystallinity between donor and acceptor usually exists because of the different chemical structures. This imperfect morphology is not benefit for the exciton dissociation and charge transport. Here, we propose sequential crystallization of polymers through regulating nucleation process and molecular diffusion, i.e., encouraging donor and acceptor to crystallize at different stages. This strategy can reduce the driving force of phase separation, thus obtaining a reduced domain size with high crystallinity. Furthermore, the matching degree of crystallinity between donor and acceptor can be optimized as well through independently regulating their crystallization processes. Consequently, a highly crystalline nano-interpenetrating network with matched crystallinity would be obtained. In this project, the influence of nucleation barrier and molecular diffusion rate on selective crystallization in polymer blends will be systematically investigated. Furthermore, the association relationship among crystallization kinetics, domain size and matching degree of crystallinity between donor and acceptor will be revealed. On this basis, the principle of morphology control will be further developed from the point of kinetics, and the relationship between morphology and device performance will be established as well. This project would provide theoretical guidance and technical support for further improving device performance.