High‐Throughput Mechanical Exfoliation for Low‐Cost Production of van der Waals Nanosheets

Abstract

A method is presented for scaling up the production of flakes of van der Waals materials via mechanical exfoliation. Using a roll‐to‐roll setup and an automatized, massive parallel exfoliation process, adhesive tapes with a high density of nanosheets of van der Waals materials are produced. The technique allows for obtaining a good trade‐off between large lateral size and excellent area scalability, while also maintaining low cost. The potential of the method is demonstrated through the successful fabrication of field effect transistors and flexible photodetectors in large batches. This low‐cost method to produce large area films out of mechanically exfoliated flakes is very general, and it can be applied to a variety of substrates and van der Waals materials and, moreover, it can be used to combine different van der Waals materials on top of each other. Therefore, it is believed that this production method opens an interesting avenue for fabrication of low‐cost devices while maintaining a good scalability and performance.

Electrical properties of disordered films of van der Waals semiconductor WS2 on paper

“…11 These resistance values are around two orders of magnitude larger than those of large-area MoS 2 films deposited on SiO 2 /Si with Au prepatterned electrodes ( L = 10 μm, W = 1000 μm) where square resistances are in the order of 5–50 MΩ □ −1 compared to our MoS 2 film where the film resistance is 1000 MΩ □ −1 . 31 This difference could be due to the different production method of MoS 2 that in ref. 31 comes from mechanically exfoliated flakes from bulk MoS 2 and in our case comes from MoS 2 micronized powder.…”

“…31 This difference could be due to the different production method of MoS 2 that in ref. 31 comes from mechanically exfoliated flakes from bulk MoS 2 and in our case comes from MoS 2 micronized powder. Interestingly, while the lower R 0 device shows similar slopes both for tensile and compressive strain with a GF = 100, the larger R 0 device shows a smaller slope for compressive strain in respect to the tensile train datapoints.…”

Encapsulation of Crystalline and Amorphous Sb2S3 within Carbon and Boron Nitride Nanotubes

“…Such studies have led to the discovery and rediscovery of many useful two-dimensional (2D), [1][2][3] one-dimensional (1D), and quasi-one-dimensional (q-1D) van der Waals (vdW) 4,5 materials with nascent physical properties. The anisotropy inherent in the structure of these materials has enabled the development of facile top-down exfoliation [6][7][8][9] or bottom-up growth [10][11][12][13] methods to achieve sub-10 nm nanocrystals with tunable morphologies such as nanosheets, nanoribbons, and nanowires, and shape-or dimension-dependent properties. This structural and chemical tunability has led to discoveries including the transition from indirect band gap in the bulk to direct band gap in monolayer MoS2 14 and the quantum spin Hall effect in graphene in 2D.…”

Encapsulation of Crystalline and Amorphous Sb2S3 within Carbon and Boron Nitride Nanotubes

“…Such studies have led to the discovery and rediscovery of many useful two-dimensional (2D), [1][2][3] one-dimensional (1D), and quasi-one-dimensional (q-1D) van der Waals (vdW) 4,5 materials with nascent physical properties. The anisotropy inherent in the structure of these materials has enabled the development of facile top-down exfoliation [6][7][8][9] or bottom-up growth [10][11][12][13] methods to achieve sub-10 nm nanocrystals with tunable morphologies such as nanosheets, nanoribbons, and nanowires, and shape-or dimension-dependent properties. This structural and chemical tunability has led to discoveries including the transition from indirect band gap in the bulk to direct band gap in monolayer MoS 2 14 and the quantum spin Hall effect in graphene in 2D.…”