The influence of thermal cycling and compressive force on the resistance of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonic acid)-coated surfaces

There is an increasing interest in the use of conducting polymers for a wide variety of applications. This includes the study and development of alternative contact-connector materials. The main aim is to achieve overall improvements in performance as well as cost effectiveness. Currently, extrinsic conducting polymers (ECPs) are employed as conductive coats or adhesives at contact interfaces. However, frictional abrasion within the metal-doped polymer (ECP) causes instability in the resistance. It is important to overcome this fretting effect, especially in automotive applications; hence, the possibilities of employing intrinsically conducting polymers (ICPs) are explored. Flat contact film coatings have been fabricated in-house using poly (3,4-ethylenedioxythiopene) / poly (4-styrenesulfonic acid) (PEDOT/PSS) with dimethylformamide as the secondary solvent. Resistance is measured using the four-wire method. The conductivities of the PEDOT/PSS-coated contacts are found to be in the order of 10(-2) S cm(-1). The change of resistance under varying compression forces has been found to be repeatable. The thermal effects on these contacts are also studied and the results are depicted as exponential negative temperature coefficients of resistance. (c) 2006 Wiley Periodicals, Inc.