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.

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.

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.

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.

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.

Flexible and wearable electronics, which require stable operation under mechanical deformation, are increasingly utilizing Eutectic Gallium-Indium (EGaIn) for their conductive components. This study presents a systematic approach to fabricating highly reliable, deformable electrodes via a direct-ink-writing (DIW) 3D printing process using EGaIn as the functional ink. We conducted a thorough optimization of key printing parameters, specifically the extrusion pressure and printing speed, to achieve stable and uniform conductive lines. Through this optimization, we successfully established an optimal process window, achieving a stable line width of approximately 130 μm at an extrusion pressure of 300 kPa and a printing speed of 16 mm/s. The fabricated flexible electrodes exhibited exceptional electromechanical stability, maintaining negligible resistance change (< 0.82%) both under severe bending (3 mm radius) and after 100 repetitive bending cycles. This work demonstrates that the 3D printing of EGaIn is a viable and effective method for creating robust, high-performance electrodes for the next generation of deformable and wearable electronic devices.

e investigated the effects of post-annealing in vacuum, nitrogen, and hydrogen atmospheres on the structural, electrical, and optical properties of 600 nm thick Al-doped ZnO (ZnO:Al) thin films deposited by RF magnetron sputtering at room temperature. Post-annealing in hydrogen atmosphere at 400℃ for 1 hour showed the most significant improvement in electrical properties. Resistivity decreased from 9.11×10⁻³ to 1.4×10⁻³ Ω·cm, electron mobility increased from 4.11 to 18.23 cm²/V·s, and electron carrier concentration increased from 1.63×10²⁰ to 4.85×10²⁰ cm⁻³. In contrast, post-annealing in vacuum and nitrogen atmospheres resulted in degraded electrical properties due to oxygen and nitrogen chemisorption at grain boundaries. The enhancement in hydrogen-annealed films was attributed to the formation of additional oxygen vacancies and desorption of adsorbed oxygen species from grain boundaries. All films maintained excellent optical transparency of 80-90% in the visible range. The optical bandgap exhibited a blue-shift from 3.365 eV to 3.624 eV due to the Burstein-Moss effect induced by the increased electron carrier concentration. These results confirmed that hydrogen atmosphere post-annealing is the most effective method for enhancing the electrical conductivity of ZnO:Al thin films while maintaining high optical transparency.

Cathodoluminescence (CL) spectroscopy provides valuable insights into the optical and electronic properties of materials by analyzing photon emission induced by electron beam excitation. In this study, we present a novel CL detection system integrated into a transmission electron microscope (TEM) specimen stage, enabling high-resolution optical analysis of internal microstructures. The system features a parabolic mirror, a focusing lens, and a UV-VIS range optical fiber to maximize light collection and transmission efficiency, with performance further enhanced by a liquid nitrogen cooling setup. Using this system, we successfully performed CL mapping of InGaN/GaN multiple quantum wells (MQWs) and GaN thin films. The results revealed that threading dislocations act as non-radiative centers in GaN and locally increase the bandgap energy in InGaN MQWs, causing a blue-shift in CL emission. These findings support a model in which dislocations induce carrier delocalization, preserving high radiative efficiency despite high dislocation densities. This work demonstrates the effectiveness of the TEM-integrated CL system for nanoscale optical characterization, offering a new pathway for studying defect-related phenomena in semiconductor materials.

The mounting demand for sustainable, self-powered biomedical devices, particularly those engineered for extreme environments, has established triboelectric nanogenerators (TENGs) as a prominent technology in energy harvesting research. This review examines state-of-the-art biomaterial synthesis strategies essential for developing high-performance bioelectronic TENGs that can operate reliably under harsh conditions, including elevated temperatures, extreme humidity, and mechanical strain. It begins with a comprehensive overview of the fundamental principles of triboelectricity and subsequently addresses the pivotal challenges associated with efficient charge generation and retention in such challenging settings. The content places particular emphasis on recent advancements in composite material engineering and structure design for high-efficiency mechanisms, with a particular focus on biocompatible and environmentally resilient materials. The integration of TENGs into wearable sensors, implantable devices, and self-powered monitoring systems is also investigated, demonstrating their transformative potential for bioelectronic applications. Our goal subsequently underscores persistent limitations to overcome, including those pertaining to fabrication scalability and long-term operational stability, while concurrently proposing prospective research directions. Consequently, this work underscores how innovative biomaterial synthesis and bioelectronic devices can enable the development of next-generation, high-performance, self-powered devices suited for extreme biomedical environments.

