Sb2Te3 nanoparticle-containing single-walled carbon nanotube films coated with Sb2Te3 electrodeposited layers for thermoelectric applications.

Single-walled carbon nanotubes (SWCNTs) are promising thermoelectric materials owing to their flexibility and excellent durability when exposed to heat and chemicals. Thus, they are expected to be used in power supplies for various sensors. However, their thermoelectric performances are inferior to those of inorganic thermoelectric materials. To improve the thermoelectric performance while maintaining the excellent characteristics of SWCNTs, a novel approach to form inorganic thermoelectric layers on the SWCNT bundle surfaces using electrodeposition is proposed. We synthesized Sb2Te3 nanoparticle-containing SWCNT films and coated them with electrodeposited Sb2Te3 layers. The Sb2Te3 nanoparticles were synthesized via a spontaneous redox reaction, which were then added to a SWCNT dispersion solution, and films were produced via vacuum filtration. At higher nanoparticle contents in the films, the Sb2Te3 electrodeposited layers completely covered the SWCNT bundles owing to the increase in the concentration of precursor ions near the SWCNT bundle surface, which in turn was the result of melted nanoparticles. The thermoelectric performance improved, and the maximum power factor at approximately 25 °C was 59.5 µW/(m K2), which was 4.7 times higher than that of the normal SWCNT film. These findings provide valuable insights for designing and fabricating high-performance flexible thermoelectric materials.

Flexible thermoelectric films formed using integrated nanocomposites with single-wall carbon nanotubes and Bi2Te3 nanoplates via solvothermal synthesis.

Single-wall carbon nanotubes (SWCNTs) and Bi2Te3 nanoplates are very promising thermoelectric materials for energy harvesting. When these two materials are combined, the resulting nanocomposites exhibit high thermoelectric performance and excellent flexibility. However, simple mixing of these materials is not effective in realizing high performance. Therefore, we fabricated integrated nanocomposites by adding SWCNTs during solvothermal synthesis for the crystallization of Bi2Te3 nanoplates and prepared flexible integrated nanocomposite films by drop-casting. The integrated nanocomposite films exhibited high electrical conductivity and an n-type Seebeck coefficient owing to the low contact resistance between the nanoplates and SWCNTs. The maximum power factor was 1.38 µW/(cm K2), which was 23 times higher than that of a simple nanocomposite film formed by mixing SWCNTs during drop-casting, but excluding solvothermal synthesis. Moreover, the integrated nanocomposite films maintained their thermoelectric properties through 500 bending cycles.