Transition of piezoresistive gauge factor tuned by lateral size in MoS₂ and WS₂ networks

Abstract Transition metal dichalcogenides (TMDs) are a family of layered two-dimensional materials which find great interest in fields such as medicine, energy conversion, water treatment, and electronics. Nevertheless, the interesting properties that arise as the number of layers is reduced, do not necessarily persist when the nanosheets are printed on substrates to form networks. Therefore, research on the networks and the influence of the nanosheets’ dimensions is valuable for scaling up prospects. It is known that strain alters the band structure of TMDs and also tune transitions between different crystal structures. The figure of merit that measures how much the resistivity changes when strain is applied is the gauge factor ( GF ). In networks, this is modeled as a sum of the nanosheet intrinsic GF and the change of the junction resistance between nanosheets due to strain. In this work we obtain the GF of devices printed on polyvinylidene fluoride membrane filters through their transport characteristics when applying uniaxial strain, both at a tensile and a compressive setup, by using a three-beam bending machine. We report a transition from a positive GF to a negative one, when applying uniaxial strain to WS 2 networks as the lateral size increases, and a transition from negative GF to a positive one, when compression is applied to MoS 2 networks as lateral size increases.