A General, Scalable and Cost-Effective Synthetic Approach for n-Doped Poly(Benzodifurandione) (n-PBDF) and Its Derivatives

Conducting polymers have attracted significant attention due to their potential applications in printable electronics, energy storage systems, sensors, and bioelectronics. Designing and synthesizing high-performance and solution-processable conducting polymers is of great interest in developing next-generation printed electronics. The development of n-type conducting polymer has long been considered a challenge, owing to poor materials stability under the ambient conditions and their thin films showing conductivities far below those of the benchmark p-type conducting polymer, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The recent discovery of highly conductive, solution-processable, n-doped poly(benzodifurandione) (n-PBDF) marks a milestone in the development of n-doped conducting polymers. Currently, n-PBDF is prepared by either duroquinone-mediated or copper-catalyzed polymerizations, where scalability and cost-effectiveness may present challenges. Here, we present a general, scalable, and cost-effective method for n-PBDF and its derivatives, namely selenium dioxide (SeO₂) catalyzed polymerization. We discovered that a catalytic amount of SeO₂ leads to almost complete monomer conversions, thus eliminating the need for the costly and slow dialysis process. Different from the previously reported oxidative polymerization mechanism involving radical pathway, we revealed for the first time that SeO₂ catalyzed polymerization employs a mechanism involving successive Riley oxidation and aldol polycondensation processes in one-pot. More importantly, we demonstrated that the SeO₂ catalyzed polymerization is not only an efficient, low-cost and scalable method to synthesize n-PBDF, but also a general synthetic method for other n-type conjugated polymers or copolymers derivatives with double-bond linked structures (n-PBDF derivatives). This study enriches the synthetic methodology of conjugated polymers and paves the way for scalable synthesis and mass production of n-PBDF, thus facilitating its adoption in various application scenarios.