Electrochemical Copolymerization of Isoindigo‐Based Donor‐Acceptor Polymers with Intrinsically Enhanced Conductivity and Near‐Infrared‐II Activity

Abstract Donor‐acceptor (D−A) polymers have excellent electronic and optical properties that allow for their use in multiple areas of research, ranging from field‐effect transistors to biosensing. However, traditional chemical polymerization strategies to form D−A polymers often require extensive purification and generate large amounts of waste. Electro‐copolymerization of complex isoindigo‐based copolymers is explored as a way to overcome traditional synthetic challenges. Herein, the electropolymerization and characterization of four isoindigo‐based D−A copolymers are studied with: II‐EDOT‐T 3 , II‐Thio‐T 3 , II‐Thio‐T 3 ‐TTDT 2 , and II‐EDOT‐T 3 ‐TTDT 2 . Scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) analysis are used to confirm the composition of the polymers. Electrochemical impedance measurements show electron‐transport resistance ( R e ) values as low as 74.7 Ω at selected potentials, indicating that highly conductive copolymers are present. These p‐doped polymers exhibit absorption bands within the near‐infrared region (NIR) with optical band gaps as low as 0.790 eV. Results confirm the electro‐synthesized D−A copolymers exhibit excellent optical properties in the solid state and enhanced conductivity relative to conventional polymers; thus, affording materials with uses in a broad spectrum of applications.