Metal halide perovskite materials have emerged as promising candidates for next-generation optoelectronic applications owing to their outstanding optical properties and tunable emission characteristics. However, their practical application is hindered by poor environmental stability, especially under conditions of heat, moisture, and UV exposure, necessitating effective encapsulation strategies. This review summarizes recent progress in enhancing the environmental stability of perovskite nanocrystals through polymer matrix embedding, inorganic oxide encapsulation, and compositionally matched core-shell structures using homogenous perovskite derivatives. We discuss how polymers enhance the environmental and moisture stability of perovskite nanocrystals, how oxide-based shells (e.g., SiO₂, TiO₂) contribute to thermal robustness and barrier protection, and how homostructural core-shells provide lattice-matched defect passivation with improved long-term durability. A comprehensive understanding of the advantages and limitations of each encapsulation strategy, along with their rational integration, can accelerate the commercialization of perovskite-based technologies in various applications such as highcolor- purity displays, color conversion filters, and flexible optoelectronic devices.

Smart electronic skin (E-skin) is an emerging technology that integrates electronic devices with human skin, enhancing human-machine interactions. One critical challenge in its development is effective thermal management to ensure device reliability, longevity, and user comfort. This review highlights passive cooling techniques - thermal conduction, convection, radiation, and phase-change materials - as key strategies to address this challenge without additional power consumption. These integrated mechanisms have demonstrated the ability to efficiently dissipate heat, preventing thermal buildup and maintaining optimal performance in E-skin devices. Recent advancements indicate that combining these methods can significantly enhance the thermal management of flexible electronics. Future research should focus on refining these materials and techniques to overcome challenges related to cost, durability, and environmental stability, thereby advancing the practical application of E-skin technology.

Iron oxide nanoparticles (NPs) have gained significant attention for their broad applicability in biomedical imaging, soft robotics, and catalysis owing to their exceptional magnetic properties and biocompatibility. A key challenge in maximizing their functionality lies in achieving a uniform size distribution and dispersity, alongside strong interfacial affinity with the surrounding medium that are essential for optimizing magnetic behavior and processibility. In this study, we present a facile solvothermal synthesis of monodisperse iron oxide NPs with tunable size and controllable surface hydrophobicity by varying precursors, capping agents, and solvents. By varying these synthesis parameters, we demonstrate a clear correlation between NP size, dispersity, and key magnetic properties, including saturation magnetization (MS) and coercivity (HC). This advancement in synthesis methodology offers a reliable, efficient approach for producing high-quality iron oxide NPs, which makes possible for practical use of them across a range of technological and biomedical applications.

This review examines the use of halide perovskite materials in electronic devices, highlighting their exceptional optoelectronic properties and the challenges associated with them. Despite their potential for high-performance devices, practical applications are limited by sensitivity to environmental factors such as moisture and oxygen, etc. We discuss advances in enhancing stability and operational reliability, featuring innovative synthesis methods and device engineering strategies that help mitigate degradation. Furthermore, we explore the integration of perovskites in applications such as field-effect transistors and LEDs, emphasizing their transformative potential. This review also outlines future research directions, stressing the need for ongoing improvements in material stability and device integration to fully realize the commercial potential of perovskites.

Due to changes in the form factor of display panels and touch screen panels in various devices, capacitive touch systems have evolved to address various issues such as low power consumption, noise immunity, and small chip size. Furthermore, some devices have applications that use a stylus. Since the stylus operates similarly to a finger touch, it encounters similar issues. Recent research trends focus on addressing key issues such as noise, which is primarily caused by the self-capacitor formed between the display cathode and the touch screen panel. In this paper, Various research papers discussing methods to eliminate external noise will be reviewed. These advancements enhance noise immunity in touch systems, making it easier to use thinner and more flexible panels. These progress make touch technology more versatile and reliable in various applications.

