Solubilizing Benzodifuranone-Based Conjugated Copolymers with Single Oxygen Containing Branched Side Chains

Achieving simple methodologies to synthesize, scale up, and process organic polymeric materials from solution is paramount to simplify access to semiconductor devices. In this context, benzodifuranone-based copolymers have shown excellent performance in different electronic applications, such as organic field effect transistors or organic thermoelectric generators. Nevertheless, these materials commonly display limited solubility due to their highly coplanar structures, giving rise to significant aggregation. Large branched alkyl side chains are commonly used to circumvent this problem; however, these side chains suffer from long and cumbersome synthetic routes and high costs. In this work, single ether-containing branched side chains synthesized employing Williamson etherification were prepared to provide a straightforward strategy to attach long side chains to p-conjugated backbones. The starting materials used were costs-economic Guerbert alcohols and α,ω-dibromoalkyls. The robustness of the method allowed both spacers as well as side chain lengths to be varied. Molar masses of benzodifuranone-thiophene copolymers reached up to 50 kg/mol, and solubilities were as high as 90mg/mL. Furthermore, n-doping of the polymers with <i>N-</i>DMBI delivered conductivity values three times superior to similar copolymers reported in the literature. The synthetic approach is furthermore extended to different backbone structures.