Insight into correlation between molecular length and exciton dissociation, charge transport and recombination in Polymer: Oligomer based solar cells

Four FTBT-based oligomers with different molecular length are utilized as acceptors in P3HT:FTBT oligomer PSCs. The effect of oligomer length on the blend morphologies, exciton dissociation and charge recombination is disclosed. The phase separation in blend films is suppressed with increasing the oligomer length resulting in efficient exciton dissociation. F3TBT3 is favorable to construct suitable phase separation in P3HT:FTBT oligomer blend that compromises between efficient exciton dissociation and balanced charge transport, leading to an optimal photovoltaic performance.443