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.

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.

The development of a large-area solution process for CuO nanowires, which are promising p-type thin film transistors (TFT) channel materials, is required. To overcome the limitations of the existing high-vacuum and high-cost deposition process, a large-area Cu nanowire network was formed on the substrate using the Mayer rod coating method, and a CuO channel was implemented by subsequent thermal annealing. Consequently, p-type TFT with an on/off current ratio of 1.4×10⁴ and a field-effect mobility µ_FE≈10^-4 cm²/(V⋅s). was fabricated and optimized. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that the sample annealed at 200°C exhibited an incomplete oxidation state with a mixed Cu/Cu₂O phase and a high fraction of M-OH species (58.78%), resulting in a low on/off current ratio (≈1.2). In contrast, annealing at 450°C leads to a CuOdominant phase, where the fraction of lattice oxygen(O1) increases to 31.11% and the oxygen vacancy (VO) component increases to 7.15%, indicating a significant improvement in hole concentration and charge transport. These phase transitions and surface chemical changes are identified as the key mechanisms for the enhanced TFT switching characteristics. The low-cost, large-area Mayer rodbased solution process proposed in this study provides a basic process platform for p-type TFTs applicable to flexible wearables and display technologies and suggests the possibility of commercialization through additional optimization of bias stability in the future.

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.

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.

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 ability to manipulate and probe biomolecules at the single-molecule level has become an essential approach for understanding molecular interactions, conformational dynamics, and nanoscale transport phenomena. Advances in experimental techniques have enabled precise control of individual molecules with high spatial resolution and piconewton-level force sensitivity. These developments have significantly expanded the capability of studying biomolecular mechanics and dynamics beyond conventional ensemble measurements. A variety of physical strategies have been developed for single-molecule manipulation, including mechanical-force-based approaches, electric-field-driven methods, and nanoscale structural confinement techniques. Mechanical-force-based methods, such as optical tweezers, magnetic tweezers, and atomic force microscopy, enable direct measurement of molecular mechanical responses. Electric-field-based manipulation, represented by dielectrophoresis, allows noncontact control of particles and biomolecules through polarization effects in non-uniform electric fields. In addition, nanopore-based systems employ nanoscale confinement to regulate molecular transport and residence behavior. This review provides an overview of representative single-molecule manipulation techniques based on mechanical, electrical, and structural control and discusses their fundamental principles and implementation strategies.

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.

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.

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.

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.

The increasing global demand for renewable energy has accelerated the deployment of offshore wind farms, thereby highlighting the need for advanced development and performance assessment techniques for dynamic submarine cables used in floating offshore wind systems. These cables are continuously subjected to combined thermal, electrical, and mechanical stresses, with mechanical loading playing a particularly dominant role. As a result, dynamic submarine cables exhibit degradation behaviors that differ significantly from those of conventional fixed submarine cables. This paper presents the design and implementation of a comprehensive evaluation system capable of applying combined thermal, electrical, and mechanical stresses to dynamic submarine cables. The system was validated using a 66 kV wet type submarine cable through commissioning tests and insulation performance measurements. Electrical stress of 72 kV, thermal stress exceeding 95°C, and mechanical stress corresponding to a bending radius of 20 times the cable diameter over 20 cycles were applied to verify system reliability. The subsequent insulation assessments quantitatively confirmed performance variations induced by the combined stresses. The results demonstrate that the proposed platform is the first system capable of simultaneously applying thermal, electrical, and mechanical stresses to dynamic submarine cables, and its operational performance has been successfully validated. This platform enables realistic reliability evaluation of dynamic cables used in floating offshore wind farms and is expected to improve the overall operational reliability of offshore wind power systems.

As electric vehicles (EVs) are rapidly adopted worldwide, large numbers are now transported by sea on dedicated car carriers. With this trend, concerns are increasing about fires and explosions caused by battery thermal runaway during marine transport, while existing SOC limits before loading remain largely empirical. This study experimentally investigates gas generation and explosion characteristics of EV lithium-ion cells under thermal runaway conditions representative of enclosed vehicle decks. We identify and quantify the main off-gas components and clarify the flammability behavior and explosion limits of key combustible species. The results provide basic data for assessing EV battery accidents at sea and support the development of safer ventilation and gas-management strategies for ships.

