Baixuan Deng, Xiang Liu, Yangqing Wu, Liangyu Sun, Weiwei Li, Xiaoyi Kuang, Jingyuan Tang, Zhan Ma, Li Y, Yangyi Shi, Wenhao Cui, Ruzhe Zhang, Junlin Lai, Huanyu Lei, Xiaoyun Yan, Qing‐Yun Guo, Xinghan Li, Zebin Su, Stephen Z. D. Cheng
ABSTRACT Polythiophenes are among the most extensively studied conjugated polymers owing to their tunable electronic structures, environmental stability, and broad applications in organic electronic devices. The performance of polythiophene‐based devices is largely governed by their molecular structure and packing, which are initially established by the polymerization strategy. This review summarizes recent advances in the synthesis of polythiophenes via chemical polymerization and electropolymerization, with emphasis on how polymerization pathways regulate backbone structure, regioregularity, and molecular packing. Polymerization strategies, together with post‐processing, govern their phase states ranging from glassy to crystalline. Polythiophene‐based materials therefore exhibit structure‐dependent properties, including charge transport, thermoelectric behavior, optical absorption, and electrochemical responsiveness, which enable a wide range of device functionalities. Finally, emerging device opportunities enabled by the intrinsic properties of polythiophenes beyond conventional applications are highlighted, pointing toward new directions for their future development.