In-situ investigation of the elastic behavior of two-dimensional MoS₂ on flexible substrate by nanoindentation

Mechanical properties are a crucial factor for the application of two-dimensional (2D) materials in flexible electronic and optoelectronic devices. Until now, mechanical properties of 2D materials have been primarily investigated from the load–deformation relationship of freely suspended 2D nanofilms by in-situ atomic force microscope probe nanoindentation measurements. Herein, we acquired the mechanical behavior of monolayer and few-layer molybdenum disulfide (MoS₂) via applying a point load on 2D MoS₂ on a soft poly-dimethylsiloxane (PDMS) substrate. The primary objective of this work is to study the elastic behavior of 2D MoS₂ based on the indentation deformation of the 2D MoS₂/PDMS substrate. Nanoindentation behavior of 2D MoS₂ mounted on PDMS substrate is also simulated by finite element method. Combining nanoindentation experiments with theoretical simulations, we can understand the mechanical behavior of 2D materials on flexible substrates perfectly well. This work provides a new method to characterize the mechanical response of atomically ultrathin 2D nanofilms with substrate-binding effect, which is essential to promote flexible devices based on functional 2D materials.