skip to main content


Title: Electrically Insulating Flexible Films with Quasi‐1D van der Waals Fillers as Efficient Electromagnetic Shields in the GHz and Sub‐THz Frequency Bands
Abstract

Polymer composite films containing fillers comprising quasi‐1D van der Waals materials, specifically transition metal trichalcogenides with 1D structural motifs that enable their exfoliation into bundles of atomic threads, are reported. These nanostructures are characterized by extremely large aspect ratios of up to106. The polymer composites with low loadings of quasi‐1D TaSe3fillers (<3 vol%) reveal excellent electromagnetic interference shielding in the X‐band GHz and extremely high frequency sub‐THz frequency ranges, while remaining DC electrically insulating. The unique electromagnetic shielding characteristics of these films are attributed to effective coupling of the electromagnetic waves to the high‐aspect‐ratio electrically conductive TaSe3atomic‐thread bundles even when the filler concentration is below the electrical percolation threshold. These novel films are promising for high‐frequency communication technologies, which require electromagnetic shielding films that are flexible, lightweight, corrosion resistant, inexpensive, and electrically insulating.

 
more » « less
Award ID(s):
1921958
NSF-PAR ID:
10452429
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Advanced Materials
Volume:
33
Issue:
11
ISSN:
0935-9648
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    Polymer composite films containing fillers comprising quasi-1D van der Waals materials, specifically transition metal trichalcogenides with 1D structural motifs that enable their exfoliation into bundles of atomic threads, are reported. These nanostructures are characterized by extremely large aspect ratios of up to ≈106. The polymer composites with low loadings of quasi-1D TaSe3 fillers (<3 vol%) reveal excellent electromagnetic interference shielding in the X-band GHz and extremely high frequency sub-THz frequency ranges, while remaining DC electrically insulating. The unique electromagnetic shielding characteristics of these films are attributed to effective coupling of the electromagnetic waves to the high-aspect-ratio electrically conductive TaSe3 atomic-thread bundles even when the filler concentration is below the electrical percolation threshold. These novel films are promising for high-frequency communication technologies, which require electromagnetic shielding films that are flexible, lightweight, corrosion resistant, inexpensive, and electrically insulating. 
    more » « less
  2. Abstract

    The synthesis and characterization of epoxy‐based composites with few‐layer graphene fillers, which are capable of dual‐functional applications, are reported. It is found that composites with certain types of few‐layer graphene fillers reveal an efficient total electromagnetic interference shielding, SEtot≈ 45 dB, in the important X‐band frequency range,f= 8.2 −12.4 GHz, while simultaneously providing high thermal conductivity,K≈ 8 W m−1K−1, which is a factor of ×35 larger than that of the base matrix material. The efficiency of the dual‐functional application depends on the filler characteristics: thickness, lateral dimensions, aspect ratio, and concentration. Graphene loading fractions above the electrical and thermal “percolation thresholds” allow for strong enhancement of both the electromagnetic interference shielding and heat conduction properties. Interestingly, graphene composites can block the electromagnetic energy even below the electrical percolation threshold, remaining electrically insulating, which is an important feature for some types of thermal interface materials. The dual functionality of the graphene composites can substantially improve the electromagnetic shielding and thermal management of airborne systems while simultaneously reducing their weight and cost.

     
    more » « less
  3. Abstract

    Lightweight, flexible, and electrically conductive thin films with high electromagnetic interference (EMI) shielding effectiveness are highly desirable for next‐generation portable and wearable electronic devices. Here, spin spray layer‐by‐layer (SSLbL) to rapidly assemble Ti3C2TxMXene‐carbon nanotube (CNT) composite films is shown and their potential for EMI shielding is demonstrated. The SSLbL technique allows strategic combinations of nanostructured materials and polymers providing a rich platform for developing hierarchical architectures with desirable cross‐functionalities including controllable transparency, thickness, and conductivity, as well as high stability and flexibility. These semi‐transparent LbL MXene‐CNT composite films show high conductivities up to 130 S cm−1and high specific shielding effectiveness up to 58 187 dB cm2g−1, which is attributed to both the excellent electrical conductivity of the conductive fillers (i.e., MXene and CNT) and the enhanced absorption with the LbL architecture of the films. Remarkably, these values are among the highest reported values for flexible and semi‐transparent composite thin films. This work could offer new solutions for next‐generation EMI shielding challenges.

     
    more » « less
  4. Abstract

    Polymer composites with electrically conductive fillers have been developed as mechanically flexible, easily processable electromagnetic interference (EMI) shielding materials. Although there are a few elastomeric composites with nanostructured silvers and carbon nanotubes showing moderate stretchability, their EMI shielding effectiveness (SE) deteriorates consistently with stretching. Here, a highly stretchable polymer composite embedded with a three‐dimensional (3D) liquid‐metal (LM) network exhibiting substantial increases of EMI SE when stretched is reported, which matches the EMI SE of metallic plates over an exceptionally broad frequency range of 2.65–40 GHz. The electrical conductivities achieved in the 3D LM composite are among the state‐of‐the‐art in stretchable conductors under large mechanical deformations. With skin‐like elastic compliance and toughness, the material provides a route to meet the demands for emerging soft and human‐friendly electronics.

     
    more » « less
  5. Abstract

    Low‐frequency current fluctuations, i.e., electronic noise, in quasi‐1D (TaSe4)2I Weyl semimetal nanoribbons are discussed. It is found that the noise spectral density is of the 1/ftype and scales with the square of the current,SI ~ I2(fis the frequency). The noise spectral density increases by almost an order of magnitude and develops Lorentzian features near the temperatureT ≈ 225 K. These spectral changes are attributed to the charge‐density‐wave phase transition even though the temperature of the noise maximum deviates from the reported Peierls transition temperature in bulk (TaSe4)2I crystals. The noise level, normalized by the channel area, in these Weyl semimetal nanoribbons is surprisingly low, ≈10−9 µm2Hz−1atf = 10 Hz, when measured below and above the Peierls transition temperature. The obtained results shed light on the specifics of electron transport in quasi‐1D topological Weyl semimetals and can be important for their proposed applications as downscaled interconnects.

     
    more » « less