Accurate localization of partial discharge (PD) in power transformers is critical for condition monitoring and fault prevention. However, localization algorithms are primarily validated through laboratory experiments or offline tests, making it difficult to assess their performance accurately in operational transformers. In this paper, a method is proposed to evaluate the positioning accuracy of PD localization algorithms by injecting pulse current into an ultra-high frequency (UHF) sensor to simulate PD source. The proposed method is first validated on an in-service 220 kV transformer equipped with six built-in UHF sensors. The results show that this method is safe, controllable, and capable of flexibly changing the location of PD. Furthermore, extensive experiments are conducted on another 220 kV transformer equipped with 18 built-in UHF sensors to systematically analyze the impact of sensor number and placement on the localization error of time difference of arrival (TDOA). It is found that increasing the number of sensors can reduce the likelihood of large positioning errors to some extent. But for highly accurate positioning, the best result is achieved when using five or six sensors. In terms of sensor placement, TDOA-based localization is less robust when sensors are placed on the same side or in adjacent areas. Uniform placement on all sides of the transformer can improve robustness, but it is difficult to achieve a high accuracy of the positioning error within 0.5m.

Non-integer quantum conductance has been reported in both valence change memory (VCM) and electrochemical metallization (ECM) memristive devices, although well-resolved intermediate conductance features in ECM systems remain difficult to achieve. Here, we demonstrate six statistically distinguishable, non-integer conductance states ranging from 0 to 2 G0 in filamentary ITO/MoS2-Ag/Pt memristors. Compared with previously reported half-integer conductance (±0.5 G0), our devices exhibit finer resolution, centered around ±0.25 G0, with occurrence probabilities exceeding 30%. The conductance can be tuned by an external magnetic field, providing an additional control knob for ECM devices. Moreover, contrasting single- and double-magnetic-layer devices indicates that interlayer ferromagnetic coupling plays an important role in the emergence of non-integer conductance features, providing insight into spin-dependent transport in filamentary memristors.

Recent advancements in near-infrared (NIR) spectroscopy have significantly contributed to the field of biomedical imaging and diagnosis, highlighting the critical importance of near-infrared detection. In this work, we report on the successful implementation of high-performance NIR detection based on the lateral photovoltaic effect (LPE) in a graphene/porous silicon (PS)/Si structure. The detector achieves exceptional linearity and active area at a modest penalty in sensitivity, mitigating the conventional trade-off between sensitivity and active area. The enhanced performance is attributed to a synergistic combination of factors within the unique architecture, including improved NIR absorption of porosity, superior carrier mobility of graphene, and carrier dynamics based on dual-junction regulation at the interfaces of graphene/PS and PS/Si. Building on these characteristics, the device transcends the typical constraints of LPE-based detectors, namely restricted active area and inefficient energy utilization. The study advances the development of the LPE in NIR detection, holding great promise for routes toward scalable and high-quality position-sensitive detectors.

Near-infrared (NIR) photodetectors are critical for numerous applications including optical communications, biomedical imaging, and night vision. However, conventional photodetectors suffer from an inherent trade-off between high photoresponsivity and fast response speed, alongside limitations in flexibility, long-term stability, and operational temperature range. To overcome these challenges, a photodetector based on atomically-thin platinum diselenide (PtSe2) film is proposed in this work, which combines the photoconductive gain of PtSe2 with rapid carrier separation and extraction at the metal-semiconductor junction. Through the synergy of these two mechanisms, it achieves ultrahigh photoresponsivity (132 A/W) and ultrafast response speed (37.5 ps), effectively resolving the traditional performance trade-off. We further realize the integration of large-area, uniform device arrays (over 1100 units) on flexible mica substrates and demonstrate high-quality imaging capability. The photodetector arrays also display outstanding flexibility, excellent long-term stability and a record-wide operating temperature range from -150 °C to 400 °C. This work highlights the great potential of atomically-thin PtSe2 for developing next-generation ultrasensitive, high-speed, robust, and flexible optoelectronic devices.

