Bi2O2Se nanosheet: An excellent high-temperature n-type thermoelectric material

Yu, Jiabing; Sun, Qiang

doi:10.1063/1.5017217

Cited by 98 publications

(76 citation statements)

References 28 publications

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“…[13][14] The ultrathin thickness may also greatly enhance thermoelectric properties. 15 Inspired by the synthesis of Bi2O2Se sheets, attentions were also paid to the related class of bismuth oxychalcogenides such as Bi2O2Te and Bi2O2S, [16][17] which were predicted to possess intriguing piezoelectricity and ferroelectricity. 17 They have adjustable bandgaps in a range between 0.2 eV and 1.5 eV, [17][18][19] and have little mismatched lattice parameters, yielding their outstanding contributions to the 2D material family.…”

Section: Introductionmentioning

confidence: 99%

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Cheng¹,

Tan²,

Zhang

et al. 2018

J. Phys. Chem. C

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A new type of two-dimensional layered semiconductor with weak electrostatic but not van der Waals interlayer interactions, Bi2O2Se, has been recently synthesized, which shown excellent air stability and ultrahigh carrier mobility. Herein, we combined theoretical and experimental approaches to study the Raman spectra of Bi2O2Se and related bismuth oxychalcogenides (Bi2O2Te and Bi2O2S). The experimental peaks lie at 160 cm −1 in Bi2O2Se and at 147 cm −1 and 340 cm −1 in Bi2O2Te. They were fully consistent with the calculated results (159.89 cm −1 , 147.48cm −1 and 340.33 cm −1 ), and were assigned to the out-of-plane A1g, A1g and B1g modes, respectively. Bi2O2S was predicted to have more Raman-active modes due to its lower symmetry.The shift of the predicted frequencies of Raman active modes was also found to get softened as the interlayer interaction decreases from bulk to monolayer Bi2O2Se and Bi2O2Te. To reveal the strain effects on the Raman shifts, a universal theoretical equation was established based on the symmetry of Bi2O2Se and Bi2O2Te. It was predicted that the doubly degenerate modes split under in-plane uniaxial/shear strains. Under a rotated uniaxial strain, the changes of Raman shifts are anisotropic for degenerate modes although Bi2O2Se and Bi2O2Te were usually regarded as isotropic systems similar to graphene. This implies a novel method to identify the crystallographic orientation from Raman spectra under strain. These results have important consequences for the incorporation of 2D Bismuth oxychalcogenides into nanoelectronic devices.

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Section: Introductionmentioning

confidence: 99%

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Cheng¹,

Tan²,

Zhang

et al. 2018

J. Phys. Chem. C

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“…Besides, Bi 2 O 2 Se has excellent air stability with thickness even down to monolayer (ML). Both high carrier mobility and air stability render 2D Bi 2 O 2 Se the very competitive 2D channel material for next‐generation FET …”

Section: Introductionmentioning

confidence: 99%

Unusual Fermi‐Level Pinning and Ohmic Contact at Monolayer Bi₂O₂Se–Metal Interface

Liu

Pan

et al. 2019

Advcd Theory and Sims

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Very recently, high‐mobility and air‐stable 2D semiconductor Bi2O2Se has been discovered and believed to be a promising channel candidate for the next‐generation field‐effect transistor (FET). High‐performance few‐layer Bi2O2Se FETs have been realized due to the existence of ohmic contact between few‐layer Bi2O2Se and the metal electrodes. However, monolayer (ML) Bi2O2Se FET exhibits poor device performance owing to lack of good contact between ML Bi2O2Se and the metal electrode. This work simulates the ML Bi2O2Se Schottky barrier field‐effect transistors with a sequence of common electrodes (Au, Pd, Pt, Ag, Sc, and Ti) for the first time by using ab initio quantum transport simulations. For Ag, Au, and Pd electrodes, a lateral n‐type Schottky contact is formed with similar Schottky barrier heights of 0.43–0.52 eV due to a strong usual Fermi‐level pinning (FLP) to the band gap of ML Bi2O2Se. Remarkably, Pt, Sc, and Ti electrodes lead to a desirable lateral n‐type ohmic contact because of an unusual FLP above the ML Bi2O2Se conduction band as a result of electrode work function modification at the interface. Therefore, high performance is anticipated for ML Bi2O2Se devices with these low‐resistance ohmic contacts.

