Simulation and experimental studies are carried out on single‐layer and double‐layer embedded metal meshes (SLEMM and DLEMM) to assess their performance as transparent electromagnetic interference (EMI) shielding. The structures consist of silver meshes embedded in polyethylene terephthalate (PET). As a transparent electrode, SLEMMs exhibit a transparency of 82.7% and a sheet resistance of 0.61 Ωsq−1as well as 91.0% and 1.49 Ωsq−1. This performance corresponds to figures of merit of 3101 and 2620, respectively. The SLEMMs achieve 48.0 dB EMI shielding efficiency (SE) in the frequency range of 8–18 GHz (X‐ and Ku‐bands) with 91% visible transmission and 56.2 dB EMI SE with 82.7% visible transmission. Samples exhibit stable performance after 1000 bending cycles with a radius of curvature of 4 mm and 60 tape test cycles. DLEMMs consist of fabricating SLEMM on opposite sides of the substrate where the distance can be varied using a spacer. Simulations are performed to investigate how varying spacer distance between two layers of metal meshes influences the EMI SE. DLEMMs are fabricated and achieved an EMI SE of 77.7 dB with 81.7% visible transmission. SLEMMs and DLEMMs may have a wide variety of applications in aerospace, medical, and military applications.
An efficient approach to obtain high shielding effectiveness (SE) in transparent shielding in an optical window field is proposed and demonstrated by fabricating an embedded double-layer metallic mesh (DLMM) comprised of randomly structured Ni meshes on both sides of a flexible substrate, employing a facile and low-cost double-sided nanoimprinting method. The unique nonperiodic random structure contributes to uniform diffraction and eliminates the Moiré fringe generated by double-layer periodic meshes, ensuring high imaging quality for optical applications. The designed DLMM films simultaneously achieve strong shielding in the X-band and high transmittance in the visible spectrum, demonstrating a high transmittance of 88.7% at the 550-nm wavelength and a SE of 46.9 dB at a frequency of 8.2 GHz. An ultra-high SE of 80 dB is achieved at 64.2% transmittance, which reveals the highest reported SE over a metallic mesh for transparent shielding, indicating the high potential for this transparent electromagnetic interference shielding material for practical optical applications.
more » « less- PAR ID:
- 10186194
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 28
- Issue:
- 18
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 26531
- Size(s):
- Article No. 26531
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Transparent electromagnetic interference (EMI) shielding is needed in many optoelectronic applications to protect electronic devices from surrounding radiation while allowing for high visible light transmission. However, very high transmission (over 92.5%), high EMI shielding efficiency (over 30 dB) structures have yet to be achieved in the literature. Bayesian optimization is used to optimize different nanophotonic structures for high EMI shielding efficiency (SE) and high visible light transmission (
). Below 90% average visible light transmission, sandwich structures consisting of high index dielectric/silver/high index dielectric films are determined to be optimal, where they are able to achieve 43.1 dB SE and 90.0% . The high index of refraction dielectric layers reduce absorption losses in the silver and can be engineered to provide for antireflection through destructive interference. However, for optimal EMI shielding with above 90%, the reflection losses at the air/dielectric interfaces need to be further reduced. Optimized double sided nanocone sandwich structures are determined to be best where they can achieve 41.2 dB SE and 90.8% as well as 35.6 dB SE and 95.1% . K-means clustering is utilized to show the performance of characteristic near-Pareto optimal structures. Double sided nanocone structures are shown to exhibit omnidirectional visible transmission with SE = 35.6 dB and over 85%at incidence angles of 70 . -
more » « less
Abstract Dynamic windows allow user control over light and heat flow to save energy and maximize comfort. Reversible metal electrodeposition (RME) dynamic windows can uniquely tint to a color‐neutral privacy state (0.1% visible light transmission). The design parameters of transparent metal mesh counter electrodes for high‐contrast RME dynamic windows: high transparency, charge capacity and surface area with low haze, sheet resistance and cost are discussed, concluding that woven metal meshes meet these design parameters. Electroplated current is measured on an indium tin oxide electrode and two meshes with different wire spacings, showing the meshes’ cylindrical geometry enable them to draw more current per square area. The mesh material composition is analyzed to ensure cycling durability in a CuBi electrolyte by developing a transparent mesh with an inert core (stainless steel, SS), a thin Au coating, and a high charge‐capacity (1.5 C cm−2) CuBi outer coating. The study demonstrates that the films maintain a consistent Cu:Bi ratio and optical properties after 250 privacy cycles or 1500 cycles to 10% transmission, showing that the Cu and Bi coating is effective in keeping the films from becoming Cu rich with cycling. Finally, a 100 cm2device with excellent uniformity and color neutrality is demonstrated.
-
more » « less
Abstract Tailoring thermal radiation using low‐infrared‐emissivity materials has drawn significant attention for diverse applications, such as passive radiative heating and thermal camouflage. However, the previously reported low‐infrared‐emissivity materials have the bottleneck of lacking independent control over visible optical properties. Here, a novel visibly transparent and infrared reflective (VTIR) coating by exploiting a nano‐mesh patterning strategy with an oxide–metal–oxide tri‐layer structure is reported. The VTIR coating shows simultaneously high transmittance in the visible region (>80% at 550 nm) and low emissivity in the mid‐infrared region (< 20% in 7–14 µm). The VTIR coating not only achieves a radiative heating effect of 6.6 °C for indoor conditions but also enables a synergetic effect with photothermal materials to keep human body warm at freezing temperatures for outdoor conditions, which is 10–15 °C warmer than normal cotton and Mylar film. Moreover, it demonstrates an excellent thermal camouflage effect at various temperatures (34–250 °C) and good compatibility with visible camouflage on the same object, making it ideal for both daytime and nighttime cloaking. With its unique and versatile spectral features, this novel VTIR design has great potential to make a significant impact on personal heat management and counter‐surveillance applications.
-
more » « less
MXenes, a new class of 2D transition metal carbides and carbonitrides, show great promise in supercapacitors, Li‐ion batteries, fuel cells, and sensor applications. A unique combination of their metallic conductivity, hydrophilic surface, and excellent mechanical properties renders them attractive for transparent conductive electrode application. Here, a simple, scalable method is proposed to fabricate transparent conductive thin films using delaminated Ti3C2MXene flakes by spray coating. Homogenous films, 5–70 nm thick, are produced at ambient conditions over a large area as shown by scanning electron microscopy and atomic force microscopy. The sheet resistances (
Rs ) range from 0.5 to 8 kΩ sq−1at 40% to 90% transmittance, respectively, which corresponds to figures of merit (the ratio of electronic to optical conductivities,σ DC/σ opt) around 0.5–0.7. Flexible, transparent, and conductive films are also produced and exhibit stableRs values at up to 5 mm bend radii. Furthermore, the films' optoelectronic properties are tuned by chemical or electrochemical intercalation of cations. The films show reversible changes of transmittance in the UV–visible region during electrochemical intercalation/deintercalation of tetramethylammonium hydroxide. This work shows the potential of MXenes to be used as transparent conductors in electronic, electrochromic, and sensor applications.
