Using Electrical Impedance Spectroscopy to Separately Quantify the Effect of Strain on Nanosheet and Junction Resistance in Printed Nanosheet Networks

Abstract

Many printed electronic applications require strain‐independent electrical properties to ensure deformation‐independent performance. Thus, developing printed, flexible devices using 2D and other nanomaterials will require an understanding of the effect of strain on the electrical properties of nano‐networks. Here, novel AC electrical techniques are introduced to fully characterize the effect of strain on the resistance of high‐mobility printed networks, fabricated from of electrochemically exfoliated MoS2 nanosheets. These devices are initially characterized using DC piezoresistance measurements and show good cyclability and a linear strain response, consistent with a low gauge factor of G ≈ 3. However, AC impedance spectroscopy measurements, performed as a function of strain, allow the measurement of the effects of strain on both the nanosheets and the inter‐nanosheet junctions separately. The junction resistance is found to increase linearly with strain, while the nanosheet resistance remains constant. This response is consistent with strain‐induced sliding of the highly‐aligned nanosheets past one another, without any strain being transferred to the sheets themselves. The approach allows for the individual estimation of the contributions of dimensional factors (G ≈ 1.4) and material factors (G ≈ 1.9) to the total gauge factor. This novel technique may provide insights into other piezoresistive systems.