Electric Field Induced Resistance Change in PEDOT-PSS Films

Resistance of PEDOT-PSS films changes considerably with time after application of DC voltage. Since, variation of resistance over time can lead to serious errors when used as a strain gauge or gas sensors or any device, a detailed study of the variation of film resistance with time has been made. It has been observed that AC resistance is stable with time (constant) compared to DC resistance which has been explained in terms of contact diode model. It has also been found that doping with graphite leads to lower variation (better stabilization) in the resistance over time. The results indicate that the variation of resistance is an interfacial phenomenon at the contacts and either an ohmic contact or AC measurement removes this behavior. The change of resistance is attributable to high electric field in the interfacial region of the PEDOT-PSS/metal contact.