Physical Unclonable Anticounterfeiting Electrodes Enabled by Spontaneously Formed Plasmonic Core–Shell Nanoparticles for Traceable Electronics

Counterfeit electronics are a growing problem for the electronic information industry worldwide, so developing unbreakable security tags is crucial to ensure the trustworthiness and traceability of electronics. Traditional anticounterfeiting and trace solutions rely on reproducible deterministic processes and additional labels, which can still be copied or faked by counterfeiters. Herein, physical unclonable functions enabled by spontaneously formed plasmonic core–shell nanoparticles on electrodes are proposed to ensure label-free traceable electronics, giving a practical solution to fight against counterfeit electronics. Random hemispherical core–shell nanoparticles are intentionally introduced on the metal electrode of different semiconductors (Si, GaAs, and GaN) from Ni/Au bilayer heterofilms by rapid thermal annealing, which can be integrated with electronics seamlessly, with no negative effect on electrical properties. The position, size, and shape of nanoparticles are random and uncontrollable; the corresponding scattering patterns, intensity, and spectra can work as nanofingerprints of the electrode, proving multidimensional unclonable labels with large encoding capacity suitable for electrodes smaller than several micrometers. It can be further combined with machine vision and artificial intelligence to identify and track electronics automatically and efficiently. The anticounterfeiting electrodes also show good thermal robustness and mechanical stability, opening up a prospect for practical anticounterfeiting of electronics.     

Highly Stable Ag–Au Core–Shell Nanowire Network for ITO-Free Flexible Organic Electrochromic Device

Solid and flexible electrochromic (EC) devices require a delicate design of every component to meet the stringent requirements for transparency, flexibility, and deformation stability. However, the electrode technology in flexible EC devices stagnates, wherein brittle indium tin oxide (ITO) is the primary material. Meanwhile, the inflexibility of metal oxide usually used in an active layer and the leakage issue of liquid electrolyte further negatively affect EC device performance and lifetime. Herein, a novel and fully ITO-free flexible organic EC device is developed by using Ag–Au core–shell nanowire (Ag–Au NW) networks, EC polymer and LiBF₄/propylene carbonate/poly(methyl methacrylate) as electrodes, active layer, and solid electrolyte, respectively. The Ag–Au NW electrode integrated with a conjugated EC polymer together display excellent stability in harsh environments due to the tight encapsulation by the Au shell, and high area capacitance of 3.0 mF cm⁻² and specific capacitance of 23.2 F g⁻¹ at current density of 0.5 mA cm⁻². The device shows high EC performance with reversible transmittance modulation in the visible region (40.2% at 550 nm) and near-infrared region ( − 68.2% at 1600 nm). Moreover, the device presents excellent flexibility ( > 1000 bending cycles at the bending radius of 5 mm) and fast switching time (5.9 s).     

Core–Shell Photoanodes for Photoelectrochemical Water Oxidation

Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising solution for the conversion and storage of solar energy. Because sluggish water oxidation is the bottleneck of water splitting, the design and preparation of an efficient photoanode is intensively investigated. Currently, all known photoanode materials suffer from at least one of the following drawbacks: ① low carriers separation efficiency; ② sluggish surface water oxidation reaction; ③ poor long-term stability; ④ insufficient water adsorption and gas desorption. Core–shell configurations can endow a photoanode with improved activity and stability by coating an overlayer that plays energetic, catalytic, and/or protective roles. The construction strategy has an important effect on the activity of a core–shell photoanode. Nonetheless, the mechanism for the improvement of performance is still ambiguous and is worthy of a closer examination. In this review, the successes and challenges of core–shell photoanodes for water oxidation, focusing on synthesis strategies as well as functionalities (facilitating carrier separation, surface reaction promotion, corrosion prevention, and bubble detachment) are explored. Finally, the perspectives of this class of materials in terms of new opportunities and efforts are discussed.     

