Supramolecular formation of fibrous nanostructure in donor–acceptor dyad film

A novel oligothiophene and its fullerene derivative were synthesized and their film morphologies were investigated. AFM images revealed that the oligothiophene formed well-aligned fiber-like nanostructures in the film after being thermally annealed at its liquid-crystalline temperature. In the oligothiophene–fullerene dyad film, fibers were already formed in the as-cast film. Thermal annealing further enhanced the structural order and a long, partially aligned fibrous nanostructure with a width of around 10 nm and a length of as long as 200 nm was observed. Combined with the results of X-ray analysis, these features were ascribed to supramolecular self-assembly via π–π interaction of the oligothiophene groups. Photovoltaic properties of the molecules were also investigated.