Giant flexoelectric effect in two-dimensional boron-nitride sheets

TL;DR

This paper reports a giant nonlinear flexoelectric effect in two-dimensional boron-nitride sheets, where bending induces significant in-plane polarization, opening avenues for advanced nanogenerator applications.

Contribution

First-principles calculations reveal a nonlinear flexoelectric effect in 2D BN sheets, demonstrating large polarization induced by bending, which is a novel electromechanical phenomenon.

Findings

High polarization values in bent BN sheets

Polarization depends non-analytically on wave vector k

Potential for efficient nanogenerator applications

Abstract

We find, with the use of first-principles calculations, that a single-atom-thick boron-nitride (BN) sheet exhibits an unusual nonlinear electromechanical effect: it becomes macroscopically polarized when bent out-of-plane. The direction of the induced polarization is in the plane of the film and it depends non-analitically on the corrugation wave vector k. The magnitude of the polarization can reach very high values in spite of being at least quadratic in atomic displacements due to BN sheets being able to tolerate large mechanical strains. The discovered effect can find many applications, in particular, in a new type of efficient and reliable nanogenerators.