Investigation of electrical conduction in polyvinyl formal

Current-voltage (I-V) characteristics of pure polyvinyl formal (PVF) were i nvestigated at different fields, range 5-100 kV/cm, as a function of temper ature, range 313-363 K. It was observed that while at low fields (up to 25 kV/cm), the conduction was Ohm's law-dependent at high fields (beyond 25 kV /cm), the conduction was Poole-Frenkel (P-F) mechanism-dependent. An attemp t was made to identify the nature of the current by comparing its observed dependence on temperature, electric field and electrode materials with thei r respective characteristic features of the existing theories of electric c onduction. The current showed a strong dependence on temperature. To identi fy the possible mechanism of conduction, current versus square root of fiel d characteristics were drawn with aluminium, silver, copper and gold as upp er electrode and Al as the lower electrodes. The observed characteristics s uggested that the charge carries were generated by the field-assisted lower ing of coulombic at the traps, and were subsequently conducted through the bulk of the material by a hopping process between the localized states by a Jonscher-Ansari-modified P-F mechanism. The calculated value of the modifi es P-F barrier was similar or equal to 1.94 x 10(-19) J(1.21 eV).