Dow Corning~ Materials for Printed Electronics

A new generation of RFID materials with de- signed-in compatibility helps raise quality, reliability and process efficiency If RFID technology is headed for the heights predicted by forecasters, it will require an ongoing evolution of new materials and re- lated technologies to help reduce card/label assembly costs and improve performance. From a materials standpoint, the critical elements in any printed RFID inlay include the chip, the chip attachment method, the antenna,     

Complex 3D-Printed Mechanochromic Materials with Iridescent Structural Colors Based on Core–Shell Particles

A scalable protocol for design and subsequent 3D-printing of polymeric core-shell-particles is reported. The particle synthesis by emulsion polymerization in starved-feed mode is used for tailoring particle architecture and composition. Control of size, mechanical properties, and chemical functionalities allow to achieve the specific requirement profile for subsequent extrusion-based additive manufacturing. The core-shell particles consist of hard polystyrene cores and a comparably soft polyalkylacrylate-based shell. Size and monodispersity, as well as core-to-shell ratio, are determined by means of dynamic light scattering and transmission electron microscopy. Thermal and rheological properties are investigated by means of dynamic scanning calorimetry and thermogravimetric analysis as well as oscillation and capillary rheometry. During 3D-printing, the monodisperse particles self-assemble into an ordered close packed lattice structure, leading to visible reflection colors according to Bragg's law of diffraction. Distinct and angle-dependent reflection colors are recorded via UV-vis spectroscopy. As the structural color depends, inter alia, on the underlying particle sizes, resulting colors are easily tunable by adjusting the applied synthesis parameters. Under mechanical deformation, the color changes due to controlled lattice deformation, which enables mechanochromic sensing with the printed objects. They are also promising candidates for decorative ornaments, smart optical coatings, or advanced security devices.     

Atomic-Precision Tailoring of Au–Ag Core–Shell Composite Nanoparticles for Direct Electrochemical-Plasmonic Hydrogen Evolution in Water Splitting

Traditionally, bandgap materials are a prerequisite to photocatalysis since they can harness a reasonable range of the solar spectrum. However, the high impedance across the bandgap and the low concentration of intrinsic charge carriers have limited their energy conversion. By contrast, metallic nanoparticles possess a sea of free electrons that can effectively promote the transition to the excited state for reactions. Here, an atomic layer of a bimetallic concoction of silver–gold shells is precisely fabricated onto an Au core via a sonochemical dispersion approach to form a core–shell of Au–Ag that exploits the wide availability of excited states of Ag while maintaining an efficient localized surface plasmon resonance (LSPR) of Au. Catalytic results demonstrate that this mix of Ag and Au can convert solar energy to hydrogen at high efficiency with an increase of 112.5% at an optimized potential of −0.5 V when compared to light-off conditions under the electrochemical LSPR. This outperforms the commercial Pt catalysts by 62.1% with a hydrogen production rate of 1870 µmol g⁻¹ h⁻¹ at room temperature. This study opens a new route for tuning the range of light capture of hydrogen evolution reaction catalysts using fabricated core–shell material through the combination of LSPR with electrochemical means.     

Recent Progress of Flexible Photodetectors Based on Low-Dimensional II–VI Semiconductors and Their Application in Wearable Electronics

Flexible photodetectors exhibit many advantages such as a good bendability, foldability, and even stretchability as well as weight light, which have triggered a widely concerned in wearable electronics including wearable monitoring, wearable image sensing, self-powered integrated electronics, etc. Recently, various II–VI semiconductor nanostructures have become promising candidates in flexible photodetectors due to their unique characteristics, such as direct bandgap semiconductors, excellent optical and electric properties, high quantum efficiency, and inherent mechanical flexibility. Herein, the most recent progress on low-dimensional (0D, 1D, 2D, and related heterostructures) II–VI semiconductors based flexible photodetectors and their application in wearable electronic is reviewed. First, a brief introduction of the main sensing mechanisms and key figures of merits for photodetectors is presented. Then, the recent progresses on flexible photodetectors are provided, in which the functional materials synthesis methods are also discussed. More importantly, the applications of the flexible photodetectors are summarized, including wearable monitoring sensors, image sensors, and self-powered integrated wearable electronics. Finally, the challenges and the future research direction of the flexible photodetectors are discussed, meanwhile the outlook for the development of flexible photodetectors in the future integration of wearable electronic is also provided.     

