全共轭聚合物共混体系相分离与光伏性质

The blending of two semiconducting polymers with offset energy levels enables efficient charge generation in thin-film ‘all-polymer’ solar cells. A key requirement for efficient charge separation and collection is the formation of interconnected phase-separated domains structured on the sub-20 nm length-scale. This project will focus on how to control the nanostructures of conjugated polymer blends and link the blend structure and device performance. The main contents include: (1) Studying the strong rod-rod interactions, chain entanglement in solution and crystallinity on the process of phase separation and on control of nanoscale morphology. (2) Developing novel routes for morphological control and evolution process of phase separation in conjugated polymer blend system, constructing phase diagram in conjugated polymer blend system and providing theoretical basis for realizing the interconnected phase-separated domains structure. (3) Developing the Novel routes to regulate the domain size, phase purity and donor/acceptor interface structure in conjugated polymer blend system, revealing the effect of film forming process, thermodynamic factors and post annealing process on film morphology. (4) Establishing the relationship between phase separation structure of conjugated polymer blend system and the corresponding device performance.

构建有利于全聚合物光伏电池性能提高所需的形态结构，揭示全共轭聚合物共混体系相分离原理，并建立形态结构与器件物理间的关联对优化光电器件性能具有指导意义。本项目结合高分子物理与有机光电器件物理相关理论，研究共轭聚合物共混体系结晶度、相分离尺寸、相分离结构、相区纯度及界面扩散程度等对激子扩散效率、电荷转移态分离效率、载流子寿命、载流子双分子复合几率及载流子收集效率间的关系，主要内容包括：（1）研究刚性主链和pi-pi相互作用对共轭聚合物共混物相分离过程的影响，揭示相分离、结晶之间的竞争与耦合关系；（2）构建共轭聚合物共混体系相图，揭示共轭聚合物共混体系相分离机理，掌握薄膜形态调控的热力学和动力学因素，构筑互穿网络相分离结构；（3）发展调控共轭聚合物共混体系相区尺寸、相区纯度及界面扩散程度的方法；（4）建立共混薄膜形态结构与光伏电池性能间的关系。

构建有利于全聚合物光伏电池性能提高所需的形态结构，揭示全共轭聚合物共混体系相分离原理，建立形态结构与器件物理间的关联对优化光电器件性能具有指导意义。但是共轭聚合物刚性强、易缠结等特点，导致全聚合物共混体系及聚合物/非富勒烯体系结晶及相分离行为竞争耦合，相分离行为可控性差。针对以上问题，提出了溶液聚集诱导相分离、分步结晶、受限结晶等制备互穿网络结构途径，实现了相区尺寸、纯度、给受体同向取向，提高了聚合物光伏器件效率。(1) 提出溶液聚集诱导相分离和受限结晶制备互穿网络结构，通过调节分子间作用力实现了相区尺寸及纯度的控制;(2) 通过受限附生结晶和增加溶液中聚集体含量和降低成膜时间，实现给受体Face-on/Face-on同向取向;（3）通过控制给受体结晶顺序，降低成核势垒及增加分子扩散速率，实现了非富勒烯分子结晶性的提高;（4）证实全共轭聚合物太阳能体系电荷转移态（CT）态寿命较短及双分子复合严重，改善相区纯度可抑制激子复合效率和改善电荷收集效率，提高光伏器件效率。在Adv. Funct. Mater.，Macromolecule等杂志发表论文24篇，相关研究成果被国内外研究小组关注，被Acc. Chem. Res., Adv. Mater.，Adv. Funct. Mater.等正面评述21次。参加相关学术会议12人次；培养博士毕业生8人，硕士毕业生2人。