Multilayer ceramic batteries (MLCBs) have attracted increasing attention as compact all-solid-state energy-storage devices that can be manufactured using multilayer ceramic processing technologies. In this study, an MLCC-compatible fabrication process for oxide-based MLCBs was developed using Li₁₊ₓAlₓTi₂₋ₓ(PO₄)₃ (LATP) solid electrolytes, Li₃V₂(PO₄)₃ (LVP) cathodes, and Cu current collectors. Commercial LATP powders were evaluated in terms of particle-size distribution, phase purity, thermal stability, and ionic conductivity. The selected LATP powder was subsequently employed for tape-cast green-sheet fabrication, and the effects of polyvinyl butyral (PVB) binder content on slurry rheology and sheet microstructure were investigated. An optimized binder composition containing 11 wt% PVB (BM-2/BH-3 = 3:7) provided improved processability and microstructural uniformity. Drying conditions during sequential electrode printing were also optimized to suppress sheet warpage and improve multilayer registration. Thermogravimetric and differential thermal analyses (TG–DTA) were used to establish an optimized two-step debinding and co-firing process under a controlled reducing atmosphere. The resulting multilayer structures exhibited uniform densification without significant blistering, delamination, or interfacial defects. Charge–discharge measurements confirmed that electrochemical functionality was retained after the complete manufacturing process, yielding a discharge capacity of approximately 2.5–2.7 μAh.

The 0.2Pb(Zn_1/3Nb_2/3)O₃-0.8Pb(Zr_0.5Ti_0.5)O₃ (0.2PZN-0.8PZT) ceramic system exhibits excellent piezoelectric properties; however, its high sintering temperature (~1,250°C) causes severe PbO volatilization, increases processing cost, and limits co-firing with low-melting-point electrodes in multilayer devices. In this study, LiBiO₂ was introduced as a sintering aid to enable lowtemperature densification of 0.2PZN–0.8PZT ceramics. The optimal composition of x = 0.3 mol% sintered at 1,050°C achieved d₃₃ = 367 pC/N, k_p = 0.54, and ε^T₃₃/ε₀ = 1,643. The Curie temperature was also enhanced to 347.8°C, compared with 297.2°C for the reference specimen sintered at 1,250°C. These results demonstrate that LiBiO₂ addition enables a 200°C reduction in sintering temperature while maintaining piezoelectric performance and improving thermal stability.

In this study, we systematically investigated the effects of thermal atomic layer deposition (ALD) conditions on the electrical characteristics of conductive-filament-based volatile threshold switching memristors with a Pt/Al₂O₃/Ag structure. Although volatile threshold switching memristors have attracted significant attention for neuromorphic computing applications such as spiking neural networks, the impact of dielectric deposition conditions on their switching behavior remains relatively unexplored. The number of ALD cycles was varied from 40 to 200, and the deposition temperature was varied from 50 to 250°C to evaluate their effects on threshold voltage (V_th), off-state resistance (R_off), and device yield. Devices fabricated using 75–150 ALD cycles showed clear volatile threshold switching behavior with relatively high device yield, whereas excessively low or high cycle numbers resulted in short-type and open-type failures, respectively. In addition, V_th and R_off tended to increase at higher deposition temperatures, while the device yield significantly degraded above 150°C. These results indicate that the number of ALD cycles and the deposition temperature define a critical process window for achieving volatile threshold switching while suppressing both short-type and open-type failures. This study provides practical guidelines for optimizing dielectric ALD conditions in conductive-filament-based volatile threshold switching memristors for future neuromorphic hardware applications.

The phase transition of Li₃PO₄ solid electrolyte for secondary batteries in vacuum has been studied by using real-time synchrotron X-ray scattering. According to the vacuum heating results, the crystal β-Li₃PO₄ phase was stable only from room temperature to 400°C. The crystal γ-Li₃PO₄ phase appeared at 410°C and the crystal β-Li₃PO₄ phase completely disappeared at 430°C. The transition from the β-Li₃PO₄ to the γ-Li₃PO₄ phases occurred primarily at 410°C, which is 40°C lower than the transition temperature of 450°C in air. The decrease in the phase transition temperature in vacuum, compared to that in air, is attributed to a relatively high concentration of oxygen vacancies. As the isothermal annealing time at 390°C was increased to 8 hours, the β-Li₃PO₄ phase was completely transitioned into the γ-Li₃PO₄ phase. Our study revealed the detailed transition behavior from the β-Li₃PO₄ to the γ-Li₃PO₄ phases during real-time annealing in vacuum.

