A polarization-sensitive, high on/off ratio and self-powered photodetector based on NbCTand NdCT@MoS.

MXene two-dimensional materials have been widely used in energy storage, catalysis, sensing and other fields, NbC as a typical two-dimensional MXene material, its exploration in the field of optoelectronics is still in its infancy, especially NbC-based photodetectors are still to be developed. This paper demonstrates that two-dimensional films based on few-layer NbC have a photoelectric response in the wavelength range from visible to near-infrared. We have found that the light response performance can be easily adjusted by controlling the thickness of the spin-coated film, and that NbC photodetectors show great advantages in terms of wide bandwidth, polarization response, high switching ratio, etc.

3D Dirac semimetals supported tunable terahertz BIC metamaterials.

Based on the 3D Dirac semimetals (DSM) supported tilted double elliptical resonators, the tunable propagation properties of quasi-bound in continuum (BIC) resonance have been investigated in the THz regime, including the effects of rotation angles, DSM Fermi level, and the configuration of resonators. The results manifest that by altering the rotation angle of elliptical resonator, an obvious sharp BIC transmission dip is observed with the -factor of more than 60. The DSM Fermi level affects the BIC resonance significantly, a sharp resonant dip is observed if Fermi level is larger than 0.

Pressure-Induced Superconductivity in HgTe Single-Crystal Film.

HgTe film is widely used for quantum Hall well studies and devices, as it has unique properties, like band gap inversion, carrier-type switch, and topological evolution depending on the film thickness modulation near the so-called critical thickness (63.5 Å), while its counterpart bulk materials do not hold these nontrivial properties at ambient pressure. Here, much richer transport properties emerging in bulk HgTe crystal through pressure-tuning are reported.

Enhanced terahertz shielding by adding rare Ag nanoparticles to TiCTMXene fiber membranes.

Polyacrylonitrile/TiCTMXene/silver nanoparticles fiber membranes with different silver nanoparticles contents and thickness of porous structure have been successfully prepared by electrospinning. Through the measurement of terahertz time domain spectrum, the shielding effect of the fiber membrane with 1% silver nanoparticles content can reach up to 12 dB. Moreover, the thickness of the spinning fiber membranes is controlled by adjusting the spinning time, so as to better analyze the influence of the thickness of the shielding performance in terahertz band.

Tunable 3D Dirac-semimetals supported mid-IR hybrid plasmonic waveguides.

Based on 3D Dirac-semimetal (DSM) modified hybrid waveguides, tunable propagation properties have been investigated, including the effects of Fermi levels, structural parameters, and operation frequency. The results show that if the operation frequency is smaller (larger) than the transition frequency (≈2||), the proposed hybrid waveguides indicate strong (weak) confinement because the DSM layer manifests a high plasmonic (dielectric low) loss property. The dielectric fiber shape affects the propagation property obviously, as the elliptical parameter decreases, the confinement and figure of merit increase, and the loss reduces.

MXene-based ultra-thin film for terahertz radiation shielding.

We have successfully fabricated Ti-based MXenes flakes, TiCT, by chemical etching, then prepared it as an organic dispersion and finally spin-coated it on polyimide plastic substrate for terahertz wave shielding. The shielding effectivity of the 12 μm ultra-thin film can reach up to 17 dB measured by the terahertz time-domain spectra. We can attribute the excellent phenomenon to the intrinsic absorption of triple-layered TiC, due to the similar double-peak type refraction curves, which have been respectively observed from the experimental samples and the simulation ones.

Enhanced photovoltaic response of lead-free ferroelectric solar cells based on (K,Bi)(Nb,Yb)O films.

Herein, we firstly present the (K,Bi)(Nb,Yb)O inorganic ferroelectric photovoltaic (FPV) film, in which a nearly ideal bandgap of ∼1.45 eV in the center of the solar spectrum and the co-existence of oxygen vacancies as well as ferroelectric polarization were confirmed. Furthermore, a novel cell structure is successfully fabricated by combining charge-transporting TiO nanoparticles, the perovskite sensitizer and a light-absorbing oxide hole p-type NiO conductor to realize a 1 V open circuit voltage, which can be increased to 1.

Investigation of terahertz all-dielectric metamaterials.

