Aqueous-Alcohol-Processable High-Mobility Semiconducting Copolymers with Engineered Oligo(ethylene glycol) Side Chains

Replacement of toxic chlorinated solvents with eco- and human-friendly solvents is an important task for the successful implemention of next-generation polymer electronics technology. Herein, we designed and synthesized five aqueous-alcohol-processable conjugated copolymers by incorporating linear or branched oligo(ethylene glycol) side chains and systematically investigated their material and electronic properties. The resulting benzothiadiazole-based donor-acceptor alternating copolymers were well-soluble in both an ethanol/water mixed solvent and a chlorinated solvent, and their thin films showed distinct morphologies and crystalline characteristics that resulted from the self-assembling properties of the engineered side chains. Moreover, the copolymers showed excellent electrical characteristics with high hole mobilities of up to 0.1 cm² V^-1 s^-1, which is among the highest values reported thus far for polymer field-effect transistors processed using truly eco- and human-friendly solvents without the use of any surfactants. These results clearly demonstrate the immense potential of branched oligo(ethylene glycol) side chains for application in green electronics.