Multifold improvement of thermoelectric power factor by tuning bismuth and antimony in nanostructured n-type bismuth antimony telluride thin films

Murmu, Peter P.; Kennedy, J.; Suman, S.; Chong, Shen V.; Leveneur, Jérôme; Storey, J. G.; Rubanov, S.; Ramanath, Ganpati

doi:10.1016/j.matdes.2018.107549

Cited by 62 publications

(15 citation statements)

References 33 publications

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“…The dominant MFPs of phonons are typically an order of magnitude larger than those of electrons, thus phonon transport suffers more in the presence of nanostructuring. Some of the best results in terms of ZT improvements, however, were achieved in cases where care was taken to avoid power factor reduction [4,17,[36][37][38][39][40][41][42][43]. This is commonly achieved in two ways, either by: (i) aligning the band edges of the nanoinclusions with those of the pristine material to keep the electronic conductivity high, or (ii) going towards the reverse direction, by introducing energy barriers that result in energy filtering and improve the Seebeck coefficient.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…The films were annealed in a quartz tube flushed with argon gas, which was placed inside a 1 kW furnace. 28 CuI goes through a phase transition at 275 °C. Therefore, the annealing temperature was varied between 100 and 250 °C for 30 min.…”

Section: Methodsmentioning

confidence: 99%

Influence of Carrier Density and Energy Barrier Scattering on a High Seebeck Coefficient and Power Factor in Transparent Thermoelectric Copper Iodide

Murmu

Karthik

Liu

et al. 2020

ACS Appl. Energy Mater.

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Transparent thermoelectric materials offer a synergetic performance for energy harvesting as smart windows. Among them, p-type copper iodide (CuI) is preferred due to its low synthesis temperature, moderate conductivity and mobility, and high optical transparency. X-ray absorption spectroscopy results showed a pre-edge feature in the Cu 2p 3/2 spectrum, which suggested the presence of Cu 0 -like defect states in γ-CuI films. Interface and grain boundaries of CuI and Cu 0 act as a potential energy barrier for energy filtering of charge carriers, which along with the decrease in charge carrier density enhanced the Seebeck coefficient, α. The α value increased by 298% upon annealing at 100 °C, α = 789.5 μVK −1 , which resulted in a 480% increase in the power factor (α 2 σ = 740.9 μWm −1 K −2 ). Our results showed that a high Seebeck coefficient resulted from a decrease in charge carrier density and energy filtering of charge carriers at the interface and grain boundaries in optically transparent (T visible ∼ 60−85%) γ-CuI films for energy harvesting as smart windows.

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“…It has been fabricated by various laboratory techniques, such as pulsed laser deposition (3), molecular beam epitaxy (4), chemical vapour deposition (5,6), electro-deposition (7), (co-)evaporation (8)(9)(10), and (co-)sputtering deposition (11,12). Sputtering and evaporation techniques show the most promising potential for scale-up to fabricate flexible electronics due to their dominance in industry, e.g.…”

Section: Introductionmentioning

confidence: 99%

Static and Dynamic Postannealing Strategies for Roll-to-Roll Fabrication of DC Magnetron Sputtered Bismuth Telluride Thin Films onto Polymer Webs

Tao

Stuart

Wan

et al. 2021

ACS Appl. Mater. Interfaces

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High-throughput roll-to-roll processes are desirable to scale up the manufacture of flexible thermoelectric generators. Whilst vacuum deposition onto a heated dynamic substrate presents a considerable engineering challenge, viable post-deposition in-line annealing processes are considered as an alternative to improve the functional performance of as-deposited films. The effect of infrared and electron-beam irradiations of 1-𝜇m thick bismuth telluride thin films, produced by a vacuum roll-to-roll process for use as thermoelectric materials, were examined. Static vacuum oven and pulsed high-energy electron beam were also studied as control groups. All annealing strategies increased the crystallite size, and decreased the Te content. Only the static vacuum oven treatment was shown to significantly improve the film's crystallinity. After 1-hour annealing, the power factor improved by 400% (from 2.8 to 14 × 10 -4 W/mK 2 ), which, to the knowledge of the authors, is the highest reported thermoelectric performance of post-annealed or hot-deposited Bi-Te films. As for inline annealing, infrared and electron-beam post treatments improved the power factor by 146% (from 2.8 to 6.9 × 10 -4 W/mK 2 ) and 64% (from 2.8 to 4.6 × 10 -4 W/mK 2 ), respectively.

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Multifold improvement of thermoelectric power factor by tuning bismuth and antimony in nanostructured n-type bismuth antimony telluride thin films

Cited by 62 publications

References 33 publications

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

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

Influence of Carrier Density and Energy Barrier Scattering on a High Seebeck Coefficient and Power Factor in Transparent Thermoelectric Copper Iodide

Static and Dynamic Postannealing Strategies for Roll-to-Roll Fabrication of DC Magnetron Sputtered Bismuth Telluride Thin Films onto Polymer Webs

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