Wide visible light-induced dioxygen evolution at an organic photoanode coated with a noble metal oxide catalyst

An organic bilayer composed of 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI, n-type semiconductor) and 29H,31H-phthalocyanine (H2Pc, p-type semiconductor) works as a photoanode capable of O2 evolution in the water phase especially when the outer surface of H2Pc is coated with an IrO2 catalyst. A typical photoelectrode is characterized by the fact that a wide and efficient visible light absorption of <750 nm by only the PTCBI induces the generation of the photocurrent involving water oxidation at the IrO2/water interface, which is based on the photophysical character of the bilayer. The exciton formed in PTCBI bulk can contribute to carrier generation through its charge separation at the p/n interface, with which the O2 evolution takes place at the IrO2/water interface coupled with the hole-conducting H2Pc layer.