residue-free-fabrication-van-der-waals-heterostructures-two

Residue-Free Fabrication of van der Waals Heterostructures of Two-Dimensional Materials

In this work, a unique methodology is presented that utilizes van der Waals (vdW) interactions to fabricate residue-free single flakes of two-dimensional ...

Gwangju Institute of Science and Technology

A light-weight, flexible electromagnetic interference (EMI) shield was prepared by creating a layer-structured metal-polymer composite film consisting of electrospun nylon 66 nanofibers with silver films. The EMI shielding effectiveness (SE), specific SE, and absolute SE of the composite were as high as 60.6 dB, 67.9 dB cm/g, and 6792 dB cm/g in the X- and K-bands, respectively. Numerical and analytical calculations suggest that the energy of EM waves is predominantly absorbed by inter-layer multiple reflections. Because the absorbed EM energy is dissipated as heat, the thermal conductivity of absorption-dominant EMI shields is highly significant. Measured thermal conductivity of the composite was found to be 4.17 WmK at room temperature, which is higher than that of bulk nylon 66 by a factor of 16.7. The morphology and crystallinity of the composite were examined using scanning electron microscopy and differential scanning calorimetry, respectively. The enhancement of thermal conductivity was attributed to an increase in crystallinity of the nanofibers, which occurred during the electrospinning and subsequent hot pressing, and to the high thermal conductivity of the deposited silver films. The contribution of each fabrication process to the increase in thermal conductivity was investigated by measuring the thermal conductivity values after each fabrication process.

Electromagnetic Interference Shield of Highly Thermal-Conducting, Light-Weight, and Flexible Electrospun Nylon 66 Nanofiber-Silver Multi-Layer Film.

2D materials have garnered considerable attention due to their distinctive properties, prompting diverse applications across various domains. Beyond their inherent qualities, the significance of 2D materials extends into the fabrication processes that can lead to the degradation of intrinsic performance through undesirable mechanical defects and surface contaminations. Herein, a novel fabrication technique to achieve residue-free 2D materials using van der Waals (vdW) interactions, primarily employing molybdenum disulfide (MoS) is proposed. Optical and electrical characterizations confirm the absence of residues, mechanical defects, oxidation, and strain, along with a prominent field-effect mobility of up to 60 cm V s and an on/off ratio of ≈10. Furthermore, the utilization of residue-free material as a stamp enables various manipulations of flakes transferred on substrates in advance, including pick-up and release, stacking, exfoliation, wiping-out, flipping, and smoothing-out processes. Additionally, the manipulation techniques also facilitate the fabrication of vdW heterostructures with precise positioning and the desired stacking order. In this regard, the feasibility of applying this method to hexagonal boron nitride and graphite is demonstrated. It is expected that this method will offer a versatile and effective approach to enhancing the qualities of 2D material-based electronic and optoelectronic devices.

Article	Year
Electromagnetic Interference Shield of Highly Thermal-Conducting, Light-Weight, and Flexible Electrospun Nylon 66 Nanofiber-Silver Multi-Layer Film. Polymers\| PubMed ID: 32796775	2020
Residue-Free Fabrication of 2D Materials Using van der Waals Interactions. Advanced materials (Deerfield Beach, Fla.)\| PubMed ID: 40171775	2025

Changho Kim

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