Interfacial control and carrier tuning of carbon nanotube/polyaniline composites for high thermoelectric performance

While approaches have been successfully devised to optimize the power factor of inorganic thermoelectric (TE) materials, the understanding and control of TE performance of organic composite materials are however still rudimentary due to their complicated structures and weak interfacial interactions. We report a facial method to tailor the interfacial interaction of amine-functionalized carbon nanotubes (A-CNT)/polyaniline (PANI) composites, which results in composites exhibiting high conductivity (2012 S cm⁻¹) and excellent power factor (273 μW m⁻¹ K⁻²) with A-CNT content of 94 wt%. By tuning PANI/camphor sulfonic acid mole ratios, the power factor is further improved to 401 μW m⁻¹ K⁻², which is higher than that of most reported organic TE materials. Beside the optimum carrier concentration, we attribute the outstanding TE property to the existence of amine functional groups on CNT that facilitate the formation of highly conductive network and a unique PANI interlayer of up to ∼10 nm that interacts strongly with A-CNT, facilitates charge transfer and endows the composites with high electrical conductivity, as evident by TEM, Raman, XRD, and solubility studies.