The analysis of the fluorescence decay of a cyanine dye linked covalently to two pyrene moieties suggests an excited state equilibrium between the locally excited state of the dye and a charge transfer state. Excitation of a mixed monolayer of this trichromophore and palmitic acid deposited on SnO2 results in a photo-sensitized anodic current. The dependence of this photocurrent on time and hydroquinone (regenerator) concentration suggests that the alien recombination of the oxidized dye with electrons in the conduction band or in suraface states as well as the irreversible degradation of the oxidized dye are slowed down compared to systems where the charge injection is mediated by dioctadecyloxacarbocyanine.