Generation Of Devices Research Articles

Combined Effects of the Electron–Hole Exchange and Förster Energy Transfer Interactions in Self‐Assembled Quantum‐Dot Pairs

Single‐photon emitters are essential components for the development of optical quantum computing and other quantum technologies, and semiconductor quantum dots are one of the most promising systems for scalable implementation of this type of light sources. However, polarization decoherence is still an important challenge to overcome. Herein, the combined influence of the electron–hole exchange and the Förster energy transfer in a pair of laterally coupled self‐assembled quantum dots, on the exciton‐spin coherence time, is studied. The numerical simulations suggest that under some conditions, the interplay between those two interactions slows the exciton‐spin decoherence as compared to the single‐dot case, which favors the applicability of quantum dots in quantum light generation devices.

Confinement and wettability-driven dispersed phase hydrodynamics in cross-flow jets at low velocity and density ratios

The evolution characteristics of a low-velocity dispersed phase into continuous shear flow have numerous applications across biomedical devices, chemical processes, water management in fuel cells, spray systems, film deposition, and atomizing devices. The flow characteristics arise from a complex interplay of wettability, hydrodynamics, and interfacial properties, which, when constrained by confined geometries such as those in fuel cells, present a fascinating multiphase-multiphysics problem. This study investigates the impact of the chemical signature of a confined geometry and the velocity ratio between the dispersed and continuous phases on the evolution of the dispersed phase. The footprint and shape of the generated droplet guide the pressure distribution, deformation, and subsequent cross-flow-induced stretching. By systematically analyzing the dynamic effects of capillarity, inertia, air-shear, gravity, viscosity, wettability, and confinement, we classify the fate of a liquid droplet within classical flow regimes: jetting, threading, and dripping. These distinct flow regimes are mapped using classical non-dimensional numbers, and a quasi-universal characteristic is obtained relative to velocity ratios. The findings of this research contribute to precise control and prediction of dispersed-phase hydrodynamics, which play a pivotal role in enhancing the efficiency of fuel cells, droplet generation devices, water harvesting systems, film deposition techniques, coatings, and point-of-care diagnostic devices. The work underscores the relevance of integrating experimental and computational insights for optimizing interface-driven processes in interdisciplinary applications.

An efficient output coupler for a terahertz generation device by stacking parallel plates with different refractive indices

Abstract In terahertz (THz) wave generation by MgO:LiNbO3 (LN) crystals, low extraction efficiency due to high refractive index (n = 4.93) in the THz region is problematic. We propose and demonstrate an output coupler that consists of parallel plates with different refractive indices to couple out a THz wave to the air (n ∼ 1) more efficiently than without plates. Without any complicated processing on the surface of LN crystals, a 1.8 times increase in the transmitted THz power was obtained.

Effects of Combined Utilization of Active Cooler/Heater and Blade-Shaped Nanoparticles in Base Fluid for Performance Improvement of Thermoelectric Generator Mounted in Between Vented Cavities

Abstract A wide range of technical applications, including solar power, waste heat recovery, electronics thermal management, and heat exchangers, employ thermoelectric generators. They can be mounted in between channels / cavities where hot and cold fluid streams exist. In this study, two novel methods of enhancing the power generation from thermoelectric generator device mounted in between vented cavities are proposed by combined utilization of active heater/cooler rectangular blocks and blade-shaped nanoparticles in base fluid. Finite element method investigation is conducted numerically for a range of hot and cold stream Reynolds numbers (250–1000), non-dimensional hot and cold block sizes (0.01 $$-$$ - 0.4), and heating/cooling increments (0–10), with nanoparticle loading limited to 0.03. Higher values of Reynolds number results in a rise in thermoelectric generator power. When comparing the cases of lowest and highest Reynolds number combinations, a 219 $$\%$$ % increase in power is achieved. The thermoelectric generator power will rise by around 27.5 $$\%$$ % when the object size reaches its maximum. However, for moderate object sizes, up to 31.6 $$\%$$ % reduction in power generation can be realized. Greater temperature differences result in a linearly rising power generation, with an achievable power increase of up to 22 $$\%$$ % . When nanoparticle loading in the base fluid for both cavities is raised to its maximum value, the resultant power increases by around $$30\%$$ 30 % . Thermoelectric generator power rises by 67.8 $$\%$$ % when an active heater/cooler with nanofluid is used in vented cavities, as opposed to the reference scenario of employing no object and only water. The thermoelectric generator device’s hot and cold interface temperatures are accurately estimated using the artificial neural network based method. The estimated temperature can be used as boundary condition for the solution of the governing equations in the thermoelectric generator device domain which will decrease the computational cost when dealing with very complex channel configurations.

