ELECTROSTATIC PHENOMENA IN POLYIMIDE LANGMUIR-BLODGETT-FILMS

Surface potential of heat-treated polyimide (PI) LB films deposited on various metal electrodes was measured in a box shielded from light while nitrogen gas flowed through the box. The surface potential depended on base-electrode materials and the number of deposited layers. The surface potential saturated when the number of deposited layers was several tens. The saturated surface potential was a linear function of the work function of metals. It was suggested that excess charges were transferred from metal-electrodes into PI LB films until the thermodynamic equilibrium was established at the metal/PI LB film interface. Spatial charge and electric field distributions in PI LB films were also estimated from the surface potential measurement. It was found that an electric field on the order of 10(8) V/m was established at the metal/PI LB film interface. The surface potential of PI LB films on Au epitaxially grown electrodes changed somewhat steeply in comparison with that on Au evaporated electrodes with the increment of the number of deposited layers.