In many applications, such as digital signal processing, multiple-constant multiplications are commonly required, where time-multiplexed constant multiplication (TMCM) is typically employed for efficient hardware utilization. Although an optimal design for a constant multiplication can be easily obtained by using shift-add operations, it is of great difficulty to find an optimal architecture supporting the multiplication of an input with multiple constants due to the exponential increase of the search space. To address this issue, in this work, we propose an efficient Ising model-based TMCM optimization framework. Specifically, the directed acyclic graphs (DAGs) for each constant multiplication are generated under the minimum adder constraint. TMCM is then designed by merging the DAGs for all constants. To achieve an optimal design, we convert the DAG merging to a Quadratic Unconstrained Binary Optimization (QUBO) problem that can be solved by the Ising model. Experimental results show that when applied to several popular fast Fourier transform (FFT) and discrete cosine transform (DCT) coefficient sets, the proposed framework can obtain TMCMs with fewer multiplexers, leading to up to 12.76%, 8.02%, and 18.48% savings in area, power, and power-delay product (PDP), compared to state-of-the-art works.

As data transmission rates scale toward unprecedented capacities, both the conventional 1.55 μm telecommunication band and the emerging 2 μm band require photodetectors with large electrical bandwidth and high responsivity. Although mature Ge- and III-V-based photodetectors can operate fast at 1.55 μm band, there cannot work efficiently at 2 μm band because of band gap and material quality. Here we report a waveguide-integrated carbon nanotube (CNT) photodetector on a silicon nitride (SiNx) platform that delivers high performance across both wavelength regimes. At 1.55 μm and a bias of -1 V, the device exhibits a 3 dB bandwidth exceeding 67 GHz. At 2 μm, it maintains a low dark current of 80 nA and a responsivity of 0.41 A/W, while delivering a similarly setup-limited 3 dB bandwidth beyond 67 GHz. This bandwidth represents a significant leap over previously reported photodetectors operating in this spectral regime. Our findings position CNT photodetectors as a promising platform for CMOS-compatible, high-speed optical interconnects across both the 1.55 and 2 μm bands. Furthermore, the demonstrated high-speed performance underscores their potential to underpin the next generation of large-scale photonic and optoelectronic integrated circuits (OEICs).

Moisture and contamination ingress lead to a prominent failure issue of the epoxy-casting current transformer (CT)-air-insulating barrier (IB) system in 40.5 kV indoor switchgears. To address this, mechanisms of insulation failure from microscale material aging to macroscale system breakdown were investigated. Epoxy resin (EP) and sheet moulding compound (SMC) samples of CTs and IBs were prepared, and tests of surface resistivity, dielectric properties, contamination level, microscopic morphology, and molecular structure were conducted. For both CTs and IBs, the results indicate that the surface resistivity decreased by over 99.9 %, dielectric properties significantly deteriorated, and microstructural defects were observed. Raman spectra revealed breakages of C-H, C-O and C=C, ester bond hydrolysis, and existence of amorphous carbon. Primary aging mechanisms included structural degradation induced by synergistic erosion of moisture and contamination, organic material carbonization caused by discharge, and accelerated insulation failure driven by aging byproducts. Additionally, impacts of increased surface conductivity and barrier displacement on electric field strength and current density were investigated through finite element simulation. The results show that the formation of weakly insulating layers on material surfaces due to aging was essential for partial discharge initiation and elevated current density. The most probable interphase flashover path was identified as initiating from one busbar, propagating along the CT surface, then through air to the IB surface, continuing along the IB surface, then through air to another CT surface, and finally reaching another busbar, which aligned well with practical experience. The risk of interphase flashover in the CT-air-IB system increased with the increment of barrier displacement and was high when the conductivity of weakly insulating layers ranged from 0.001 to 0.01 S/m.

