Temperature and Frequency-Dependent Electric Response in Conductive Polymer Composite*

Conductive polymers doped with metal nanoparticles can give rise to interesting interfacial properties that affect electrical and thermal transport, such that their conductivities no longer follow an effective medium model. Here, we studied electrical transport in poly (3,4-ethylenedioxythiophene): poly (styrenesulphonate): Au nanoparticle films (PEDOT: PSS: AuNP). By studying the composites of these two fairly well-studied materials, we hope to better identify and model the role of the interface on transport. Samples were fabricated using two different processes: in-situ method and ex-situ method, and at different thicknesses and gold volume fractions. In the in-situ method, we expect a thin PSS-rich insulating coating to form on the nanoparticles during the fabrication process, while in the ex-situ method, the nanoparticles are prepared and coated separately before being mixed into the PEDOT: PSS. The admittance response was measured at frequencies varying from 100 Hz to 100 kHz, and at temperatures ranging from 80 K to 400 K. The sample morphology was monitored with scanning electron microscopy and atomic force microscopy. The samples had very different admittance responses. These results will be discussed.