Broadband metamaterial absorber (MA) in the whole visible regime has attracted an enormous amount of attention for its potential applications in thermophotovoltaic cells, thermal emitters, and other optoelectronic devices. Nonetheless, complicated device configuration is still involved in achieving broadband, polarization-independent MA and it results in a cost-ineffective fabrication process. In this paper, a novel MA composed of a periodic array of dielectric cylinder sandwiched by the non-noble metal of nickel (Ni) film is demonstrated. Experimental results show that the proposed MA exhibits strong absorptive behavior independent of polarization in the whole visible regime (400-700 nm). The absorption still remains 80% when the incident angle is 60°. The proposed fabrication method is well compatible with the conventional soft nano-imprinting lithography technique, thus it is economic and scalable for a large-format substrate. These results provide an alternative method for the realization of high-performance visible light absorber and offer new opportunities for potential applications in related fields.
despite their sophisticated designs, most of these devices only work in a narrow bandwidth range and require complicated fabrication procedures. These issues impede large-area applications for energy harvesting and photothermal energy generation. A large-area, wide angular tolerance, broadband absorber with ultrathin metallic nanoparticles has been recently proposed. [38] However, the suitability of this device for photothermal energy generation applications remains unclear because the stability of these metallic nanostructures at high temperatures is usually low.Due to the outstanding properties, such as compatibility with the complementary metal oxide semiconductor (CMOS) processes, high temperature resistance, large loss in the visible range, and high reflectivity in the infrared (IR) range, [39] titanium nitride (TiN) has emerged as an ideal material for the preparation of near-perfect absorbers for the high-temperature solar/thermophotovoltaics applications. [39,40] A 5-cycle TiN/silicon dioxide (SiO 2 ) multilayer-based absorber has been reported with an average solar absorptivity of 0.68 [1] and a near-perfect absorption, which requires further enhancement. The high average absorptivity of ≈95% by a ringlike TiN layer using a metamaterial absorber was achieved for the entire visible range. [41] However, the bandwidth of these devices is limited in the visible range. For ultrabroadband light absorption, 3D-truncated TiN nanopillars have been demonstrated for the visible and NIR spectral regions with an average absorptivity of 0.94. [42] This TiN nanopillar-based device, which comprises silicon nanopillars with a large thickness (>1 µm), typically requires expensive, time-consuming fabrication processes, and its thermal emissivity is not verified. Therefore, there are few experimental reports on the large-area ultrathin TiN-based metasurfaces for the strong ultrabroadband light absorption with low thermal emissivity.In this paper, we demonstrate wide-angle ultrabroadband strong light absorption that covers almost the whole solar spectrum (250-2250 nm) by the TiN-based metasurface with an ultrathin thickness (330 nm) on a quartz substrate. The metasurface incorporates dielectric cylinder arrays, a TiN layer, and SiN x layers. This metasurface fundamentally differs from the previously reported absorbers. This device, which uses a symmetrical SiO 2 grating, is independent of incident polarization. Specifically, the carefully designed metasurface exhibits a prominent absorption of both polarizations over wide angles. The outstanding performances of this absorber are realized by Large-area, ultrathin devices with strong ultrabroadband absorption and high angular tolerance are in demand for applications such as ultraviolet protection, energy harvesting, photodetectors, and thermal imaging technology. Although there have been considerable efforts to design and fabricate these devices, the simultaneous realization of all desired properties has not been achieved. A 330 nm thick metasurface with an area of 3 cm 2 is e...
We present an omnidirectional broadband metasurface absorber whose dielectric-metal-dielectric layers are modulated by cylinder arrays. The simultaneous excitation of surface plasmon resonance and localized surface plasmon resonance affords an average optical absorption of 0.97 (0.9, experiment), with peak absorption up to 0.99 (0.984, experiment), for the wavelength range of 400-1100 nm, and absorption >0.93 (0.87, experiment) for incident angles up to 60°. The device, which is fabricated by continuously variable spatial frequency photolithography, outperforms previously reported absorbers in cost. Moreover, it exhibits considerably lower emissivity (weak absorption) in the mid-infrared range, which makes it promising for energy harvesting.
aroused tremendous interest for potential applications in anti-counterfeiting, [15,16] display/image devices, [17][18][19] and printing, [20,21] showing great prospects for sustainable production and recycling. [11] Recently, structural colors based on perforated metal films, [39,41] silicon dioxide (SiO 2 )loaded aluminum (Al), [34] Al-silicon nitride (SiN x ) nanowire arrays, [35] metalinsulator-metal nanoresonators, [10,27,28] and Al nanopatches/cylinders have been presented. [32,40] In these cases, colorrendering samples are generally fabricated on micrometer scales by focused ion beam or electron-beam lithography. Given this drawback, multilayer stacked films, such as silver (Ag)-SiO 2 -Ag, [21] Ag-titanium oxide (TiO 2 )-Ag, [22] and Ag-amorphous silicon (a-Si)-Ag, [23] with large areas have been explored. However, the variation range of the colors from these films is usually limited, and for that reason the films cannot be applied for optical security. Furthermore, in these configurations, noble metals are usually involved, which limits their practical applications. The metal Al, with low cost, natural abundance, high stability, good adhesion to various platforms, and compatibility with the complementary-metal-oxide-semiconductor process, [42,43] has been regarded as the most promising material for a variety of practical industrial applications. Moreover, its plasma frequency is higher than that of gold (Au) or Ag, making it the most promising metal for structural colors covering the entire visible range.Here, we develop a plasmonic metasurface that consists of one-dimensional (1D) dielectric grating arrays incorporating an Al nanopatch array and a SiN x layer. The metasurface transmits polarization-dependent colors in perpendicular planes at the same incident angle, which results from the asymmetric geometric of the metasurface. A wide range of high-purity colors, including red (R), green (G), and blue (B), is obtained in the transmission by fine-tuning the period of the nanograting. A peak efficiency of ≈60% is obtained as a result of surface plasmonic resonance (SPR) and guided mode resonance (GMR). Finally, large-area (3 cm × 3 cm) samples with various grating periods are experimentally demonstrated, incorporating highthroughput and low-cost continuously variable spatial frequency photolithography, which has advantages in fabrication speed, fabrication area, and cost.Structure design. The proposed metasurface is schematically illustrated in Figure 1, where a 230 nm thick dielectric grating, a 30 nm thick Al layer and a 200 nm thick SiN x film are stacked Color printing based on plasmonic nanostructures has attracted much attention due to its broad potential applications. It is still an open question regarding how to achieve large-area plasmonic colors for practical use. In this study, large-area plasmonic metasurfaces that incorporate a dielectric grating, an aluminum nanopatch array, and a silicon nitride layer are designed and fabricated. The asymmetric geometry of the metasurfaces produces a strong ...
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