Giant Flexoelectric Effect In Two-Dimensional Boron-Nitride Layers

The direct conversion of ambient motion into electrical energy is a challenging fundamental and technological problem that is currently a focus of research. Boron-Nitride non-centrosymmetric monolayers are piezoelectrics that can sustain much larger structural and produce very large (a few Volts) voltage drop across flexed nanostrips. We show, by way of first-principles calculations, the existence of giant nonlinear flexoelectric effect in BN 2D strips. The induced polarization is quadratic in amplitude of atomic displacements $A$, yet the dipole moment per unit cell is about four times larger compared to PbZrTiO3 [1]. The new effect may find a variety of practical applications and, in particular, as nanogenerators and tactile sensors powered by an ambient motion or agitation. BN material is inert and can be used in biological environment.\\[3pt] [1] I.Naumov, A.Bratkovsky, V.Ranjan, arXiv:0810.1775 (2008).