Temperature and photoirradiation dependence of electrostatic phenomena at metal/polyimide LB film interface

Surface potentials of heat-treated PI LB films deposited on Au, Cr, Al and ITO electrodes were measured in a dark vacuum vessel at various temperatures before and after photoirradiation. 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 electrodes at temperatures between -100°C and 150°C before photoirradiation, and at room temperature after photoirradiation. It was suggested that excess charges were transferred from electrodes into PI LB films until thermodynamic equilibrium was established at the interface. We also measured the surface potential of four kinds of PI LB films. The potential of polyimide with electron acceptors changed negatively, and the potential of polyimide with electron donors changed positively as the temperature increased. In contrast, the potential of polyimide with electron acceptors changed positively, and the potential of polyimide with electron donors changed negatively with photoirradiation