Vitrimeric electrolytes - overview and perspectives.

Lithium batteries, essential for consumer electronics, transportation and the energy sector, still require further improvement in performance, safety, and sustainability. Traditonal organic solvent-based electrolytes, widely used in current systems, pose significant safety risks and restrict the development of next generation devices. Vitrimers are materials with unique physical and chemical properties, which offer a promising alternative to overcome these limitations, finally reaching processability and recyclability of solid electrolytes. Despite their potential a comprehensive overview of vitrimeric electrolytes' design and application in lithium batteries is lacking. This review article summarizes the key concepts, design principles, and notable advancements in vitrimeric electrolytes. We will also discuss the challenges still restricting the widespread adoption of vitrimeric electrolytes and explore future perspectives for leveraging vitrimeric materials in high-performance, safer, and more sustainable lithium battery technologies.

Development and Validation of a Capacitor–Current Circuit Model for Evaporation-Induced Electricity

Evaporation-induced electricity is a promising approach for sustainable energy generation which is particularly suited for off-grid and Internet-of-Things (IoT) applications. Despite significant progress, the mechanism of electricity generation remains debated due to complex factors. In this study, we introduce a simplified capacitor–current circuit model to describe the behavior of evaporation-induced electricity. The primary objective of this work is to provide a framework for understanding the transient and steady-state behavior of this phenomenon. We validated this model using experimental data from wood-based nanogenerators with citric acid modified microchannels. The fitting results revealed a steady-state current of approximately 9.832 μA and an initial peak current of 16.168 μA with a time constant of 621.395 s. These findings were explained by a hybrid model incorporating a capacitor and current source components, and subsequent discharge through internal resistance. This simplified model paves the way for better understanding and optimization of evaporation-induced electricity, highlighting potential improvements in device design for enhanced performance. While improving device performance is beyond the scope of this study, the insights gained from this model offer a foundation for future optimization and the enhanced performance of evaporation-induced electricity generation devices.

Design and preparation of a simplified microdroplet generation device for nanoliter volume collection and measurement with liquid microjunction–surface sampling probe–mass spectrometry

AbstractGiven recent interest in laboratory automation and miniaturization, the microdroplet research space has expanded across research disciplines and sectors. In turn, the microdroplet field is continually evolving and seeking new methods to generate microdroplets, especially in ways that can be integrated into diverse (microfluidic) workflows. Herein, we present a convenient, low‐cost, and re‐usable microdroplet generation device, termed as the “NanoWand,” which enables microdroplet formation in the nanoliter volume range through modulated surface energy and roughness, that is, an open surface energy trap (oSET), using commercially available and readily assembled coating and substrate materials. A wand‐like shape is excised from a microscope glass cover slip via laser‐micromachining and rendered hydrophobic; a circle is then cut‐out from the hydrophobically modified wand's tip using laser‐micromachining to create the oSET. By adjusting the size of the oSET with laser‐micromachining, the volume of the microdroplet can be similarly controlled. Using liquid microjunction–surface sampling probe–mass spectrometry (LMJ‐SSP‐MS), specific NanoWand droplet capture volumes were estimated to be 117 ± 23.6 nL, 198 ± 30.3 nL, and 277 ± 37.1 nL, corresponding to oSET diameters of 0.75, 1.00, and 1.25 mm, respectively. This simple approach provides a user‐friendly way to form and transfer microdroplets that could be integrated into different liquid handling applications, especially when combined with the LMJ‐SSP and ambient ionization MS as a powerful and rapid analytical tool.

