Numerical Study of a Wide-angle Near-Perfect Absorber for the Visible Regime Incorporating Metal-Dielectric-Metal Subwavelength Grating Structure

Abstract A near-perfect absorber for the visible regime based on metal-dielectric-metal subwavelength grating structure with the refractory metals is designed and demonstrated numerically. The absorber presents an average absorption over 98.4% in the visible regime at normal incidence. Angle-relative analysis shows that the proposed structure has good angle-tolerance. The high average absorption (86.6%) in the visible region can be maintained with the incident angles up to 60°. Through the analysis of the magnetic field, the physical origin is verified that this excellent absorption performance mainly stems from the cooperative effect of surface plasmonic resonances and the intrinsic broadband spectral responses by the refractory metals. In addition, the dependence of the absorption spectrum of the proposed absorber on the structural parameters is analyzed. This work provides an idea for the design of high-performance absorbers and has potential applications in advanced light energy capture and integration systems.

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Hybrid Nanodisk Film for Ultra-Narrowband Filtering, Near-Perfect Absorption and Wide Range Sensing

Nanomaterials ◽

10.3390/nano9030334 ◽

2019 ◽

Vol 9 (3) ◽

pp. 334 ◽

Cited By ~ 7

Author(s):

Wenli Cui ◽

Wei Peng ◽

Li Yu ◽

Xiaolin Luo ◽

Huixuan Gao ◽

...

Keyword(s):

Plasmon Resonance ◽

High Performance ◽

Near Infrared ◽

Structural Parameters ◽

Normal Incidence ◽

Plasmonic Nanostructures ◽

Perfect Absorption ◽

Biomedical Sensing ◽

Wide Range ◽

Plasmon Resonances

The miniaturization and integration of photonic devices are new requirements in the novel optics field due to the development of photonic information technology. In this paper, we report that a multifunctional layered structure of Au, SiO2 and hexagonal nanodisk film is advantageous for ultra-narrowband filtering, near-perfect absorption and sensing in a wide refractive index (RI) region. This hexagonal nanostructure presented two remarkable polarization independent plasmon resonances with near-zero reflectivity and near-perfect absorptivity under normal incidence in the visible and near-infrared spectral ranges. The narrowest full width at half maximum (FWHM) of these resonances was predicted to be excellent at 5 nm. More notably, the double plasmon resonances showed extremely obvious differences in RI responses. For the first plasmon resonance, an evident linear redshift was observed in a wide RI range from 1.00 to 1.40, and a high RI sensitivity of 600 nm/RIU was obtained compared to other plasmonic nanostructures, such as square and honeycomb-like nanostructures. For the second plasmon resonance with excellent FWHM at 946 nm, its wavelength position almost remained unmovable in the case of changing RI surrounding nanodisks in the same regime. Most unusually, its resonant wavelength was insensitive to nearly all structural parameters except the structural period. The underlying physical mechanism was analyzed in detail for double plasmon resonances. This work was significant in developing high-performance integrated optical devices for filtering, absorbing and biomedical sensing.

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Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors

Nanophotonics ◽

10.1515/nanoph-2017-0101 ◽

2018 ◽

Vol 7 (5) ◽

pp. 819-825 ◽

Cited By ~ 3

Author(s):

Mahtab Aghaeipour ◽

Håkan Pettersson

Keyword(s):

High Performance ◽

Incidence Angle ◽

Solar Spectrum ◽

Normal Incidence ◽

Absorption Efficiency ◽

Nanowire Arrays ◽

Bragg Reflectors ◽

Broadband Absorption ◽

Photovoltaic Applications ◽

Direct Band

AbstractA near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III–V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.

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Perfect Selective Metamaterial Absorber With Thin-Film of GaAs Layer In The Visible Region For Solar Cell Applications

10.21203/rs.3.rs-557651/v1 ◽

2021 ◽

Author(s):

Raj Kumar ◽

Bipin K Singh ◽

Rajesh K Tiwari ◽

Praveen C Pandey

Keyword(s):