Epoxy resin post insulators, when operated in high-humidity environments without regular cleaning, often suffer from a decline in insulation performance after several years of service. This deterioration is primarily caused by insulation aging of the epoxy material and the accumulation of surface contamination, which may lead to discharge events and pose a threat to the safety of power systems. This study presents a preliminary investigation into methods for restoring the surface insulation performance of epoxy resin insulators. Several restoration approaches, including oven drying, solvent immersion, and wiping, were applied to aged insulators. The effectiveness of these treatments was evaluated through surface resistance measurements and Fourier-transform infrared (FTIR) spectroscopy. The results indicate that: Drying significantly improves surface resistance by removing adsorbed moisture. All three cleaning methods (immersion in anhydrous ethanol, immersion in an organic cleaning agent, and wiping with cable cleaning tissue) led to substantial surface resistance restoration, although through different mechanisms and with different applicability. FTIR spectroscopy confirms hydroxyl group reduction after cleaning, with no damage to the chemical structure of the epoxy matrix.

While classical memristors demonstrate reliable binary switching, multi-level states remain constrained by scalability and mechanism variability. Quantum conductance memristors, with discrete quantized conductance steps, offer a promising alternative. However, achieving stable quantized states requires precise atomic-scale filament control and quantum state stability, posing even greater challenges. Here, we address these challenges by constructing a multilayer MoS2/MoS2:Ag structure that stably yields previously elusive conductance steps. Combined with a non-reset voltage scanning method and supported by a scattering center model, our approach markedly improves reproducibility. Moreover, we observe light-induced half-integer conductance states in a non-magnetic system. Such phenomena, previously reported only in oxygen-vacancy-based devices, are here realized for the first time in a cation-migration-based quantum conductance memristor. This arises from the strong photoresponse of MoS2 and the offset between the Ag work function and the MoS2 conduction band minimum, which together enable spin-selective transport. This finding surpasses classical multi-level limits and opens new paths for optoelectronic quantum conductance control.

Hysteresis loop is a vital feature in the study of electronic devices, like ferroelectric hysteresis loop in ferroelectric devices, magnetic hysteresis loop in spin-electronic devices, and current–voltage (I–V) loop in memristors. Here, we report a type of I–V loop observed in the Ag/SrTiO3/Si structure, which can be dynamically varied by purely electrical modulation. This phenomenon can be attributed to the capacitive effect based on the resistance–capacitance circuit model. Additionally, we further explore the carrier transport mechanism by establishing different modulation methods of I–V hysteresis loops. This work expands our understanding of the behavior of electronic devices.

An in-depth study of new phenomena emerging from the interaction between light and matter is a vital scientific research effort. In this report, we investigate the lateral photovoltaics and spatial resistance on p-Si surfaces under 520 nm laser stimulation. Because of the surface states of p-Si, the lateral photovoltage sensitivity can reach 286 mV/mm, and the spatial resistance change ratio can reach 1059%. Then, we modulate these two effects by growing three different morphologies of MoS 2 on the Si surface. Due to the photosensitive properties of MoS 2 nanoparticles, the lateral photovoltage sensitivity can be enhanced up to 368 mV/mm, while the spatial resistance change ratio can reach 2202%. In this process, we observe a new phenomenon that the p-Si surface modified by MoS 2 no longer shows the traditional bipolar-resistance effect, and the laser position corresponding to the minimum resistance has been shifted. Based on this finding, we refine the previously proposed bipolar-resistance effect theory and confirm our findings through theoretical calculations. Our modulation strategy can realize both photovoltage-based detection and photoconductivity-based detection, which provides a reliable reference for the study of photoelectric devices.

In modern photonics, a semiconductor homojunction or heterojunction is the core of optoelectronic devices and photonic integrated circuits. Here, a strategy is demonstrated to create tunable bandgap carbon nanotube intramolecular junctions via uniaxial strain modulation. The fabrication of photodetectors based on this mechanism is controllable, reproducible, and scalable, which is completely superior to other pathways for forming intramolecular junctions. Compared to ordinary detectors without strain, the intramolecular junction photodetector shows an ≈10‐fold reduction in dark current and a more than 4 times enhancement in responsivity under zero bias. Furthermore, it is shown that the active area of this short‐wave infrared photodetector can be scaled down to 0.5 µm 2 , while maintaining high performance. Significantly, with its tunable spectral response, this work provides a promising and effective approach to engineering various nanotube intramolecular junctions through strain modulation, addressing a critical technological challenge and meeting the demands of optoelectronic applications.