Sheath-enhanced concentration and on-chip detection of bacteria from an extremely low-concentration level.

Microfluidic-based sheath flow focusing methods have been widely used for efficiently isolating, concentrating, and detecting pathogenic bacteria for various biomedical applications due to their enhanced sensitivity and exceptional integration. However, such a microfluidic device usually needs complicated device fabrication and sample dilution, hampering the efficient and sensitive identification of target bacteria. In this study, we develop and fabricate a sheath-assisted and pneumatic-induced nano-sieve device for achieving the improved on-chip concentration and sensitive detection of Staphylococcus aureus (MRSA). The optimized nanochannel design with diverging configuration is beneficial to the regulation of the hydrodynamic flow while the sheath flow is focusing the sample to the confined region as expected. Per the experimental finding, a high flow ratio (sheath flow/sample flow) presents enhanced target concentration by comparing with a low flow ratio. With this setup, MRSA bacteria with an extremely low concentration of ∼100 CFU mL-1 are successfully and sensitively detected under a fluorescence microscope, less than 30 min, demonstrating a reliable sheath-enhanced concentration and on-chip detection for target bacteria. Additionally, the theoretical model introduced here further rationalizes the working principle of our nano-sieve device, potentially guiding the optimization of next generation devices for highly sensitive and accurate on-chip bacteria detection at a much lower concentration level below 100 CFU mL-1.

Current evidence and indications for left atrial appendage closure.

Atrial fibrillation (AF) is the most common arrhythmia worldwide and its prevalence increases with age. The main and most severe complication of AF is ischemic stroke, yet an estimated 50 % of eligible patients cannot tolerate or are contraindicated to receive oral anticoagulation (OAC). In patients with AF, the left atrial appendage (LAA) is the main source of thrombus formation. Percutaneous LAA closure (LAAC) has emerged over the past two decades as a valuable alternative to OAC for reducing the risk of strokes and systemic embolisms in patients with AF who cannot tolerate long-term OAC. With newer generation devices such as the Watchman (Boston Scientific, Natick, MA, USA) and Amulet (Abbott, Abbott Park, IL, USA) gaining approval from the US Food and Drug Administration in recent years, the safety and efficacy of LAAC in specific populations intolerant to OAC have increased and more patients are being treated. This systematic review provides the indications for LAAC and the evidence for evaluating the use of the currently available device therapies. We also examine the current unsolved problems with patient selection and postprocedural antithrombotic regimens.

Stability Improvement of Power MOSFET-Driven Plasma Generation Device for Thin Film Deposition and Chamber Cleaning

Stability Improvement of Power MOSFET-Driven Plasma Generation Device for Thin Film Deposition and Chamber Cleaning

Modulating Acceptor Phase Leads to 19.59% Efficiency Organic Solar Cells

AbstractNonfullerene acceptors are critical in advancing the performance of organic solar cells. However, unfavorable morphology and low photon‐to‐electron conversion in the acceptor range continue to limit the photocurrent generation and overall device performance. Herein, benzoic anhydride, a low‐cost polar molecule with excellent synergistic properties, is introduced in combination with the traditional additive 1‐chloronaphthalene to optimize the aggregation of nonfullerene acceptors. This dual additive approach precisely modulates the morphology of various acceptors, significantly enhancing device performance. Notably, the method induces the formation of fine fibers with dense polymorph structures in BTP‐base derivatives, achieving an optimal balance between exciton dissociation and charge collection in the active layers. As a result, the external quantum efficiency of the optimal devices is markedly improved in the wavelength range of 700–850 nm. Ultimately, power conversion efficiencies of 18.27% and 19.59% are achieved for devices comprising PM6:Y6 and PM6:L8‐BO, respectively. The results reveal a convenient and effective method to control the morphology of nonfullerene acceptors and improve the photovoltaic performance of organic solar cells, paving the way for more efficient and practical organic photovoltaic technologies.

