Liang Jiaen, Pan Mingao, Chai Gaoda, Peng Zhengxing, Zhang Jianquan, Luo Siwei, Han Qi, Chen Yuzhong, Shang Ao, Bai Fujin, Xu Yuan, Yu Han, Lai Joshua Yuk Lin, Chen Qing, Zhang Maojie, Ade Harald, Yan He
Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, 999077, China.
Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA.
Adv Mater. 2020 Dec;32(52):e2003500. doi: 10.1002/adma.202003500. Epub 2020 Nov 13.
Developing high-performance donor polymers is important for nonfullerene organic solar cells (NF-OSCs), as state-of-the-art nonfullerene acceptors can only perform well if they are coupled with a matching donor with suitable energy levels. However, there are very limited choices of donor polymers for NF-OSCs, and the most commonly used ones are polymers named PM6 and PM7, which suffer from several problems. First, the performance of these polymers (particularly PM7) relies on precise control of their molecular weights. Also, their optimal morphology is extremely sensitive to any structural modification. In this work, a family of donor polymers is developed based on a random polymerization strategy. These polymers can achieve well-controlled morphology and high-performance with a variety of chemical structures and molecular weights. The polymer donors are D-A1-D-A2-type random copolymers in which the D and A1 units are monomers originating from PM6 or PM7, while the A2 unit comprises an electron-deficient core flanked by two thiophene rings with branched alkyl chains. Consequently, multiple cases of highly efficient NF-OSCs are achieved with efficiencies between 16.0% and 17.1%. As the electron-deficient cores can be changed to many other structural units, the strategy can easily expand the choices of high-performance donor polymers for NF-OSCs.
开发高性能供体聚合物对于非富勒烯有机太阳能电池（NF-OSCs）至关重要，因为只有当最先进的非富勒烯受体与具有合适能级的匹配供体耦合时，它们才能表现良好。然而，用于NF-OSCs的供体聚合物选择非常有限，最常用的是名为PM6和PM7的聚合物，它们存在几个问题。首先，这些聚合物（特别是PM7）的性能依赖于对其分子量的精确控制。此外，它们的最佳形态对任何结构修饰都极其敏感。在这项工作中，基于随机聚合策略开发了一类供体聚合物。这些聚合物可以通过各种化学结构和分子量实现形态的良好控制和高性能。聚合物供体是D-A1-D-A2型无规共聚物，其中D和A1单元是源自PM6或PM7的单体，而A2单元包含一个缺电子核心，两侧是带有支链烷基链的两个噻吩环。因此，实现了多例高效NF-OSCs，效率在16.0%至17.1%之间。由于缺电子核心可以改变为许多其他结构单元，该策略可以轻松扩展用于NF-OSCs的高性能供体聚合物的选择。