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“…Compared to Bi 2 O 2 Se, the BiCuSeO sample has both lower electrical and thermal conductivity, with higher ZT value with the increased temperature. Furthermore, a recent theoretical study showed great potential for Bi 2 O 2 Se nanosheet as high efficiency thermoelectric materials . The calculated band gap of Bi 2 O 2 Se nanosheet (2.09eV) is significantly larger than that of bulk pristine Bi 2 O 2 Se (0.8 eV), which contributed to its large Seebeck coefficient.…”

Section: Structures and Properties Of Layered Thermoelectric Materialsmentioning

confidence: 96%

Section: Structures and Properties Of Layered Thermoelectric Materialsmentioning

confidence: 99%

“…The calculated band gap of Bi 2 O 2 Se nanosheet (2.09eV) is significantly larger than that of bulk pristine Bi 2 O 2 Se (0.8 eV), which contributed to its large Seebeck coefficient. The thermal conductivity of Bi 2 O 2 Se nanosheet was also expected to decrease, and a high ZT value was predicted to be 3.35 at 800 K …”

Section: Structures and Properties Of Layered Thermoelectric Materialsmentioning

confidence: 99%

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Recent Advances of Layered Thermoelectric Materials

Liu

Wang

Yang

et al. 2018

Advanced Sustainable Systems

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of electronic and phononic subsystems, the enhancement in a parameter can frequently deteriorate another, making the improvement of ZT very challenging. [2b-d] Based on Peltier and Seebeck effects, thermoelectric materials are widely used in up-to-date thermoelectric refrigeration and power-generation devices. [3] The schematic illustration of typical thermoelectric refrigeration and power-generation modes are shown in Figure 1. As shown in the figure, the thermoelectric module consists of a p-type and an n-type material, which are interconnected by a metallic electrical contact pads. The actual thermoelectric module is composed of an array of these couples, allowing an efficient thermoelectric energy conversion when a temperature gradient is applied. Conversely, when the current is passed through a thermoelectric module, a temperature gradient will be generated due to Peltier effect. [3] The heat could then be absorbed in the cold side and eventually being withdrawn by the sink, and therefore leads to the effect of refrigeration. In order to improve the efficiency, Lim et al. proposed a cascade refrigeration system using the thermoelectric modules. [4] In the cascade system, the heat absorption efficiency is 1.7 times better than the single system, and temperature difference of the thermoelectric module is significantly lowered to 30 °C compared to 60 °C of the single system, which made it possible to apply thermoelectric refrigerators to small capacity household applications. In 2018, a novel wearable thermoelectric generator was designed and fabricated by Kim et al. [5] This application could be easily attached to human skin for utilizing human body heat as the heat source, and thus could be used in various applications, such as self-powered wearable electrocardiography, and self-powered wireless sensor network for industry. This reflects the recent trend for developing thermoelectric technology with strong focuses on portable, flexible household and industry devices.Layered materials have long been investigated as promising thermoelectric materials in the past 50 years, from the early prototypes of PbTe and Bi 2 Te 3 . [2b] With different strengths of interlayer chemical bondings, the layered materials could be divided into two categories: typical covalent/ionic natural bulk layered materials, such as layered cobalt oxides, [7] bismuth oxyselenide, [8] artificial layered materials, such as superlattices including Bi 2 Te 3 /Sb 2 Te 3 , [9] SrTiO 3 /SrTi 0.8 Nb 0.3 O 3 , [10] GaAs/AlAs; and van der Waals layered materials including Te-based alloy, [2b] as well as artificially engineered van der Waals heterostructures like organic intercalated TiS 2 . [11] In the former case, both the intra-and interlayer chemical bondings With the continuous demands on developing renewable energy technologies to solve the global energy crisis, thermoelectric materials have attracted huge attention due to their ability to convert waste heat to useful electricity. The main advantage of layer-structured materials for thermoel...

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Bi2O2Se nanosheet: An excellent high-temperature n-type thermoelectric material

Cited by 98 publications

References 28 publications

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Unusual Fermi‐Level Pinning and Ohmic Contact at Monolayer Bi₂O₂Se–Metal Interface

Recent Advances of Layered Thermoelectric Materials

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Bi2O2Se nanosheet: An excellent high-temperature n-type thermoelectric material

Cited by 98 publications

References 28 publications

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Unusual Fermi‐Level Pinning and Ohmic Contact at Monolayer Bi2O2Se–Metal Interface

Recent Advances of Layered Thermoelectric Materials

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Product

Resources

About

Unusual Fermi‐Level Pinning and Ohmic Contact at Monolayer Bi₂O₂Se–Metal Interface