Structural Parameters ◽

Short Circuit ◽

Effective Permittivity ◽

Visible Region ◽

Special Kind ◽

Short Circuit Current ◽

Gaas Layer ◽

Visible Range ◽

Perfect Absorber ◽

Perfect Absorption

Abstract In this paper, we have presented a new design of a metamaterial perfect absorber (MPA) consisting of three layers of metal-dielectric-metal in which the top layer is considered of special kind square patches at different places in a unit cell. This MPA exhibits wideband, wide-angle, and polarization-independent absorption performance in the visible region. This structure originates the plasmonic resonance which is responsible for the perfect absorption in the optical region. Under a specific condition, this simulated absorber structure exhibits an extremely high broadband absorption between 591.54 nm to 704.40 nm wavelength range with near-unity absorption, and a single peak observed at 385.33 nm with absorption 94.16%. We extracted the impedance of the absorber and matched it with free space, and also demonstrated the effective permittivity and permeability. Moreover, the parametric study of the resonators, dielectric layer, and multi-band topology has also been investigated. The polarization-insensitive-based metamaterial may be utilized to improve the efficiency of different devices in the visible range. Furthermore, we have calculated the absorption of the proposed MPA under the solar radiation (AM1.5) for different structural parameters. The proposed absorber greatly enhances the conversion efficiency which is highly useful for solar cells. We also determined the short circuit current density of this absorber for different thicknesses of the GaAs layer. Al metal patches at meta-surface provide nearly similar performance in comparison with other costly metals. Therefore, the proposed structure with cheaper Al metal may be used for different devices as the perfect absorber.

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High Performance of a Metal Layer-Assisted Guided-Mode Resonance Biosensor Modulated by Double-Grating

Biosensors ◽

10.3390/bios11070221 ◽

2021 ◽

Vol 11 (7) ◽

pp. 221

Author(s):

Chengrui Zhang ◽

Yi Zhou ◽

Lan Mi ◽

Jiong Ma ◽

Xiang Wu ◽

...

Keyword(s):

High Performance ◽

High Efficiency ◽

Structural Parameters ◽

Metal Layer ◽

High Sensitivity ◽

Grating Structure ◽

Surface Sensitivity ◽

Guided Mode ◽

Guided Mode Resonance ◽

Low Sensitivity

Guided-mode resonance (GMR) sensors are widely used as biosensors with the advantages of simple structure, easy detection schemes, high efficiency, and narrow linewidth. However, their applications are limited by their relatively low sensitivity (<200 nm/RIU) and in turn low figure of merit (FOM, <100 1/RIU). Many efforts have been made to enhance the sensitivity or FOM, separately. To enhance the sensitivity and FOM simultaneously for more sensitive sensing, we proposed a metal layer-assisted double-grating (MADG) structure with the evanescent field extending to the sensing region enabled by the metal reflector layer underneath the double-grating. The influence of structural parameters was systematically investigated. Bulk sensitivity of 550.0 nm/RIU and FOM of 1571.4 1/RIU were obtained after numerical optimization. Compared with a single-grating structure, the surface sensitivity of the double-grating structure for protein adsorption increases by a factor of 2.4 times. The as-proposed MADG has a great potential to be a biosensor with high sensitivity and high accuracy.

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Co-planar two-dimensional Metal-Insulator-Semiconductor Capacitor: Numerical study of the device electrostatics.

10.26434/chemrxiv.5398000 ◽

2017 ◽

Author(s):

Varun Bheemireddy

Keyword(s):

Space Charge ◽

High Performance ◽

Numerical Study ◽

2D Materials ◽

Space Charge Density ◽

Two Dimensional ◽

Short Channel ◽

Metal Insulator ◽

Metal Insulator Semiconductor ◽

New Family

The two-dimensional(2D) materials are highly promising candidates to realise elegant and e cient transistor. In the present letter, we conjecture a novel co-planar metal-insulator-semiconductor(MIS) device(capacitor) completely based on lateral 2D materials architecture and perform numerical study of the capacitor with a particular emphasis on its di erences with the conventional 3D MIS electrostatics. The space-charge density features a long charge-tail extending into the bulk of the semiconductor as opposed to the rapid decay in 3D capacitor. Equivalently, total space-charge and semiconductor capacitance densities are atleast an order of magnitude more in 2D semiconductor. In contrast to the bulk capacitor, expansion of maximum depletion width in 2D semiconductor is observed with increasing doping concentration due to lower electrostatic screening. The heuristic approach of performance analysis(2D vs 3D) for digital-logic transistor suggest higher ON-OFF current ratio in the long-channel limit even without third dimension and considerable room to maximise the performance of short-channel transistor. The present results could potentially trigger the exploration of new family of co-planar at transistors that could play a signi significant role in the future low-power and/or high performance electronics.<br>

