Tailoring Nanoporous Structures in Bi<sub>2</sub>Te<sub>3</sub> Thin Films for Improved Thermoelectric Performance

Qiao, Jixiang; Zhao, Yang; Jin, Qing; Tan, Jun; Kang, Siqing; Qiu, Jianhang; Tai, Kaiping

doi:10.1021/acsami.9b13920

Cited by 44 publications

(31 citation statements)

References 65 publications

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“…The carrier scattering becomes strongly energy dependent, which increases the Seebeck coefficient. Another nano-feature that has been widely explored are nanopores, which drastically reduce thermal conductivity [26,28,141,142,143,144,145,146,147,148,149]. Porosity could lead to an increase in the Seebeck coefficient due to the increase of the entropy per charge carrier due to energy filtering at the pore boundaries, but as we will show later on, this improvement is not significant.…”

Section: Nanostructuring: Materials Methods and State-of-the-artmentioning

confidence: 99%

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

et al. 2020

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The field of thermoelectric materials has undergone a revolutionary transformation over the last couple of decades as a result of the ability to nanostructure and synthesize myriads of materials and their alloys. The ZT figure of merit, which quantifies the performance of a thermoelectric material has more than doubled after decades of inactivity, reaching values larger than two, consistently across materials and temperatures. Central to this ZT improvement is the drastic reduction in the material thermal conductivity due to the scattering of phonons on the numerous interfaces, boundaries, dislocations, point defects, phases, etc., which are purposely included. In these new generation of nanostructured materials, phonon scattering centers of different sizes and geometrical configurations (atomic, nano- and macro-scale) are formed, which are able to scatter phonons of mean-free-paths across the spectrum. Beyond thermal conductivity reductions, ideas are beginning to emerge on how to use similar hierarchical nanostructuring to achieve power factor improvements. Ways that relax the adverse interdependence of the electrical conductivity and Seebeck coefficient are targeted, which allows power factor improvements. For this, elegant designs are required, that utilize for instance non-uniformities in the underlying nanostructured geometry, non-uniformities in the dopant distribution, or potential barriers that form at boundaries between materials. A few recent reports, both theoretical and experimental, indicate that extremely high power factor values can be achieved, even for the same geometries that also provide ultra-low thermal conductivities. Despite the experimental complications that can arise in having the required control in nanostructure realization, in this colloquium, we aim to demonstrate, mostly theoretically, that it is a very promising path worth exploring. We review the most promising recent developments for nanostructures that target power factor improvements and present a series of design ‘ingredients’ necessary to reach high power factors. Finally, we emphasize the importance of theory and transport simulations for materialoptimization, and elaborate on the insight one can obtain from computational tools routinely used in the electronic device communities. Graphical abstract

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Section: Nanostructuring: Materials Methods and State-of-the-artmentioning

confidence: 99%

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

et al. 2020

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“…Thus, the carrier concentration decreases while the Seebeck coefficient increases due to the decreased Te concentration. 11 Therefore, sample 623-3 showed a lower Seebeck coefficient than sample 673-3. The effect of the porosity and lattice defects is also observed in the decrease of the peak temperature from 353 K to 348 K.…”

Section: Seebeck Coefficientmentioning

confidence: 92%

“…These results show that the intensities of some of the peaks also increased slightly, probably due to surplus Te atoms in the sample milled for 3 h. This indicates that this milling time was insufficient to complete the reaction for Bi 2 Te 3 formation. 11 Due to this insufficient MA time, the process of cold welding between the powders and the proper treatment of the powders and steel balls were not performed adequately. Consequently, the sample milled for 4 h was chosen for sintering by the SPS method.…”

Section: Phase and Structurementioning

confidence: 99%

“…In general, phonon scattering by pores has extremely negative effects on the thermoelectric behavior of materials. [43][44][45] According to Qiao et al, 11 the excess Te in sample 623-3 will produce antisite defects that affect the ntype conduction behavior. Indeed, the excess Te will substitute for Bi (Te Bi ) to form a single donor and Te vacancy (V Te ) as a double donor.…”

Section: Seebeck Coefficientmentioning

confidence: 99%

“…5,6 Recent studies have investigated the effect of nanoporous structures on the lattice thermal conductivity of Bi 2 Te 3 compound. [7][8][9][10] Qiao et al 11 reported that porous structure decreases the lattice thermal conductivity without affecting the electrical conductivity. Xu et al 10 synthesized Bi 2 Te 2.5 Se 0.5 nanocomposites with a porous structure by a spark plasma sintering (SPS) method.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Synthesis Parameters and Thickness on Thermoelectric Properties of Bi2Te3 Fabricated Using Mechanical Alloying and Spark Plasma Sintering

