Rectified photocurrent of biophotodiode composed of cytochrome c/chlorophyll a heterostructure

Photoelectrical rectifying property of biomolecular heterostructure is investigated in molecular scale. Cytochrome c and chlorophyll a were used as an electron acceptor and a sensitizer, respectively, in the molecular layer by mimicking photosynthesis. A self-assembled monolayer of cytochrome c was formed on gold surface, and then chlorophyll a was deposited onto the cytochrome c layer by Langmuir–Blodgett method. The formation of cytochrome c/chlorophyll a hetero-layers was confirmed by the surface plasmon resonance spectroscopy, and the surface was observed by the scanning tunneling microscopy. The rectifying property by the scanning-tunneling-spectroscopy based current–voltage characteristics was achieved in the cytochrome c/chlorophyll a hetero-layer. Therefore, proposed hetero-layer can be usefully applied for the development of molecular-scale bioelectronic devices.