Multilayered graphitic materials are not suitable as load-bearers due to their inherent weak interlayer bonding (for example, graphite is a solid lubricant in certain applications). This situation is largely improved when two-dimensional (2D) materials such as a monolayer (SLG) graphene are employed. The downside in these cases is the presence of thermally or mechanically induced wrinkles which are ubiquitous in 2D materials. Here we set out to examine the effect of extensive large wavelength/amplitude wrinkling on the stress transfer capabilities of exfoliated simply supported graphene flakes. Contrary to common belief we present clear evidence that this type of "corrugation" enhances the load-bearing capacity of few-layer graphene as compared to "flat" specimens. This effect is the result of the significant increase of the graphene/polymer interfacial shear stress per increment of applied strain due to wrinkling and paves the way for designing affordable graphene composites with highly improved stress-transfer efficiency.
Interfacing of materials with different dimensionalities becomes increasingly relevant for many applications which can utilize the exceptional properties of low‐dimensional materials on one hand, and build‐up on the existing production know‐how for bulk (3D) materials on the other. Numerous appealing possibilities are offered by such combinations. In this work, the authors focus on 2D–3D heterostructures composed of mechanically exfoliated single‐ and few‐layer layer graphene (Gr) coupled to freshly etched n‐doped silicon. Two ways of characterizing the photovoltaic (PV) properties of such junctions by Conductive Atomic Force Miscroscopy (C‐AFM) under illumination are shown: 1) by measuring the I–V curves directly at selected points, while the flakes are scanned in intermittent mode and 2) by scanning the samples in contact mode at different bias voltages, followed by reconstruction of I–V curves using mean photocurrent quantified in selected areas. The direct I–V curves measurement has been employed to discriminate the effect of increased p‐doping of the graphene layer, and the contact mode has been utilized to evaluate the separation between the graphene flake and the substrate. Additionally, pros and cons of the two routes are briefly discussed and outlook for further advanced nanoscale characterization of such junctions is proposed.
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