Development of Technique for Making Ohmic Contacts to PEDOT-PSS Films

摘要

Conducting polymers (PEDOT-PSS) belong to a category of materials which are peizoresitive and are used in variety of applications like strain gauges, gas sensors and many more. Since these conducting polymers are semiconductors, four probe measurement of film resistance is necessary to avoid errors due to contact resistance and spreading resistances. In a device, it is cumbersome to make four probe measurements and convenient to make two probe measurements. Large differences in the work function of polymers and contacts metals lead to rectifying contacts rather than ohmic contacts. A two probe measurement technique of making ohmic contacts to PEDOT-PSS film pristine and doped with 5 % DMSO is presented. It has been shown that by coating the contact probes with carbon nano powder, ohmic contacts can be achieved. This method can be employed for all conducting polymer measurements.