Enhanced piezoelectric response in two-dimensional layered ferroelectric <i>α</i>-In₂Se₃ via indentation-induced shear strain

Abstract Controlling the piezoelectric response of layered two-dimensional (2D) materials is essential for advancing nanoelectromechanical systems and piezoelectric devices. However, the impact of interlayer shear strain on piezoelectric properties remains unclear. In this study, we investigate the enhancement of the out-of-plane (OOP) piezoelectric response in 2D ferroelectric α -In 2 Se 3 through nanoindentation-induced shear deformation. We employ piezoresponse force microscopy to evaluate the piezoelectric properties of deformed regions while maintaining the shear-induced state. Our findings reveal that shear deformation leads to a threefold increase in the OOP piezoelectric coefficient d 33 compared with the undeformed regions. This enhancement correlates with shear strain, suggesting that shear-induced interlayer sliding and atomic rearrangements within the van der Waals (vdW) layers play a key role in modifying the piezoelectric properties. These results establish interlayer shear deformation as a new mechanism for tuning piezoelectric responses in 2D materials. Our approach offers a promising strategy for optimizing electromechanical properties, expanding the potential of vdW sliding engineering for next-generation nanoelectromechanical devices.