Transmitter Module Research Articles

Bilayer structure niobium oxide/titanium oxide film with improved electrochromism

A combination of simple hydrothermal and electrodeposition techniques is proposed for the synthesis of niobium oxide/titanium oxide (Nb2O5/TiO2) bilayer films, which can improve the electrochromic performance for niobium oxide (Nb2O5)-based materials, including response time, cycle stability, coloration efficiency and optical properties. The structure, morphology, electrochemical and electrochromic performance of the Nb2O5/TiO2 film are improved via the systematic study of TiO2 electrodeposition period. X-ray diffraction shows that TiO2 is amorphous and Nb2O5 is orthogonal. The vibration modes and structural properties are studied by the Raman spectroscopy. The chemical compositions, elemental states, and surface features are studied via the X-ray photoelectron spectroscopy. The effects of TiO2 electrodeposition periods on the morphology of Nb2O5/TiO2 films are analyzed by the field emission scanning electron microscopy. These results show that NTO-20 film has high efficiency Li+ reaction kinetics, which shows remarkable electrochromic properties, including wide transmittance modulation (76.94 %), good reversibility (98.15 %), large coloration efficiency (91.6 cm2/C) and high cycle stability. For the electrochromic device with NTO-20 film, it shows conspicuous transmittance modulation (69.1 %) and excellent cycle stability. Thus, Nb2O5/TiO2 bilayer films have important research value in the field of electrochromism.

FPGA Realization of an Image Encryption System Using a 16-CPSK Modulation Technique

Nowadays, M-Quadrature Amplitude Modulation (M-QAM) techniques are widely used to modulate information by bit packets due to their ability to increase transfer rates. These techniques require more power when increasing the modulation index M to avoid interference between symbols. This article proposes a technique that does not suffer from interference between symbols, but instead uses memory elements to store the modulation symbols. In addition, the aim of this paper is to implement a four-dimensional reconfigurable chaotic oscillator that generates 16-Chaotic Phase Shift Keying (16-CPSK) modulation–demodulation carriers. An encryption and modulation transmitter module, a reception module, and a master–slave Hamiltonian synchronization module make up the system. A 16-CPSK modulation scheme implemented in Field Programmable Gate Array (FPGA) and applied to a red-green-blue (RGB) and grayscale image encryption system are the main contributions of this work. Matlab and Vivado were used to verify the modulation–demodulation scheme and synchronization. This proposal achieved excellent correlation coefficients according to various investigations, the lowest being −15.9×10−6 and 0.13×10−3 for RGB and grayscale format images, respectively. The FPGA implementation of the 16-CPSK modulation–demodulation system was carried out using a manufacturer’s card, Xilinx’s Artix-7 AC701 (XC7A200TFBG676-2).

Smart Zone-Based Vehicle Speed Retarding System Utilizing Radio Frequency (RF) in Electronic Vehicles

The proposed system aims in designing an efficient automatic wireless vehicle speed control in low-speed zones using RF communication. The advent of new high-speed technology and the growing computer capacity provided realistic opportunity for new robot controls and realization of new methods of control theory. This technical improvement together with the need for high performance robots created faster, more accurate and more intelligent robots using new robots control devices, new drivers and advanced control algorithms. The proposed method uses RF transmitter and receiver modules for establishing wireless communication, DC motors for the vehicle movement controller. The status of the project will display on LCD display. The controlling device of the whole system is a Microcontroller to which RF receiver module, DC motors are interfaced through a motor driver. Whenever the vehicle enters into a low-speed zone, the data from RF transmitter of low-speed zone will be received by the vehicle system. The microcontroller in the vehicle system automatically slows down the speed to the speed limit of that zone. The microcontroller checks the data with the program embedded in it and performs appropriate actions on the electric motors. The microcontroller is programmed using Embedded C language.

