Spectroscopic Analyses of Rose Bengal Sensitized and NaI Supersensitized Photocurrent

Electron injection from excited rose bengal into the conduction band of a thin film of semiconductor in acetonitrile was investigated in an electrochemical cell, ITO//rose bengal, NaI or , /Pt. It was observed that NaI enhanced the supersensitized photocurrent, followed by the slow reduction, whereas yielded a fast decaying photocurrent. Spectroscopic analyses of the dye solution containing NaI revealed that electron is transferred to the electrode from the reduced rose bengal and iodide is responsible for the reduction of the dye in triplet state. However appears to possess neither the reducing ability of the oxidized dye nor the retardation of the dehalogenation of RB.