New Family of Two-Dimensional Ternary Photoelectric Materials

Xu, Wangping; Wang, Rui; Zheng, Baobing; Wu, Xiaoyan; Xu, Hu

doi:10.1021/acsami.9b00969

Cited by 40 publications

(37 citation statements)

References 50 publications

(72 reference statements)

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“…Also, the special heat transport behaviors may occur in other 2D isostructural materials with ultraweak interlayer interaction, such as layered AAgX (A = Na, K, and Rb; X = S, Se, and Te), which have been recently predicted to possess high carrier mobility and good optical properties. [ 32 ]…”

Section: Resultsmentioning

confidence: 99%

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: 99%

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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“…In recent years, two‐dimensional materials have attracted extensive attention due to their excellent electronic and thermal properties, and they have been widely applied in nanoelectronics, photoelectric devices, and other fields. [ 1 ] In the past two decades, due to the decreasing size of electronic devices, high heat dissipation efficiency, high thermal stability, high conductivity, and high carrier mobility have become important factors determining the performance of electronic devices. [ 2,3 ] Graphene is a famous two‐dimensional carbon material and has received great attention since 2004.…”

Section: Introductionmentioning

confidence: 99%

Strain‐tunable electronic properties and optical properties of Hf₂CO₂ MXene

Zhang

et al. 2020

Int J of Quantum Chemistry

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Two-dimensional materials have been extensively applied because of their unusual electronic, mechanical, and optical properties. In this paper, the electronic structure and optical properties of Hf 2 CO 2 MXene under biaxial and uniaxial strains are investigated by the Heys-Scuseria-Ernzerhof (HSE06) method. Monolayer Hf 2 CO 2 can sustain stress up to 6.453 N/M for biaxial strain and 3.072 N/M for uniaxial strain. Monolayer Hf 2 CO 2 undergoes the transition from semiconductor to metal under −12% strain whether it is under biaxial or uniaxial strain. With the increasing biaxial compressive strain, the blue shift of Hf-d, O-p, and C-p orbitals in valence band maximum results in the metallization of monolayer Hf 2 CO 2 , while the red shift of Hf-d and O-p orbitals in conduction band minimum results in the metallization of monolayer Hf 2 CO 2 with increasing uniaxial compressive strain. The analysis of optical properties indicates that uniaxial strain weakens the reflectivity and refractive index of monolayer Hf 2 CO 2 in the visible-light range. In addition, the effective mass and the charge distribution under biaxial and uniaxial strains are also explored.

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“…Recently, a new class of 2D layered semiconductors known as XYZ (X = Rb, K; Y = Au, Ag, Cu; Z = Te, Se, S) have been reported, which have high carrier mobility, moderate band gap, favorable stability, and superior optoelectronic properties. 19–21 Bulk KAgX (X = S, Se, Te) materials were found to possess low and anisotropic lattice thermal conductivity. 22 Very recently, Zhang et al 23 revealed that few-layer KAgSe nanosheets featured intrinsically low lattice thermal conductivity and a considerable power factor due to the strong interlayer vibrations and the complete band-extrema alignment, with an optimal ZT value of 2.08.…”

Section: Introductionmentioning

confidence: 99%

Ultralow lattice thermal conductivity at room temperature in 2D KCuSe from first-principles calculations

et al. 2022

Phys. Chem. Chem. Phys.

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New Family of Two-Dimensional Ternary Photoelectric Materials

Cited by 40 publications

References 50 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

Strain‐tunable electronic properties and optical properties of Hf₂CO₂ MXene

Ultralow lattice thermal conductivity at room temperature in 2D KCuSe from first-principles calculations

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New Family of Two-Dimensional Ternary Photoelectric Materials

Cited by 40 publications

References 50 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

Strain‐tunable electronic properties and optical properties of Hf2CO2 MXene

Ultralow lattice thermal conductivity at room temperature in 2D KCuSe from first-principles calculations

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Strain‐tunable electronic properties and optical properties of Hf₂CO₂ MXene