Durability improvement of electrochromic WO3 thin films by deposition of an ultra-thin Al2O3 layer via atomic layer deposition

Introduction of an ultra-thin Al2O3 protective layer via atomic layer deposition (ALD) significantly enhances the durability and performance of amorphous tungsten trioxide (a-WO3) thin films for electrochromic devices. The Al2O3 layer, despite being less than 4 nm thick, effectively suppresses the dissolution of WO3 that typically occurs through hydration reactions forming WO3·H2O and tungstic acid (H2WO4). XRD and XPS analyses confirmed the presence of Al2O3 and its minimal impact on the amorphous structure of WO3 thin films. Optical transmittance measurements showed that the Al2O3-protected a-WO3 thin films maintained a higher transmittance modulation (ΔT) compared to bare a-WO3 thin films, with the ALD30 sample retaining 87.9 % of its initial transmittance modulation after 1000 cycles, in contrast to the rapid degradation observed in unprotected films. Microstructural analysis revealed significantly fewer surface cracks and reduced thickness loss in Al2O3-coated films after 100 cycles. Additionally, ICP-MS analysis indicated a much lower W concentration in the electrolyte for Al2O3-protected samples, confirming reduced dissolution.

Reversible multimode modulations in photochromic transparent Eu3+doped K0.5Na0.5NbO3 based ceramics

Rare-earth doped transparent photochromic materials have attracted extensive attention in applications of optical information storage and optical switching, in which the high transparency and large fluorescence modulation ratio are required. In this work, 0.94 (K0.5Na0.5)NbO3-0.06 (Sr0.5Ba0.5) (Zn1/3Bi2/3)O3: x wt% Eu2O3 ceramics (KNN-SBZB: xEu) with x=0.1, 0.2, 0.3, 0.4 were prepared by traditional high temperature solid state sintering reaction method. High transmittance (T) was achieved due to the small grain size (less than 110 nm) and the highly symmetrical phase structure. High optical transmittance of 69.27 % at 780 nm and 78.24 % at 1100 nm were obtained in the KNN-SBZB: 0.3Eu ceramic, while large luminescence intensity modulation ratio (∆RL) ∼94.9 %, transmittance (∆RT) ∼5.76 % and diffuse reflectivity (∆ABS) ∼12.59 % were achieved in KNN-SBZB: 0.2Eu ceramic (T ∼62.92 % at 780 nm). Additionally, both the transmittance modulation and luminescence intensity modulation of KNN-SBZB: xEu ceramics show good stability after 10 cycles.

Bridging to Commercialization: Record-Breaking of Ultra-Large and Superior Cyclic Stability Tungsten Oxide Electrochromic Smart Window.

Electrochromic smart windows (ESWs) can significantly reduce energy consumption in buildings, but their cost-effective, large-scale production remains a challenge. In this study, the instability of black phosphorus is leveraged to induce the growth of the tungsten oxide film through its decomposition process, inspired by the 2D material-assisted in situ growth (TAIG) method. This approach results in the preparation of large-scale, high-performance WO3-x·nH2O (n<2) films. Characterization techniques and DFT calculations confirm efficient regulation ofstructural water and oxygen vacancies during TAIG preparation. The WO3-x·nH2O films exhibit excellent electrochromic (EC) properties, including high transmittance modulation (74.2%@1100nm), fast switching time (tc=5.5s, tb=3.8s), high coloration efficiency (124.7cm2C-1), and superior cyclic stability (transmittance modulation retained 94.7% after 20000 cycles). Ultra-largeWO3-x·nH2O film are prepared via a simple immersion process, and fabricated into a large-area ESW under facile laboratory conditions, demonstrating the economic and practical feasibility of this approach in industrial-scale production. Operated by the intelligent control circuit, the ESWexhibits remarkable EC properties and cyclic stability This research represents a milestone in improving the performance and industrial-scale production of ESWs, bridging the gap to the commercialization of EC technology.

Wireless image transfer by various antennas using transmitter and receiver modules at 5.8 GHz

Abstract This research proposes an inexpensive technique for wireless image transfer for security and surveillance applications. The technique uses a 5.8 GHz transmitter and receiver module, along with external antennas in the real-time image transfer within a radius of 100 m. The transferred images are stored in a laptop using a Python code-based graphical user interface application. Different antennas, dipole, circular split-ring resonators, hexagonal split-ring resonators, and metamaterial antennas are utilized for comparison. The Blind/Referenceless Image Spatial Quality Evaluator method is used to assess the picture quality of transferred images to quantify image transfer performance when no ground truth or reference photos are supplied. According to the presented results, images transferred using metamaterial antennas have higher quality than those transferred with other types of antennas. For security considerations, such a system can communicate and store the images in real time.

