Janus B2XY (X, Y = S, Se, Te) monolayers as piezoelectric Materials: A First-Principle study

Herein the piezoelectric properties of two-dimensional (2D) Janus B2XY (X, Y = S, Se, Te) monolayers are studied using first principles calculations. Theoretical results reveal that their in-plane piezoelectric response is comparable with that of the well-known 2D piezoelectric materials. Meanwhile, single-layer B2STe can play a role in top/bottom technologies because of considerable out-of-plane piezoelectricity. On the other hand, exerting tensile biaxial strain prominently enhance the piezoelectric effect of all B2XY monolayers. Their structures are still dynamically and mechanically stable under biaxial strain. In brief, this work defines the B2XY monolayers as ultrathin piezoelectric materials, and thus will stimulate related experimental discoveries.