Molecular Dynamcis Study of Thermomechanical Behavior of WSe2 (Tungsten Diselenide) for Flexible Wearable Sensors

Abstract

Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) stand out for their exceptional electrical, optical, and mechanical properties, with tungsten diselenide (WSe2)beingaparticularly promisingcandidate for next-generation nanoelectromechanical and flexible devices. However, imperfections such as pits, which frequently arise during synthesis or device fabrication, act as crack initiators that degrade the intrinsic mechanical stability and compromise device reliability. In this study, we employ molecular dynamics (MD) simulations to investigate the fracture response of monolayer WSe2 nanosheets containing circular and triangular pit defects under uniaxial tensile loading along both armchair and zigzag orientations. Using the Stillinger–Weber (SW) interatomic potential within LAMMPS at a strain rate of 108 s−1 and room temperature (300 K), we analyze stress–strain behavior, crack initiation, and propagation mechanisms. The results show that the zigzag orientation provides superior mechanical resistance, with circular pits achieving a maximum yield strength of about 4.08 GPa at 6.0% strain, whereas triangular pits fractured earlier at around 3.00 GPa and 4.8% strain. In the armchair direction, circular pits reached approximately 3.55 GPa at 6.3% strain, while triangular pits failed at 3.06 GPa and 4.0% strain. Results reveal the anisotropic nature of WSe2 and demonstrate that both defect geometry and loading direction significantly alter mechanical performance. This work provides fundamental insights into defect-driven fracture mechanisms in WSe2, offering useful guidelines for the design and reliability assessment of TMD-based nanodevices.