Photocatalytic activity tuning in a novel Ag2S/CQDs/CuBi2O4 composite: Synthesis and photocatalytic mechanism

We present an ultra-broadband perfect absorber composed of metal-insulator composite multilayer (MICM) stacks by placing the insulator-metal-insulator (IMI) grating on the metal-insulator-metal (MIM) film stacks. The absorber shows over 90% absorption spanning between 570 nm and 3539 nm, with an average absorption of 97% under normal incidence. The ultra-broadband perfect absorption characteristics are achieved by the synergy of guided mode resonances (GMRs), localized surface plasmons (LSPs), propagating surface plasmons (PSPs), and cavity modes. The polarization insensitivity is demonstrated by analyzing the absorption performance over arbitrary polarization angles. The ultra-broadband absorption remains more than 80% over a wide incident angle up to 50°, for both transverse electric (TE) and transverse magnetic (TM) modes. The ultra-broadband perfect absorber has tremendous potential for various applications, such as solar thermal energy harvesting, thermoelectrics, and imaging.

Ultra-broadband perfect absorber utilizing refractory materials in metal-insulator composite multilayer stacks

A broad dual-band switchable graphene-based terahertz metamaterial absorber

In this paper, we propose a graphene nanoribbon-ring cross structure. A multi-band absorber is obtained by a simple combination of graphene nanoribbons and and graphene ring. We obtain that the theoretical absorption of three resonance wavelengths are 99.8%, 98.4% and 65.7%, respectively. We carefully analyzed each resonance wavelength, and the compact structure makes that small changes in the position of graphene nanoribbons and graphene ring have a great influence on the number of resonance wavelength. Meanwhile, the small changes in the chemical potential of graphene can tune the position of resonance wavelengths in the spectrum. At last, we discuss the sensing properties of this structure. The FoM (figure of merit) values of the three resonance wavelengths are high, and the FoM of the three peaks can reach 4.1, 3.679 and 12.66. The absorbers have great adjustability and great application potential in sensing.

Nanoribbon-ring cross perfect metamaterial graphene multi-band absorber in THz range and the sensing application

In this paper, TiO2 nanotube arrays were prepared by anodic oxidation method. The effects of water content, anodizing time and sample post-treatment on the morphology and crystal structure of TiO2 nanotube arrays were systematically investigated. We explored the performance of dye-sensitized solar cells (DSSCs) based on dye N-719. The TiO2 nanotube arrays prepared under different water content and different anodizing time conditions were used as photoanodes. The results show that DSSC has best photovoltaic performance when the water content is 2 vol%. With the increase of oxidation time, Jsc increases continuously, open voltage (Voc) and fill factor (FF) increase first and then decrease. The best optoelectronic properties obtained that the short circuit current, open circuit voltage, fill factor and photoelectric conversion efficiency as following, Jsc = 5.2 mA/cm2, Voc = 0.7 V, FF = 0.54, η = 1.96% respectively.

Synthesis, surface properties, crystal structure and dye-sensitized solar cell performance of TiO2 nanotube arrays anodized under different parameters

The optical performance of a periodically tunable plasma perfect metamaterial absorber based on a square-square-circle array we propose in the terahertz region is analyzed in this work by the finite difference time domain (FDTD) method. We not only discuss the impact of various parameters such as period a, length L, radius R, and incident angle θ under transverse magnetic (TM)- and transverse electric (TE)-polarization on the absorption spectra of the absorber but also study the effect of the Fermi energy EF and relaxation time τ. Finally, we simulate the spectra as the surrounding refractive index n changes to better evaluate the sensing performance of the structure, producing a sensitivity S of the structure of up to 15006 nm/RIU. On account of this research, we find that the absorber is beneficial to sensors and detectors in the terahertz region.

Tunable Graphene-based Plasmonic Perfect Metamaterial Absorber in the THz Region.

A five-band tunable ideal terahertz metamaterial absorber based on subwavelength range is proposed. It consists of a reflective layer, a dielectric layer, and an absorbing layer consisting of an internal closed square ring and an outer open square circle. We have found that the five absorption peaks can reach more than 97% on average. Meanwhile, in order to analyze the absorption mechanism, we studied the different structures and geometric parameters of the absorber and drew the electric field intensity diagram and surface current density diagram at different peaks. Moreover, we also studied the effect of similar opening structures based on this structure on absorption. Therefore, the designed absorber has good frequency selectivity and can be applied to terahertz imaging, detection, and so on.

Wei Luo

Papers

Tunable Graphene-based Plasmonic Perfect Metamaterial Absorber in the THz Region.

Five-Band Terahertz Perfect Absorber Based on Metal Layer–Coupled Dielectric Metamaterial