Study of photoanode kinetics at metal-free phthalocyanine in an organic p/n bilayer with respect to the pH conditions employed

Using an organic p/n bilayer comprised of 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI, an n-type semiconductor) and 29H,31H-phthalocyanine (H(2)Pc, a p-type semiconductor) as a photoanode in the presence of Fe(II)(CN)(6)(4-) (an electron donor), the oxidation kinetics on the H(2)Pc surface was investigated with respect to the pHs employed (i.e. pH = 4, 7, and 10). The kinetic analysis of the rate-limiting charge transfer between H(2)Pc and Fe(II)(CN)(6)(4-) was conducted by assuming the Langmuir adsorption equilibrium at the H(2)Pc/water interface. In addition to a demonstration of the PTCBI/H(2)Pc photoanode under the weakly acidic-alkaline conditions, the present work evidently shows that the photoanodic reaction is kinetically independent of the pH conditions employed. (C) 2010 Elsevier Masson SAS. All rights reserved.