Direct Measurements of In-plane Thermal and Electrical Transport in P-type Single-walled Carbon Nanotube Thin Films

Abstract

In order to optimize next-generation thermoelectrics for use in converting waste heat into useable energy, the close correlation between the thermal conductivity, electrical conductivity, and Seebeck coefficient or thermopower in these materials must be decoupled. As promising alternatives to traditional inorganic semiconductor materials, nanocomposites constructed of conducting polymers with organic inclusions such as single-walled carbon nanotubes (SWCNTs) offer simple fabrication techniques, reduced cost, and low toxicity. They also offer the possibility of decoupling the thermal and electrical transport pathways which would enable more efficient organic composites for thermoelectric conversion. However, in order to develop high-performance organic thermoelectric devices, it is necessary to develop a detailed fundamental understanding of the factors governing directionally dependent thermal and electrical transport through these materials in reduced geometries such as thin films. In this talk, we describe our suspended membrane technique for directly measuring the in-plane thermal and electrical transport through thin films and present results for several different thin film samples. We present our approach to developing p-type materials with tunable transport behavior, by fabricating composites consisting of SWCNTs dispersed in a polymer matrix. Finally, we discuss fabrication and post-fabrication treatments of the SWCNT thin films and the benefits offered by nanostructuring these architectures to optimize the thermoelectric dimensionless figure-of-merit, ZT .