Drug-Coated Balloons for the Treatment of Coronary Artery Disease

Drug-coated balloon (DCB) angioplasty has emerged as an alternative to drug-eluting stent (DES) implantation for percutaneous coronary intervention (PCI) in patients with coronary in-stent restenosis (ISR) as well as de novo coronary artery disease. DCBs are balloons coated with antiproliferative agents and excipients, whose aim is to foster favorable vessel healing after appropriate lesion preparation. By providing homogeneous antiproliferative drug delivery in the absence of permanent foreign body implantation, DCBs offer multiple advantages over DES, including preservation of vessel anatomy and function and positive vessel remodeling. As such, DCBs have become appealing for treatment of ISR, small-vessel disease, long lesions, simplification of bifurcation procedures, and treatment of diffuse distal disease after recanalization of chronic total occlusions. In addition, patients with high bleeding risk, diabetes, and acute coronary syndrome might also stand to benefit from DCB angioplasty. Although commercially available in numerous countries now for more than a decade, DCB only recently obtained US Food and Drug Administration approval for the treatment of coronary ISR. Moreover, preliminary results from newer generation devices tested in different clinical scenarios have raised the interest of the international community. Accordingly, an up-to-date review is timely particularly with the anticipated wave of research on the matter. Herein, this review encompasses DCB technologies, their worldwide usage, details on relevant indications, and key procedural aspects of DCB angioplasty.

Unraveling the Synergistic Role of Sm3+ Doped NiFe-LDH as High-Performance Electrocatalysts for Improved Anion Exchange Membrane and Water Splitting Applications.

Effective first-row transition metal-based electrocatalysts are crucial for large-scale hydrogen energy generation and anion exchange membrane (AEM) devices in water splitting. The present work describes that SmNi0.02Fe-LDH nanosheets on nickel foam are used as a bifunctional electrocatalyst for water splitting and AEM water electrolyzer study. Tuning the Ni-to-Fe ratios in NiFe-LDH and doping with Sm ions improves the electrical structure and intrinsic activity. SmNi0.02Fe-LDH has higher oxygen evolution reaction (OER), HER, and TWS activity, achieving 10 mAcm⁻2 current density at lower overpotentials (230 mV, 95 mV, and 1.62 V, respectively). In AEMWE cells, SmNi0.02Fe-LDH as a cathode and anode pair exhibits outstanding activity (0.9 Acm⁻2 at 2 V) and stability over 120 h. Density Functional Theory (DFT) investigations reveal that the Sm doping in NiFe-LDH surface enhances its bifunctional activity toward OER and HER. These findings emphasize the potential of non-noble composites for long-term water electrolysis in total water splitting and AEMWE applications.

Solar Cells Manufactured Using Concentrated Solar Energy Toward Carbon Neutralization

AbstractThe high photoelectric conversion efficiency (PCE) of solar cells and their environmentally friendly, low‐carbon manufacturing processes are crucial for advancing carbon neutrality goals. This study introduces Fresnel lenses to focus sunlight for the sintering of mesoporous titanium dioxide (m‐TiO2) layers as an innovative method for fabricating perovskite solar cells (PSCs), effectively circumventing the energy‐intensive and carbon‐emitting high‐temperature furnace sintering traditionally required. Through this concentrated solar annealing technique, an efficient and eco‐friendly sintering of the m‐TiO2 layer is successfully achieved by removing organic residues from the precursor film and enhancing the film's transmittance, electrical conductivity, and grain size. Consequently, this has led to improved coverage of the perovskite layer and enhanced overall photovoltaic performance of the solar cells. Experimental results indicate that the m‐TiO2 film subjected to 60 min of concentrated sunlight sintering (CSS) demonstrates optimal photovoltaic performance, with the fabricated compact‐layer‐free PSCs achieving an impressive photoelectric conversion efficiency of up to 17.69%. This research not only offers a novel, cost‐effective approach for the sustainable production of PSCs but also contributes tangible solutions for the green transformation of the photovoltaic industry and the achievement of carbon neutrality. This work points the way toward using solar energy to prepare solar power generation devices.

