Regioregular pyridyl[2,1,3]thiadiazole-co-indacenodithiophene conjugated polymers

Regioregular conjugated polymers containing alternating pyridyl[2,1,3]thiadiazole (PT) and indacenodithiophene (IDT) structural units were synthesized. In these copolymers, the pyridyl nitrogen atoms on PT are precisely arranged along the backbone so that each one has an adjacent proximal and an adjacent distal counterpart across the two IDT flanking units. We find that despite the absence of obvious differences in orbital energy levels and optical bandgap, the regioregular materials exhibit larger charge carrier mobilities, as determined by using field effect transistor devices, and can yield higher solar cell power conversion efficiencies when mixed with fullerenes in bulk heterojunction active layers.