The quench behavior of wires for superconducting fault current limiters at DC faults was simulated, with a focus on the effect of capacitor discharge on the quench. The behavior was also expressed in mathematical forms to facilitate a better understanding of the simulation results and for rough analytical estimations of the wire length suitable for the circuit voltage and capacitance. The quench resistance development behavior for various wire lengths and circuit capacitances was simulated using the model developed in the previous work. The quench behavior was expressed in mathematical forms, reflecting the concept of heat balance. During the quench, the wire temperature increased more slowly for longer wires, but was found to increase in a similar pattern. The wire length estimated by the mathematical formula was close to the one obtained by the simulation, with an error range of a few %. The calculations will be used to estimate effectively the length of wires needed to build superconducting fault current limiters for applications in DC power systems.

Cellulose nanofiber (CNF) has attracted significant attention as a next-generation insulating material due to its ecofriendly nature and outstanding functionalities. However, conventional kraft insulation paper suffers from limited dielectric breakdown strength and long-term reliability under high-voltage conditions, highlighting the need for alternative materials. In this study, kraft pulp was combined with five types of CNFs (A, B, C: wood-based / D, E: non-wood-based) to fabricate composite insulation papers, and their electrical and mechanical properties were systematically evaluated. The results showed that CNF incorporation generally enhanced density and tensile strength, while certain types contributed to lowering dielectric constant and improving breakdown strength. Among the wood-based CNFs, type C exhibited the most balanced performance in terms of dielectric stability and mechanical reinforcement. Among the non-wood-based CNFs, type E demonstrated notable improvements in structural compactness and tensile strength, suggesting favorable reliability. Therefore, this study identifies CNF C among wood-based types and CNF E among non-wood-based types as the most promising candidates for insulation performance enhancement, suggesting their applicability as next-generation insulating materials for power equipment and ecofriendly electronic devices.

Organic photovoltaics (OPVs) are attractive candidates for sustainable energy conversion due to their flexibility, lowcost processing, and compatibility with large-area fabrication. However, their efficiency is hindered by interfacial defects and vertical phase separation in the active layer, which induce charge imbalance and recombination losses. This work presents an interfacial engineering approach to overcome these limitations in P3HT:PC₇₀BM-based OPVs. Two key strategies were employed: (i) reducing the post-deposition annealing time of the active layer to suppress PC₇₀BM accumulation at the bottom electrode, and (ii) using a DCB:DCM mixed solvent system to regulate solvent evaporation, thereby promoting uniform film formation during PC₇₀BM overlay deposition. Devices fabricated with these optimizations exhibited notable enhancements, achieving short-circuit current density up to 15.83 mA/cm² and a 58.1% increase in power conversion efficiency compared to control devices. X-ray photoelectron spectroscopy confirmed reduced surface aggregation of PC₇₀BM, while X-ray diffraction indicated improved P3HT crystallinity and molecular ordering. These results highlight the critical role of interfacial and morphological control in enhancing charge separation and transport, offering a practical route toward efficient, reproducible, and stable OPVs.

The continuous rise of atmospheric carbon dioxide (CO₂) emissions highlights the urgent need for sustainable air purification technologies. Current Direct Air Capture (DAC) filters often rely on toxic amines, which limit long-term stability and safe application. Here, we report a non-toxic PAN-based nanofiber air filter fabricated by electrospinning and urea-assisted carbonization. Structural analyses confirmed the introduction of nitrogen functionalities that enhanced CO₂ affinity, while SEM and FT-IR revealed graphitic carbon formation. In air-chamber tests, the optimized carbonized nanofiber reduced CO₂ concentration from 25,000 ppm to 2,000 ppm, a level generally regarded as acceptable for indoor environments, while simultaneously removing over 95% of PM₁₀, PM_2.5, and PM_0.1 particulates. This dual functionality, combined with facile fabrication and material safety, demonstrates strong potential for PAN-derived carbon nanofiber membranes in DAC systems and eco-friendly air purification devices. These findings suggest a viable pathway toward scalable, sustainable air-filter technologies for carbon-neutral applications.

In this study, Y₂O₃ thin films were deposited on Si(100) wafers using an RF sputtering system with a Y₂O₃ target. The Y₂O₃ thin film was confirmed to have a thickness of 227 nm/min and a uniformity of 1.34% at a substrate temperature of 400℃. All samples were annealed at 600, 800, and 1,000℃ for 1 hour in an O₂ gas atmosphere using the furnace. The analysis of the XRD patterns revealed that the peak intensity increased with annealing up to 800℃, but decreased when the annealing temperature was raised to 1,000℃. The XPS analysis confirmed the onset of crystallization at 800℃, in agreement with the trends observed in the XRD results. According to the AFM results, the surface became slightly smoother after heat treatment, as indicated by a reduced RMS roughness of approximately 1.792 nm.