Enhanced Cryogenic Thermoelectric Performance of Textured Bi1-xSbx Ribbons with Electronic Phase Transition.

Bi1-xSbx alloys are promising cryogenic thermoelectric materials for generator and refrigeration devices at temperatures below 200 K. Herein, we prepared highly (00l) textured Bi1-xSbx (x = 0-0.05) ribbons by a melt-spinning technique and tuned its band structure with a Dirac electronic phase transition via Sb doping for improving the thermoelectric performance. The results indicate that the lamellar grains with (00l) orientation facilitate the alignment of the Fermi pocket of ribbon samples and cause a higher Seebeck coefficient compared with the nonoriented Bi1-xSbx bulk. Meanwhile, the Fermi level of Bi1-xSbx ribbons moves down by Sb doping, inducing the decrease of the carrier concentration and the increment of the Seebeck coefficient. Particularly, the Dirac electron phase is modulated when x reaches 0.04, which enlarges the carrier mobility and results in a well-maintained conductivity. Therefore, the optimized transport properties yield a large power factor of 61.1 μW·cm-1·K-2 at 140 K for the x = 0.04 sample, a significant 65% increase compared to the x = 0 ribbon. Besides, a planar thermoelectric device composed of 8 legs was assembled with the optimized ribbon, which produces a high open-circuit voltage of 39.8 mV. The output power maximum and the corresponding power density reach up to 402 nW and 125.7 μW·cm-2 under a temperature gradient of 80 K, respectively. Our work suggests that modulating the Dirac phase transition can effectively enhance the thermoelectric performance of Bi1-xSbx alloys.

Electric Field-Induced Synergetic Enhancement of Local Hydroxyl Concentration and Photogenerated Carrier Density for Removal of COads in Electrocatalytic Formic Acid Oxidation.

Direct formic acid fuel cell (DFAFC) is an efficient power generation device, due to its high energy density, low fuel crossover and low emission. However, the anodic reaction of DFAFC, formic acid oxidation (FAOR), inevitably proceeds through an indirect pathway, adsorbing carbon monoxide intermediate (COads), resulting in a rapid decline of activity for FAOR. Therefore, effectively removing COads is the key to the development of DFAFC. In this work, Pd/CeO2 catalyst is synthesized by in situ growth of Pd nanoparticles on the hollow CeO2. Due to the difference of work function between Pd and CeO2, a built-in electric field from Pd side to CeO2 side is formed, which induces a synergistic enhancement of the photogenerated carrier density and the local high hydroxyl concentration at the Pd/CeO2 interface, thus promoting the oxidative removal of COads and significantly improving the stability of FAOR. Therefore, in photo-assisted electrocatalytic FAOR, Pd/CeO2 not only possessed high mass activity (4161.72 mA mg-1 Pd), and its mass activity decreases by only 20.1% after 40000 s chronoamperometry test, which is superior to most Pd-based catalysts. This work provides a new strategy for efficient removal of COads in FAOR through constructing built-in electric fields, which promotes the DFAFC application.