The propagation properties of Si-based all-dielectric metamaterials (ADMs) structures were investigated systematically, taking into account the effects of structural parameters, operation frequencies, and graphene Fermi levels. The results manifested that ADMs indicated sharp resonant curves with large Q-factors of more than 60, and a figure of merit of approximately 20. Compared with that of thin metal metamaterial counterparts, the thickness of ADMs (in the range of tens of micrometers) required to excite obvious resonant curves was much larger.

Terahertz electromagnetically-induced transparency of self-complementary meta-molecules on Croatian checkerboard.

A terahertz (THz) electromagnetically-induced transparency (EIT) phenomenon is observed from two types of self-complementary meta-molecules (MMs) based on rectangular shaped electric split-ring resonators (eSRR) on Croatian checkerboard. Each MM contains a couple of identical size eSRRs and a couple of structural inversed eSRRs twisted π/2 in checkerboard pattern. In the first type of MM (type-I), the gap is in the middle line of eSRR.

Selective determination of acetone by carbon nanodots based on inner filter effect.

Fluorescent sensing of acetone has been achieved taking advantage of the unique optical property of acetone. However, the complicated synthesis process of the fluorescent probes limited their application. Here, carbon nanodots (CNDs) derived from glucose were chosen as the sensing material for the first time, which could be obtained by a one-pot microwave-assisted synthesis within 2 min.

Tunable MoS modified hybrid surface plasmon waveguides.

The tunable propagation properties of MoS supported hybrid surface plasmon waveguides based on dielectric fiber-gap-metal substrate structures have been investigated by using the finite element method, including the effects of structural parameters, the dielectric fiber shape and carrier concentration of the MoS layer. The results reveal that as the dielectric fiber radius increases, the confinement of the hybrid mode increases, and the losses show a peak. The shape of the dielectric fiber affects the propagation properties obviously, with an optimum structural parameter (a large value of the elliptical parameter) the confinement and figure of merits increase, and the dissipation decreases simultaneously.

Tunable high Q-factor terahertz complementary graphene metamaterial.

Based on the complementary graphene asymmetric double bars patterns, the tunable Fano resonances with large Q-factors have been investigated in the terahertz regime, including the effects of Fermi levels, structural parameters and operation frequency. The results reveal that compared with existed graphene tunable devices, the Fano resonant curve is very narrow and indicates a large Q-factor of about 60. The strong Fano resonant curves can be convenient tailored.

Graphene patterns supported terahertz tunable plasmon induced transparency.

The tunable plasmonic induced transparency has been theoretically investigated based on graphene patterns/SiO/Si/polymer multilayer structure in the terahertz regime, including the effects of graphene Fermi level, structural parameters and operation frequency. The results manifest that obvious Fano peak can be observed and efficiently modulated because of the strong coupling between incident light and graphene pattern structures. As Fermi level increases, the peak amplitude of Fano resonance increases, and the resonant peak position shifts to high frequency.

Localized terahertz electromagnetically-induced transparency-like phenomenon in a conductively coupled trimer metamolecule.

We experimentally investigate the terahertz (THz) electromagnetically-induced transparency (EIT)-like phenomenon in a metamolecule (MM) of three-body system. This system involves a couple of geometrically identical split-ring resonators (SRRs) in orthogonal layout conductively coupled by a cut-wire resonator. Such a three-body system exhibits two frequency response properties upon to the polarization of incident THz beam: One is the dark-bright-bright layout to the horizontally polarized THz beam, where there is no EIT-like effect; the other is bright-dark-dark layout to the vertically polarized THz beam, where an EIT-like effect is observable.

Terahertz tunable graphene Fano resonance.

By depositing graphene circular double rings (DR) on a SiO/Si/polymer substrate, the tunable Fano resonance has been theoretically investigated in the terahertz regime, including the effects of the graphene Fermi level, structural parameters and operation frequency. The results demonstrate that the obvious Fano peak can be efficiently modulated because of strong coupling between the incident waves and graphene ribbons. As the Fermi level increases, the peak amplitude of the Fano curve increases, and the resonant peak position shifts to a high frequency.

A further comparison of graphene and thin metal layers for plasmonics.

Which one is much more suitable for plasmonic materials, graphene or metal? To address this problem well, the plasmonic properties of thin metal sheets at different thicknesses have been investigated and compared with a graphene layer. As demonstration examples, the propagation properties of insulator-metal-insulator and metamaterials (MMs) structures are also shown. The results manifest that the plasmonic properties of the graphene layer are comparable to that of thin metal sheets with the thickness of tens of nanometers.

