Segregated Network Polymer Nanocomposites for Thermoelectric Energy Conversion

Segregated network (latex-based) composites containing carbon nanotubes can produce electricity from a thermal gradient.  These thermoelectric materials harvest electricity from waste heat or any temperature gradient in the environment.  The present work demonstrates that nanotube-filled polymer composites can be viable for light-weight and economical thermoelectric energy conversion.  By combining double-walled carbon nanotubes (DWNTs), stabilized with poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) [PEDOT:PSS] in water, an electrical conductivity (σ) near 2000 S/cm is achieved in a poly(vinyl acetate) [PVAc] latex-based matrix.  When this conductivity is combined with a Seebeck coefficient (S) above 40 mV/K, a power factor (S²σ) above 370 mW/m·K² is achieved at room temperature. Thermal conductivity (k) of these composites can be tailored between 0.3 and 10 W/m∙K, suggesting the thermoelectric figure of merit (ZT = S²σT/k) could be as high as 0.4 at room temperature, which would make these fully organic composites competitive with bismuth telluride (i.e., the most efficient thermoelectric material) at room temperature.