Two novel trichromophore amphiphilic dyes 1-methyl-2,4,6-tris[2-(3＇-methoxy-4＇-(octadecycloxy)phenyl)-ethenyl]pyridinium iodide (MTMS) and 1-methyl-2,4,6-tris[2-(4＇-(octadecyloxy)phenyl)ethenyl]pyridnium iodide (MTOS) have been synthesized and successfully transferred on semiconducting transparent indium-tin oxide (ITO) electrodes by a Langmuir-Blodgett (LB) technique. The observed photocurrent strongly depends on the applied electrode potential, the presence of O-2, the concentrations of methyl viologen (MV2+) and hydroquinone (H(2)Q), and the pH of the electrolyte. Action spectra of the photocurrent generation are coincident with the absorption spectra of the LB film-modified ITO electrode, indicating that the dyes aggregated in the LB film are responsible for the photocurrent. Under favorable conditions the quantum yield are as high as 1.40% and 1.54% for the monolayer films of MTMS and MTOS, respectively. Models for the mechanism of photocurrent generation under different conditions are proposed.