Note: High-power piezoelectric transformer fabricated with ternary relaxor ferroelectric Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3 single crystal.

A plate-shaped piezoelectric transformer was designed and fabricated using ternary relaxor ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3. Both the input and output sections utilized the transverse-extensional vibration mode. The frequency and load dependences of the electrical properties for the proposed transformer were systematically studied.

Gravure-printed interdigital microsupercapacitors on a flexible polyimide substrate using crumpled graphene ink.

In this paper, we demonstrate gravure printing of crumpled graphene ink to obtain a highly porous pattern of interdigitated electrodes, leading to an interdigital microsupercapacitor (MSC) on a flexible polyimide substrate. During the process of synthesizing crumpled graphene ink, Mg(OH)2 nanosheets as nanospacers were inserted into graphite oxide layers, resulting in sufficient crumples in graphene nanosheets to prevent the graphene sheets from restacking to enhance the ion transport and expose the electrochemical active area with oxygen-containing groups to provide more pseudo-capacitance. The gravure-printed interdigital MSCs achieved a high energy density (1.

Band structure and dispersion engineering of strongly coupled plasmon-phonon-polaritons in graphene-integrated structures.

We theoretically investigate the polaritonic band structure and dispersion properties of graphene using transfer matrix methods, with strongly coupled graphene plasmons (GPs) and molecular infrared vibrations as a representative example. Two common geometrical configurations are considered: graphene coupled subwavelength dielectric grating (GSWDG) and graphene nanoribbons (GNR). By exploiting the dispersion and the band structure, we show the possibility of tailoring desired polaritonic behavior in each of the two configurations.

Single Crystal Formamidinium Lead Iodide (FAPbI3): Insight into the Structural, Optical, and Electrical Properties.

5 mm-scale large FAPbI 3 single crystals and corresponding photoconductive properties are shown. The phase transition of FAPbI3 between the α-phase and δ-phase is studied. The carrier mobility is 4.

Ultrafast properties of femtosecond-laser-ablated GaAs and its application to terahertz optoelectronics.

We report on the first terahertz (THz) emitter based on femtosecond-laser-ablated gallium arsenide (GaAs), demonstrating a 65% enhancement in THz emission at high optical power compared to the nonablated device. Counter-intuitively, the ablated device shows significantly lower photocurrent and carrier mobility. We understand this behavior in terms of n-doping, shorter carrier lifetime, and enhanced photoabsorption arising from the ablation process.

Graphene-supported tunable near-IR metamaterials.

By integrating the metallic metamaterials (MMs) with a graphene layer, the resonant properties of an active tunable device based on the metal-SiO(2)-graphene (MSiO(2)G) structure have been theoretically investigated in the near-IR spectral region. The results manifest that the influences of the graphene layer on the propagation properties are significant. Owing to the tunability of the Fermi level of graphene, the resonance of transmitted or reflected curves can be tuned in a wide range (160-193 THz).

Electric field-induced giant strain and photoluminescence-enhancement effect in rare-earth modified lead-free piezoelectric ceramics.

In this work, an electric field-induced giant strain response and excellent photoluminescence-enhancement effect was obtained in a rare-earth ion modified lead-free piezoelectric system. Pr(3+)-modified 0.93(Bi0.

Highly-ordered silicon inverted nanocone arrays with broadband light antireflectance.

In this work, highly-ordered silicon inverted nanocone arrays are fabricated by integration of nanosphere lithography with reactive ion etching (RIE) method. The optical characteristics of as-prepared Si inverted nanocone arrays are investigated both by experiments and simulations. It is found that the Si nanocone arrays present excellent broadband light antireflectance properties, which are attributed to the gradient in the effective refractive index of nanocones and enhanced light trapping owing to optical diffraction.

Optical absorption and photocurrent enhancement in semi-insulating gallium arsenide by femtosecond laser pulse surface microstructuring.

We observe an enhancement of optical absorption and photocurrent from semi-insulating gallium arsenide (SI-GaAs) irradiated by femtosecond laser pulses. The SI-GaAs wafer is treated by a regeneratively amplified Ti: Sapphire laser of 120 fs laser pulse at 800 nm wavelength. The laser ablation induced 0.