Photoelectrode characteristics of a perylene/phthalocyanine bilayer film in acetonitrile

An organic bilayer film, composed of 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI, an n-type semiconductor) and metal-free phthalocyanine (H2Pc, a p-type semiconductor), was employed as a photoelectrode in acetonitrile containing a I3−/I− couple. The H2Pc surface in the PTCBI/H2Pc bilayer induces the oxidation of I− through hole conduction, via a mechanism that involves the entire visible-light energy of <750 nm being available for carrier generation at the p/n interface, through which oxidation takes place at the solid/liquid interface. The typical photoanodic characteristics of the p/n bilayer in the organic solution phase are described in terms of voltammetry as well as action spectral measurements for photocurrents.