Vectorial photoinduced electron transfer in multicomponent film systems of poly(3-hexylthiophene), porphyrin—fullerene dyad, and perylenetetracarboxidiimide

Multistage electron transfer in a film system consisting of a hole-transporting layer (HTL), donor—acceptor pair (D—A), and an electron-transporting layer (ETL) was studied by photovoltage and flash-photolysis techniques. Poly(3-hexylthiophene) (PHT) was used as the HTL, while a symmetric porphyrin—fullerene dyad (P-F) and perylenetetracarboxidiimide (PTCDI) layers were functioning as the D—A pair and ETL, respectively. The photoexcitation of this three-component film system causes charge separations in the monomolecular P-F film, followed by electron transfer from the PHT polymer film and the fullerene anions to the porphyrin cations and the PTCDI layer, respectively. The final transient state is a charged PHT+|P-F|PTCDI− system, with significantly increased amplitude and lifetime of the photoelectrical signals compared to previously studied P-F|PTCDI and PHT|P-F systems, due to the its increased charge-separation distance. The study promotes the knowledge on the charge transfer mechanism in multilayered film systems.