Inkjet deposition of liquid-exfoliated graphene and MoS₂nanosheets for printed device applications

Abstract

Here we demonstrate inkjet printing of nanosheets of both graphene and MoS2 prepared by liquid exfoliation. We describe a protocol for the preparation of inks of nanosheets with well-defined size distribution and concentration up to 6 mg/ml. Graphene traces were printed at low temperature (<70 °C) with no subsequent thermal or chemical treatment. Thin traces displayed percolation effects while traces with thickness above 160 nm displayed thickness-independent conductivity of 3000 S/m. We also demonstrate the printing of semiconducting traces using solvent exfoliated MoS2. Such traces can be combined with inkjet-printed graphene interdigitated array electrodes to produce all-printed photodetectors.Keywords: suspension, dispersion, printing, exfoliation, layered compound, photoconductivity. ToC figLow temperature inkjet printing of exfoliated nanosheets has been demonstrated leading to conductive graphene traces and all-inkjet printed devices.2

Inkjet Printing of MoS2

“…However, at small N region (N < 15), σ significantly increases with N as a power law σ ~ (N-N0) n with N0 ≈ 3.6 and n ≈ 1.7, suggesting the dominance of the percolation effects. [23] Photoluminescence (PL) is observed from our printed MoS2 devices (Figure 4). Figure 4a indicates some printed MoS2 devices under illumination of white light, while Figure 4b shows their PL image under an excitation laser with wavelength 532 nm.…”

“…The low concentration diminishes the printing efficiency, and the solvent toxicity causes environmental concerns. As a matter of fact, in spite of experimental attempts in the field, [14,23,24] no efficient inkjet printing technology has been demonstrated for mass production of MoS2 patterns/devices in sub-mm scale. In this work we combine the solvent exchange [21,26] and polymer stabilization [27] techniques developed for graphene dispersions to address the above issues concerning inkjet printing of MoS2.…”

“…[1][2][3]23] With the pretreatments of bulk MoS2 powders through grinding [14] or intercalation by alkali ions, [24,25] MoS2 nanosheets can be effectively exfoliated in water. In general, however, none of the as-prepared MoS2 dispersions are excellent for inkjet printing.…”

Turbulence-assisted shear exfoliation of graphene using household detergent and a kitchen blender

“…In particular, a number of applications will require access to large volumes of graphene dispersions or inks. Using standard solution deposition techniques such as inkjet printing 5,6 or spray coating, 7,8 such inks can be used to prepare a range of lms, coatings or patterned structures. In particular, applications in areas such as printed electronics will require the production of conductive lms or traces.…”

“…Here, defect free graphene performs particularly well, giving high conductivity structures without high temperature post treatments. 5 Thus, it is clear that large scale production techniques for defect-free graphene are urgently required.…”