SEMICONDUCTING CHARACTERISTICS OF PHTHALOCYANINE SOLID FILMS FORMED BY AN ELECTROCHEMICAL METHOD

Semiconducting properties of phthalocyanine (Pc) solid films prepared on an indium-tin oxide substrate by an electrolytic micelle disruption (EMD) method are investigated in the electrochemical system with and without illumination. Rectifying behaviors of the Pc solid ranging in film thickness from 0.18 to 0.59-mu-m are featured through low series resistance of 10 to 60 OMEGA cm2 and through the increase in exchange current density by increasing Pc layer thicknesses. Both characteristics are interpreted in terms of the enhancement of an effective surface area due to the porous structure of the Pc solids to allow electrolyte permeation. The electrolyte permeability and the resulting low series resistance elucidate some unusual aspects of photoelectrochemical responses of the ITO/Pc(EMD) electrodes in I2/KI and hydroquinone/benzoquinone redox solutions. Extremely high photoactivities of the Pc(EMD) solids are also discussed on the bases of these features of a structural origin.