新型多环Thienoacene衍生物及其共轭聚合物合成、表征与光伏器件阴极界面修饰研究

Following our prophase researches about the syntheses and characterizations of conjugated polymers based on polycyclic thienoacene and the modification of the photovoltaic cells' cathode interface via alcohol soluble conjugated polymers and/or polyelectrolytes, In this project, three novel polycyclic thienoacenes have been designed and would be synthesized. Then， three series of conjugated polymers with different energy levels and photoresponse properties, which were derived from the novel polycyclic thienoacenes and various electron acceptor units such as benzothiadiazole, alkylthieno[3,4-b]thiophene-2-carboxylate, 4-fluoro-alkyl- thieno[3,4-b]thiophene-2-carboxylate, 4,7-bis(thieno-2-yl)-2,1,3-benzothiadiazole etc,will be synthesized. On the other hand, alcohol soluble conjugated polymers/polyelectrolytes based on the polycyclic thienoacene derivatives will also designed and synthesized. We expected that high performance polymer solar cells (power conversion efficiency about 10%) would be achieved by the modification of the conjugated polymers and devices cathode. In the end, the approaches of the design and synthesis of novel polycyclic thienoacene-based CPs and alcohol soluble conjugated polymers for PSCs polymer could be abstracted through the studies of the relations between the charge transporting and photovoltaic properties etc of the polycyclic thienoacene-based polymers and the coplanar of the monomer, energy levels etc of the thienoacene-based conjugated polymers.

本项目首先拟通过分子理性设计并合成三类新的多环thienoacene衍生物及其共轭聚合物（约20-30种）；其次通过综合多环thienoacene衍生物分子重组能、共轭面、共轭长度对多环thienoacene基共轭聚合物 （CPs）电荷迁移性能、基态-激发态局域偶极与光伏性能等的影响的研究，形成对合成新的用于构建高性能的多环thienoacen衍生物及其CPs有指导意义的设计规则；再次通过设计、合成适用于新的多环thienoacene基CPs为电子给体材料的聚合物太阳能电池（PSCs）的醇溶性聚合物/聚合物电解质阴极修饰材料，认识PSCs电子给体材料主链结构和阴极修饰层醇溶性聚合物/聚合物电解质主链结构、极性官能团数目等之间的关联；最后通过醇溶性聚合物阴极修饰材料和多环thienoacene 基共轭聚合物的优选、器件制备工艺的优化等，实现能量转换效率接近或达到10%的PSCs。

本项目以多环thienoacene单元DTBDT和DTNDT为主要切入点，通过在DTBDT的5,10-位引入烷氧基、烷噻吩基和烷硫噻吩侧基而得到一维、二维的双锡共聚单体，与强缺电子单元异靛蓝（ID）、苯并噻二唑（BT）、二噻吩基苯并噻二唑（DTBT）、二噻吩基萘并双噻二唑（DTNT）、中等缺电子单元TPTI和寡聚噻吩单元（T、TT、3T）等制备了系列thienoacene基聚合物，实现了4.43%~8.75%的能量转化效率（PCE），发现聚合物骨架单元、氟取代基可显著影响聚合物光物理性质，溶剂添加剂（DPS和DIO）调控活性层微观纳米形貌，实现电池性能提高。同时在以NT为缺电子单元的系列D–π–A型聚合物中，发现D、π桥、A单元和柔性侧链均对聚合物的光物理和电池性能产生重要影响。其次，将烷硫噻吩基侧链引入DTBDT上构建聚合物，发现烷硫基可显著提高聚合物材料的介电常数并降低激子束缚能进而促进激子解离，从而有力提升电池性能。接着，将醇溶性共聚物引入到PDTBDT-BT/FBT:PC71BM体系，首次在实验室证实了以醇溶性聚合物为阴极修饰层倒置聚合物太阳能电池拥有有利于器件性能提高的活性层垂直相分离。最后将高效聚合物作为第三组分构建三元太阳能电池，发现其可显著改善活性层吸光能力并且所形成的瀑布能级和给受体“合金”提高激子解离和电传输，从而提升器件性能。