Prediction of Giant Piezoelectric Properties in Puckered Two-Dimensional Monolayers: SiTe, GeTe, SnTe

2020 ◽  
Vol 15 (12) ◽  
pp. 1436-1441
Author(s):  
Tao Zhang ◽  
Jing Xu ◽  
Ming-Lin Li

The discovery of intrinsic piezoelectricity in two-dimensional (2D) nanomaterials (NDs) have increasingly attracted extensive interests for their potential applications in next generation piezoelectric devices. Among a wide range of 2D NDs, monolayer group IV monochalcogenides with black phosphorus like structures have been revealed to have giant piezoelectricity. In this letter, the piezoelectricity of puckered group IV monochalcogenides monolayer NDs, i.e., GeTe, SnTe, and SiTe, is first calculated by using the density functional first-principles theory. The lattice structures, band structures, and elastic properties of these puckered monolayer NDs (GeTe, SnTe, and SiTe) are evaluated based on the PBE functional. ?Berry-phase? polarization theory and density functional perturbation theory (DFPT) are respectively used for calculating the piezoelectric coefficients. It is found that all these puckered monolayer NDs (GeTe, SnTe, and SiTe) exhibit highly strong piezoelectric properties. The calculated superior piezoelectricity makes these puckered monolayer NDs promising applications in the nanoscale flexible electronic and energy transfer devices.

Author(s):  
Hui Wang ◽  
Chen Pan ◽  
Sheng-Yan Wang ◽  
Hong Jiang ◽  
Yin-Chang Zhao ◽  
...  

Using first-principles calculations based on density functional perturbation theory, we demonstrate hydrogenation-induced superconductivity in monolayer TiB2H. Hydrogen adatoms destroy the Dirac state of monolayer TiB2 and monolayer TiB2H has a high vibration frequency. Monolayer TiB2H is a phonon-mediated superconductor. Monolayer TiB2H has a predicted [Formula: see text] of 8[Formula: see text]K, which further increases under external tensile strain. Thus, this study extends our understanding of superconductivity in two-dimensional (2D) materials and its potential applications.


2017 ◽  
Vol 34 (8) ◽  
pp. 087701 ◽  
Author(s):  
Jing Shi ◽  
Yong Gao ◽  
Xiao-Li Wang ◽  
Si-Ning Yun

Author(s):  
Li-Ren Ng ◽  
Guan-Fu Chen ◽  
Shi-Hsin Lin

We calculated the piezoelectric properties of asymmetrically defected MoS2 with density functional theory. By creating uneven numbers of defects on the either sides of two-dimensional MoS2, the out-of-plane centrosym- metry...


2018 ◽  
Vol 9 ◽  
pp. 1247-1253 ◽  
Author(s):  
Sri Kasi Matta ◽  
Chunmei Zhang ◽  
Yalong Jiao ◽  
Anthony O'Mullane ◽  
Aijun Du

The properties of bulk compounds required to be suitable for photovoltaic applications, such as excellent visible light absorption, favorable exciton formation, and charge separation are equally essential for two-dimensional (2D) materials. Here, we systematically study 2D group IV–V compounds such as SiAs2 and GeAs2 with regard to their structural, electronic and optical properties using density functional theory (DFT), hybrid functional and Bethe–Salpeter equation (BSE) approaches. We find that the exfoliation of single-layer SiAs2 and GeAs2 is highly feasible and in principle could be carried out experimentally by mechanical cleavage due to the dynamic stability of the compounds, which is inferred by analyzing their vibrational normal mode. SiAs2 and GeAs2 monolayers possess a bandgap of 1.91 and 1.64 eV, respectively, which is excellent for sunlight harvesting, while the exciton binding energy is found to be 0.25 and 0.14 eV, respectively. Furthermore, band-gap tuning is also possible by application of tensile strain. Our results highlight a new family of 2D materials with great potential for solar cell applications.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3338
Author(s):  
Jiali Wang ◽  
Xiuwen Zhao ◽  
Guichao Hu ◽  
Junfeng Ren ◽  
Xiaobo Yuan

van der Waals heterostructures (vdWHs) can exhibit novel physical properties and a wide range of applications compared with monolayer two-dimensional (2D) materials. In this work, we investigate the electronic and optical properties of MoSTe/MoGe2N4 vdWH under two different configurations using the VASP software package based on density functional theory. The results show that Te4-MoSTe/MoGe2N4 vdWH is a semimetal, while S4-MoSTe/MoGe2N4 vdWH is a direct band gap semiconductor. Compared with the two monolayers, the absorption coefficient of MoSTe/MoGe2N4 vdWH increases significantly. In addition, the electronic structure and the absorption coefficient can be manipulated by applying biaxial strains and changing interlayer distances. These studies show that MoSTe/MoGe2N4 vdWH is an excellent candidate for high-performance optoelectronic devices.


Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 522 ◽  
Author(s):  
Bohayra Mortazavi ◽  
Masoud Shahrokhi ◽  
Gianaurelio Cuniberti ◽  
Xiaoying Zhuang

Group IV–V-type layered materials, such as SiP, SiAs, GeP and GeAs, are among the most attractive two-dimensional (2D) materials that exhibit anisotropic mechanical, optical and transport properties. In this short communication, we conducted density functional theory simulations to explore the prospect of SiP, SiAs, GeP and GeAs nanosheets for the water-splitting application. The semiconducting gaps of stress-free SiP, SiAs, GeP and GeAs monolayers were estimated to be 2.59, 2.34, 2.30 and 2.07 eV, respectively, which are within the desirable ranges for the water splitting. Moreover, all the considered nanomaterials were found to yield optical absorption in the visible spectrum, which is a critical feature for the employment in the solar water splitting systems. Our results furthermore confirm that the valence and conduction band edge positions in SiP, SiAs, GeP and GeAs monolayers also satisfy the requirements for the water splitting. Our results highlight the promising photocatalytic characteristics of SiP, SiAs, GeP and GeAs nanosheets for the application in solar water splitting and design of advanced hydrogen fuel cells.


Author(s):  
Saeed Choopani ◽  
Mustafa Menderes Alyoruk

Abstract Piezoelectricity is a property of a material that converts mechanical energy into electrical energy or vice versa. It is known that group-III monochalcogenides, including GaS, GaSe, and InSe, show piezoelectricity in their monolayer form. Piezoelectric coefficients of these monolayers are the same order of magnitude as the previously discovered two-dimensional (2D) piezoelectric materials such as boron nitride (BN) and molybdenum disulfide (MoS2) monolayers. Considering a series of monolayer monochalcogenide structures including boron and aluminum (MX, M =B, Al, X = O, S, Se, Te), we design a series of derivative Janus structures (AlBX2, X = O, S, Se, Te). Ab-initio density functional theory (DFT) and density functional perturbation theory (DFPT) calculations are carried out systematically to predict their structural, electronic, electromechanical and phonon dispersion properties. The electronic band structure analysis indicate that all these 2D materials are semiconductors. The absence of imaginary phonon frequencies in phonon dispersion curves demonstrate that the systems are dynamically stable. In addition, this study shows that these materials exhibit outstanding piezoelectric properties. For AlBO2 monolayer with the relaxed-ion piezoelectric coefficients, d11=15.89(15.87) pm/V and d31=0.52(0.44) pm/V, the strongest piezoelectric properties were obtained. It has large in-plane and out-of-plane piezoelectric coefficients that are comparable to or larger than those of previously reported non-Janus monolayer structures such as MoS2 and GaSe, and also Janus monolayer structures including: In2SSe, Te2Se, MoSeTe, InSeO, SbTeI, and ZrSTe. These results, together with the fact that a lot of similar 2D systems have been synthesized so far, demonstrate the great potential of these materials in nanoscale electromechanical applications.


2010 ◽  
Vol 650 ◽  
pp. 313-319 ◽  
Author(s):  
Dong Lin Li ◽  
Ping Chen ◽  
Jian Xiong Yi ◽  
Bi Yu Tang ◽  
Li Ming Peng ◽  
...  

Ab inito density functional theory (DFT) and density function perturbation theory (DFPT) have been applied to investigate the thermal properties of the face-center-cubic (fcc) Al3Zr alloy over a wide range of pressure and temperature. Phonon dispersions were obtained at equilibrium and strained configurations by density functional perturbation theory. Using the quasiharmonic approximation for the free energy, several interesting physical quantities such as thermal Grüneisen parameter, heat capacity at constant pressure and volume, thermal expansion coefficient and entropy, as well as adiabatic bulk modulus and isothermal bulk modulus, were calculated as a function of temperature and pressure, and the variation features of these quantities were discussed in details.


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