Enhanced Piezoelectric Response of Layered In₂Se₃/MoS₂ Nanosheet-Based van der Waals Heterostructures

Two-dimensional (2D) piezoelectricity has been extensively addressed in recent years, which leads to great potential applications in advanced smart devices. However, the vertical piezoelectric response of numerous 2D layered materials is theoretically absent when applying electric field or strain perpendicular to its surface because of the inversion symmetry. Recently, vertical piezoelectric properties of In2Se3, which exhibits a low piezoelectric response, were reported. Therefore, enhancing the piezoelectric performance in 2D layered materials is still challenging. Here, we report a remarkable out-of-plane piezoelectric performance in the In2Se3/MoS2 van der Waals (vdW) heterostructure. Such a vdW heterostructure shows a high positive value of piezoelectric coefficient d33. By combining the experimental studies and density functional theory calculations, the excellent piezoelectric properties result from the type II band alignment, which causes a larger interfacial dipole moment. Moreover, the high-precision piezoelectric actuators in 2D atomic scale are demonstrated. By changing the driven voltage, the deformation of the upper surface of piezoelectric actuators linearly modulated. Our study opens the door to design next-generation nanoelectronics and multifunctional coupling atomic-scale devices.