含DTF推拉电子结构共轭聚合物的设计合成及光电性能研究

This project is designed to introduction of DTF and malononitrile units with push-pull electronic character into conjugated polymers. By utilizing the charge transfer between the two units, the polar structure would be formed in the conjugated system, which is used to lowering the band gap and enhancing the carrier mobility of the material. Considering the above issues, two different polymer systems are designed: (1) connect DTF and malononitrile units with double bond to construct DCDT unit and introduct into conjugated polymers. The charge transfer in the structure would generate the aromatic DTF+, which is in favor of expanding the conjugate system of polymer and make the absorption spectrum red shift. (2) DTF and malononitrile units are connected to the two sides of fused aromatic backbone of conjugated polymer. The charge transfer would affect the π-electron distribution and induce the formation of quinoidal-like structure. Thus the band gap could be reduced in this effect. In this project, three novel conjugated polymers containing polar structure will be synthesized and the devices of organic thin-film transistor (OTFT) and organic photovoltaic (OPV) will be prepared. Through the performance characterization of the material and device, the effect of polar unit on the material performance will be studied and the mechanism will be investigated deeply. This research will provide the basis for designing novel organic photo-electronic material with good performance.

本项目拟在共轭聚合物中引入具有推拉电子性质的二硫富瓦烯（DTF）和丙二腈结构单元，利用二者之间的电荷转移（CT），在共轭体系中形成偶极结构，以此来降低体系的带隙宽度，提高材料的载流子迁移率。出于以上考虑，我们设计了两类不同的聚合物体系：(1)将DTF与丙二腈以双键相连构建DCDT结构，并引入共轭聚合物中，该结构中的电子转移可以形成芳香性的DTF+，有助于扩展聚合物中共轭体系的扩展，使光谱吸收得以红移；(2)将DTF与丙二腈分别连于共轭聚合物稠芳环骨架的两侧，其电荷转移会对共轭单元的电子分布产生影响，促使醌式结构的形成，从而降低体系的带隙。在本项目中，我们将合成三种新颖的具有偶极结构的共轭聚合物，并制备有机晶体管及光伏电池器件，通过对材料和器件的性能表征，研究偶极单元的引入对材料性能的影响，深入研究其作用机理，为进一步设计性能优良的有机光电功能材料提供参考依据。

有机太阳能电池是一种将光能转换为电能的器件结构，相比于传统硅基电池它具有柔性、质轻及便于大面积制备等优点。本项目通过设计含有二硫富瓦烯结构的共轭聚合物，以此作为给体与PC61BM共混制备光伏器件，光电效率仅为1%。另外我们对苯并二噻吩（BDT）基团进行了功能化，设计合成了含苯炔基、胺基等官能团的结构，研究了各自在光伏及荧光材料中的应用，我们还将苯并二噻吩从苯环的空位接入共轭主链中，合成了一系列宽光谱的光伏聚合物，其开路电压可以达到1.1 V，可以用于串联电池器件的构建。