Macroscopic weavable fibers of carbon nanotubes with giant thermoelectric power factor

Abstract

Low-dimensional materials have recently attracted much interest as thermoelectric materials because of their charge carrier confinement leading to thermoelectric performance enhancement. Carbon nanotubes are promising candidates because of their one-dimensionality in addition to their unique advantages such as flexibility and light weight. However, preserving the large power factor of individual carbon nanotubes in macroscopic assemblies has been challenging, primarily due to poor sample morphology and a lack of proper Fermi energy tuning. Here, we report an ultrahigh value of power factor (14 ± 5 mW m−1 K−2) for macroscopic weavable fibers of aligned carbon nanotubes with ultrahigh electrical and thermal conductivity. The observed giant power factor originates from the ultrahigh electrical conductivity achieved through excellent sample morphology, combined with an enhanced Seebeck coefficient through Fermi energy tuning. We fabricate a textile thermoelectric generator based on these carbon nanotube fibers, which demonstrates high thermoelectric performance, weavability, and scalability. The giant power factor we observe make these fibers strong candidates for the emerging field of thermoelectric active cooling, which requires a large thermoelectric power factor and a large thermal conductivity at the same time.

Anisotropic Electrical Conductivity and Isotropic Seebeck Coefficient Feature Induced High Thermoelectric Power Factor >1800 µW m−1 K−2 in MWCNT Films

“…reported that double‐walled carbon nanotube (DWCNT) fibers exhibited an ultrahigh PF of ≈14 000 µW m −1 ‐K −2 . [ 32 ] Zhou et. al.…”

Reactor Design for Manufacturing Carbon Hybrid Materials

“…This thickness of fabric is time consuming to manufacture and the cost is currently prohibitive for most textile applications where typically yards of material are needed to from layers in garments. Compared to other methods of manufacturing CNT fabric [36][37][38][39][40][41], such as forest grown nanotubes [37,40,41] and buckypaper formed from powdered nanotubes [42], the floating catalyst method offers a combination of tunability of material properties and good manufacturing throughput in a one-step process, but the cost of material must be reduced.…”

“…A garment design that uses CNT fabric inside is shown in Fig- 8. Recent work is also helping to move CNT fabric synthesis to an industrial level of manufacturing [38,39].…”

Joint-Free Single-Piece Flexible Thermoelectric Devices with Ultrahigh Resolution p–n Patterns toward Energy Harvesting and Solid-State Cooling

“…The TPP doped n-type CNT film showed the highest n-type power factor of 154.8 μW/m·K 2 at the mass ratio of 3% among the four n-type dopants, which was even higher than that of the N-DMBI doped n-type CNT film. The high power factor and relatively high thermal conductivity of the CNT films were essential for active thermoelectric cooling as suggested by Kono et al The higher power factor of the TPP doped n-type CNT film should be attributed to its higher Seebeck coefficient compared to that of N-DMBI doped n-type CNT film. Typically, N-DMBI was a better n-type dopant than TPP because of its higher highest occupied molecular orbital (HOMO) as reported in the literature. , Density functional theory calculation showed that N-DMBI had the highest HOMO of −4.65 eV which was consistent with the literature value .…”