This study proposes an innovative methodology for developing flexible printed circuit boards (FPCBs) capable of conforming to three-dimensional shapes, meeting the increasing demand for electronic circuits in diverse and complex product designs. By integrating a traditional flat plate-based fabrication process with a subsequent three-dimensional thermal deformation technique, we have successfully demonstrated an FPCB that maintains stable electrical characteristics despite significant shape deformations. Using a modified polyimide substrate along with Ag flake-based conductive ink, we identified optimized process variables that enable substrate thermal deformation at lower temperatures (~130℃) and enhance the stretchability of the conductive ink (ε ~30%). The application of this novel FPCB in a prototype 3D-shaped sensor device, incorporating photosensors and temperature sensors, illustrates its potential for creating multifunctional, shape-adaptable electronic devices. The sensor can detect external light sources and measure ambient temperature, demonstrating stable operation even after transitioning from a planar to a three-dimensional configuration. This research lays the foundation for next-generation FPCBs that can be seamlessly integrated into various products, ushering in a new era of electronic device design and functionality.

Next-generation wide-bandgap semiconductors such as SiC, GaN, and Ga₂O₃ are being considered as potential replacements for current silicon-based power devices due to their high mobility, larger size, and production of high-quality wafers at a moderate cost. In this study, we investigate the gradual modulation of chemical composition in multi-stacked metal oxide semiconductor thin films to enhance the performance and bias stability of thin-film transistors (TFTs). It demonstrates that adjusting the Ga ratio in the indium gallium oxide (IGO) semiconductor allows for precise control over the threshold voltage and enhances device stability. Moreover, employing multiple deposition techniques addresses the inherent limitations of solution-processed amorphous oxide semiconductor TFTs by mitigating porosity induced by solvent evaporation. It is anticipated that solution-processed indium gallium oxide (IGO) semiconductors, with a Ga ratio exceeding 50%, can be utilized in the production of oxide semiconductors with wide band gaps. These materials hold promise for power electronic applications necessitating high voltage and current capabilities.

This study investigates the post-thermal treatment effects on the efficiency of silicon heterojunction solar cells, specifically examining the influence of annealing on p-type microcrystalline silicon oxide and ITO thin films. By assessing changes in carrier concentration, mobility, resistivity, transmittance, and optical bandgap, we identified conditions that optimize these properties. Results reveal that appropriate annealing significantly enhances the fill factor and current density, leading to a notable improvement in overall solar cell efficiency. This research advances our understanding of thermal processing in siliconbased photovoltaics and provides valuable insights into the optimization of production techniques to maximize the performance of solar cells.

Laser-induced plasmonic sintering of metal nanoparticles (NPs) holds significant promise as a technology for producing flexible conducting electrodes. This method offers immediate, straightforward, and scalable manufacturing approaches, eliminating the need for expensive facilities and intricate processes. Nevertheless, the metal NPs come at a high cost due to the intricate synthesis procedures required to ensure long-term reliability in terms of chemical stability and the prevention of NP aggregation. Herein, we induced the self-generation of metal nanoparticles from Ag organometallic ink, and fabricated highly conductive electrodes on flexible substrates through laser-assisted plasmonic annealing. To demonstrate the practicality of the fabricated flexible electrode, it was configured in a mesh pattern, realizing multi-touchable flexible touch screen panel.

The advantage of OTFT technology is that large-area circuits can be manufactured on flexible substrates using a lowcost solution process such as inkjet printing. Compared to silicon-based inorganic semiconductor processes, the process temperature is lower and the process time is shorter, so it can be widely applied to fields that do not require high electron mobility. Materials that have utility as electrode materials include carbon that can be solution-processed, transparent carbon thin films, and metallic nanoparticles, etc. are being studied. Recently, a technology has been developed to facilitate charge injection by coating the surface of the Al electrode with solution-processable titanium oxide (TiOx), which can greatly improve the performance of OTFT. In order to commercialize OTFT technology, an appropriate method is to use a complementary circuit with excellent reliability and stability. For this, insulators and channel semiconductors using organic materials must have stability in the air. In this study, carbon-doped Mo (MoC) thin films were fabricated with different graphite target power densities via unbalanced magnetron sputtering (UBM). The influence of graphite target power density on the structural, surface area, physical, and electrical properties of MoC films was investigated. MoC thin films deposited by the unbalanced magnetron sputtering method exhibited a smooth and uniform surface. However, as the graphite target power density increased, the rms surface roughness of the MoC film increased, and the hardness and elastic modulus of the MoC thin film increased. Additionally, as the graphite target power density increased, the resistivity value of the MoC film increased. In the performance of an organic thin film transistor using a MoC gate electrode, the carrier mobility, threshold voltage, and drain current on/off ratio (I_on/I_off) showed 0.15 cm²/V·s, -5.6 V, and 7.5×10⁴, respectively.

