RESUMEN
Scalable and low-cost manufacturing of broadband absorbers for use in the long-wave infrared region are of enormous importance in various applications, such as infrared thermal imaging, radiative cooling, thermal photovoltaics and infrared sensor. In recent years, a plethora of broadband absorption metasurfaces made of metal nano-resonators with plasmon resonance have been synthesized. Still, their disadvantages in terms of complex structure, production equipment, and fabrication throughput, limit their future commercial applications. Here, we propose and experimentally demonstrate a broadband large-area all-dielectric metasurface absorber comprised of silicon (Si) arrys of square resonators and a silicon nitride (Si3N4) film in the long-wave infrared region. The multiple Mie resonance modes generated in a single-size Si resonator are utilized to enhance the absorption of the Si3N4 film to achieve broadband absorption. At the same time, the transversal optical (TO) phonon resonance of Si3N4 and the Si resonator's magnetic dipole resonance are coupled to achieve a resonator size-insensitive absorption peak. The metasurface absorber prepared by using maskless laser direct writing technology displays an average absorption of 90.36% and a peak absorption of 97.55% in the infrared region of 8 to 14 µm, and still maintains an average absorption of 88.27% at a inciedent angle of 40°. The experimentally prepared 2 cm × 3 cm patterned metasurface absorber by markless laser direct writing lithography (MLDWL) exhibits spatially selective absorption and the thermal imaging of the sample shows that the maximum temperature difference of 17.3 °C can exist at the boundary.
RESUMEN
It has been a great challenge to design an extremely flexible and stretchable electrochromic device (ECD), due to the physical deformation and fracture of the conductive materials and supporting substrates after plenty of bending. To solve the aforementioned shortcoming of ECDs, in this paper, a self-supporting metal Ni gird electrode is mentioned, which discarded solid or flexible polymeric substrates, having outstanding features of extremely foldability (bending radius lower 50 µm), stretchability (stretching to 117.6%), excellent conductivity (sheet resistance lower 0.4 Ω/sq), high transmittance (about 90% in full spectra), and ultra-thin thickness (3.7 µm). By assembling the metal electrode, the electrochromic material and the hydrogel, a paper-thin, ultra-flexible, and stretchable ECD with an overall thickness of 113 µm was prepared, which could be attached to the manifold and undulating surface of things and be stretched without compromising the dynamic bleaching and coloration performance. The triple-layered and substrate-free ECD with excellent flexibility and wearability could serve as futuristic electronics used for multiple purposes, like flexible displays, camouflage wearables and medical monitoring, etc.
RESUMEN
A unique freestanding nickel (Ni) metallic mesh-based electromagnetic interference shielding film has been fabricated though the direct-writing technique and a subsequent selective metal electrodeposited process. The structured freestanding Ni mesh film demonstrates a series of advantages, including ultrathin thickness (2.5-6.0 µm) and ultralight weight (0.23 mg cm-2), extraordinary optoelectronic performance (sheet resistance about 0.24-0.7 Ω sq-1 with transparency of 92%-93%), high figure of merit (18000) and outstanding flexibility as it can withstand folding, rolling and crumpling into various shapes while keeping the conductivity constant. Furthermore, by using this high-performance Ni mesh, an ultrathin, lightweight, freestanding and transparent electromagnetic interference shielding (EMI) film with extraordinary optoelectronic properties (shielding effectiveness about 40 dB with transparency of 92%) is demonstrated in X-band, with no performance attenuation observed even in bending state. This freestanding metallic mesh-structured electrode can be further explored or applied in various potential applications, such as conformal microwave antennas, transparent EMI windows, and wearable electronics.
RESUMEN
Flexible transparent electrochemical supercapacitors are critical components for the rapid development of fully flexible transparent electronics; however, typical flexible transparent supercapacitor electrodes store limited energy due to the requirements of transparency. Self-standing core-shell structure metal oxide mesh electrodes with metal oxide as active "shell" and metallic mesh as current collector "core" are efficient for simultaneously achieving high capacity, flexibility, and transparency. In this work, we perform a morphology-controlled electrodeposition of MnO2 on a self-standing flexible transparent metallic Ni mesh electrode to achieve a high-capacity flexible transparent supercapacitor electrode. Under optimized conditions, the MnO2 nanosheet-composed flowerlike multiscale microstructure was constructed. The open, loose, and porous MnO2 multiscale microstructure "shell" and high electrical conductivity of self-standing metallic mesh "core" synergistically enable efficient ionic and electronic transport and meanwhile retain high structural stability. The metal oxide mesh electrode yields an outstanding areal capacitance of 1.15 F/cm2 at an optical transmittance of 69.4% and excellent cycling stability. The symmetric solid-state supercapacitor device exhibits a high areal capacitance value (78.46 mF/cm2), superior cycling life, as well as high optical transmittance and mechanical flexibility, superior to the most reported flexible transparent supercapacitors. This work provides a comprehensive understanding on how to achieve high-capacity flexible transparent supercapacitor electrodes and solid-state devices.