Microfluidic Multi-Scale Homogeneous Mixing with Uniform Residence Time Distribution for Rapid Production of Various Metal Core–Shell Nanoparticles

Seed-mediated growth of core–shell nanoparticles, which is conventionally performed in a batch reactor, is successfully reproduced in a microfluidic reactor for a facile production of uniform metal core–shell nanoparticles. The proposed microfluidic design is based on the microstructure inversion for achieving multi-scale homogeneous mixing with uniform nanoparticle residence time. Simulations demonstrate that among the staggered herringbone microstructures investigated in this study, the upper herringbone (UH) structure can rapidly and homogeneously mix multiple-sized reagents and can also prevent both the irreversible trapping and long residence time of the nanoparticles inside the microfluidic channel. A wide variety of metal core–shell nanoparticles, namely Au@Ag, Au@Pd, and Au@Au with an interior nanogap, are synthesized by using the microfluidic reactor with built-in UH microstructures. The proposed microfluidic synthesis produces a more uniform shell size than the conventional batch synthesis. This work could significantly expand the practical utility of metal core–shell nanoparticles in a multitude of applications ranging from catalysis to nanomedicine.     

Organic-Carbon Core–Shell Structure Promotes Cathode Performance for Na-Ion Batteries

The organic-carbon core-shell structure is constructed for the cathode material of [N,N'-bis(2-anthraquinone)]-perylene-3,4,9,10-tetracarboxydiimide (PTCDI-DAQ, 200 mAh g⁻¹) through an interesting strategy called the surface self-carbonization. As expected, the organic-carbon core–shell structure (PTCDI-DAQ@C) can endow PTCDI-DAQ the outstanding cathode performance in Na-ion batteries. In half cells using 1 m NaPF₆/DME, PTCDI-DAQ@C can maintain 173 mAh g⁻¹ for nearly one year, while PTCDI-DAQ quickly decreases from 203 to 121 mAh g⁻¹ only after 100 cycles. Meanwhile, the constructed Na-ion full cells with the Na-intercalated hard carbon anode can deliver the peak discharge capacity of 195 mAh g⁻¹_cathode and the high median voltage of 1.7 V in 0.9–3.2 V, corresponding to the peak energy densities of 332 Wh kg⁻¹_cathode and 184 Wh kg⁻¹_{total mass}, respectively. Notably, the electrode materials only include the very cheap elements of C, H, O, N, and Na. Furthermore, the Na-ion full cells can also show the very impressive high-temperature (197 mAh g⁻¹_cathode at 50 °C) and subzero (185/90 mAh g⁻¹_cathode at −10/−40 °C) performances, respectively. To the best of the authors’ knowledge, the comprehensive properties of the Na-ion full cells are the best results based on organic cathodes.     

Novel and Simple Solution-processed MIS Ultraviolet (UV) Detector Based on Core–Shell Si/SiO2 Nanocrystals

In the present study, we report a simple and solution-processed visible blind metal–insulator–semiconductor (MIS) ultraviolet (UV) detector based on core–shell Si/SiO₂ nanocrystals that are fabricated on interdigitated electrodes. The fabricated photo detector shows high photosensitivity in the UV-B and UV-C wavelength ranges. The absorption spectra of the nano-structured materials used in this work is simulated by the density functional theory (DFT) method and analyzed based on the electronic structure. It is then compared with the experimental results. The synthesized nano materials show very low density of structural defects based on the measured photoluminescence spectra, which results in a fast response time for the fabricated photodetector. Compared to the previously reported similar Si/SiO₂-based photo-detectors, the fabricated detector shows very good photo responsivity.     

Addressing Particle Compositional Heterogeneities in Super-Resolution-Enhanced Live-Cell Ratiometric pH Sensing with Ultrasmall Fluorescent Core–Shell Aluminosilicate Nanoparticles

The interrogation of metabolic parameters like pH in live-cell experiments using optical super-resolution microscopy (SRM) remains challenging. This is due to a paucity of appropriate metabolic probes enabling live-cell SRM-based sensing. Here, ultrasmall fluorescent core–shell aluminosilicate nanoparticle sensors (FAM–ATTO647N aC′ dots) that covalently encapsulate a reference dye (ATTO647N) in the core and a pH-sensing moiety (FAM) in the shell are introduced. Only the reference dye exhibits optical blinking enabling live-cell stochastic optical reconstruction microscopy (STORM). Using data from cells incubated for 60 min with FAM–ATTO647N aC′ dots, pixelated information from total internal reflection fluorescence (TIRF) microscopy-based ratiometric sensing can be combined with that from STORM-based localizations via the blinking reference dye in order to enhance the resolution of ratiometric pH sensor maps beyond the optical diffraction limit. A nearest-neighbor interpolation methodology is developed to quantitatively address particle compositional heterogeneity as determined by separate single-particle fluorescence imaging methods. When combined with STORM-based estimates of the number of particles per vesicle, vesicle size, and vesicular motion as a whole, this analysis provides detailed live-cell spatial and functional information, paving the way to a comprehensive mapping and understanding of the spatiotemporal evolution of nanoparticle processing by cells important, e.g., for applications in nanomedicine.     

