<i>n</i>-Type Ultrathin Few-Layer Nanosheets of Bi-Doped SnSe: Synthesis and Thermoelectric Properties

Chandra, Sushmita; Banik, Ananya; Biswas, Kanishka

doi:10.1021/acsenergylett.8b00399

Cited by 78 publications

(64 citation statements)

References 42 publications

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“…However, because of the lower κ L, it shows better TE performance than KAgSe monolayer. The p‐type ZT at 700 K reaches an ultrahigh value of 2.08, which is significantly higher than those of recently reported promising nanoscale TE materials (0.025, 0.45, and 0.63 for SnSe nanosheets, single‐layer Bi 2 Se 3 , and Tellurium nanofilms) [ 36,37,39 ] and Ag‐based bulk TE materials (0.7, 0.85, and 0.9 for CsAg 5 Te 3 , Ag 8 SnSe 6 , and AgBi 3 S 5 , respectively) [ 40–44 ] (Figure 5g). More importantly, such a high ZT, only realized in bulk SnSe (2.6 ± 0.3) [ 45 ] and microscale Ge‐alloyed SnSe (≈2.1), [ 46 ] will be of important practical significance for nanoscale TE applications.…”

Section: Resultsmentioning

confidence: 77%

“…The calculated maximum p‐type PF of KAgSe mono‐ and bi‐layers are 1.56 and 1.78 mW m −1 K −2 at 700 K, respectively. These values are much larger than those of experimentally realized 2D materials (0.43, 0.47, and 0.73 mW m −1 K −2 for SnSe thin films, Bi 2 Te 2.7 Se 0.3 nanoplates, and single‐layered Bi 2 Se 3 , respectively), [ 35–37 ] and comparable to those of some bulk materials (2.00 and 2.85 mW m −1 K −2 for PbSe− x %HgSe and Ge 1− x Mn x Te, respectively). [ 8,38 ]…”

Section: Resultsmentioning

confidence: 81%

See 1 more Smart Citation

High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment

Zhang

Liu

Tao

et al. 2020

Adv Funct Materials

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The discovery of a record high figure of merit (ZT) of ≈2.6 associated with bulk SnSe has stimulated considerable enthusiasm in searching for 2D systems with similar high ZT. However, previously reported 2D thermoelectric (TE) materials generally possess very low ZT due to the high lattice thermal conductivity (κ L ) and/or small power factor (PF). Herein, a very high ZT (≈2.08) value associated with atomically thin 2D KAgSe nanosheet is reported, which also exhibits an unprecedented low intrinsic κ L (≈0.03 Wm −1 K −1 at 700 K for trilayer) and fairly large PF. The low κ L mainly stems from the high lattice anharmonicity induced by both the "interfacial shear slip" vibrations and the asymmetric "AgSe pair" vibrations from distorted AgSe 4 tetrahedrons. Meanwhile, the complete band-extrema alignment and coexistence of heavy and light bands result in an optimal Seebeck coefficient and electrical conductivity, thereby a large PF. This work suggests not only an alternative way to acquiring high lattice anharmonicity but also a highly competitive 2D TE candidate for wide applications.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.202001200.devices, recently much attention has been devoted to the development of 2D highefficiency TE materials with controllable thickness. [5][6][7] In general, the TE efficiency is characterized by the dimensionless figure of merit ZT = S 2 σT/(κ L + κ e ), where S, σ, T, κ L , and κ e are Seebeck coefficient, electrical conductivity, absolute temperature, lattice thermal conductivity and electronic thermal conductivity, respectively. Apparently, the high TE efficiency can be achieved by increasing the power factor (PF = S 2 σ) together with suppressing the sum of thermal conductivity (κ L + κ e ).Currently, the TE efficiency can be improved by two approaches: i) Tuning effective mass to improve the electronic transport and ii) increasing phonon scattering to suppress the lattice thermal transport. [8][9][10][11] For a given carrier concentration, a large carrier effective mass (m*) contributes to a large S, and the m* is proportional to the band effective mass (m b *) according to m* = N V 2/3 m b *, where N V refers to the band degeneracy. [10,12] A large m b *, however, will reduce the carrier mobility μ since m b 1/ * 2 µ ∝ (2D systems). [13][14][15][16] Hence, to optimize S 2 σ, it is important to attain high N V and moderate m b * simultaneously. A high N V can be achieved either by mixing two types of low-symmetric compounds into a reconstructed highly symmetric structure or by alloying/doping to converge different bands in the Brillouin zone. [8,[17][18][19] For electronic bands at the band edge, a moderate m b * can be realized in principle through element doping or strain engineering. [20] However, in practice, many compounds have limited doping capability and are easily damaged by strain; and the crystal symmetry of the reconstructed structure is uncontrollable. Regarding increasing phonon scattering, intro...