Bolghanabadi

Sajjadi

Babakhani

et al. 2021

Journal of Elec Materi

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Bi 2 Te 3 compound has been shown to exhibit the highest thermoelectric figure of merit at 573 K to 673 K. Bi 2 Te 3 samples were synthesized by mechanical alloying (MA) followed by spark plasma sintering (SPS) in this work. The effects of the milling and SPS parameters as well as the specimen thickness were evaluated to obtain the best microstructural and thermoelectric properties. To synthesize Bi 2 Te 3 , Bi and Te powders were mechanically alloyed under argon atmosphere in a stainless-steel vial with a ball-to-powder weight ratio of 15:1 for different durations. The synthesized powders were then sintered using SPS at different temperatures. To characterize the Bi 2 Te 3 powders and bulk samples, x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) analysis were applied. Furthermore, the bandgap energy was measured by ultraviolet-visible (UV-Vis) spectroscopy. Moreover, the Seebeck voltage and electrical conductivity were determined at different temperatures. The experimental results illustrate that, by enhancing the sintering temperature from 623 K to 673 K, the maximum Seebeck coefficient was increased from 136 lV/K to 156 lV/K. To investigate the effect of thickness, specimens were sintered at the optimum temperature of 673 K with thicknesses of 1 mm, 1.5 mm, 2 mm, 3 mm, and 4 mm. The results showed that, by decreasing the thickness, the maximum Seebeck coefficient was increased from 144 lV/K to 166 lV/K while the electrical conductivity was increased from 0.35 9 10 5 S/m to 1.42 9 10 5 S/ m, resulting in an increase in the power factor from 0.76 mW/m-K 2 to 3.94 mW/m-K 2 .

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Novel Thermal Diffusion Temperature Engineering Leading to High Thermoelectric Performance in Bi₂Te₃‐Based Flexible Thin‐Films

et al. 2021

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Flexible Bi 2 Te 3 ‐based thermoelectric devices can function as power generators for powering wearable electronics or chip‐sensors for internet‐of‐things. However, the unsatisfied performance of n‐type Bi 2 Te 3 flexible thin films significantly limits their wide application. In this study, a novel thermal diffusion method is employed to fabricate n‐type Te‐embedded Bi 2 Te 3 flexible thin films on flexible polyimide substrates, where Te embeddings can be achieved by tuning the thermal diffusion temperature and correspondingly result in an energy filtering effect at the Bi 2 Te 3 /Te interfaces. The energy filtering effect can lead to a high Seebeck coefficient ≈160 µV K −1 as well as high carrier mobility of ≈200 cm 2 V −1 s −1 at room‐temperature. Consequently, an ultrahigh room‐temperature power factor of 14.65 µW cm −1 K −2 can be observed in the Te‐embedded Bi 2 Te 3 flexible thin films prepared at the diffusion temperature of 623 K. A thermoelectric sensor is also assembled through integrating the n‐type Bi 2 Te 3 flexible thin films with p‐type Sb 2 Te 3 counterparts, which can fast reflect finger‐touch status and demonstrate the applicability of as‐prepared Te‐embedded Bi 2 Te 3 flexible thin films. This study indicates that the thermal diffusion method is an effective way to fabricate high‐performance and applicable flexible Te‐embedded Bi 2 Te 3 ‐based thin films.

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Tailoring Nanoporous Structures in Bi₂Te₃ Thin Films for Improved Thermoelectric Performance

Cited by 44 publications

References 65 publications

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Effects of Synthesis Parameters and Thickness on Thermoelectric Properties of Bi2Te3 Fabricated Using Mechanical Alloying and Spark Plasma Sintering

Novel Thermal Diffusion Temperature Engineering Leading to High Thermoelectric Performance in Bi₂Te₃‐Based Flexible Thin‐Films

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Tailoring Nanoporous Structures in Bi2Te3 Thin Films for Improved Thermoelectric Performance

Cited by 44 publications

References 65 publications

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Effects of Synthesis Parameters and Thickness on Thermoelectric Properties of Bi2Te3 Fabricated Using Mechanical Alloying and Spark Plasma Sintering

Novel Thermal Diffusion Temperature Engineering Leading to High Thermoelectric Performance in Bi2Te3‐Based Flexible Thin‐Films

Contact Info

Product

Resources

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Tailoring Nanoporous Structures in Bi₂Te₃ Thin Films for Improved Thermoelectric Performance

Novel Thermal Diffusion Temperature Engineering Leading to High Thermoelectric Performance in Bi₂Te₃‐Based Flexible Thin‐Films