Improved thermoelectric properties of metal ion doped aniline tetramer/carbon nanotube composite films

Abstract

Carbon nanotubes and their composites have attracted much attention in the field of thermoelectric conversion for potential application in wearable electronics owing to their good electrical conductivity and excellent mechanical properties. However, low Seebeck coefficient of carbon nanotubes limit the improvement of their thermoelectric properties. In this work, metal ions (Mn+ = Fe3+, Ni2+, Cu2+) are used to further improve the thermoelectric properties of aniline tetramer (ANIT)/single-walled carbon nanotubes (SWCNT) composites, and Mn+@ANIT/SWCNT films are prepared by physical mixing and vacuum filtration method. The metal ions and concentrations for improving Mn+@ANIT/SWCNT thermoelectric films are optimized, and the metal ions doping optimizes carrier concentration and promotes carrier transport of the composites appropriately, which increased the Seebeck coefficient. Amone the prepared Mn+@ANIT/SWCNT films, the Cu2+@ANIT/SWCNT demonstrates the highest PF value of 145.3 ± 3.9 μW m−1 K−2 at the molar ratio of Cu2+/ANIT to being 5:100 with the σ of 560.1 ± 22.1 S cm−1, and the S of 51.0 ± 1.3 μV K−1 at room temperature. Finally, five pairs of p-type Cu2+@ANIT/SWCNT films and n-type copper sheets are connected in series to assemble a self-powered thermoelectric device, which demonstrates an actual output power of about 426 nW under a temperature difference of 50 K. Therefore, this work offers a metal ions doping strategy to improve the SWCNT composites with enhanced thermoelectric properties.