The effects of BaZrO₃ addition on the structural and electrical properties of BaTiO₃-based base-metal-electrode (BME) multilayer ceramic capacitor (MLCC) ceramics were investigated. Dielectric compositions containing 0–9 wt% BaZrO₃ were fabricated using a conventional MLCC process, and their crystal structure, dielectric behavior, temperature stability, frequency stability, and insulation resistance were evaluated. X-ray diffraction and Rietveld refinement confirmed the formation of a single-phase perovskite structure for all compositions. Increasing BaZrO₃ content resulted in a systematic shift of diffraction peaks toward lower angles and an increase in unit-cell volume from 64.61 to 66.05 ų, indicating successful Zr incorporation into the BaTiO₃ lattice. The dielectric permittivity increased with BaZrO₃ addition and reached a maximum value of approximately 2,110 at 6 wt%, while dielectric loss decreased significantly. Capacitance stability against temperature and frequency variations was markedly improved with increasing BaZrO₃ content. In addition, insulation resistance increased substantially over the investigated temperature range, demonstrating enhanced electrical reliability.

X-ray photon correlation spectroscopy (XPCS) provides access to nanoscale dynamics, yet practical approaches for interpreting its data remain limited. This tutorial presents a systematic framework for XPCS data analysis, illustrated using measurements performed at the NSLS-II CHX beamline. The fundamental concepts of speckle pattern and the intensity autocorrelation function are introduced, followed by ferroelectric case studies demonstrating how polarization switching and phase transition dynamics can be extracted from XPCS measurements. The influence of the probed q-range experimental conditions such as X-ray transmittance is examined for data interpretation. These elements are consolidated into practical guidelines for the reliable analysis of XPCS data.

Two-dimensional van der Waals (2D vdW) magnets have attracted enormous attention as an emerging material platform for magnetism, spintronics, and multifunctional applications. Their single-crystalline layered structures, layer-number controllability, and unique 2D properties provide unique opportunities that are difficult to achieve in conventional magnetic materials. However, the discovery and development of new 2D magnetic compounds require considerable time and effort, and only a limited number of these materials have been reported to be suitable for practical use. Therefore, materials engineering based on already established 2D vdW magnets has become an important research direction to explore new characteristics and find a practical route for device applications. This review summarizes recent materials engineering pathways for 2D vdW magnets. The main contents focus on the engineering strategy through electrostatic, chemical, lattice, symmetry, and heterostructure ways. These approaches provide practical design routes for tailoring magnetic properties beyond intrinsic 2D vdW magnets. Further progress will require broader application to various types of materials and delicate optimization that connects expanding fundamental magnetism with electromagnetic device applications.

Smart windows capable of dynamically controlling light transmission are gaining increasing attention as a means of reducing building energy consumption while improving indoor comfort. However, indium tin oxide (ITO), the most widely used transparent electrode in such devices, suffers from poor mechanical flexibility due to its intrinsic brittleness, limiting its use in curved or flexible window applications. Here, we demonstrate a flexible ITO/DPP hybrid transparent electrode, fabricated by depositing a dimethyl sulfoxide (DMSO)-doped PEDOT:PSS (DPP) layer on ITO, that achieves markedly improved bending durability while maintaining electro-optical performance comparable to bare ITO. The hybrid electrode with an optimized DPP thickness of 120 nm exhibited a sheet resistance of 23.3 Ω/sq., about 20% lower than that of ITO (29 Ω/sq.), while maintaining comparable visible-range transmittance. A polymer-dispersed liquid crystal (PDLC) device fabricated with this electrode showed only a slight decline in driving voltage and transmittance relative to ITO. Notably, its resistance change under repeated bending at a curvature radius of 30 mm was only 25.1%, less than half that of ITO (51.6%). These results suggest that the ITO/DPP hybrid electrode is a promising candidate for transparent electrodes in curved and flexible smart windows and other flexible optoelectronic devices.

We have studied the thermal stability of NCM622 cathode material for Li-ion batteries using real-time synchrotron x-ray scattering below 600°C in both air and vacuum. The expansion of the mean particle size, which reached maximum values of 10.3 μm in air and 10.6 μm in vacuum at 200°C, was attributed to the dehydration of intergranular water within the NCM622 powders. Across all annealing temperatures, the amount of crystal NCM622 phase in air was consistently higher than that in vacuum. The crystal domain sizes in air showed less variation than that in vacuum during annealing from RT to 500°C. These indicate that the crystal NCM622 phase is more thermally stable during annealing in air than in vacuum. This stability is attributed to the presence of 21% oxygen in air, which is absent under vacuum conditions.

