High thermoelectric performance of flexible nanocomposite films based on Bi2Te3 nanoplates and carbon nanotubes selected using ultracentrifugation

Abstract

Thermoelectric generators with flexibility and high performance near 300 K have the potential to be employed in self-supporting power supplies for Internet of Things (IoT) devices. Bismuth telluride (Bi2Te3) exhibits high thermoelectric performance, and single-walled carbon nanotubes (SWCNTs) show excellent flexibility. Therefore, composites of Bi2Te3 and SWCNTs should exhibit an optimal structure and high performance. In this study, flexible nanocomposite films based on Bi2Te3 nanoplates and SWCNTs were prepared by drop casting on a flexible sheet, followed by thermal annealing. Bi2Te3 nanoplates were synthesized using the solvothermal method, and SWCNTs were synthesized using the super-growth method. To improve the thermoelectric properties of the SWCNTs, ultracentrifugation with a surfactant was performed to selectively obtain suitable SWCNTs. This process selects thin and long SWCNTs but does not consider the crystallinity, chirality distribution, and diameters. A film consisting of Bi2Te3 nanoplates and the thin and long SWCNTs exhibited high electrical conductivity, which was six times higher than that of a film with SWCNTs obtained without ultracentrifugation; this is because the SWCNTs uniformly connected the surrounding nanoplates. The power factor was 6.3 μW/(cm K2), revealing that this is one of the best-performing flexible nanocomposite films. The findings of this study can support the application of flexible nanocomposite films in thermoelectric generators to provide self-supporting power supplies for IoT devices.

Flexible Thermoelectric Films Based on Bi2Te3 Nanowires and Boron Nitride Nanotube Networks with Carbon Doping

“…Recently, Chiba et al investigated thin films composed of Bi 2 Te 3 nanosheets and thin and long single-walled carbon nanotubes (SWCNTs). The films exhibited excellent electrical conductivity with a PF of 6.3 μW/(cm·K 2 ) . The properties of Bi 2 Te 3 –SWCNTs composite films were also investigated by Chen et al A high electrical conductivity of 253.9 S/cm and a corresponding PF of 57.8 μW/(m·K 2 ) were obtained at 386 K .…”

“…The films exhibited excellent electrical conductivity with a PF of 6.3 μW/(cm•K 2 ). 23 The properties of Bi 2 Te 3 −SWCNTs composite films were also investigated by Chen et al A high electrical conductivity of 253.9 S/cm and a corresponding PF of 57.8 μW/(m•K 2 ) were obtained at 386 K. 24 In contrast, little research has been conducted on the TE properties of Bi 2 Te 3 − BNNTs composites. In particular, the TE properties of Bi 2 Te 3 −BNNTs composite films have received little attention.…”

Ultrafast and Cost-Effective Fabrication of High-Performance Carbon-Based Flexible Thermoelectric Hybrid Films and Their Devices

“…1−7 Thermoelectric technology, enabling the solid-state conversion from heat to electricity, can harvest sustainable electricity from the environmental waste heat for power generation. 1,2,8 Thermoelectric materials are key components in thermoelectric devices that realize this goal. Their thermoelectric potential is evaluated by the dimensionless figure-of-merit ZT = S 2 σT/κ, where T is the absolute temperature, σ is the electrical conductivity, S is the Seebeck coefficient, and κ is the thermal conductivity.…”

“…The increasing consumption of fossil energy considerably threatens the global ecology, and the exhaustion of fossil energy is inevitable with continuous exploitation. − Thermoelectric technology, enabling the solid-state conversion from heat to electricity, can harvest sustainable electricity from the environmental waste heat for power generation. ,, Thermoelectric materials are key components in thermoelectric devices that realize this goal. Their thermoelectric potential is evaluated by the dimensionless figure-of-merit ZT = S 2 σ T /κ, where T is the absolute temperature, σ is the electrical conductivity, S is the Seebeck coefficient, and κ is the thermal conductivity. , Additionally, the power factor S 2 σ is widely used to evaluate the thermoelectric performance of film-based thermoelectric materials since their κ is difficult to be correctly measured due to the limitation of current techniques .…”

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

“…In addition to these studies, excellent thermoelectric materials have been proposed by combining CNTs with inorganic and organic compounds 21,22 . In our previous study, we prepared a SWCNT dispersion solution in Bi 2 Te 3 nanoplates using a solvothermal synthesis and produced flexible films through drop-casting, resulting in an increase in the thermoelectric performance [23][24][25] .…”