Piezoelectricity is a property of electric polarization caused by macroscopic strains, a coupling between the mechanical and electrical behaviors to allow efficient mechanical-to-electrical energy conversion. The non-centrosymmetric material is an important research field because of the associated polarization and its potential application. Among them, piezoelectric and ferroelectric 2D materials have drawn a growing interest in recent years. 8 Particularly, the 2D layered materials with non-centrosymmetric structure have great potential for nanoscale electromechanical systems and electronic device applications. Atomically thin 2D materials exhibit a wide range of unique electrical, 2, 3 optical, 4, 5 mechanical 6, and thermal 7 properties, which do not exist in their bulk counterparts, and the outstanding advantages of properties enlighten the development in light-weight and high-performance multifunctional applications. in 2004, 1 worldwide scientific efforts have been focused on wide range of two-dimensional (2D) layered materials, driven by the fundamental interest and their potential applications. Since the successful isolation of graphene by Novoselov et al.

Piezoelectric effect