Dye-sensitized solar cells (DSSCs) suffer from efficiency limitations due to interfacial charge recombination at the TiO₂/dye/electrolyte interface. In this study, aminopropyltrimethoxysilane (APS) was introduced onto nanoporous TiO₂ photoelectrodes via a dip-coating process with controlled coating times to investigate the effect of silanization time on interfacial charge transport behavior. Unlike concentration-driven structural modification, this work focuses on the evolution of the APS-modified interface governed by reaction time. The DSSC with 30 min APS treatment exhibited the highest power conversion efficiency of 5.34%, representing a 19% enhancement compared to the untreated device (4.49%), mainly due to increased short-circuit current density and open-circuit voltage. However, prolonged coating times (2 h and 24 h) resulted in a significant decrease in photocurrent density, leading to reduced device performance despite partial improvement in recombination resistance. These results are attributed to the time-dependent evolution of the APS interfacial layer. At moderate coating time, APS provides effective surface functionalization, enhancing dye adsorption and suppressing interfacial recombination. In contrast, prolonged coating is expected to induce increased surface coverage and silane condensation, which can hinder electron injection and increase charge transport resistance. Therefore, the photovoltaic performance is governed by a trade-off between recombination suppression and charge injection efficiency, controlled by the silanization time. This study highlights the critical role of interfacial reaction kinetics in determining charge transport behavior and provides an effective strategy for optimizing DSSC performance through time-dependent interface engineering.

Citations

• Enhanced charge transport characteristics of hydrothermally grown rutile TiO2 nanorod arrays for dye-sensitized solar cells
  Kyu Seop Choi, Hyung Jin Kim, Byungyou Hong
  Surfaces and Interfaces.2026; 98: 110402.     CrossRef

Dye adsorption is one of the most time-consuming processes in the fabrication of dye-sensitized solar cells (DSSCs), typically requiring approximately 24 h at room temperature. In this study, the effect of adsorption temperature and time on photovoltaic performance of DSSCs was investigated in order to reduce processing time and improve device productivity. Nanoporous TiO₂ photoelectrodes were immersed in N719 dye solution at 60°C for 3 h, 10 h, 17 h, and 24 h, and their performance was compared with that of cells sensitized at room temperature for 24 h. Photovoltaic characterization under AM 1.5 illumination showed that DSSCs sensitized at 60°C exhibited improved performance compared to those sensitized at room temperature. The device sensitized at 60°C for 3 h showed comparable or higher conversion efficiency than the reference cell sensitized for 24 h at room temperature. The improvement in device performance is attributed to enhanced dye adsorption kinetics resulting from increased reaction rate between the carboxyl groups of N719 dye molecules and hydroxyl groups on the TiO₂ surface. Electrochemical impedance spectroscopy analysis revealed reduced recombination resistance at the TiO₂/dye/electrolyte interface for cells sensitized at elevated temperature. UV–Vis absorption analysis confirmed increased dye loading on the TiO₂ surface for the 60°C condition. These results demonstrate that elevated temperature dye adsorption significantly reduces processing time while maintaining photovoltaic performance, providing an effective strategy for improving manufacturing efficiency of DSSCs.

Citations

• Enhanced charge transport characteristics of hydrothermally grown rutile TiO2 nanorod arrays for dye-sensitized solar cells
  Kyu Seop Choi, Hyung Jin Kim, Byungyou Hong
  Surfaces and Interfaces.2026; 98: 110402.     CrossRef

The dielectric and piezoelectric properties of the ferroelectric BaTiO₃ were measured and analyzed using both strong and weak electric field conditions. To measure the electric field induced polarizations and strains, a high voltage source and the measuring circuit were used and the dielectric constants were measured with an impedance analyzer. The spontaneous polarization of BaTiO₃ at room temperature was calculated as 17 μC/cm² based on the lattice structure and internal ion location, which is in good agreement with the experimental results. The polarization and strain hysteresis curve according to the electric field were analyzed in terms of lattice structure and ion position. The magnitude of remanent polarization is proportional to the offset distance of Ti⁴⁺ ion from the lattice center. The magnitude of dielectric permittivity is proportional to the degree to which Ti⁴⁺ ion can move freely inside the lattice. The magnitude of piezoelectric constant d₃₃ is proportional to how much Ti⁴⁺ ion distorts the lattice as it moves inside the lattice.