Silicon carbide (SiC) power devices are attracting increasing attention for high-voltage and high-efficiency applications due to their superior material properties. However, achieving an optimal trade-off between specific on-resistance (Ron,sp) and breakdown voltage (BV) remains a key design challenge in planar MOSFET structures. In this study, twodimensional TCAD simulations were conducted to investigate the impact of varying the doping concentrations of the P-well (from 3 × 10¹⁷ to 6 × 10¹⁷ cm^-3) and JFET regions (from 1 × 10¹⁶ to 7 × 1016 cm^-3) on the electrical characteristics of 2.4 kVclass planar SiC MOSFETs. To maintain comparable BV conditions for 2.4 kV operation, two groups with P-well doping concentrations of 4.5 × 10¹⁷ cm^-3 and 5.3 × 1017 cm^-3 were analyzed and compared. When the P-well and JFET doping concentrations were 4.5 × 10¹⁷ cm^-3 and 1.5 × 10¹⁶ cm^-3, respectively, the simulated Ron,sp and BV were 1.41 mΩ·cm² and 3,150 V. In contrast, with P-well and JFET doping concentrations of 5.3 × 10¹⁷ cm^-3 and 5.0 × 10¹⁶ cm^-3, the Ron,sp was reduced to 1.31 mΩ·cm² while the BV slightly increased to 3,200 V. Based on these results, an optimized device structure was proposed, demonstrating its potential for integration into high-voltage SiC-based power systems. This study provides practical design insights and is expected to contribute to the advancement of wide bandgap semiconductor technologies for next-generation power electronics.

With the advancement of the information society, the demand for highly integrated and multi-functional electronic devices is rapidly increasing. To meet these demands, high-performance transistors with low power consumption, high-speed operating, and mechanical flexibility are essential. Among various candidates, semiconducting single-walled carbon nanotubes (s-SWCNT)-based transistors, which exhibit intrinsically ambipolar characteristics, have emerged as promising components for CMOS-like circuits. In this study, s-SWCNT were selectively dispersed using rr-P3DDT, a thiophene-based conjugated polymer, and filed-effect transistors (FETs) were fabricated by inducting directional alignment for enhanced charge transport through an off-centered spin-coating process. The electrical characteristics of the fabricated s-SWCNT FETs were evaluated under various thermal annealing conditions (100℃, 150℃, 200℃, and 250℃). Off-centered spin-coated and high temperature annealed s- SWCNT FETs exhibited high field-effect mobilities over 5 cm²/Vs in both p-type and n-type operation, along with ideal Vshaped ambipolar transfer curves. These results indicate a significant enhancement in ambipolar performance due to efficient desorption of residual oxygen and water molecules in active channel via high temperature annealing. Furthermore, CMOS-like inverter circuits demonstrated an ideal inversion voltage (VIN = V_DD/2) and a high voltage gain of approximately 9.5. These findings highlight the potential of SWCNT-based materials for realizing next-generation flexible electronic circuits that combine high-performance, energy efficiency, and simplified solution-processing.

Rietveld refinement has become an essential tool for the quantitative analysis of crystal structures in polycrystalline systems using X-ray diffraction data. This tutorial paper focuses on the background, case studies, and practical implementation of Rietveld refinement using the open-source software PROFEX. Key structural parameters, such as lattice constants and phase fractions, can be quantitatively extracted through full-pattern fitting. Case studies involving compositional variation, electric fields, temperature changes, and battery cycling demonstrate the broad applicability of Rietveld refinement in materials science, energy storage, and catalysis. A step-by-step procedure for performing Rietveld refinement is presented using Bi_1/2Na_1/2TiO₃ perovskite ceramic as an example, providing guidance on software installation, preparing crystal structure information files, performing Rietveld refinement, evaluating results using R-factor and χ² values, and summarizing the results. This tutorial aims to improve understanding and accessibility of Rietveld refinement for researchers seeking to investigate structure-property relationships in complex material systems.

Abstract In this study, to develop composition ceramics for energy harvesting devices, Pb(Ni_1/3Nb_2/3)O₃-Pb(Zr Ti)O₃ system ceramics substituted with Pb(Mg_1/2W_1/2)O₃ were manufactured by conventional mixed oxide method using Li₂CO₃ and Na₂CO₃ (LNCO) as sintering aids. Their microstructure and piezoelectric properties were also investigated. At the specimen sintered at 930℃, high values of piezoelectric properties appeared: the dielectric constant (εr) of 2,522 planar electromechanical coupling factor kp of 0.602, and k₃₁ of 0.385, d31 = 229 [pC/N], g₃₁ = 10.13 [mV.m/N], Qm of 70, respectively. These values were suitable for the application of devices such as energy harvesting devices and ultrasonic devices.

