Fig. 5

Schematic illustration of additional light harvesting by near-IR dye molecules at the donor/acceptor interface in ternary blend films: Top) direct absorption of SiPc6 molecules, which can harvest the near-IR light in the solar light that cannot be absorbed by P3HT or PCBM. Middle) Exciton harvesting due to long-range FRET, which can harvest P3HT excitons generated far from the interface more efficiently. Bottom) Exciton harvesting due to long-range FRET from the P3HT energy donor to the SiPc6 energy acceptor, which can more efficiently harvest P3HT excitons that cannot reach the interface by random exciton diffusion