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

Developing polymers with high electrical conductivity (sigma) 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 & sdot;& sdot;& sdot;S interaction and enhanced intermolecular Se & sdot;& sdot;& sdot;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 sigma of 164.0 S cm-1 and a power factor of 49.0 mu W m-1 K-2 in the series when applied in OTEs after n-doping. The sigma 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.+image