Flash lamp annealing (FLA) of metal nanoparticle (NP) ink has provided powerful strategies to fabricate highperformance electrodes on a flexible substrate because of its rapid processing capability (in milliseconds), low-temperature process, and compatibility with to roll-to-roll process. However, metal NPs [e.g., gold (Au), silver (Ag), copper (Cu), etc.] have limitations such as difficulty in synthesizing fine metal NPs (diameter less than 10 nm), high price, and degradation during ink storage and FLA processing. In this regard, organometallic ink has been proposed as a material that can replace metal NPs due to their low-cost (usually 1/100 times cheaper than metal nano inks), low-temperature processability, and high material stability. Despite these advantages, the fabrication of flexible electrodes through FLA treatment of organometallic compounds has not been extensively researched. In this paper, we experimentally guide how to determine the optimal conditions for forming electrodes on flexible substrates by considering material parameters, and flashlight processing parameters (energy density, pulse duration, etc) to minimize the difficulties that may arise during the FLA of organometallic ink.

The utilization of scanning transmission electron microscopy (STEM) in conjunction with cathodoluminescence (CL) has emerged as a valuable tool for the investigation of material optical properties. In recent years, this technique has facilitated significant advancements in the fields of plasmonics and quantum emitters by surpassing prior technical restrictions. The review commences by providing an outline of the diverse STEM-CL operating modes and technical aspects of the instrumentation. The review explains the fundamental physics of light production under electron beam irradiation and the physical basis for interpreting STEM-CL experiments for different types of excitations. Additionally, the review compares STEM-CL to other related techniques such as scanning electron microscope CL, photoluminescence, and electron energy-loss spectroscopy.

Perovskite materials are promising candidates for next-generation optoelectronic devices owing to their outstanding external quantum efficiency, high color purity, and ability to tune the light emission wavelength. However, conventional thermal annealing processes caused the degradation of perovskite, resulting in poor optoelectronic properties and a short lifetime. Herein, we propose a laser-induced recrystallization of perovskite thin film to enhance its light-emitting properties. Laser-induced recrystallization process was performed using rapid and instantaneous laser heating, which successfully induced grain growth of the perovskite material. The laser processing conditions were thoroughly optimized based on theoretical calculations and various material analyses such as x-ray diffraction, scanning electron microscope, and photoluminescence spectroscopy.

Nickel oxide is a nonstoichiometric transparent conductive oxide with p-type conductivity, a wide-band energy gap of 3.4~4.0 eV, and excellent chemical stability, making it a very important candidate as a material for bipolar devices.P-type conductivity in Transparent Conductive Oxides (TCO) is controlled by the oxygen vacancy concentration. During the TCO film deposition process, additional oxygen diffusing into the NiO structure causes the formation of Ni 3p ions and Ni vacancies. This eventually affects the hole concentration of the p-type oxide thin film. In this work, the surface morphology and the electrical characteristics were confirmed in accordance with the annealing atmosphere of the nickel oxide thin film.

We investigated the properties of vanadium oxide (VOx) buffer layers deposited by a dual RF magnetron sputtering method under various target powers for inverted organic solar cells (IOSCs). Sputter fabricatged VOx thin films exhibited higher crystallinity with the increase of target power, resulting in a uniform and large grain size. The electrical properties of VOx films are improved with the increase of target power because of the increase of V content. In the results, the performance of IOSCs critically depended on the target power during the film growth because the crystalllinity of the VOx film affects the carrier mobility of the VOx film.

