Flexoelectric and Piezoelectric Coupling in a Bended WS2 Monolayer

Transition metal dichalcogenides (TMDs) in the form of nanolayers are very attractive for fundamental and promising for applied research. Applying a strain and a strain gradient to them makes it possible to tune their electric properties. The tuning can be explained by the presence of piezoelectric and flexoelectric effects. We considered the curved 2H-WS2 monolayer and analyzed its flexoelectric and piezoelectric properties using phenomenological Landau approach and the density functional theory. The strain, strain gradient, and dipole moment values in atomic arrangement coordinates were calculated. The dependences of these parameters on the longitudinal axis of the layer were fitted. From these dependences the components of the flexoelectric and piezoelectric tensors have been determined and analyzed. The obtained results are useful for the applications of LD-TMDs in strain engineering and flexible electronics.