Details
| Original language | English |
|---|---|
| Article number | 125402 |
| Journal | Physical Review Materials |
| Volume | 3 |
| Issue number | 12 |
| Publication status | Published - 11 Dec 2019 |
Abstract
Due to their combination of mechanical stiffness and flexibility, two-dimensional (2D) materials have received significant interest as potential electromechanical materials. Flexoelectricity is an electromechanical coupling between strain gradient and polarization. Unlike piezoelectricity, which exists only in noncentrosymmetric materials, flexoelectricity theoretically exists in all dielectric materials. However, most work on the electromechanical energy conversion potential of 2D materials has focused on their piezoelectric and not flexoelectric behavior and properties. In the present paper, we demonstrate that the intrinsic structural asymmetry present in monolayer Janus transition-metal dichalcogenides (TMDCs) enables significant flexoelectric properties. We report these flexoelectric properties using a recently developed charge-dipole model that couples with classical molecular dynamics simulations. By employing a prescribed bending deformation, we directly calculate the flexoelectric constants while eliminating the piezoelectric contribution to the polarization. We find that the flexoelectric response of a Janus TMDC is positively correlated to its initial degree of asymmetry, which contributes to stronger σ-σ interactions as the initial degree of asymmetry rises. In addition, the high transfer of charge across atoms in Janus TMDCs leads to larger electric fields due to π-σ coupling. These enhanced σ-σ and π-σ interactions are found to cause the flexoelectric coefficients of the Janus TMDCs to be several times higher than traditional TMDCs, such as MoS2, whose flexoelectric constant is already ten times larger than graphene.
ASJC Scopus subject areas
- Materials Science(all)
- Physics and Astronomy(all)
- Physics and Astronomy (miscellaneous)
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In: Physical Review Materials, Vol. 3, No. 12, 125402, 11.12.2019.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - High flexoelectric constants in Janus transition-metal dichalcogenides
AU - Javvaji, Brahmanandam
AU - He, Bo
AU - Zhuang, Xiaoying
AU - Park, Harold S.
N1 - Funding information: The authors gratefully acknowledge the sponsorship from the ERC Starting Grant COTOFLEXI (Grant No. 802205).
PY - 2019/12/11
Y1 - 2019/12/11
N2 - Due to their combination of mechanical stiffness and flexibility, two-dimensional (2D) materials have received significant interest as potential electromechanical materials. Flexoelectricity is an electromechanical coupling between strain gradient and polarization. Unlike piezoelectricity, which exists only in noncentrosymmetric materials, flexoelectricity theoretically exists in all dielectric materials. However, most work on the electromechanical energy conversion potential of 2D materials has focused on their piezoelectric and not flexoelectric behavior and properties. In the present paper, we demonstrate that the intrinsic structural asymmetry present in monolayer Janus transition-metal dichalcogenides (TMDCs) enables significant flexoelectric properties. We report these flexoelectric properties using a recently developed charge-dipole model that couples with classical molecular dynamics simulations. By employing a prescribed bending deformation, we directly calculate the flexoelectric constants while eliminating the piezoelectric contribution to the polarization. We find that the flexoelectric response of a Janus TMDC is positively correlated to its initial degree of asymmetry, which contributes to stronger σ-σ interactions as the initial degree of asymmetry rises. In addition, the high transfer of charge across atoms in Janus TMDCs leads to larger electric fields due to π-σ coupling. These enhanced σ-σ and π-σ interactions are found to cause the flexoelectric coefficients of the Janus TMDCs to be several times higher than traditional TMDCs, such as MoS2, whose flexoelectric constant is already ten times larger than graphene.
AB - Due to their combination of mechanical stiffness and flexibility, two-dimensional (2D) materials have received significant interest as potential electromechanical materials. Flexoelectricity is an electromechanical coupling between strain gradient and polarization. Unlike piezoelectricity, which exists only in noncentrosymmetric materials, flexoelectricity theoretically exists in all dielectric materials. However, most work on the electromechanical energy conversion potential of 2D materials has focused on their piezoelectric and not flexoelectric behavior and properties. In the present paper, we demonstrate that the intrinsic structural asymmetry present in monolayer Janus transition-metal dichalcogenides (TMDCs) enables significant flexoelectric properties. We report these flexoelectric properties using a recently developed charge-dipole model that couples with classical molecular dynamics simulations. By employing a prescribed bending deformation, we directly calculate the flexoelectric constants while eliminating the piezoelectric contribution to the polarization. We find that the flexoelectric response of a Janus TMDC is positively correlated to its initial degree of asymmetry, which contributes to stronger σ-σ interactions as the initial degree of asymmetry rises. In addition, the high transfer of charge across atoms in Janus TMDCs leads to larger electric fields due to π-σ coupling. These enhanced σ-σ and π-σ interactions are found to cause the flexoelectric coefficients of the Janus TMDCs to be several times higher than traditional TMDCs, such as MoS2, whose flexoelectric constant is already ten times larger than graphene.
UR - http://www.scopus.com/inward/record.url?scp=85077356276&partnerID=8YFLogxK
U2 - https://doi.org/10.48550/arXiv.2208.09640
DO - https://doi.org/10.48550/arXiv.2208.09640
M3 - Article
AN - SCOPUS:85077356276
VL - 3
JO - Physical Review Materials
JF - Physical Review Materials
IS - 12
M1 - 125402
ER -