用于非富勒烯聚合物太阳能电池的苯并三氮唑类二维共轭聚合物

Benefitted from their advantages of nofullerene acceptors, such as easy–accessible, strong absorption and easily adjustable energy levels, fullerene–free polymer solar cells (PSCs), in which both polymer donor and nonfullerene organic/polymer acceptor absorb light and transport charges, have great potential to replace fullerene/polymer devices. Among the reported non-fullerene acceptors, low bandgap acceptors are more attractive to harvest light in the solar spectrum range. Thus developing suitable medium bandgap polymer donors providing complementary absorption with the low bangdgap nonfullere acceptors for fullerene free PSCs is very important to improve their performance. Based on our recently work and the characteristic of non–fullerene PSCs, we proposed to developing “two–dimension–conjugated medium bandgap polymers based on fluorobenzotriazole (FTAZ) units” That is, (1) selecting FTAZ as acceptor unit, taking the advantages of its weak electron accepting properties, to build medium bandgap polymer donors, thus providing complementary absorption with low bandgap acceptors; (2) Introducing conjugated side chains on the aromatic donor building blocks to construct two-dimension-conjugated polymers; (3) Introducing fluorine substitution on the conjugated backbone, to improving backbone planarity for a higher hole mobility and reducing charge carrier recombination; (4) Using side-chain engineering to optimize balancing solubility and the physicochemical properties of the conjugated polymers.

得益于非富勒烯受体合成容易、吸光强、能级易调控的优点，基于聚合物给体和非富勒烯受体吸光和传输电子的聚合物太阳能电池，具有替代富勒烯聚合物太阳能电池的巨大优势。在非富勒烯受体中，窄带隙受体因其对太阳光强的捕获而备受关注，而发展中间带隙的聚合物给体与窄带隙受体匹配提供互补吸收，对于提升聚合物太阳能电池的性能至关重要。在此，项目申请人在已有的非富勒烯聚合物太阳能电池的工作基础上，根据非富勒烯受体的特点，提出了发展“基于苯并三氮唑类中间带隙的二维共轭聚合物”的设想：即(1) 选用苯并三氮唑弱的吸电子特性构筑中间带隙聚合物，与窄带隙受体匹配实现吸收互补，得到宽广吸收，提高光电流； (2) 在芳香稠环给体单元上(例如BDT)引入共轭支链，构筑二维共轭聚合物；(3) 利用氟原子增强主链的平面性，提高迁移率，减少体系内载流子复合；(4) 利用侧链工程调控光物理性能、溶解度和聚集态形貌。

设计合成合适的给体材料与窄带隙受体匹配，对于制备高性能聚合物太阳能电池具有重要意义。该项目通过共轭侧链和噻吩Π桥的化学工程，发展了一些列二维共轭聚合物给体材料，也就是通常所说的J-系列聚合物。J-系列聚合物具有合适的中间带隙能级（1.80 eV）和强的吸收光谱（在400−650nm吸光范围内）；另外他们还具有高的结晶性和迁移率，并且随共轭侧链的不同具有可调的能级。这些性质造就了J-系类聚合物为一类重要的聚合物给体光伏材料。另外，考虑到J-系列聚合物的优异性能，我们基于其分子骨架合成了小分子给体材料并获得了高性能光伏器件。本项目发表标注本项目资助的研究论文23篇，其中第一作者/通讯作者文章11篇，包括2篇《自然：通讯》，2篇《德国应用化学》，1篇《美国化学会志》和1篇《先进材料》。

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