A Distannylated Monomer of a Strong Electron‐Accepting Organoboron Building Block: Enabling Acceptor–Acceptor‐Type Conjugated Polymers for n‐Type Thermoelectric Applications

Acceptor–acceptor (A‐A) copolymerization is an effective strategy to develop high‐performance n‐type conjugated polymers. However, the development of A‐A type conjugated polymers is challenging due to the synthetic difficulty. Herein, a distannylated monomer of strong electron‐deficient double B←N bridged bipyridine (BNBP) unit is readily synthesized and used to develop A‐A type conjugated polymers by Stille polycondensation. The resulting polymers show ultralow LUMO energy levels of −4.4 eV, which is among the lowest value reported for organoboron polymers. After n‐doping, the resulting polymers exhibit electric conductivity of 7.8 S cm−1 and power factor of 24.8 μW m−1 K−2. This performance is among the best for n‐type polymer thermoelectric materials. These results demonstrate the great potential of A‐A type organoboron polymers for high‐performance n‐type thermoelectrics.