Chlorinated Bithiophene Imide‐Based n‐Type Polymers: Synthesis, Structure–Property Correlations, and Applications in Organic Electronic Devices

Abstract Developing electron‐deficient (hetero)arenes with optimized geometries and electronic properties is imperative for advancing n ‐type polymers and organic electronic devices. We report here the design and synthesis of two chlorinated imide‐functionalized electron‐deficient heteroarenes, namely chlorine‐substituted bithiophene imide (ClBTI) and its fused dimer (ClBTI2). The corresponding polymers show a near‐planar framework, appropriate frontier molecular orbital levels, and good solubility. When integrated into organic thin‐film transistors, ClBTI2‐based n‐type polymer afforded unipolar electron mobility of up to 0.48 cm 2 V −1 s −1 . The binary all‐PSCs based on PM6 and new polymers show a power conversion efficiency (PCE) exceeding 1%. Interestingly, by introducing these polymers with ordered structure, high crystallinity, and sizable electron mobility as the third component into the host system PM6:PY‐IT, continuous interpenetrating networks with large fibrillar structures can be formed. Investigations of charge transfer kinetics and energy loss analyses unveiled that ClBTI2‐based n‐type polymer P(ClBTI2‐BTI) enables optimized charge transport, reduced charge recombination, and minimized non‐radiative loss within the all‐polymer ternary blends, yielding a remarkable PCE of 19.35% (certified: 19.20%) through optimizing the state‐of‐the‐art PM6:PY‐IT blend. The structure–property–performance relationships provide valuable insights into the design of electron‐deficient (hetero)arenes and n‐type polymers, marking a great progress in the development of high‐performance n‐type polymers for organic electronic devices.