Seo Yeon Han

1 Introduction Due to asymmetric crystal structures, numerous 2D materials have been recognized to possess in-plane or out-of-plane piezoelectricity.[1-5] Most 2D piezoelectric materials have intrinsic limitations in inducing sufficient polarization depending on the number of layers and the dipole orientation.[6-10] For instance, piezoelectricity in 2H-MoS2 exists only in an odd number of layers; otherwise, it causes the electric dipoles to offset each other with the 180° rotation between...