Giant Piezoelectricity in Monolayer Group IV Monochalcogenides: SnSe, SnS, GeSe and GeS

TL;DR

This paper predicts that monolayer group IV monochalcogenides exhibit extraordinarily large piezoelectric effects, surpassing many existing 2D materials, due to their unique symmetry and bonding characteristics, with potential applications in nano-sensors and energy devices.

Contribution

The study provides first-principle predictions of giant piezoelectric coefficients in monolayer group IV monochalcogenides, highlighting their superior properties over other 2D materials.

Findings

Piezoelectric coefficients are about 100 times larger than MoS2 and GaSe.

The giant effect is due to 'puckered' symmetry and weaker bonds.

Potential for use in sensors, piezotronics, and energy harvesting.

Abstract

We predict enormous piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their characteristic piezoelectric coefficients are about two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique "puckered" C2v symmetry and weaker chemical bonds of monolayer group IV monochalcogenides. Given the achieved experimental advances in fabrication of monolayers, their flexible character and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications, such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.