The short-circuit current and open-circuit voltage of moisture absorbed polyimide thin films with different electrode materials

This paper describes the short-circuit current and open-circuit voltage of moisture absorbed polyimide thin films with different electrode materials. Relative humidity dependences of their short-circuit current and open-circuit voltage in the room temperature were measured and their mechanism was discussed. The short-circuit current and open-circuit voltage increased with relative humidity. It is suggested that the short-circuit current flows due to an electromotive force, possibly associated with an oxidation-reduction reaction at electrode metals. Since the electrical conduction of moisture absorbed polyimide may be ionic, Au-Polyimide-Al system forms a galvanic cell and electromotive force is generated by the chemical reaction at the metal-polyimide interface. Furthermore, since the conduction current under an external field and the short-circuit current have similar relative humidity dependence, it shows that in moisture absorbed polyimide thin films ion an generation may be promoted, which leads to ionic conduction. It is suggested from the open-circuit voltage that the voltage characteristics are affected by a distribution of internal carriers in sample