Decoupling Junction and Nanosheet Transport in Graphene Networks via Simple DC Temperature-Dependent Measurements

Printed nanosheet networks are important for various applications in electronics, sensing, and energy storage. Understanding charge transport in such systems requires separately assessing the contributions of both the nanosheets themselves as well as the inter-nanosheet junctions. However, achieving this using standard electrical characterization methods can be challenging. Here, a broadly applicable method is presented for the separation and extraction of the temperature-dependent junction resistance (R_J) and nanosheet resistivity (ρ_NS) by combining a simple theoretical model with temperature-dependent resistivity measurements on networks fabricated using different nanosheet sizes. R_J is found to be the bottleneck for transport in networks composed of large, thick nanosheets, whereas ρ_NS begins to dominate in networks composed of smaller, thinner nanosheets. The extracted ρ_NS shows weak temperature dependence consistent with semiconducting behavior arising from a mixture of Bernal and rhombohedral layer stacking. R_J exhibits a power-law dependence which is best described by inter-sheet hopping via delocalized states just above a disorder-induced mobility edge. This approach enables simultaneous quantification of junction and nanosheet transport in any nanomaterial network. It provides a simple yet powerful method to achieve an extensive understanding of the transport mechanisms, facilitating the design of optimized printed electronic devices.