The direct utilization of steelmaking by-product gases in solid oxide fuel cells (SOFCs) offers a promising pathway to improve energy efficiency and reduce carbon emissions in the steel industry. In this study, a Sr-deficient and Ni-doped double perovskite oxide, Sr_1.95Fe_1.35Ni_0.15Mo_0.5O_6-δ (SFNM), was investigated as an anode material for direct Linz-Donawitz converter gas (LDG)-fueled SOFCs. A single-phase double perovskite structure was successfully obtained after calcination at 1,200°C for 12 h, while exsolved metallic Ni nanoparticles were generated on the SFNM surface after reduction at 800°C. Electrochemical performance was evaluated using H₂, simulated-LDG, and CO/CO₂ (85:15) fuels at 800°C. The maximum power densities achieved were 1.23, 0.70, and 0.40 W cm^-2 for H₂, simulated-LDG, and CO/CO₂ fuels, respectively. Although CO-containing fuels exhibited lower opencircuit voltages and power outputs than H₂, the SFNM anode maintained stable operation and appreciable performance under direct simulated-LDG utilization. Impedance analysis revealed that the increased polarization resistance in simulated-LDG and CO/CO₂ atmospheres was mainly associated with fuel adsorption/desorption and gas diffusion, while interfacial charge-transfer resistance remained relatively small. The superior performance obtained with simulated-LDG compared to the CO/CO₂ mixture was attributed to the presence of a small amount of H₂, which facilitated anode reaction kinetics. These results demonstrate that SFNM is a promising mixed ionic-electronic conductor anode for the direct electrochemical conversion of CO-rich steelmaking by-product gases into electricity.

Wearable temperature sensors are becoming increasingly important for continuous health monitoring, personalized healthcare, and biointegrated electronic systems. However, conventional temperature-sensing platforms often suffer from limited thermal sensitivity, insufficient mechanical compliance, and unstable performance under repeated deformation, making it difficult to detect subtle physiological temperature variations in real time. Here, this tutorial status report presents a fabrication strategy for highly sensitive wearable temperature sensors based on gold-doped crystalline silicon nanomembranes. Gold diffusion into crystalline silicon introduces deep-level impurity states that modulate the Fermi level and shift the freeze-out region toward the physiological temperature range, enabling an ultrahigh negative temperature coefficient of resistance. By integrating the gold-doped silicon nanomembrane with a polyimide-supported ultrathin platform, neutral mechanical plane design, and serpentine mesh interconnects, the resulting device can provide high thermal sensitivity, fast response, conformal skin attachment, and stable operation under mechanical deformation. This fabrication approach is expected to broaden the use of impurity-engineered silicon nanomembranes in next-generation wearable sensors, flexible bioelectronics, and multifunctional healthcare monitoring systems.

This review offers a critical overview of recent developments in lead-free piezoelectric materials and flexible device architectures for self-powered wearable and Internet of Things systems. It examines the scientific and technological rationale for replacing conventional battery-dependent power sources with ambient mechanical energy harvesters, and it evaluates the relative merits of inorganic ceramics, organic polymers, and composite systems in achieving efficient electromechanical conversion under practical operating conditions. The discussion further considers compositional tuning, phase boundary engineering, microstructural optimization, and device-level integration as key strategies for improving piezoelectric output, mechanical compliance, durability, and manufacturability. By connecting fundamental materials design with application-driven device requirements, the review identifies the principal challenges and emerging directions necessary for the realization of reliable, scalable, and sustainable electronic platforms.

Renewable energy harvesting technologies, which convert ambient resources such as wind into electrical energy, have attracted significant attention as sustainable power sources for self-powered systems. However, the long-term applicability of wind energy harvesters in remote or extreme environments has not yet been fully discussed, particularly in terms of structural robustness and environmental adaptability. In this study, we designed a double-clamped flutter-type triboelectric generator (DFTEG) for efficient wind energy harvesting and evaluated its output performance under various simulated outdoor conditions. The DFTEG features a modular acrylic frame with a magnet-based assembly for easy maintenance and film replacement, utilizing PTFE films and aluminum electrodes to maximize the charge density difference according to the triboelectric series. Structural optimization revealed that a single-film configuration with a length of 110 mm produced the most stable flutter vibration and a large effective contact area, achieving a maximum open-circuit voltage of 42.28 V and a short-circuit current of 2.89 μA. Furthermore, performance evaluations under various environmental variables, including relative humidity, temperature, and sand particles interference, confirmed consistent electrical output across diverse environmental conditions. These results demonstrate the potential of the proposed DFTEG as an environmentadaptive independent power source capable of stable operation under complex environmental factors.

