<i>Ab Initio</i> Prediction of Piezoelectricity in Two-Dimensional Materials

TLDR

Two‑dimensional materials exhibit properties that can differ markedly from their bulk counterparts, and piezoelectricity in these systems is crucial for micro‑ and nanoelectromechanical applications. The study aims to determine the independent piezoelectric coefficients, particularly the in‑plane d11 values, for 37 predicted and synthesized 2D metal dichalcogenides, metal oxides, and III–V semiconductors using symmetry analysis. The authors employ symmetry analysis and density‑functional perturbation theory to calculate the stiffness and piezoelectric tensors of the selected 2D materials. Most examined structures, including CrSe₂, CrTe₂, CaO, CdO, ZnO, and InN, exhibit d11 > 5 pm V⁻¹, buckled 2D materials show an out‑of‑plane d31 ranging 0.02–0.6 pm V⁻¹, and CdO, ZnO, and CrTe₂ emerge as promising candidates with large piezoelectricity and low formation energy.

Abstract

Two-dimensional (2D) materials present many unique materials concepts, including material properties that sometimes differ dramatically from those of their bulk counterparts. One of these properties, piezoelectricity, is important for micro- and nanoelectromechanical systems applications. Using symmetry analysis, we determine the independent piezoelectric coefficients for four groups of predicted and synthesized 2D materials. We calculate with density-functional perturbation theory the stiffness and piezoelectric tensors of these materials. We determine the in-plane piezoelectric coefficient d11 for 37 materials within the families of 2D metal dichalcogenides, metal oxides, and III–V semiconductor materials. A majority of the structures, including CrSe2, CrTe2, CaO, CdO, ZnO, and InN, have d11 coefficients greater than 5 pm/V, a typical value for bulk piezoelectric materials. Our symmetry analysis shows that buckled 2D materials exhibit an out-of-plane coefficient d31. We find that d31 for 8 III–V semiconductors ranges from 0.02 to 0.6 pm/V. From statistical analysis, we identify correlations between the piezoelectric coefficients and the electronic and structural properties of the 2D materials that elucidate the origin of the piezoelectricity. Among the 37 2D materials, CdO, ZnO, and CrTe2 stand out for their combination of large piezoelectric coefficient and low formation energy and are recommended for experimental exploration.