Cationic Conjugated Polymers with Enhanced Doped-State Planarity for n-Type Organic Thermoelectrics

To date, extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains. However, these sidechains are insulators, limiting further performance enhancement in doped conjugated polymers. Moreover, the most widely used chlorinated solvents are toxic, limiting the practical applications of many conjugated polymers. Here, we report a water/ alcohol processable n-type conjugated polymer P(Py2FT), featuring side chain-free cationic backbones. P(Py2FT) exhibits a high n-type electrical conductivity of up to 28.1 S cm(-1) and a high thermoelectric power factor of up to 28.7 mu W m (-1) K-2 comparable to some conventional n-type conjugated polymers reported recently. More importantly, cationic polymers display tight molecular packings and interesting enhanced backbone planarity after n-doping, which, we envision, provides a new research direction to address the sidechain issue in conventional conjugated polymers. Our work demonstrates that sidechain-free cationic polymers have great potential for green-solvent-processed heavily doped organic electronics.