Organic Photoanode of Fullerene/Phthalocyanine Working in the Water Phase with Respect to Preparation Methods of the Bilayer Film

Abstract

The photoanodic characteristics of an organic p/n bilayer of fullerene (C60, n-type semiconductor) and metal-free phthalocyanine (H2Pc, p-type semiconductor) in the water phase were investigated. For this purpose, C60/H2Pc films were prepared by vapor deposition (degree of vacuum = 5×10-4 Pa) with and without annealing. Irrespective of annealing treatment, the photoanode kinetics of the films was dominated by the charge separation of excitons at the p/n interface, particularly under low-intensity irradiation (<0.5 mW·cm-2). By comparing the bilayer film prepared at 50 °C with that prepared at room temperature, the former showed an increasing area of the p/n interface, which was confirmed through transmission electron microscopy (TEM). Consequently, the photoanodic output at the H2Pc/water interface increased owing to an increase in the number of carriers generated at the p/n interface.