scholarly journals Demonstration of valley anisotropy utilized to enhance the thermoelectric power factor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Airan Li ◽  
Chaoliang Hu ◽  
Bin He ◽  
Mengyu Yao ◽  
Chenguang Fu ◽  
...  
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
Thermoelectric Power Factor ◽  
Higher Carrier Mobility ◽  
P Type

AbstractValley anisotropy is a favorable electronic structure feature that could be utilized for good thermoelectric performance. Here, taking advantage of the single anisotropic Fermi pocket in p-type Mg3Sb2, a feasible strategy utilizing the valley anisotropy to enhance the thermoelectric power factor is demonstrated by synergistic studies on both single crystals and textured polycrystalline samples. Compared to the heavy-band direction, a higher carrier mobility by a factor of 3 is observed along the light-band direction, while the Seebeck coefficient remains similar. Together with lower lattice thermal conductivity, an increased room-temperature zT by a factor of 3.6 is found. Moreover, the first-principles calculations of 66 isostructural Zintl phase compounds are conducted and 9 of them are screened out displaying a pz-orbital-dominated valence band, similar to Mg3Sb2. In this work, we experimentally demonstrate that valley anisotropy is an effective strategy for the enhancement of thermoelectric performance in materials with anisotropic Fermi pockets.

scholarly journals Macroscopic weavable fibers of carbon nanotubes with giant thermoelectric power factor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Natsumi Komatsu ◽  
Yota Ichinose ◽  
Oliver S. Dewey ◽  
Lauren W. Taylor ◽  
Mitchell A. Trafford ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Fermi Energy ◽  
Performance Enhancement ◽  
Thermoelectric Performance ◽  
Thermoelectric Power Factor ◽  
Large Power ◽  
Energy Tuning

AbstractLow-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.

scholarly journals Backbone Effects on the Thermoelectric Properties of Ultra-Small Bandgap Conjugated Polymers

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2486
Author(s):  
Dexun Xie ◽  
Jing Xiao ◽  
Quanwei Li ◽  
Tongchao Liu ◽  
Jinjia Xu ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Power Factor ◽  
Carrier Mobility ◽  
Polymeric Materials ◽  
Thermoelectric Performance ◽  
Organic Thermoelectric Materials ◽  
Higher Power ◽  
Donor Acceptor ◽  
Maximum Power Factor ◽  
Higher Carrier Mobility

Conjugated polymers with narrower bandgaps usually induce higher carrier mobility, which is vital for the improved thermoelectric performance of polymeric materials. Herein, two indacenodithiophene (IDT) based donor–acceptor (D-A) conjugated polymers (PIDT-BBT and PIDTT-BBT) were designed and synthesized, both of which exhibited low-bandgaps. PIDTT-BBT showed a more planar backbone and carrier mobility that was two orders of magnitude higher (2.74 × 10−2 cm2V−1s−1) than that of PIDT-BBT (4.52 × 10−4 cm2V−1s−1). Both exhibited excellent thermoelectric performance after doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, where PIDTT-BBT exhibited a larger conductivity (0.181 S cm−1) and a higher power factor (1.861 μW m−1 K−2) due to its higher carrier mobility. The maximum power factor of PIDTT-BBT reached 4.04 μW m−1 K−2 at 382 K. It is believed that conjugated polymers with a low bandgap are promising in the field of organic thermoelectric materials.

A High Thermoelectric Performance ZT in p-Type LaSe2 Crystal

2021 ◽  
Vol 871 ◽  
pp. 203-207
Author(s):  
Jian Liu
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
High Power ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
High Power Factor ◽  
P Type

In this work, we use first principles DFT calculations, anharmonic phonon scatter theory and Boltzmann transport method, to predict a comprehensive study on the thermoelectric properties as electronic and phonon transport of layered LaSe2 crystal. The flat-and-dispersive type band structure of LaSe2 crystal offers a high power factor. In the other hand, low lattice thermal conductivity is revealed in LaSe2 semiconductor, combined with its high power factor, the LaSe2 crystal is considered a promising thermoelectric material. It is demonstrated that p-type LaSe2 could be optimized to exhibit outstanding thermoelectric performance with a maximum ZT value of 1.41 at 1100K. Explored by density functional theory calculations, the high ZT value is due to its high Seebeck coefficient S, high electrical conductivity, and low lattice thermal conductivity .

Thermoelectric Power Factor of Polycrystalline La0.75Sr0.25Co1-xMnxO3-δCeramics

2009 ◽  
Vol 1166 ◽  
Author(s):  
Julio E. Rodríguez ◽  
J. A. Niño
Keyword(s):  
Transport Properties ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Manganese Content ◽  
Solid State Reaction Method ◽  
Measured Temperature ◽  
Thermoelectric Power Factor ◽  
Temperature Range

AbstractThermoelectric properties of polycrystalline La0.75Sr0.25Co1-xMnxO3-δ(0<x<0.08) (LSCoO-Mn) compounds have been studied. The samples were grown by solid-state reaction method; their transport properties were studied in the temperature range between 100 and 290K, as a function of temperature and the manganese content. The Seebeck coefficient (S) is positive over the measured temperature range and its magnitude increases with the manganese content up to values close to 160 μV/K. The electrical resistivity (ρ) goes from metallic to semiconducting behavior as the Mn level increases, at room temperature, ρ(T) exhibit values less than 4mΩ-cm. From S(T), ρ(T) and κ(T) data, the thermoelectric power factor and the figure of merit were determined. These performance parameters reach maximum values around 18 μW/K2-cm and 0.2, respectively. The observed behavior in the transport properties become these compounds potential thermoelectric materials, which could be used in thermoelectric applications.