With the rapid expansion of electric vehicles (EVs) and energy storage systems (ESS), ensuring the operational safety of lithium-ion batteries has become a critical technical challenge. Conventional battery management systems (BMS) primarily rely on threshold-based rule logic, which is limited in detecting coupled anomalies and early-stage degradation patterns. In this study, a deep learning-based framework for multivariate anomaly detection is proposed using BMS sensor data, including voltage, current, temperature, state of charge (SOC), and state of health (SOH). Five representative fault scenarios were defined, including thermal runaway precursors, cell voltage imbalance, SOC inconsistency, internal resistance increase, and communication delay. The proposed CNN-LSTM model was compared with conventional Rule-based methods and machine learning models, including Isolation Forest, Autoencoder, and LSTM. Experimental results show that the proposed model achieved the highest performance, with an F1-score of 0.885, an AUC of 0.94, and a detection delay of 8.1 s. In contrast, the Rule-based method exhibited a significantly higher false negative rate of 42.0%, indicating limitations in detecting complex anomaly patterns. These results demonstrate that the proposed spatiotemporal deep learning approach can significantly improve the accuracy and responsiveness of battery anomaly detection. Furthermore, the proposed method is expected to contribute to enhancing safety, reliability, and predictive diagnostics in next-generation intelligent BMS platforms.

This study proposes an optimization strategy for the over-current protection (OCP) parameters of a lithium iron phosphate (LiFePO₄, LFP) battery system used in electric golf carts operating under high motor-load conditions. Real-world hillclimbing tests were conducted under four clearly defined payload/passenger conditions to analyze the transient discharge-current pro-file, voltage sag, and cell-temperature response. The maximum discharge current reached -238.2 A under the 200 kg cargopayload and one-passenger condition, and the current interval exceeding 150 A lasted up to 27 s. The maximum instantaneous power was 11.05 kW. Thermal analysis showed that the cell-temperature rise was within 2°C and the maximum measured cell temperature was 22.3°C. Linear regression of voltage and current yielded R² = 0.9368 and dV/dI = 0.0126 Ω, which was used as the DC internalresistance estimate. Based on these quantitative results and the cell specification limit of 300 A continuous discharge, the OCP threshold was reviewed from 250 A to 280 A to improve driving continuity while remaining below the allowable continuous-discharge current. EIS-based SOH estimation and the AI-BMS variable protection logic are presented as an extension framework for reflecting temperature and aging effects in future OCP-setting decisions.

This paper reviews the energy yield enhancement characteristics of bifacial photovoltaic systems combined with solar tracking, focusing on their performance relative to conventional monofacial fixed-tilt configurations. The fundamental mechanisms of yield improvement are summarized, highlighting the largely additive contributions of solar tracking, which increases front-side irradiance, and bifacial modules, which utilize rear-side reflected and diffuse radiation. Reported results from previous studies indicate that bifacial systems with single-axis tracking typically achieve 25–35% higher annual energy yield compared with standard monofacial fixed-tilt systems, with variations depending on environmental and design conditions. Key design and environmental considerations influencing system performance are discussed to provide practical insights for the application of bifacial tracking systems in utilityscale photovoltaic installations.

The expansion of smart healthcare and wearable electronics has intensified the need for fabric-based sensors that integrate conformally with the human body for continuous bio signal monitoring. However, the heavy reliance of conventional devices on external batteries remains a major obstacle to commercialization, necessitating the development of flexible piezoelectric energy harvesters that convert biomechanical energy into sustainable power. Here, we present a highly flexible and wearable piezoelectric energy harvester (PEH) fabricated by a screen-printing of BaTiO₃ nanoparticlePDMS composites onto a fabric substrate. An optimized piezo-ceramic filler concentration of 70 wt% yielded a peak output voltage of 0.52 V and a current of 40 nA under the mechanical bending deformations. The fabricated PEH demonstrated exceptional mechanical and electrical stability, showing no performance degradation of over 5,000 repetitive bending cycles. These results indicate that a PEH can function as a stable self-powered source within complex clothing environments, offering a promising pathway for next-generation autonomous wearable sensor systems.