Improved transparency and charge matching of electrochromic devices with Ce-doped NiO counter electrode

The quest for cost-effective and efficient electrochromic electrodes, featuring high color contrast and rapid response times, has sparked increasing interest in research of metal oxides for electrochromic applications. In this study, nickel oxide thin films with various cerium dopant concentrations are synthesized, with the optimized doping concentration identified as 1 at%. X-ray diffraction analysis confirmed that the dopant successfully reduces crystal size and alters the preferred orientation to (111). The 1 % Ce:NiO thin film exhibits enhanced electrochromic performance, with a transmittance modulation increase of 27.4 % at 633 nm, a 27.1 % rise in coloration efficiency and faster response time (tb=9.64 s and tc=6.76 s) compare to the undoped NiO. Importantly, the charge density of 1 % Ce:NiO thin film increases from 4.86 to 8.14 mC cm−2, representing a 67.5 % improvement, which becomes a better charge matching with WO3 in electrochromic devices. The incorporation of Ce into the NiO thin films not only leads to increased transmittance in the bleached state and optical modulation in the electrochromic devices but also contributes to a rise in the optical band gap of the NiO thin films and improved charge balance matching. These results underscore the positive impact of cerium doping on microstructure and electrochromic performance, indicating a promising future for electrochromic devices.

Design and Scalable Synthesis of Thermochromic VO2-Based Coatings for Energy-Saving Smart Windows with Exceptional Optical Performance.

We report strongly thermochromic YSZ/V0.855W0.018Sr0.127O2/SiO2 coatings, where YSZ is Y-stabilized ZrO2, prepared by using a scalable deposition technique on standard glass at a low substrate temperature of 320 °C and without any substrate bias voltage. The coatings exhibit a transition temperature of 22 °C with an integral luminous transmittance of 63.7% (low-temperature state) and 60.7% (high-temperature state) and a modulation of the solar energy transmittance of 11.2%. Such a combination of properties, together with the low deposition temperature, fulfills the requirements for large-scale implementation on building glass and has not been reported yet. Reactive high-power impulse magnetron sputtering with a pulsed O2 flow feedback control allows us to prepare crystalline W and Sr codoped VO2 of the correct stoichiometry. The W doping of VO2 decreases the transition temperature, while the Sr doping of VO2 increases the luminous transmittance significantly. A coating design utilizing second-order interference in two antireflection layers is used to maximize both the integral luminous transmittance and the modulation of the solar energy transmittance. A compact crystalline structure of the bottom YSZ antireflection layer further improves the VO2 crystallinity, while the top SiO2 antireflection layer provides also the mechanical and environmental protection for the V0.855W0.018Sr0.127O2 layer.

Experimental Analysis of Terahertz Wave Scattering Characteristics of Simulated Lunar Regolith Surface

This study investigates terahertz (THz) wave scattering from a simulated lunar regolith surface, with a focus on the Brewster feature, backscattering, and bistatic scattering within the 325 to 500 GHz range. We employed a generalized power-law spectrum to characterize surface roughness and fabricated Gaussian correlated surfaces from Durable Resin V2 using 3D printing technology. The complex dielectric permittivity of these materials was determined through THz time-domain spectroscopy (THz-TDS). Our experimental setup comprised a vector network analyzer (VNA) equipped with dual waveguide frequency extenders for the WR-2.2 band, transmitter and receiver modules, polarizing components, and a scattering chamber. We systematically analyzed the effects of root-mean-square (RMS) height, correlation length, dielectric constant, frequency, polarization, and observation angle on THz scattering. The findings highlight the significant impact of surface roughness on the Brewster angle shift, backscattering, and bistatic scattering. These insights are crucial for refining theoretical models and developing algorithms to retrieve physical parameters for lunar and other celestial explorations.

Layer-by-Layer-Assembled Polyaniline/MXene Thin Film and Device for Improved Electrochromic and Energy Storage Capabilities.

