Heteroblock copolymers consisting of poly(3-hexylthiophene) and fullerene-attached poly(3-alkylselenophene) (T-b-Se-PCBP) were synthesized for organic photovoltaic applications by quasi-living catalyst transfer polycondensation and subsequent conversion reactions. Characterization of the polymers confirmed the formation of well-defined diblock structures with high loading of the fullerene at the side chain (∼40 wt %). Heteroblock copolymer cast as a thin film showed a clear microphase-separated nanostructure approximately 30 nm in repeating unit after thermal annealing, which is identical to the microphase-separated nanostructure of diblock copolymer consisting of poly(3-hexylthiophene) and fullerene-attached poly(3-alkylthiophene) (T-b-T-PCBP). These heteroblock copolymers provide an ideal platform for investigating the effects of nanostructures and interfacial energetics on the performance of organic photovoltaic devices.
Keywords: block copolymers; energy cascade; microphase separation; organic solar cells; self-organization; semiconducting polymers; thin films.