Elemental Sulfur Mediated One-Pot Synthesis of Poly(benzodifurandione) (PBFDO) with High Conductivity for Organic Electronics

Poly(benzodifurandione) (PBFDO) is a benchmark n-type conductive polymer that combines exceptional electrical conductivity with outstanding environmental stability, positioning it as a pivotal material for the future of organic electronics. However, its practical deployment has been severely limited by intrinsic synthetic constraints. All reported routes suffer from unavoidable trade-offs: the original method requires weeks of dialysis in large volumes of DMSO to remove unreacted monomers, while later approaches either depend on toxic catalysts or involve energy-intensive purification processes. Here we report a transformative, metal-free, sulfur-mediated synthetic strategy that overcomes these longstanding bottlenecks and represents a decisive advance in PBFDO fabrication. Elemental sulfur (S8), an abundant and non-toxic oxidant, drives polymerization through a highly efficient cascade mechanism while simultaneously generating reducing species (hydrogen sulfide, H2S, and dimethyl sulfide, DMS) that in situ dope PBFDO into its conductive state. Consequently, the 2 resulting reaction solution can be used directly as a conductive polymer ink, completely eliminating prolonged purification processes-a major barrier to scalable PBFDO synthesis across all existing methods. This approach yields PBFDO with electrical conductivities up to 2059 S cm-1 , matching the highest values reported to date. Crucially, the method exhibits excellent scalability, enabling synthesis at the 500 mL scale while maintaining high conductivity (>1300 S cm-1), effectively resolving the scalability limitations that have hampered previous routes. Devices based on the resulting PBFDO demonstrate outstanding performance in thermoelectric and organic electrochemical transistor applications. Overall, this sulfur-mediated strategy simultaneously eliminates toxic reagents, complex and energy-intensive purification, and poor scalability in PBFDO synthesis, paving the way for the much desired widespread adoption of this highly promising n-type conductive polymers in organic electronics.