Polyaniline (PANI) is an attractive electrochromic and storage material due to its reversible and sustainable electrochemical redox processes. However, the insufficient surface area and excessive charge intercalation after long-term cycling results in limited charge capacitance and unsatisfactory cycling stability. In this work, we demonstrate an innovative method to increase PANI's electrochromic and energy storage performance by incorporating MXene, to enhance electrochemical activity and reveal more active areas of ion/electron intercalation/deintercalation and charge transfer. The hydrogen bonds formed between N-H, C-H, and C-N of PANI and -OH and -O surface functional terminations of MXene further enhance the interface interaction. With substantial optical transmittance modulation and charge capacitance, excellent coloration efficiency, and outstanding durability, the PANI/MXene thin film demonstrates exceptional color-switching and energy storage characteristics. Furthermore, the sandwich device with a PANI/MXene thin film as the positive electrode and zinc foil as the negative electrode demonstrates exceptional electrochromic and Zn2+ storage capability. This work raises possibilities for next-generation intelligent energy conversion and storage technologies and offers fresh perspectives on the design of ionic devices.

Significant dependence of the efficiency of energy-saving thermochromic VO2 on slight changes of its properties in the visible due to strain and/or vacancies

There are worldwide efforts to maximize the energy saving achieved by VO2-based thermochromic coatings. In particular, there are very different values of the modulation of integral solar energy transmittance, reported by various laboratories on various templates even for seemingly very similar coatings. A detailed analysis reveals that this is largely due to the combination of the intentional and well understood transmittance modulation in the infrared (always beneficial) with not yet understood slight transmittance modulation in the visible (sometimes beneficial, sometimes harmful, and always multiplied by strong solar irradiance). Ab-initio calculations are used to examine the hypothesis that the transmittance modulation in the visible can be controlled by lattice strain and/or slightly off-stoichiometric [O]/[V] ratio. The presented phenomenon opens a pathway which may lead, in a case of reproducible preparation of correctly altered VO2, to significantly enhanced energy saving.

Thermochromic properties and surface chemical states of reactive magnetron sputtered vanadium oxide thin films at various deposition pressures

Vanadium oxide thin films were prepared using reactive magnetron sputtering method, varying the deposition pressures from 4 to 10 mTorr while maintaining the other sputtering parameters constant. Our investigations revealed sensitive dependence of deposition pressure, chemical states of the V and O atoms, crystal phases, and thermochromic (TC) optical modulation. Specifically, the film deposited at 8 mTorr displayed distinct TC characteristics with a prevalent monoclinic m-VO2 phase according to X-ray diffraction (XRD), supported by X-ray photoelectron spectroscopy (XPS). Optical transmittance modulation and electrical property measurements revealed a metal–insulator transition (MIT), confirming the intimate connection between TC characteristics and presence of the m-VO2 phase. Films deposited at pressures lower or higher than 8 mTorr exhibited typical semiconductor behavior without TC characteristics, further supported by in situ XRD, where (110) plane shifted to lower angle upon heating above τC. Chemical state analysis by XPS revealed a clear correlation between V−O peaks and the presence of a VO2 phase, with the film deposited at 8 mTorr displaying relatively large peak fitted area indicative of the VO2 phase. These findings highlight the critical and sensitive dependence of the deposition conditions in tailoring the properties of vanadium oxide thin films and provide valuable insights for potential applications in chromogenic films.

Controlled assembly and synthesis of oxygen-deficient W18O49 films based on solvent molecular strategy for electrochromic energy storage smart windows

18O49 is a promising electrochromic material with abundant oxygen vacancy and high carrier mobility. However, the electrochromism of W18O49 is not satisfactory, the regulation and synthesis of high-performance W18O49 have become the research hotspot. In this work, it is found that the main chain and side chain structure of solvent molecules can control the assembly and synthesis of W18O49 film, so as to achieve excellent electrochemical and electrochromic properties. The porous reticular W18O49 film synthesized in short-chain molecular solvent shows the excellent transmittance modulation (81.6 % at 633 nm, 77.0 % at 1050 nm), and exhibits the high energy storage of 41.7 mF cm−2 at 0.1 mA cm−2. Solvent molecular strategy provides a new way for the synthesis and regulation of W18O49 electrochromic films and promotes the further development of high-performance electrochromic materials.

