Charge storage phenomena observed in ultra-thin polyimide Langmuir-Blodgett films deposited on metal electrodes

The surface potentials of multilayers of polyimide (PI) and poly-isobutyl-methacrylate (PIBM) which were deposited on base Au, Cr, and Al electrodes were measured by the conventional surface potential technique. A comparison is made between the surface potential of clean base electrodes and the surface potential of base electrodes onto which various numbers of layers have been deposited. The surface potential of PI strongly depends on the materials of base electrodes, whereas the surface potential of PIBM does not depend on them. It was suggested that the surface potential of PI multilayers originates from charges displaced from base electrodes to the PI multilayers, whereas that of PIBM multilayers originates from the constituent molecules themselves