Nature of the processes of charge-carrier generation at ITIES by the photoexcitation of porphyrins

Abstract

The kinetics of the photocurrent through the interface between two immiscible electrolyte solutions (ITIES) was investigated under high intensity irradiation when the organic phase was a concentrated solution of tetraphenylporphine or protoporphyrin. A number of different processes of charge-carrier generation are analysed. The reaction of the excited porphyrin molecule with ground state porphyrin and with oxidized forms of porphyrins was found to generate charge carriers in the volume near the interface. The mathematical description of the generation, diffusion and transformation of charge carriers, as well as relationships between these processes, is presented in the form of a system of differential equations. Numerical simulation has shown that the depletion of the irradiated zone by the oxidized forms of porphyrins strongly affects the kinetics of the photocurrent.