Polymer nanocomposites incorporating inorganic nanofillers have emerged as highly promising electromagnetic interference (EMI) shielding materials, combining mechanical compliance with robust conductive percolation networks. Carbon nanotubes (CNTs) are particularly attractive as conductive fillers because their high aspect ratio facilitates percolation at low loadings. Also, CNTs offer superior mechanical durability under deformation compared to rigid, fracture-prone metal nanowires. For EMI shielding, high electrical conductivity is critical as it enhances both reflection and absorption through efficient charge dissipation and conduction losses. However, achieving highly aligned conductive pathways without degrading the intrinsic electrical properties of CNTs remains a significant challenge. Here, we demonstrate a non-destructive magnetic surface-functionalization and alignment strategy. Using a polydopamine (PDA)-mediated route, pristine multiwalled CNTs are uniformly decorated with Fe₃O₄ nanoparticles (FMWCNTs). This enables highly effective magnetic field-driven alignment at fields as low as 10 mT, promoting the strategic formation of percolation networks. By optimizing the Fe₃O₄/MWCNT ratio for high saturation magnetization and uniform coverage, the aligned FMWCNTs exhibit significant electrical anisotropy, delivering a 10.7-fold higher electrical conductivity in the parallel configuration compared to the vertical configuration. These findings present a scalable, room-temperature platform for engineering directionally enhanced conductivity in polymer nanocomposites, with broad applicability in advanced EMI shielding, flexible electronics, and advanced packaging technologies.

Citations

• Interfacial Engineering of Composite Piezoelectric Fibers Via an Anchor-Chain Architecture
  Jun Liu, Qiao Zhou, Pengcheng Zhang, Shuying Hu, Fang Zhou, Shuangshuang Ren, Ting Guo, Leiying Miao
  ACS Applied Engineering Materials.2026; 4(8): 4367.     CrossRef

GaN nanowire (NW)-based hybrid structures have attracted attention for optoelectronic applications due to their high surface area and efficient carrier transport. However, the optical transparency of GaN NWs is often limited by unintended residual species accumulated on the surface and in the inter-wire regions, as well as defect-related absorption, leading to reduced light transmission. In this work, we demonstrate that thermal annealing significantly improves the optical transparency of GaN NWs grown on indium tin oxide (ITO)/glass substrates. The transmittance increased from 47.9% to 78.5% at 550 nm after rapid thermal annealing at 800^oC for 3 min, while a comparable value (~75.5%) was achieved at 600^oC for 5 min. PbBr₃ was deposited onto the GaN NWs to form hybrid structures, and temperature-dependent photoluminescence (TDPL) measurements revealed enhanced emission stability with suppressed peak shift and reduced spectral broadening. Arrhenius analysis based on a two-channel model revealed that the activation energy of the dominant non-radiative recombination pathway increased from 62 meV in the as-grown sample to 85 meV after thermal annealing, while its relative contribution remained nearly unchanged. In contrast, the shallow trap-assisted pathway exhibited a similar activation energy of approximately 6 meV in both samples, but its contribution decreased from 0.35 to 0.17 after annealing. As a result, the internal quantum efficiency (IQE) improved from 75.9% to 87.4%. These results show that thermal annealing improves optical transparency by removing residuals and suppresses defect-related recombination, leading to enhanced carrier dynamics and improved optical performance of PbBr₃-based hybrid structures.

This paper proposes a circular sequential lighting control method to reduce current imbalance and luminance deviation among multiple LED modules in AC-powered LED lighting systems. Conventional fixed-sequence lighting control repeatedly prioritizes the same LED modules in every rectified voltage cycle, which leads to unequal current distribution, luminance non-uniformity, and the accelerated degradation of specific modules during long-term operation. To address these limitations, a circular sequential lighting strategy is introduced, in which the lighting order is cyclically rotated at every rectified cycle, ensuring that all LED modules experience equal lighting opportunities. A prototype AC-LED lighting system consisting of four series-connected LED modules was implemented and experimentally evaluated. The results demonstrate that, while the conventional fixed-sequence method produces a maximum average current deviation of up to 1.6 mA among modules, the proposed method equalizes the average current across all modules to approximately 17.1 mA. Furthermore, the flicker index remains at 0.13, which is comparable to that of the conventional method, indicating that luminance uniformity is improved without degradation of optical performance. The proposed circular sequential lighting control effectively distributes electrical stress, enhances luminance uniformity, and improves long-term reliability, making it a practical and efficient solution for high-quality AC-LED lighting applications.

The rapid advancement of large-scale language models and artificial intelligence technologies has highlighted the importance of data processing efficiency. This study outlines a measurement optimization method for high-speed pulse equipment to accurately analyze the operating dynamics of ReRAM, a core hardware component for simulating neural networks. An optimized evaluation methodology combining connection compensation and a dual-channel configuration was established to minimize measurement errors caused by parasitic resistance and capacitance during pulse measurements using the Keithley 4200A-SCS and 4225-PMU modules, and to address HRS/LRS measurement errors caused by mismatches between the measurement range and source limits. The proposed precision measurement guidelines can be applied to the evaluation of semiconductor devices that require pulse measurements, such as transistors and DRAM.

