Exploring tensile piezoelectricity and bending flexoelectricity of diamane monolayers by machine learning

B Javvaji and B Mortazavi and XY Zhuang and T Rabczuk, CARBON, 185, 558-567 (2021).

DOI: 10.1016/j.carbon.2021.09.007

The investigation of electromechanical properties for the newly added two-dimensional materials is challenging and enthralling. In this work, we consider studying the piezoelectric and flexoelectric properties of diamane monolayers, firstly proposed by density functional simulations and later synthesized in experiments. For this aim, we develop machine learning-based inter-atomic moment-tensor potentials along with the charge-dipole model to calculate the electrical polarization under mechanical deformations in AB stacked Janus diamane monolayers with hetero halogenation. The developed potential parameters efficiently predict the AB stacked non-Janus diamane lattices and their AA stacked counterpart lattices. Tensile stretching of Janus diamanes produces the in-plane piezoelectricity along with the generation of significant out- of-plane polarization. The piezoelectricity is absent in AB stacked non- Janus diamanes. The increase in structural asymmetry in C4ClH monolayer under bending deformation increase the total polarization by the local electric fields originated from the pi - sigma and the sigma - sigma electron interactions. The flexoelectricity of C4ClH is lower than C4FH due to the removal of its high out-of-plane piezoelectric contribution. The Janus diamane monolayer has promising electromechanical energy applications due to its high out-of-plane piezoelectric coefficient, which is nearly 15 times higher than Janus transitional metal dichalcogenide monolayer. (C) 2021 Elsevier Ltd. All rights reserved.

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