Electrically induced insulator-to-metal transition in InP-based ion-gated transistor

With the growing awareness of energy savings and consumption for a sustainable ecosystem, the concept of iontronics, that is, controlling electronic devices with ions, has become critically important. Composite devices made of ions and solid materials have been investigated for diverse applications, ranging from energy storage to power generation, memory, biomimetics, and neuromorphic devices. In these studies, three terminal transistor configurations with liquid electrolytes have often been utilized because of their simple device structures and relatively easy fabrication processes. To date, oxide semiconductors and layered materials have mainly been used as active materials. However, inorganic compound semiconductors, which have a long history of basic and applied research, hardly function as channel materials in ion-gated transistors, partly because of the Schottky barrier at the electrode interface. Herein, we show that a typical group III–V compound semiconductor, InP, is available as a high-performance channel for ion-gated transistors with an on/off current ratio of ≈ 105 and a subthreshold swing as small as 93 mV/dec at room temperature. We fabricated AuGe/Ni contact electrodes via annealing to obtain the Ohmic contacts over a wide temperature range. The electrical resistance of InP was drastically decreased by the ionic liquid gating, which led to an electrically induced insulator-to-metal transition. Bulk compound semiconductors are well characterized and have relatively high carrier mobilities; thus, devices combined with electrolytes should prompt the development of iontronics research for novel device functionalities.

Doped-δ-doped transferred electron device for sustained terahertz signal generation

Abstract The performance of a novel transferred electron device structure aimed at sustaining high-frequency signals in the terahertz (THz) range is investigated. The device uses a highly doped δ-layer to split the n-doped device into two distinct regions, forming a doped-δ-doped configuration. The first region generates high-speed electrons toward the δ-layer, while the second region utilizes negative differential resistance to modulate electron speeds and sustain oscillations. An ensemble self-consistent Monte Carlo model is employed to analyze electron dynamics and THz signal generation in this structure under a constant bias. The design demonstrates superior performance, achieving a fundamental operating frequency of 427 GHz in a 600 nm length InP device, nearly a 50% increase over conventional notch-doped design, while maintaining the current harmonic amplitude. This design achieves higher frequencies without reducing device length and increasing doping density, effectively addressing the trade-off of the Kroemer criterion. The study of the effects of varying doping densities and region lengths on device performance, highlighting the importance of optimizing these parameters to sustain current oscillations and efficiently generate THz signals. This design offers a promising solution for a compact and efficient THz source.

Remarks On the Use of Variational mode decomposition for Chaos and Nonlinear Dynamics Analysis in Fractional-Order Systems applications

This study investigates the dynamics of an electromechanical device for energy generation. The device utilizes a motor with an unbalanced mass coupled to a piezoelectric substrate. The central focus of the analysis is measuring the average power generated by the piezoelectric material, which is stimulated by the motor's vibrations. We explore the fractional dynamics of the system, examining variables such as the parameter of the fractional derivative operator and the control parameter. Using techniques like bifurcation diagrams and recurrence analysis, we investigate the routes to chaos and their implications on the stability and behavior of the system. The study is enhanced by the implementation of Variational Mode Decomposition, a technique that allows us to decipher the complexities of the system's dynamics.

DFT study of structural, electronic, optical and elastic properties of lead-free Bi based perovskites X2NaBiCl6 (X= K and Rb) with pressure

The pressure dependent structural, electronic, optical and mechanical properties of Bi-based cubic halide double perovskites, X2NaBiCl6 (X = K and Rb) are explored by implementing full-potential linearized augmented plane wave (FP-LAPW) method. At zero pressure, K2NaBiCl6 and Rb2NaBiCl6 posses indirect band gaps of 3.746 and 3.735eV, respectively and the band gaps decrease with increasing pressure for both compounds. The elliptical shape of charge density contours under high pressure ensured a strong covalent bonding between K/Rb and Cl atoms along (110) plane. We explored the essential optical properties for both compounds with different pressures and found a red-shift with increase in pressure. Furthermore, all the values of mechanical parameters, viz. elastic constants and moduli, Vickers hardness, Debye and melting temperatures are enhanced with increasing pressure. Due to suitable band gaps and appropriate mechanical parameters, both perovskites are proved as promising candidates in thermoelectric power generation and high temperature devices.