EFFECT OF SURFACTANT ON TPP(TETRAPHENYLPORPHYRIN)-SNO2 PHOTOVOLTAIC CELL

A simple photovoltaic cell has been constructed by using Nesa glass coated with SnO2 on both sides as transparent electrodes, one of which is further coated with a photosensitizing dyestuff, tetraphenylporphyrin (TPP), forming the photocathode, and by using an aqueous solution of Fe3+/Fe2+ redox couple as the electrolytic solution. By adding an anionic surfactant, sodium dodecyl sulfonate (SDS), to the solution, both the photovoltage and the photocurrent of the cell are markedly enhanced. The power conversion efficiency of the SDS-containing cell is about eight times the value of the original cell. Other anionic surfactants (e.g., sodium octyl sulfate and sodium dodecyl sulfate) have a similar effect. From the data of the surface tension and the contact angle which we have measured, the interface excess of SDS at the interface between the TPP film of the photocathode and the solution has been calculated. The relationship between the photovoltage of the cell and the conformation of the adsorbed SDS molecules at the interface as well as the critical micelle concentration (CMC) of SDS in the solution are discussed. Other types of surfactant were also tested. © 1994 by Academic Press, Inc.