PHOTOELECTRIC CONVERSION BY AN A-S-D TRIAD MONOLAYER COVERED WITH A PROTECTIVE MONOLAYER

A heterogeneous bilayer structure of a Langmuir-Blodgett film was form ed at an Au/water interface as a molecular photodiode in a photoelectr ochemical cell. In this structure, an A-S-D triad monolayer, as a phot o-responsive monolayer, was deposited first on an Au electrode and the n the resulting surface was covered with a protective monolayer of ara chidic acid. The protective layer was deposited in order to stabilize orientation of the triad molecules in the first monolayer, where a hyd rophilic head group A was expected to orient towards the Au electrode, a hydrophobic D moiety towards the protective layer, and an S moiety to be located in between them. In the absence of the protective layer, the hydrophobic tail group D was supposed to face to the electrolyte solution with unfavorable surface energetics. The effect of the presen ce and the absence of the protective monolayer on measured photocurren ts was examined.