RESUMO
Flexible thermoelectric devices can be potentially used for flexible cooling and energy harvesting from various heat sources such as the human body. However, the development of flexible thermoelectric materials with excellent thermoelectric performance is still very challenging. In this study, a simple solution process is proposed for the preparation of flexible inorganic/carbon nanotube hybrid films with record power factors among those of the reported flexible n-type thermoelectric materials. The hybrid films fabricated by bar-coating a carbon nanotube-dispersed Sb2Te3 solution exhibit n-type power factors of up to 2440 ± 267 µV m-1 K-2 at room temperature. The dissolved Sb2Te3 recrystallizes on the carbon nanotube surfaces and form hybrid solids. The ultrahigh power factor may be originated from the effective n-doping of carbon nanotubes by the oxidation of neighboring Sb2Te3. Using the thermoelectric hybrid film, a multilayer stacked thermoelectric generator is fabricated. The flexible device with a thermal contact area of 3.8 cm2 exhibits an output power of up to 11.3 µW at a vertical ΔT of 7.5 K. This study paves the way for the realization of flexible thermoelectric devices with various device geometries.
RESUMO
In this study, shape-deformable thermoelectric p- and n-type doughs are fabricated by blending single-walled carbon nanotubes with excess amounts of nonvolatile liquid surfactants for efficient energy harvesting from diverse heat sources. The shape-deformable thermoelectric doughs exhibit touch-healing properties and can be easily molded into arbitrary shapes by simple shaping methods, such as those commonly used for rubber play dough. We used cube-shaped thermoelectric doughs to fabricate a vertical thermoelectric generator. Considering the shape-deformable properties of the thermoelectric doughs, a contraction strain of â¼2% in the through-plane direction of the thermoelectric generator can be applied for an effective application of ΔT. We show that the thermoelectric generator we built with eight p-n pairs exhibits a maximum output power of 2.2 µW at a vertical ΔT of 15 K. Our results demonstrate the energy harvesting capability of thermoelectric generators with shape-deformable p- and n-type doughs. Owing to the properties of this material, thermoelectric generators with various device geometries can be fabricated for energy harvesting from a diverse range of nonflat heat sources.
RESUMO
Freestanding single-walled carbon nanotube (SWCNT) buckypapers with thicknesses of â¼30 µm are fabricated using a simple bar-coating process. The Seebeck coefficient and electrical conductivity of the SWCNT buckypapers are affected by the composition of the dispersion solvent mixture. The maximum p-type power factor of a SWCNT buckypaper is 411 ± 13 µW m-1 K-2. The inverse relationship between the Seebeck coefficient and electrical conductivity of the SWCNT buckypapers may be explained by the number density of junctions between the SWCNT bundles. Using the SWCNT buckypapers, which can be cut, folded, and pasted, a foldable thermoelectric generator is fabricated. The thermoelectric generator folded to an area of 2.25 cm2 exhibits a maximum power of 10.3 µW at a vertical temperature difference of 30 K.
RESUMO
High-performance thermoelectric composite fibers were prepared via simple wet-spinning of single-walled carbon nanotube (SWCNT)/poly(vinylidene fluoride) (PVDF) pastes using a common solvent/coagulation system. By improving the content and dispersion state of SWCNTs in the composite fibers, the thermoelectric performance could be effectively enhanced. With n-type doping of SWCNTs using polyethylenimine, high-performance n-type SWCNT/PVDF composite fibers could be prepared. The power factors of the p- and n-type SWCNT/PVDF composite fibers with the SWCNT content of 50 wt% were 378 ± 56 and 289 ± 98 µW m-1 K-2, respectively. The electric power generation capability of an organic thermoelectric generator with the p- and n-type composite fibers was confirmed.