scholarly journals Centimeter-Long Weavable Fibers of Carbon Nanotubes with Giant Thermoelectric Power Factor

2021 ◽  
Author(s):  
Natsumi Komatsu ◽  
Yota Ichinose ◽  
Oliver Dewey ◽  
Lauren Taylor ◽  
Mitchell Trafford ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Fermi Energy ◽  
Performance Enhancement ◽  
Thermoelectric Performance ◽  
Thermoelectric Power Factor ◽  
Electronic Density ◽  
Large Power

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 unprecedentedly high value of power factor (14±5 mWm-1K-2) for centimeter-long weavable fibers of aligned carbon nanotubes with ultrahigh electrical and thermal conductivity. Our theoretical simulations show that the observed giant power factor originates from the one-dimensional quantum confinement of charge carriers, appearing when the Fermi energy is near a van Hove singularity in the electronic density of states. We fabricated a textile thermoelectric generator based on these carbon nanotube fibers, which demonstrated high thermoelectric performance, weavablity, and scalability. The giant power factor we observed 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.

scholarly journals Deposition potential controlled structural and thermoelectric behavior of electrodeposited CoSb3 thin films

RSC Advances ◽  
2017 ◽  
Vol 7 (33) ◽  
pp. 20336-20344 ◽  
Author(s):  
Suchitra Yadav ◽  
Brajesh S. Yadav ◽  
Sujeet Chaudhary ◽  
Dinesh K. Pandya
Keyword(s):  
Thin Films ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Room Temperature ◽  
Deposition Potential ◽  
Micro Structure ◽  
Thermoelectric Power Factor

Deposition potential controlled evolution of (420) textured CoSb3 phase and micro structure correlated to enhancement in near room temperature thermoelectric power-factor.

PHONON-DRAG EFFECT OF ULTRA-THIN FeSi2 AND MnSi1.7/FeSi2 FILMS

2011 ◽  
Vol 25 (22) ◽  
pp. 1829-1838 ◽  
Author(s):  
Q. R. HOU ◽  
B. F. GU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Crystals ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Low Temperatures ◽  
Room Temperature ◽  
Phonon Drag ◽  
Drag Effect ◽  
Thermoelectric Power Factor

Phonon-drag effect usually occurs in single crystals at very low temperatures (10–200 K). Strong phonon-drag effect is observed in ultra-thin β- FeSi 2 films at around room temperature. The Seebeck coefficient of a 23 nm-thick β- FeSi 2 film can reach -1.375 mV/K at 343 K. However, the thermoelectric power factor of the film is still small, only 0.42×10-3 W/m-K2, due to its large electrical resistivity. When a 27 nm-thick MnSi 1.7 film with low electrical resistivity is grown on it, the thermoelectric power factor of the MnSi 1.7 film can reach 1.5×10-3 W/m-K2 at around room temperature. This value is larger than that of bulk MnSi 1.7 material in the same temperature range.

scholarly journals Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg3Sb2-based materials

2017 ◽  
Vol 114 (40) ◽  
pp. 10548-10553 ◽  
Author(s):  
Jun Mao ◽  
Jing Shuai ◽  
Shaowei Song ◽  
Yixuan Wu ◽  
Rebecca Dally ◽  
...  
Keyword(s):  
Power Factor ◽  
Carrier Mobility ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Substantial Improvement ◽  
Thermoelectric Performance ◽  
Scattering Mechanism ◽  
Carrier Scattering ◽  
Ionized Impurity Scattering ◽  
Higher Carrier Mobility

Achieving higher carrier mobility plays a pivotal role for obtaining potentially high thermoelectric performance. In principle, the carrier mobility is governed by the band structure as well as by the carrier scattering mechanism. Here, we demonstrate that by manipulating the carrier scattering mechanism in n-type Mg3Sb2-based materials, a substantial improvement in carrier mobility, and hence the power factor, can be achieved. In this work, Fe, Co, Hf, and Ta are doped on the Mg site of Mg3.2Sb1.5Bi0.49Te0.01, where the ionized impurity scattering crosses over to mixed ionized impurity and acoustic phonon scattering. A significant improvement in Hall mobility from ∼16 to ∼81 cm2⋅V−1⋅s−1 is obtained, thus leading to a notably enhanced power factor of ∼13 μW⋅cm−1⋅K−2 from ∼5 μW⋅cm−1⋅K−2. A simultaneous reduction in thermal conductivity is also achieved. Collectively, a figure of merit (ZT) of ∼1.7 is obtained at 773 K in Mg3.1Co0.1Sb1.5Bi0.49Te0.01. The concept of manipulating the carrier scattering mechanism to improve the mobility should also be applicable to other material systems.

Carrier dilution in TiSe2 based intergrowth compounds for enhanced thermoelectric performance

2015 ◽  
Vol 3 (40) ◽  
pp. 10451-10458 ◽  
Author(s):  
S. R. Bauers ◽  
D. R. Merrill ◽  
D. B. Moore ◽  
D. C. Johnson
Keyword(s):  
Thin Film ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Thermoelectric Performance ◽  
Thermoelectric Power Factor

Synthesis and electrical properties of kinetically stabilized (PbSe)1+δ(TiSe2)n thin-film intergrowths are reported for 1 ≤ n ≤ 18. The carriers donated to the TiSe2 from PbSe are diluted with increasing n, leading to a systematic increase in the Seebeck coefficient and thermoelectric power factor.

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