Flexible and Air-Stable Near-Infrared Sensors Based on Solution-Processed Inorganic–Organic Hybrid Phototransistors

Flexible and air-stable phototransistors are highly demanded for wearable near-infrared (NIR) image sensors. However, advanced NIR sensors via low-cost, solution-based processes remained a challenge. Herein, high-performance inorganic–organic hybrid phototransistors are achieved based on solution processed n-type metal oxide/polymer semiconductor heterostructures of In₂O₃/poly{5,5′-bis[3,5-bis(thienyl)phenyl]-2,2′-bithiophene-3-ethylesterthiophene]} (PTPBT-ET). The In₂O₃/PTPBT-ET hybrid phototransistor combines the advantages of both fast electron transport in In₂O₃ and high photoresponse in PTPBT-ET, showing high saturation mobility of 7.1 cm² V⁻¹ s⁻¹ and large current on/off ratio of >10⁷. As a result, the phototransistor exhibits high performance towards NIR light sensing with a responsivity of 200 A W⁻¹, a specific detectivity of 1.2 × 10¹³ Jones, and fast photoresponse with rise/fall time of 5/120 ms. Remarkably, the hybrid phototransistor, without any passivation, demonstrates excellent electrical stability without performance degradation even after 160 days in air. A 10 × 10 phototransistor array is also enabled by virtue of the high device uniformity. Lastly, flexible In₂O₃/PTPBT-ET phototransistor on polyimide substrate is attained, exhibiting outstanding mechanical flexibility up to 1000 bending/releasing cycles at a bending radius of 5 mm. These achievements pave the way for constructing air-stable hybrid phototransistors for flexible NIR image sensor applications.     

Solubility-Boosted Molecular Sieving-Based Separation for Purification of Acetylene in Core–Shell IL@MOF Composites

Considering the small amount of CO₂ as a contaminant in industrial gas mixtures, developing CO₂-selective adsorbents exhibit advantages in directly obtaining pure C₂H₂ in one-step to reduce the energy consumption. However, it is still a great challenge due to the essential molecular feature of C₂H₂, including the triple bond and high polarizability. Herein, a simple but effective CO₂-facilitated transport strategy is presented to realize the overwhelming adsorption of CO₂ over C₂H₂ by constructing core–shell composite structures using ionic liquid (IL) and metal-organic framework (MOF). With the aid of excellent solubility of CO₂ in IL and almost total exclusion of C₂H₂, the obtained materials boost molecular sieving-based separation of CO₂/C₂H₂. Density functional theory calculations combining molecular dynamic simulations revealed the solution-diffusion mechanism for CO₂, which is rarely reported in solid adsorbents. Ideal adsorbed solution theory selectivity for CO₂/C₂H₂ with 1/1 and 1/3 volume ratios can reach over 10⁴ and 4000 at 100 kPa with a high CO₂ uptake of 40.3 cm³ g⁻¹, superior to those of the reported materials so far. More importantly, this solution-based separation strategy can avoid the difficulty for precise control of the regulation of adsorbent structure, which may be beneficial to practical production.     

In Situ Induced Core–Shell Carbon-Encapsulated Amorphous Vanadium Oxide for Ultra-Long Cycle Life Aqueous Zinc-Ion Batteries

