A strong regioregularity effect in self-organizing conjugated polymer films and high-efficiency polythiophene: fullerene solar cells - Kim, Y; Cook, S; Tuladhar, SM; Choulis, SA; Nelson, J; Durrant, JR; Bradley, DDC; Giles, M; Mcculloch, I; Ha, CS; Ree, M (NATURE MATERIALS, 2006)