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 81%

High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment

Zhang

Liu

Tao

et al. 2020

Adv Funct Materials

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“…[1] Tw odimensional (2D) materials have attracted increasing attention in the past decade.T he structure of these materials is formed by atomically thin layers that display strong covalent in-plane bonding and weak layer-to-layer bonding. [5] In particular,p -type SnSe single crystals have shown unprecedentedly high thermoelectric (TE) figures of merit:Z T= 2.6 at 923 K. [6] On the other hand, n-type SnSe 2 could be an ideal compound to complement an all Sn-Se based device,b ut the measurement of its TE properties and their optimization has been rarely targeted. [4] Among them, tin chalcogenides are especially interesting materials for energy conversion.…”

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confidence: 99%

Tin Diselenide Molecular Precursor for Solution‐Processable Thermoelectric Materials

et al. 2018

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In the present work, we detail af ast and simple solution-based method to synthesize hexagonal SnSe 2 nanoplates (NPLs) and their use to produce crystallographically textured SnSe 2 nanomaterials.W ea lso demonstrate that the same strategy can be used to produce orthorhombic SnSe nanostructures and nanomaterials.N PLs are grown through as crew dislocation-driven mechanism. This mechanism typically results in pyramidal structures,b ut we demonstrate here that the growth from multiple dislocations results in flower-like structures.C rystallographically textured SnSe 2 bulk nanomaterials obtained from the hot pressing of these SnSe 2 structures displayhighly anisotropic charge and heat transport properties and thermoelectric (TE) figures of merit limited by relatively low electrical conductivities.T oimprove this parameter,SnSe 2 NPLs are blended here with metal nanoparticles.The electrical conductivities of the blends are significantly improved with respect to bare SnSe 2 NPLs,w hat translates into at hree-fold increase of the TE Figure of merit, reaching unprecedented ZT values up to 0.65.The use of molecular precursors to produce inorganic nanomaterials in the form of nanoparticles,t hin films, supported nanostructures or self-standing porous or dense nanomaterials is potentially advantageous in terms of reducing fabrication costs and improving performances.I nt his direction, the amine-dithiol system has been reported as av ersatile solvent to prepare molecular precursors from the dissolution at ambient conditions of metal chalcogenides, pure metals and metal oxides,a mong others. [1] Tw odimensional (2D) materials have attracted increasing attention in the past decade.T he structure of these materials is formed by atomically thin layers that display strong covalent in-plane bonding and weak layer-to-layer bonding. This type of structure results in extraordinary and at the same time highly anisotropic physical, electronic and optical properties.Inparticular, charge and heat transport properties are especially affected by the strong lattice asymmetry,a nd much higher thermal and electrical conductivities are measured in-plane than cross-plane.O wing to these highly anisotropic properties,t op roduce bulk 2D nanomaterials with aproper crystallographic texture is necessary to optimize their performance in most applications.H owever,t oc ontrol the crystallographic texture of materials produced by bottomup procedures and/or solution-based approaches is not straightforward.Ap articularly interesting 2D material family is that of metal chalcogenides,o wing to their good chemical stability and semiconducting characteristics.2 Dm etal chalcogenides are used in numerous applications in av ariety of fields, including energy conversion and storage, [2] flexible electronics [3] and medical diagnosis. [4] Among them, tin chalcogenides are especially interesting materials for energy conversion. [5] In particular,p -type SnSe single crystals have shown unprecedentedly high thermoelectric (TE) figures of merit:Z T= 2.6 at 92...

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“…It is a unique low‐symmetry, strong in‐plane anisotropic 2D material with a black‐phosphorus‐like crystal structure . Recently, great attention has been increasingly paid to 2D SnSe nanosheets because of their excellent optoelectronic, thermoelectric, spin transport, multiferroic, and piezoelectric properties in applications to photodetectors, storage switching devices, etc . SnSe has a second‐order phase transition, and the crystal structure will change from Pnma to Cmcm space group when the temperature is above 810 K .…”

mentioning

confidence: 99%

“…[7][8][9] Recently, great attention has been increasingly paid to 2D SnSe nanosheets because of their excellent optoelectronic, thermoelectric, spin transport, multiferroic, and piezoelectric properties in applications to photodetectors, storage switching devices, etc. [10][11][12][13][14][15][16][17] SnSe has a second-order phase transition, and the crystal structure will change from Pnma to Cmcm space group when the temperature is above 810 K. [18] In addition, SnSe crystals have an ultralow thermal conductivity and excellent thermoelectric properties at high temperatures. Such unusual behaviors are closely related to the layer number of 2D SnSe nanosheets.…”

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confidence: 99%

Nanoscale Thermal Behavior of 2D SnSe Nanosheets

Liu

Zeng

et al. 2019

Physica Rapid Research Ltrs

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The thickness‐dependent nanoscale thermal behaviors of 2D SnSe nanosheets are studied via 3ω thermal mode atomic force microscopy and local Raman spectra. It is found that the 2D SnSe nanosheets demonstrate a decreasing thermal behavior with the reduction of thickness in the range of 6–40 nm. The unique thermal behavior is ascribed to the nonharmonic interlayer coupling along the armchair direction of SnSe crystal structure, in which the redshift of in‐plane vibration (Anormalg2, B3g) gives rise to phonon softening and finally the thickness‐dependent thermal behavior of SnSe nanosheets. Such nanoscale thermal behavior provides a new insight to understand the local thermal transport of 2D materials and their applications in energy consumption.

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n-Type Ultrathin Few-Layer Nanosheets of Bi-Doped SnSe: Synthesis and Thermoelectric Properties

Cited by 78 publications

References 42 publications

High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment

High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment

Tin Diselenide Molecular Precursor for Solution‐Processable Thermoelectric Materials

Nanoscale Thermal Behavior of 2D SnSe Nanosheets

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