SPATIAL DISTRIBUTION OF CHARGES IN ULTRATHIN POLYIMIDE LANGMUIR–BLODGETT FILMS

The spatial distribution of charges in ultrathin polyimide (PI) Langmuir–Blodgett (LB) films, with a monolayer thickness of 0.4 nm, deposited onto metals was determined by measuring the surface potential of the PI LB films as a function of the number of deposited layers. The depth of penetration of the excess charges displaced from metal electrodes into the PI LB films was about 3 nm. The saturated surface potential was an accurately linear function of the work function of the metal. We concluded that excess charges (mainly electrons) were transferred from metals into as‐deposited PI LB films until thermodynamic equilibrium was established at the metal/PI interface by electron tunneling.

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