The control of local order in polymer semiconductors using non-covalent interactions may be used to engineer materials with interesting combinations of mechanical and optoelectronic properties. To investigate the possibility of preparing n-type polymer semiconductors in which hydrogen bonding plays an important role in structural order and stability, we have used solution-phase polycondensation to incorporate dicyanoperylene bisimide repeat units into an aliphatic polyamide chain backbone. The morphology and thermomechanical characteristics of the resulting polyamides, in which the aliphatic spacer length was varied systematically, were comparable with those of existing semiaromatic engineering polyamides. At the same time, the charge carrier mobility as determined by pulse-radiolysis time-resolved microwave conductivity measurements was found to be about 10-2 cm2 V-1 s-1, which is similar to that reported for low molecular weight perylene bisimides. Our results hence demonstrate that it is possible to use hydrogen bonding interactions as a means to introduce promising optoelectronic properties into high-performance engineering polymers.

Polymer semiconductors show unique combinations of mechanical and optoelectronic properties that strongly depend on their microstructure and morphology. Here, we have used a model π-conjugated bithiophene repeat unit to incorporate optoelectronic functionality into an aliphatic polyamide backbone by solution-phase polycondensation. Intermolecular hydrogen bonding between the amide groups ensured stable short-range order in the form of lamellar crystalline domains in the resulting semiaromatic polyamides, which could be processed from the melt and exhibited structural and thermomechanical characteristics comparable with those of existing engineering polyamides. At the same time, however, pulse-radiolysis time-resolved microwave conductivity measurements indicated charge carrier mobilities that were an order of magnitude greater than previously observed in bithiophene-based materials. Our results hence provide a convincing demonstration of the potential of amide hydrogen bonding interactions for obtaining unique combinations of mechanical and optoelectronic properties in thermoplastic polymers.