Fabrication and Performance Evaluation of a Nanostructured ZnO-Based Solid-State Electrochromic Device.

In this study, we present an all-solid-state electrochromic device (ECD) that eliminates the need for hard-to-obtain materials and conventional liquid/gel electrolytes. Using a cost-effective and industrially scalable spray coating technique, we developed an ECD containing a layer of zinc oxide nanorods (ZnOnano) synthesized via a simple solochemical route. The device configuration includes a preformed Al-coated glass substrate, acting as a counter electrode, within a glass/Al/ZnOnano/PEDOT:PSS architecture. The device exhibits reversible switching between light blue and dark blue states upon application of -1.2 V and +2.8 V, respectively, with a significant difference in transmittance between bleached and colored states in the visible-NIR spectrum, featuring a high coloration efficiency of 275.62 cm2/C at 600 nm. The response times required for both coloring and bleaching states were 9.92 s and 7.51 s, respectively, for a sample with an active area of 5.5 × 2.5 cm2. Regarding the electrochemical stability of the ZnO-based ECD, the transmittance modulation reached around 8.01% at 600 nm after 12,800 s, following initial variations observed during the first 10 cycles. These results represent significant progress in electrochromic technology, offering a sustainable and efficient alternative to traditional ECDs. The use of economical fabrication techniques and the exclusion of critical materials highlight the potential for widespread industrial adoption of this novel ECD design.

Synergistic design of processable Nb2O5-TiO2 bilayer nanoarchitectonics: enabling high coloration efficiency and superior stability in dual-band electrochromic energy storage

This paper introduces a proof of concept for a dual-band electrochromic (EC) device to modulate solar light transmission across visible and near-infrared regions selectively. EC materials based on ion insertion/extraction mechanisms also present the possibility for energy storage, widening its functionality to the supercapacitor platform. The bi-functional performance of dual-band radiation control and energy storage was achieved by exploiting two earth-abundant metal oxides that could absorb two different spectral regions when electrochemically charged. The bilayer structure was prepared using a one-step hydrothermal method, which produced Nb2O5-TiO2 bilayer on fluorine-doped tin oxide (FTO) conducting glass substrates. The nano-dimensions of the active materials endorse the development of high-transparency thin film under open circuit conditions. The variations in the TiO2 annealing temperature influence the crystallinity and surface morphology of the thin films, which influence the performance of dual-band EC energy storage. The well-optimized NT-500 sample facilitated exclusive electron-charge transport, producing excellent electrochemical performance in dual-band EC and energy storage. A large optical modulation of 80.4 % and 89.8 % at 600 nm and 800 nm (near-infrared) was achieved with an enhanced areal capacitance of 88.1 mF/cm2 and excellent cycling stability after continuous coloring/bleaching cycles for 18,000 s. This paper presents a prototype bi-functional device based on NT-500, which showed independent control and modulation of visible and near-infrared transmittance. Notably, the device retained excellent energy storage performance alongside its advanced optical functionalities. This bilayer nanostructure capitalizes on the inherent electrochemical properties of both materials and introduces novel features that can potentially revolutionize the platform of EC-energy storage.

Multispectral smart window: Dynamic light modulation and electromagnetic microwave shielding

A novel multispectral smart window has been proposed, which features dynamic modulation of light transmittance and effective shielding against electromagnetic microwave radiation. This design integrates liquid crystal dynamic scattering and dye doping techniques, enabling the dual regulation of transmittance and scattering within a single-layer smart window. Additionally, the precise control of conductive film thickness ensures the attainment of robust microwave signal shielding. We present a theoretical model for ion movement in the presence of an alternating electric field, along with a novel approach to manipulate negative dielectric constant. The proposed model successfully enables a rapid transition between light transparent, absorbing and haze states, with an optimum drive frequency adjustable to approximately 300 Hz. Furthermore, the resistive design of the conductive layer effectively mitigates microwave radiation within the 2−18 GHz range. These findings offer an innovative perspective for future advancements in environmental construction.

