Surface Potential of Heat-Treated PI Langmuir-Blodgett Films Deposited on Metal Electrodes

Abstract

The surface potential of polyimide (PI) Langmuir-Blodgett (LB) films deposited on base-Au or -Cr electrodes was measured in a box shielded from light while nitrogen gas flowed through the box. Potential differences across PI LB films before and after heat treatment (at 100°C) were measured as a function of the number of deposited layers. The surface potential observed after the heat treatment was independent of the time elapsed. It was found that the surface potentials obtained after heat treatment depend on the base-electrode materials and the number of deposited layers, possibly due to the displacement of electrons from base-Au and -Cr electrodes into as-deposited PI multilayers. Finally, we concluded that photogenerated carriers in PI LB films were conveyed along the electric field established by the electrons displaced into as-deposited PI LB films from base-Au or Cr electrodes.