This paper is a study on frequency analysis and electronic noise reduction of energy storage system (ESS). We acquired 4 necessary data for about 2 minutes and 4 seconds using a sampling frequency of 10,000 Hz in ESS. Fast Fourier transform (FFT) was used for electronic noise analysis from the acquired data. As a result, it was confirmed that DC component, fundamental wave, second and higher harmonic component exist. For the attenuation of harmonics, low-pass filter (LPF) was applied. We confirmed that an attenuation of approximately 59.3% appears from the second harmonic. The presence of many harmonic components in the data of the ESS was expected to occur due to the insufficiency of optimization among the modules inside the ESS. Therefore, we propose that a national certification system for ESS should be introduced to settle down the issue properly.

Generally, diamond-like carbon films (a-C:H, DLC) have been shown to have a low coefficient of friction, a high hardness and a low wear rate. Pd-doped C thin film was fabricated using a dual magnetron sputtering with two targets of graphite and palladium. Graphite target RF power was fixed and palladium target RF power was varied. The structural, physical, and surface properties of the deposited thin film were investigated, and the correlation among these properties was examined. The doping ratio of Pd increased as the RF power increased, and the surface roughness of the thin film decreased somewhat as the RF power increased. In addition, the hardness value of the thin film increased, and the adhesive strength was improved. It was confirmed that the value of the contact angle indicating the surface energy increases as the RF power increases. It was concluded that the increase in RF power contributed to the improvement of the physical properties of Pd-doped C thin film.

The development of efficient electron donor (or hole-transporting) molecules that can be used in various optoelectronic device fields is highly demanded. In this work, a novel class of triptycene-based three-dimensional (3D) triphenylamine (TI-TPA) derivatives with different end substituents was designed and prepared for transparent electron donor materials. Owing to the rigid 3D triptycene framework, the obtained TI-TPA derivatives had an amorphous morphology with high thermal decomposition temperature. The oxidation potential of these TI-TPA derivatives decreased as the electron donating strength of the end substituent increased. Among TI-TPA derivatives, TI-TPA-OMe exhibited the highest HOMO level (-5.31 eV) which is similar to that of Spiro-OMeTAD (-5.22 eV). In addition, TI-TPA-OMe was found to form a strong charge transfer complex with the triptycene-based acceptor TI-BQ, leading to a new absorption band at around 640 nm. These results can be applied for developing efficient electron donor materials that can mimic the advantages of the spiro-linked structure and TPA units of Spiro-OMeTAD.

Bulky iron-core potential transformers (PT) are installed in a tank of gas insulated switchgears (GIS) for a system voltage measurement in power substations. In this paper, we studied an electronic voltage transformer (EVT) embedded in a spacer for miniaturization, eco-friendliness, and performance improvement of GIS. The prototype EVT consists of a capacitive probe (CP) that can be embedded in a spacer and a voltage Follower with a high input and a low output impedance. The CP was fabricated in the form of a Flexible-PCB to acquire the insulation performance and to withstand vibration and shock during operation. Voltage ratio of the prototype EVT is about 42,270, and the frequency bandwidth of -3 dB ranges from 0.33 Hz to 3.9 MHz. The voltage ratio error evaluated at about 6%, 12% and 18% of the rated voltage of 170 kV was 0.32%, and the phase error was 12.9 minutes. These results were within the accuracy for the class 0.5 specified in IEC 60044-7 and satisfy even in ranges from 80% to 120% of the rated voltage. If the prototype EVT replaces the conventional iron-core potential transformer, it is expected that the height of the GIS could be reduced by 11% and the amount of SF6 will be reduced by at least 10%.

Thermal batteries are specialized as primary reserve batteries that operate when the internal heat source is ignited and the produced heat (450~550oC) melts the initially insulating salt into highly conductive eutectic electrolyte. The heat source is composed of Fe powder and KClO4 with different mass ratios and is inserted in-between the cells (stacks) to allow homogeneous heat transfer and ensure complete melting of the electrolyte. An ideal heat source has following criteria to satisfy: sufficient mechanical durability for stacking, appropriate heat calories, ease of combustion by an igniter, stable combustion rate, and modest peak temperature. To satisfy the aforementioned requirements, Fe powder must have high surface area and porosity to increase the reaction rate. Herein, the hydrothermal and spray drying synthesis techniques for Fe powder samples are employed to investigate the physicochemical properties of Fe powder samples and their applicability as a heat source constituent. The direct comparison with the state-of-the-art Fe powder is made to confirm the validity of synthesized products. Finally, the actual batteries were made with the synthesized iron powder samples to examine their performances during the battery operation.