Coordination Compound Guided a Novel Composite Film with Zn2V2O7 Nanoflake and VO2@Zn2V2O7 Nanoparticle for Enhanced Thermochromism Smart Window.

Thermochromic vanadium dioxide (VO2) can intelligently modulate the transmittance of indoor solar radiation to reduce the energy consumption of air conditioning in buildings. Nevertheless, it remains a great challenge to simultaneously improve the luminous transmittance (Tlum) and solar modulation ability (ΔTsol) of VO2. In this study, a novel approach is employed utilizing a coordination compound to finely tune the growth of a VO2 based composite film, yielding a hierarchical film comprising Zn2V2O7 nanoflakes and VO2@Zn2V2O7 core-shell nanoparticles. Remarkably, the resulting composite films showcase exceptional optical performance, achieving a Tlum of up to 73.0% and ΔTsol of 15.7%. These outcomes are attributed to the antireflection properties inherent in the nanoflake structure and the localized surface plasmon resonance of well-dispersed VO2 nanoparticles. In addition, the Zn2V2O7-VO2 film demonstrates remarkable environmental durability, retaining 90% of its initial ΔTsol even after undergoing aging at 100°C under 50% relative humidity for a substantial period of 30 days - a durability equivalent to ≈20 years under ambient conditions. This work not only achieves a harmonious balance between Tlum and ΔTsol but also introduces a promising avenue for the design of distinctive composite nanostructures.

Simultaneous transmission of multi-format signals in the mid-infrared over free space

Mid-infrared (MIR) light within the 3–5 μm spectrum offers distinct advantages over the 1.5 μm band, particularly in adverse atmospheric conditions, rendering it a favorable option for free-space optical (FSO) communication. The transmission capacity within the 3–5 μm band is relatively low due to the immature state of its devices. In this study, we demonstrate multi-format signals FSO transmission with a total of 40 Gbps capacity in the 3 μm band, utilizing our developed MIR transmitter and receiver modules. These modules facilitate wavelength conversion between the 1.5 μm and 3 μm bands through the utilization of difference-frequency generation (DFG) effect. The MIR transmitter effectively produces three MIR signals: On-Off Keying (OOK), Binary Phase Shift Keying (BPSK), and Quadrature Phase Shift Keying (QPSK) optical signals. The generated MIR power is 7.8 dBm, covering a wavelength range from 3.5864 to 3.5885 μm. The MIR receiver regenerates the three format signals with a power of −29.6 dBm. Relevant results of regenerated signal demodulation have been collected in detail, including bit error ratio (BER), constellation diagram, and eye diagram. The required powers for the 10 Gbps OOK, BPSK, and QPSK are −37.82, −40.24, and −39.4 dBm at BER of 1 × 10−6. It is expected to further push the data capacity to the terabit-per-second level by adding more 1.5 μm band laser sources and using wider-bandwidth chirped nonlinear crystals.

Improved electrochromic device based on mesoporous TiO2 and NiO films

Fabrication of electrochromic films with micro/nanostructures is one of the most feasible ways to improve their properties for high-performance electrochromic devices (ECDs). In this work, mesoporous TiO2 and NiO electrochromic films are prepared by sol-gel technique with an auxiliary solvent of F108 (PEO[Formula: see text]PPO[Formula: see text]PEO[Formula: see text]). By adjusting the content of F108 and heat treatment temperature, the transparent and uniform mesoporous films are successfully prepared. The TiO2 and NiO films are composed of inter-connected nanoparticles with a size of about 20 nm. The thicknesses of the films are about 300 nm and the mesoporous sizes are about 13 nm. The films have a short response time during the electrochromic process. When supplied with positive/negative voltages for 50 s, the coloring/bleaching times of TiO2 and NiO mesoporous films are 15/13 and 17/12 s, respectively. The ECD fabricated with TiO2 and NiO mesoporous films shows good electrochromic properties: short response time (14/19 s, for bleaching/coloring time), wide transmittance modulation range ([Formula: see text]37.21% at 540 nm), high coloration efficiency (CE) (100.6 cm2/C at 540 nm) and outstanding cycle stability (800 cycles). These are attributed to the mesoporous channels of films, which can increase reaction activity site, shorten ions transport path, and thus improve electrochromic reaction.