Structural Engineering in Polymer Semiconductors with Aromatic N‑Heterocycles

• Published in: Chemistry of materials 2021-03, Vol.33 (5), p.1513-1539
• Main Authors: Huang, Jianyao, Yu, Gui
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.0c03975

The materials community has witnessed a complexity expansion in semiconducting polymers by structural engineering. The most thriving area of polymeric semiconductors lies in the adoption of the highly tunable donor–acceptor motif. This motif has revolutionized the design strategy of semiconducting polymers. The appeal of replacing benzene or thiophene rings with sp2-hybridized N-heteroaromatic rings (azine or azole heterocycles) has directed design efforts toward materials amenable to n-type or ambipolar charge transport behaviors. The introduced nitrogen atoms allow for lowered frontier molecular orbital energy levels to enhance electron injection and reduce the steric effect to maximize electronic coupling. This review provides an overview of recent progress in azine- or azole-type N-heteroaromatics for use in structural engineering of high-mobility polymeric semiconductors. Various synthetic routes to these N-heteroaromatic building blocks and corresponding polymers are reviewed and may inspire new development in molecular engineering. Important structural features are discussed including their electronic structures and conformational preferences. This review also discusses how the molecular structures of these N-heteroaromatics are correlated to the device performances. Collectively, the N-heteroaromatics-containing semiconducting polymers are lead candidates for functional design for specific applications in modern organic electronics.