In this study, the dielectric and electrical properties of high-capacitance base metal electrode (BME) multilayer ceramic capacitors (MLCCs) fabricated using a BaTiO₃-MgO-Mn₃O₄-(Na₀.₅Bi₀.₅)TiO₃ (NBT)-(BaCa)SiO₃ dielectric system were investigated under reducing atmospheres with oxygen partial pressures (PO₂) ranging from 10⁻1⁰ to 10⁻12 MPa. By incorporating NBT, the dielectric performance remained stable across the entire range of reducing atmospheres. The fabricated MLCCs exhibited consistent capacitance values, low dielectric loss (<2.8%), and high insulation resistance, reaching up to 2.4 GΩ at 25℃ and 0.675 GΩ at 125℃. Furthermore, excellent breakdown voltage performance (up to 550 V at 25℃) and Class II-compatible temperature coefficient of capacitance (TCC) behavior were observed, meeting the X8R specification. The BaTiO₃-MgO-Mn₃O₄-NBT-(BaCa)SiO₃ dielectric system demonstrates that NBT can serve as a promising alternative to conventional rare-earth dopants in BME MLCCs, enabling excellent thermal and electrical stability, high capacitance, and longterm reliability even under reducing conditions. These results confirm the feasibility of developing cost-effective, sustainable, and rare-earth-free MLCCs for high-performance applications in automotive, industrial, and energy storage systems.

Lithium-ion batteries are utilized as an energy source for electric vehicles because of their advantages such as excellent cyclability, high energy density, high capacity, high efficiency, and low price. However, lithium-ion batteries use combustible electrolytes, which have also reported problems related to fire safety. Therefore, research on the fire safety of lithium-ion batteries is actively being conducted. In this study, detection criteria for the fire safety of lithium-ion batteries were proposed through incremental capacity analysis (ICA) and frequency analysis. The experimental results showed that the battery micro internal short circuit (MISC) indicator could be identified through changes in specific frequency bands and fluctuations in the ICA curve.

Aggressive device scaling has severely degraded the switching characteristics of CMOS transistors. This issue has led to the development of tunneling FETs (TFETs) as an alternative. TFETs, with their asymmetric doping of the source and drain regions, offer improved subthreshold swing (SS) compared to conventional MOSFETs. However, despite this advantage, TFETs still suffer from ambipolar current, which increases off-state current (IOFF). This paper introduces an approach to applying hetero gate dielectrics (HGDs) in nanosheet (NS) TFETs to reduce ambipolar current characteristics. The magnitude of the drain electric field is reduced by selectively forming a high-k dielectric near the source region This configuration allows the TFETs to avoid unintended band-to-band tunneling (BTBT) and suppress ambipolar current during the off-state.

This study aimed to elucidate factors limiting power conversion efficiency (PCE) in GaN-based micro-light-emitting diodes (μ-LEDs). To this end, we investigated the effects of operating temperature and chip-size of μ-LEDs on their efficiency. For the investigation, 460 nm-emitting μ-LEDs with various chip-sizes were fabricated; then their characteristics were carefully measured from 100 to 400 K. As the chip-size decreases and the operating temperature increases, their PCE and external quantum efficiency (EQE) decrease, while voltage efficiency (VE) increases. This indicates that the EQE plays a more important role than the VE in determining the PCE of μ-LEDs. Particularly, for a chip-size of 20 × 20 μm², the EQE was very lower and the ideality factor was unexpectedly higher compared to the others for all operating temperatures, which is believed to be due to the critical plasma damage at the sidewall during dry-etching process for the chip-size < 20 × 20 μm².

Ceramic powder is an important material used for various purposes in advanced industries, and the fundamental properties of ceramic powder such as particle size, particle size distribution, and flow properties play a decisive role in determining the quality and performance of the final product. In general, these properties have been evaluated through particle size and shape analysis. However, these methods have limitations in providing a comprehensive understanding phenomena related to powder flow, coagulation, and wear. Consequently, performance evaluation based on the analysis of powder flow properties has been increasingly adopted. Previously, flow properties were primarily assessed using funnel-based methods. However, these methods have limitations, as they are challenging to apply to powders smaller than a few micrometers or those with strong coagulation tendencies, and they also suffer from low reliability. To address these issues, this paper introduces a novel piece of equipment that measures flow properties using image analysis and presents various parameters for static and dynamic flow behavior based on this technique. The proposed equipment offers exceptional versatility, as it can be applied to all types of ceramic powders regardless of their size or shape. The principles and measurement methods of the equipment are demonstrated through static and dynamic image analysis of ceramic powders with varying sizes and shapes used as examples.