Beijing National Laboratory for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Adv Mater. 2019 Nov;31(46):e1903104. doi: 10.1002/adma.201903104. Epub 2019 Sep 4.
Recent decades have witnessed the rapid development of semiconducting polymers in terms of high charge mobilities and applications in transistors. Significant efforts have been made to develop various conjugated frameworks and linkers. However, studies are increasingly demonstrating that the side chains of semiconducting polymers can significantly affect interchain packing, thin film crystallinity, and thus semiconducting performance. Ways to modify the side alkyl chains to improve the interchain packing order and charge mobilities for conjugated polymers are first discussed. It is shown that modifying the branching chains by moving the branching points away from the backbones can boost the charge mobilities, which can also be improved through partially replacing branching chains with linear ones. Second, the effects of side chains with heteroatoms and functional groups are discussed. The siloxane-terminated side chains are utilized to enhance the semiconducting properties. The fluorinated alkyl chains are beneficial for improving both charge mobility and air stability. Incorporating H bonding group side chains can improve thin film crystallinities and boost charge mobilities. Notably, incorporating functional groups (e.g., glycol, tetrathiafulvalene, and thymine) into side chains can improve the selectivity of field-effect transistor (FET)-based sensors, while photochromic group containing side chains in conjugated polymers result in photoresponsive semiconductors and optically tunable FETs.
近几十年来，半导体聚合物在高电荷迁移率和晶体管应用方面取得了快速发展。人们已经做出了巨大的努力来开发各种共轭框架和连接体。然而，研究越来越表明，半导体聚合物的侧链可以显著影响链间堆积、薄膜结晶度，从而影响半导体性能。本文首先讨论了修饰侧烷基链以改善共轭聚合物的链间堆积有序性和电荷迁移率的方法。结果表明，通过将支链点从主链上移开，可以提高支化链的电荷迁移率，也可以通过部分用线性链替代支化链来提高电荷迁移率。其次，讨论了含杂原子和官能团的侧链的影响。硅氧烷封端的侧链被用来增强半导体性能。氟化烷基链有利于提高电荷迁移率和空气稳定性。引入氢键基团侧链可以提高薄膜结晶度并提高电荷迁移率。值得注意的是，将官能团（如乙二醇、四硫富瓦烯和胸腺嘧啶）引入侧链可以提高基于场效应晶体管（FET）的传感器的选择性，而在共轭聚合物中引入含光致变色基团的侧链则可以得到光响应半导体和光可调 FET。