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Plasmon-Enhanced Sunlight Harvesting in Thin-Film Solar Cell by Randomly Distributed Nanoparticle Array

Materials ◽

10.3390/ma14061380 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1380

Author(s):

Marwa M. Tharwat ◽

Ashwag Almalki ◽

Amr M. Mahros

Keyword(s):

Thin Film ◽

Solar Cells ◽

Solar Cell ◽

Near Infrared ◽

Structural Parameters ◽

Visible Region ◽

Nanoparticle Array ◽

Solar Energy Harvesting ◽

Infra Red ◽

Crucial Parameter

In this paper, a randomly distributed plasmonic aluminum nanoparticle array is introduced on the top surface of conventional GaAs thin-film solar cells to improve sunlight harvesting. The performance of such photovoltaic structures is determined through monitoring the modification of its absorbance due to changing its structural parameters. A single Al nanoparticle array is integrated over the antireflective layer to boost the absorption spectra in both visible and near-infra-red regimes. Furthermore, the planar density of the plasmonic layer is presented as a crucial parameter in studying and investigating the performance of the solar cells. Then, we have introduced a double Al nanoparticle array as an imperfection from the regular uniform single array as it has different size particles and various spatial distributions. The comparison of performances was established using the enhancement percentage in the absorption. The findings illustrate that the structural parameters of the reported solar cell, especially the planar density of the plasmonic layer, have significant impacts on tuning solar energy harvesting. Additionally, increasing the plasmonic planar density enhances the absorption in the visible region. On the other hand, the absorption in the near-infrared regime becomes worse, and vice versa.

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Exploring the Structure–Performance Relationship of Sulfonated Polysulfone Proton Exchange Membrane by a Combined Computational and Experimental Approach

Polymers ◽

10.3390/polym13060959 ◽

2021 ◽

Vol 13 (6) ◽

pp. 959

Author(s):

Cataldo Simari ◽

Mario Prejanò ◽

Ernestino Lufrano ◽

Emilia Sicilia ◽

Isabella Nicotera

Keyword(s):

High Performance ◽

Mechanical Stability ◽

Structural Parameters ◽

Hydration Number ◽

Pem Fuel Cells ◽

Proton Exchange ◽

Water Dynamics ◽

Mechanical Resistance ◽

Theoretical Simulation ◽

Sulfonated Polysulfone

Sulfonated Polysulfone (sPSU) is emerging as a concrete alternative to Nafion ionomer for the development of proton exchange electrolytic membranes for low cost, environmentally friendly and high-performance PEM fuel cells. This ionomer has recently gained great consideration since it can effectively combine large availability on the market, excellent film-forming ability and remarkable thermo-mechanical resistance with interesting proton conductive properties. Despite the great potential, however, the morphological architecture of hydrated sPSU is still unknown. In this study, computational and experimental advanced tools are combined to preliminary describe the relationship between the microstructure of highly sulfonated sPSU (DS = 80%) and its physico-chemical, mechanical and electrochemical features. Computer simulations allowed for describing the architecture and to estimate the structural parameters of the sPSU membrane. Molecular dynamics revealed an interconnected lamellar-like structure for hydrated sPSU, with ionic clusters of about 14–18 Å in diameter corresponding to the hydrophilic sulfonic-acid-containing phase. Water dynamics were investigated by 1H Pulsed Field Gradient (PFG) NMR spectroscopy in a wide temperature range (20–120 °C) and the self-diffusion coefficients data were analyzed by a “two-sites” model. It allows to estimate the hydration number in excellent agreement with the theoretical simulation (e.g., about 8 mol H2O/mol SO3− @ 80 °C). The PEM performance was assessed in terms of dimensional, thermo-mechanical and electrochemical properties by swelling tests, DMA and EIS, respectively. The peculiar microstructure of sPSU provides a wider thermo-mechanical stability in comparison to Nafion, but lower dimensional and conductive features. Nonetheless, the single H2/O2 fuel cell assembled with sPSU exhibited better features than any earlier published hydrocarbon ionomers, thus opening interesting perspectives toward the design and preparation of high-performing sPSU-based PEMs.

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