Inevitable dissolution in aqueous electrolytes, intrinsically low electrical conductivity, and sluggish reaction kinetics have significantly hampered the zinc storage performance of vanadium oxide-based cathode materials. Herein, core–shell N-doped carbon-encapsulated amorphous vanadium oxide arrays, prepared via a one-step nitridation process followed by in situ electrochemical induction, as a highly stable and efficient cathode material for aqueous zinc-ion batteries (AZIBs) are reported. In this design, the amorphous vanadium oxide core provides unobstructed ions diffusion routes and abundant active sites, while the N-doped carbon shell can ensure efficient electron transfer and greatly stabilize the vanadium oxide core. The assembled AZIBs exhibit remarkable discharge capacity (0.92 mAh cm⁻² at 0.5 mA cm⁻²), superior rate capability (0.51 mAh cm⁻² at 20 mA cm⁻²), and ultra-long cycling stability (≈100% capacity retention after 500 cycles at 0.5 mA cm⁻² and 97% capacity retention after 10 000 cycles at 20 mA cm⁻²). The working mechanism is further validated by in situ X-ray diffraction combined with ex situ tests. Moreover, the fabricated cathode is highly flexible, and the assembled quasi-solid-state AZIBs present stable electrochemical performance under large deformations. This work offers insights into the development of high-performance amorphous vanadium oxide-based cathodes for AZIBs.     

Technology for Producing Schottky Contacts Based on an IrSi–Si Composite

Russian Microelectronics - In this study, in order to obtain Schottky contacts based on an IrSi–Si composite, n- and p-type silicon wafers doped, respectively, with boron and phosphorus with...     

One-Step Fabrication of Al/Sn-Bi Core–Shell Spheres via Phase Separation

Al/Sn-Bi core–shell spheres, which have potential for use in advanced electronic packaging, were fabricated in one step via phase separation by spraying liquid (Al_0.345Bi_0.655)_67.8Sn_32.2 alloy into silicone oil. The core–shell spheres changed morphology from three-layer to concentric or eccentric dual-layer type with decreasing melt superheat and increasing oil temperature. The spheres are Al-rich in the core, covered with a Sn-Bi-rich periphery, showing a two-stage melting behavior suitable for electronic packaging. The (Al_0.345Bi_0.655)_67.8Sn_32.2 alloy was identified through thermal analysis to undergo liquid-phase separation, monotectic reaction, and eutectic reaction one after another during cooling. Finally, the solidification path of (Al_0.345Bi_0.655)_67.8Sn_32.2 alloy was analyzed and was schematically illustrated.     

l 2–l ∞ Filtering for Multirate Systems Based on Lifted Models

For a multirate sample-data system where the output sampling rate is slower than the input updating rate, we study the l ₂–l _∞ filtering problems for fast state estimation by using the lifted model. The filtering problem is handled in the framework of linear matrix inequalities (LMIs) with a nonconvex constraint, which is numerically solved by the product reduction algorithm. Finally, the effectiveness of the proposed method is illustrated and verified by simulation examples. This research was supported by the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation and the National Natural Science Foundation of China (60372105 and 60672118).     

Evaporation-Induced Closely-Packing of Core–Shell PDMS@Ag Microspheres Enabled Stretchable Conductor with Ultra-High Conductance

Stretchable conductors are indispensable building blocks for stretchable electronic devices that are used in next-generation wearable electronics, on-skin electronics, and soft robotics. Whereas, the ability to realize synergy high conductance and sufficient conductivity under high strain remains challenging. Herein, a stretchable conductor made from tightly assembled core–shell polydimethylsiloxane@silver microspheres (PDMS@Ag MPs) is elaborated. By judiciously using evaporation-induced capillary effect, 3D interconnected conductive paths consisting of closely packed conductive PDMS@Ag MPs are constructed inside the elastic matrix. The spatially selective distributed Ag-shell enables conductor metallic conductivity (67185 S cm⁻¹) at ultralow Ag fraction (19.5 wt.%), and well-maintained conductance over wide strain (820 S cm⁻¹ at 400%). Due to the suppressed Ag content, both the rapture strain and Young's modulus (613%, 0.79 MPa for CPSC4) of the conductor are largely retained. Besides, the synergy hierarchical surface topology and low surface energy endow conductors with high water-repellent properties. The fabricated conductors with remarkably high conductivity, well-retained conductance under large strain, and robust hydrophobicity are of great significance for advanced stretchable electronics.     

Automatic Parameters Selection for SVM Based on PSO

Motivated by the fact that automatic parameters selection for Support Vector Machine （SVM） is an important issue to make SVM practically useful and the common used Leave - One - Out （LO0） method is complex calculation and time consuming,an effective strategy for automatic parameters selection for SVM is proposed by using the Particle Swarm Optimization （PSO） in this paper. Simulation results of practice data model demonstrate the effectiveness and high efficiency of the proposed approach.