Metamaterials, as artificially engineered structures with unconventional mechanical and acoustic properties, have recently emerged as a transformative platform for enhancing the capabilities of triboelectric nanogenerator (TENG) systems. Since the invention of TENG devices, extensive efforts have been devoted to improving charge density, output stability, and overall performance. Conventional performance optimization strategies mainly rely on device-level improvements such as surface chemistry modification, microstructuring, and nanopatterning. However, limited emphasis has been given to system-level development of smart self-powered intelligent systems. The integration of metamaterials into TENG devices opens a new era by enabling frequency-selective localization, mechanical impedance matching, and controllable deformation pathways. These engineered mechanical structures not only improve energy harvesting efficiency but also introduce new functionalities into the system. This review systematically summarizes recent advances in metamaterial-integrated TENG systems across four major application domains: (i) energy harvesting, (ii) acoustic telecommunication and acoustic-to-electric conversion, (iii) self-powered sensing, and (iv) vibration suppression and monitoring. Overall, the integration of metamaterials into TENG systems will pave the way for next-generation sustainable, intelligent, self-powered devices with diverse functionalities.

Citations

• Fabrication and performance of integrated self-powered PAAM hydrogel flexible pressure sensors
  Huaikuan Zang, Chao Hu, Pan Niu, Yong Zhang
  Materials Science in Semiconductor Processing.2026; 214: 110899.     CrossRef
• Highly Stretchable Multiphase Composite Piezoelectret With Large Longitudinal and Transverse Piezoelectric Sensitivity for Self-Powered Electromechanical Sensors
  Yanfeng Lyu, Tiantian Gao, Jian Li, Zheng Hu, Xunlin Qiu, Yanxun Xiang, Fu-Zhen Xuan, Wee Chen Gan, Dietmar Auhl
  IEEE Sensors Journal.2026; 26(18): 27090.     CrossRef

Lead-free bismuth sodium titanate (BNT)-based ceramics have attracted strong attention as environmentally benign dielectric materials for high-efficiency electrostatic energy-storage capacitors. A key challenge is that pristine BNT typically exhibits large hysteresis, high remnant polarization, and limited dielectric reliability, which restrict recoverable energy storage and efficiency under practical electric fields. Here, we present a focused mini-review of recent studies to clarify how composition design, phase boundary tuning, defect chemistry, and microstructural control collectively enable slim or pinched polarization-electric field (P-E) behavior and improved energy-storage functionality in BNT-related bulk ceramics. The reviewed outcomes consistently show that stabilizing relaxor states governed by polar nanoregions (PNRs), often via solid-solution engineering and secondary relaxor/antiferroelectric-like incorporation, suppresses irreversible switching and reduces hysteresis loss, while densification and grain-size control enhance electrical homogeneity and breakdown strength. In addition, defect-mediated tuning of oxygen vacancy-related complexes is highlighted as an independent lever to control relaxor ergodicity and polarization reversibility, providing a complementary route to slim-loop optimization. These insights are expected to guide integrated design strategies that couple phase/relaxor-state engineering with defect and microstructure optimization, accelerating the development of reliable, temperature-robust, lead-free dielectric capacitors based on BNT-related ceramics.

Citations

• Progress and outlook of dielectric energy storage characteristics of Lead–free (K,Na)NbO3 based bulk ceramics/composite films for capacitors
  Twinkle, Varun Kamboj, Chetna, Arun Kumar Singh, Gurpreet Singh, Sanjeev Kumar
  Current Opinion in Solid State and Materials Science.2026; 44: 101297.     CrossRef
• Structural Stability and Electromechanical Response of Lead-Free (Bi1/2Na1/2)TiO3‒SrTiO3 Ceramics Under A-Site Strontium Non-Stoichiometry
  Yubin Kang, Trang An Duong, Gwang-Hwi Jeong, Chang Won Ahn, Yong-Jai Kwon, Hyoung-Su Han
  Journal of Electrical and Electronic Materials.2026; 39(5): 549.     CrossRef

The recent rapid adoption of electric vehicles (EVs) is creating new load characteristics in the distribution system, and in particular, the widespread use of single-phase charging methods is exacerbating phase load imbalances, leading to voltage unbalance issues. Such voltage imbalances can undermine the stability of the distribution system and may cause side effects such as reduced power quality and shortened equipment lifespan. This study proposes a smart distribution panel system that can detect voltage imbalance issues caused by uneven electric vehicle charging loads in real time and actively compensate for them. The proposed system aims to contribute to the stability and power quality improvement of the distribution network by integrating a load balancing algorithm with inter-phase voltage monitoring functionality.

