Photoinduced charge transfer through films containing poly(hexylthiophene), phthalocyanine, and porphyrin–fullerene layers

Efficient photoinduced interlayer electron transfer from a phthalocyanine derivative, ZnPH4, to porphyrin cation of a porphyrin–fullerene donor–acceptor dyad was demonstrated by using time-resolved photovoltage technique. Multicomponent thin films with desired layer arrangements were constructed by the Langmuir–Blodgett and spin-coating methods in order to study charge transfer in solid state. As a contradiction to the photovoltage experiments, the dyad monolayer in the film structure did not enhance the current amplitude in electrochemical photocurrent measurements. This is associated with a weak electronic interaction between fullerene and aqueous electrolyte, reducing the photocurrent generation. The use of poly(3-hexylthiophene) as a hole conducting layer was shown to improve photocurrent yield of the device by forming efficient heterojunction together with the ZnPH4 layer.