Photocatalytic Reaction of Sensitizer, Rose Bengal and Supersensitizer, Allylthiourea

The enhancement of the solar energy conversion efficiency into the electrical energy by the dye sensitization with a photoelectrochemical cell was studied. The magnitude of the rose bengal sensitized photocurrent containing the supersensitizer, thiourea was five times greater than that in the absence of thiourea. It was observed, however, that the long time span of irradiation causes the decrease in the photocurrent. Spectroscopic analysis of the dye solution showed that the dye molecule was photobleached and the insoluble aggregate which settles down in the solution, was formed as a result of the possible photocatalytic reaction and the disappearance of dye from the solution was the cause of the decreased photocurrent in the sensitization run.