Molecular Hydrogen Evolution by Organic p/n Bilayer Film of Phthalocyanine/Fullerene in the Entire Visible-Light Energy Region

This article presents a novel approach to photo-chemical energy conversion by employing organic compounds. We demonstrated that water can be photoelectrochemically split into H-2 and O-2 using an organic photodevice responsive to the entire visible-light energy range of < 750 nm. When an organic p/n bilayer of metal-free phthalocyanine (H2Pc, a p-type semiconductor) and fullerene (C-60,C- an n-type semiconductor) was applied to a photocathode in the water phase, H-2 was evolved at Pt-coated C-60 along with the conductin of the electron carriers photogenerated at the p/n interface, concurrently yielding O-2 at the counter electrode. This is the first example of C-60 participation in H-2 evolution: a mechanism was proposed, involving the formation of an active species (i.e., C-60(2-)) on the basis of the results of in situ spectroelectrochemical measurements.