A STUDY OF THERMALLY STIMULATED DISCHARGE CURRENTS IN IODINE-DOPED POLYVINYL PYRROLIDONE FILMS

Mechanisms of charge production and its persistence in vacuum-metalliz ed pure and iodine doped polyvinyl pyrrolidone (PVP) films of about 20 mum in thickness, have been analyzed using short circuit thermally st imulated discharge current (TSDC) technique. The TSDC spectra of pure and iodine doped PVP have been found to be characterized with two prom inent peaks located at 106 +/- 6-degrees-C for Al-Al electrode system. The TSDC spectra of Cu-Al system consist of two peaks (in the same di rection and position as found for Al-Al, system) along with an additio nal current maxima, which have been found around 198 +/- 2-degrees-C, in a direction which is opposite to both the peaks. The results show t he existence of heterocharge due to dipole orientation and ionic charg e drift together with the injection of charge carriers from electrodes with their subsequent localization in surface and bulk traps. Various characteristics of thermograms indicated the injection of charge carr iers from electrodes during short circuit TSC under electric field cre ated at the interface by the strong heterocharge. Increase in current on iodine doping is attributed to the formation of charge transfer com plexes.