Carbon nanotube (CNT) devices and electronics are achieving maturity and directly competing or surpassing devices that use conventional materials. CNTs have demonstrated ballistic conduction, minimal scaling effects, high current capacity, low power requirements, and excellent optical/photonic properties; making them the ideal candidate for a new material to replace conventional materials in next-generation electronic and photonic systems. CNTs also demonstrate high stability and flexibility, allowing them to be used in flexible, printable, and/or biocompatible electronics. However, a major challenge to fully commercialize these devices is the scalable placement of CNTs into desired micro/nanopatterns and architectures to translate the superior properties of CNTs into macroscale devices. Precise and high throughput patterning becomes increasingly difficult at nanoscale resolution, but it is essential to fully realize the benefits of CNTs. The relatively long, high aspect ratio structures of CNTs must be preserved to maintain their functionalities, consequently making them more difficult to pattern than conventional materials like metals and polymers. This review comprehensively explores the recent development of innovative CNT patterning techniques with nanoscale lateral resolution. Each technique is critically analyzed and applications for the nanoscale-resolution approaches are demonstrated. Promising techniques and the challenges ahead for future devices and applications are discussed.
A template-guided, self-assembly patterning technique called discontinuous
dewetting (DD) and liquid bridge transfer (LBT) was applied to successfully
pattern single-walled carbon nanotubes (SWCNTs): the first 1D nanomaterials
patterned using the technique. The technique could efficiently and
simply pattern SWCNTs with 2.5–10 μm resolution using
little energy, low temperature (≤90 °C), and low cost
and is potentially compatible with roll-to-roll manufacturing. Many
variables were investigated to determine successful patterning conditions.
The SWCNT patterning technique demonstrates the potential to obtain
the often mutually exclusive properties for SWCNT patterning of high
resolution and fast throughput/manufacturability. Due to the low concentration
attainable in SWCNT dispersions, a preliminary wetting layer and evaporation-driven
deposition were required to achieve a uniform and high-density deposition
of SWCNTs inside the patterned cavities of a polydimethylsiloxane
transfer stamp. The wetting layer allowed for uniform SWCNT deposition
inside the cavities by preventing depinning of the SWCNT ink solution
in the cavities. The wetting layer also doubled as a release layer
during LBT, allowing easy transfer of the SWCNT lines onto hydrophilic
substrates. SWCNT lines were patterned with widths down to 2.5 μm,
up to centimeter lengths, and a resistivity of 1.9 × 10–3 Ω m without any annealing. This work demonstrates the potential
of DD and LBT patterning of SWCNTs for high-resolution R2R printing
of cheap and/or flexible next-generation electrodes and interconnects.
We explore piezoelectricity in 2D crystals, envisioning assessment, prediction, and engineering 2D piezoelectricity via chemical, computational, and physical approaches.
Topographical discontinuous dewetting (TDD) patterning is a nascent 2D printing technique explored for high‐throughput nanoscale patterning of functional material inks. However, variables affecting the z thickness and morphology of the deposited functional materials inside the patterned microchannels remain unexplored. We developed a theoretical model that can determine the thickness of the deposited functional material layers using the TDD patterning technique. We then confirmed the model with experimental data by depositing colloidal dispersions into microchannels using TDD patterning to systematically study the effects of different processing variables. The contribution of evaporation‐driven flow to the deposited layer thickness was significant, with the relationship of thickness to inking speed different to that previously determined for thin film blade coating of colloidal dispersions in the evaporative regime. Additionally, a viscosity dampening effect was observed, unique to TDD of microchannels, which slowed the evaporation‐driven flow due to local viscosity increase in the microchannels. Channel dimensions and ink dispersion concentration affected thickness as hypothesized. Internal flows in the microchannels normal to the sidewalls and perpendicular to the microchannel length (“coffee ring” effect capillary flow/Marangoni flow) were found to contribute significantly to the final morphology/thickness of the deposited layers for the systems/dispersions experimentally measured.
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a primary candidate for the conductive material in printable electronics. Currently, lateral resolutions down to only 30 µm have been demonstrated for roll-to-roll (R2R)-compatible PEDOT:PSS printing. However,...
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