Multi‐Selenophene Incorporated Thiazole Imide‐Based n‐Type Polymers for High‐Performance Organic Thermoelectrics

Developing polymers with high electrical conductivity (σ) after n‐doping is a great challenge for the advance of the field of organic thermoelectrics (OTEs). Herein, we report a series of thiazole imide‐based n‐type polymers by gradually increasing selenophene content in polymeric backbone. Thanks to the strong intramolecular noncovalent N⋅⋅⋅S interaction and enhanced intermolecular Se⋅⋅⋅Se interaction, with the increase of selenophene content, the polymers show gradually lowered LUMOs, more planar backbone, and improved film crystallinity versus the selenophene‐free analogue. Consequently, polymer PDTzSI−Se with the highest selenophene content achieves a champion σ of 164.0 S cm−1 and a power factor of 49.0 μW m−1 K−2 in the series when applied in OTEs after n‐doping. The σ value is the highest one for n‐type donor‐acceptor OTE materials reported to date. Our work indicates that selenophene substitution is a powerful strategy for developing high‐performance n‐type OTE materials and selenophene incorporated thiazole imides offer an excellent platform in enabling n‐type polymers with high backbone coplanarity, deep‐lying LUMO and enhanced mobility/conductivity. Selenophene substitution is a powerful strategy for developing high‐performance n‐type organic thermoelectric materials, because it can realize higher mobility, lower‐lying LUMO level compared with thiophene analogues. Here, we synthesize a thiazole imide‐based n‐type polymer with maximum selenophene content and achieve a champion conductivity of 164.0 S cm−1, which is more than twice of that of selenophene‐free analogue.