The Effect of Sodium Dodecyl Sulfonate on TPP(Tetraphenylporphine)-SnO2 Photovoltaic Cell

TPP (tetraphenylporphine)-SnO² photovoltaic cell is constructed with two transparent electrodes made of a single plate of Nesa glass coated on both sides, one of which is further coated with TPP, producing a photovoltaic effect and serving as a photocathode under illumination. It is found that the photovoltage (Voc) of the cell is greatly enhanced from 350 mv by adding sodium dodecyl sulfonate (SDS) to the solution of redox electrolyte Fe³⁺/Fe²⁺. Some other anion surfactants have 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 layer of the photocathode and the solution has been calculated. Then the relationship between the Voc of the cell and the conformation of the adsorbed SDS molecules at the interface as well as the critical micell concentration (CMC) of SDS in the solution are discussed.