Long lifetime, low power consumption, and environmental friendliness have enabled light-emitting diode (LED) lighting to rapidly replace conventional light sources such as incandescent and fluorescent lamps. In particular, AC-LED lighting systems can be directly powered by commercial alternating current (AC) sources; however, they suffer from significant luminance deviation caused by uneven current distribution among LED light-emitting modules. This paper proposes a lighting control method that improves flicker performance while maintaining lamp brightness and effectively reduces luminance deviation in AC-LED lighting. The proposed method reduces luminance deviation by controlling the lighting order of multiple LED light-emitting modules. Among four LED modules, only the required number of modules is continuously turned on, and the lighting priority alternates between rectification cycles. Specifically, during odd rectification cycles, LED modules are activated sequentially in ascending order (11→12→13→14), whereas during even rectification cycles, they are activated in descending order (14→13→12→11). By alternately applying continuous lighting control with opposite activation orders, the proposed reverse alternating lighting control method equalizes the current distribution among LED modules. As a result, luminance uniformity is improved, electrical stress concentration on specific modules is reduced, and the operational lifetime of the LED modules is extended compared with the conventional fixed-sequence lighting control method.

Citations

• Reduction of Luminance Deviation in Multi-Module AC-LED Lighting Systems Using a Circular Sequential Lighting Control Method
  Dong Won Lee, Byungcheul Kim
  Journal of Electrical and Electronic Materials.2026; 39(3): 267.     CrossRef

This study investigates the effect of dielectric layer thickness on the electrical and reliability characteristics of BaTiO₃- based X8R multilayer ceramic capacitors (MLCCs) for automotive applications. MLCCs with 30 dielectric layers and thicknesses ranging from 5 to 30 μm were fabricated, and key parameters―including capacitance, equivalent series resistance (ESR), insulation resistance (IR), breakdown voltage (BDV), DC-bias characteristics, temperature coefficient of capacitance (TCC), and ripple current-induced heating―were evaluated. The dielectric constant (~2,000) and sintering shrinkage (~-25%) were nearly independent of thickness, confirming stable microstructure formation. ESR increased with thickness, while normalized BDV (V/μm) decreased due to defect accumulation. IR improved with increasing thickness but dropped sharply above 125℃. Dielectrics thinner than 10 μm exhibited significant capacitance degradation under DC-bias and temperature variation, reflecting strong internal field effects. Ripple-induced heating correlated directly with ESR. These results indicate that, although thinner layers enhance capacitance density, reducing the thickness below 10 μm compromises bias stability and thermal reliability. A minimum dielectric thickness of 10 μm is therefore recommended to achieve an optimal balance between electrical performance and durability in high-reliability X8R MLCCs.

Citations

• Structural Analysis of Electric Field-Induced Polarization and Strain in Ferroelectric BaTiO₃
  Jae Hwan Park
  Journal of Electrical and Electronic Materials.2026; 39(4): 374.     CrossRef

Neuromorphic computing, which mimics the energy-efficient parallel processing capabilities of the human brain, has emerged as an alternative to traditional von Neumann architectures that struggle with high power consumption in the era of artificial intelligence (AI). Despite the potential of Si-based neuromorphic chips, they often face fundamental limitations in integration density and biological compatibility, necessitating the development of next-generation devices that can better emulate the ionic signaling of biological systems. This review provides a comprehensive analysis of the recent research trends in artificial synapses and neurons based on organic electrochemical transistors (OECTs), highlighting their unique ability to achieve high transconductance and mixed ionic-electronic conduction at ultra-low operating voltages. We discuss how OECTs successfully replicate diverse synaptic plasticities and complex neuronal spiking behaviors through advanced material engineering and structural optimizations such as vertical architectures. Furthermore, this review discusses the implementation of high-order neural functions, including associative learning and logic operations, which are facilitated by the inherent electrochemical dynamics of organic semiconductors. Finally, overcoming current challenges in reliability and scalability will establish OECTs as a pivotal platform for low-power neuromorphic hardware and bio-integrated electronics.

Citations

• Analysis of Yield and Electrical Characteristics of Ag Electrode-Based Volatile Threshold Switching Memristors with Al2O3 Dielectric Films Under Different ALD Process Conditions
  Wan-Sik Woo, Seung-Jin Lee, Moon-Seok Kim, Seung-Bae Jeon
  Journal of Electrical and Electronic Materials.2026; 39(5): 493.     CrossRef