Multivalued logic (MVL) technology has great potential in the exploration of breaking through the traditional von Neumann architecture. Compared with the binary logic system, MVL can effectively reduce the complexity of the system and improve the integration density of devices to process larger amounts of data. Recently, some preliminary studies have been conducted on negative differential resistance (NDR) effect devices, which can be applied to ternary logic processing based on their nonlinear response characteristics of current and voltage. In this study, the type III heterojunction formed by MoS2-XOX and TiOX is used to achieve the NDR effect, and we analyze its potential in ternary logic processing. Then, utilizing the photosensitive characteristics of the structure, a laser is introduced to regulate the effect so that the device additionally presents quaternary/binary logic under low/high bias. Finally, we achieve the processing of binary/ternary/quaternary logic on a single device through different modulation methods. This work provides effective ideas and directions for the development of MVL technology.

Semiconductor heterostructures can be used to explore band structures for creating optoelectronic devices. In this work, we demonstrate an all-optical-driven artificial vision system based on a porous silicon heterojunction with in-sensor processing capabilities. The abundant surface states of porous silicon enable light trapping and photoelectric conversion, which allow the sensor to exhibit high sensitivity and detect weak light signals. By utilizing differential optoelectronic signals, the integrated device can perform multiple functions within a single unit, such as in-sensor encoding and trajectory tracking of dynamic optical signals. The neuromorphic vision systems based on this photoelectric retina can perform optoelectronic modulation, trajectory reconstruction, and handwritten text recognition and can emulate functions of the human retina with temporal and spatial resolution. The design strategy here can be used to implement in-sensor processing of dynamic optical signals in machine vision systems.

Optoelectronic brain-like devices have been widely investigated in recent years and are considered a new generation of hardware platforms for neuromorphic computing. Inspired by the biological visual perception system, the devices integrate sensing, computing, and memory in a single functional unit. Compared with the electronically controlled memristor, the introduction of optical signals can further improve the computational efficiency and physically integrate the sensing unit and the processing unit. This efficient and intelligent information processing method can effectively overcome the bottleneck of traditional computing under von Neumann architecture. However, the development of optoelectronic brain-like devices is still in the preliminary stage, and its mechanism is complex and not uniform. Therefore, it is necessary to deeply understand the quantum process between optical input and electrical output to provide a better reference for the development of this field. This article aims to comprehensively review the latest progress in optoelectronic brain-like devices, summarizing the device performance and structures. It also provides a comprehensive summary of multiple mechanisms under different material systems, such as direct photoelectric conversion or photoelectric conversion triggering subsequent effects. In addition, a variety of potential application scenarios for optoelectronic devices are introduced. Finally, we present some possible problems in the development of this field. This review can help researchers better understand the whole picture of the development of optoelectronic devices.

Both stability and multi-level switching are crucial performance aspects for resistive random-access memory (RRAM), each playing a significant role in improving overall device performance. In this study, we successfully integrate these two features into a single RRAM configuration by embedding Ag-nanoparticles (Ag-NPs) into the TiN/Ta2O5/ITO structure. The device exhibits substantially lower switching voltages, a larger switching ratio, and multi-level switching phenomena compared to many other nanoparticle-embedded devices. We attribute it to the embedded Ag-NPs effectively switching the mechanism of conductive filaments and the controlled distribution of Ag-NPs facilitates the occurrence of multi-level switching. Additionally, the fabricated structure demonstrated an impressive optical transmittance of nearly 85%. Undoubtedly, this combined feature of RRAM not only enhances stability but also enables multi-level switching, thereby demonstrating an approach to fabricating versatile and practical electronic devices aimed at boosting storage capacity and speed.

The lateral photovoltaic effect demonstrates versatility across various applications, including photodetectors, imaging, spectroscopy, biosensing, and environmental monitoring. Challenges arise from the low energy of near-infrared photons, regarded as a bottleneck for high-sensitivity photodetector development in this spectrum, limiting applications like optical fiber communication and image sensors. However, this study achieved a remarkable 720.57 mV/mm sensitivity for the lateral photovoltaic effect in the near-infrared region with a 980 nm laser irradiation on an Ag/Porous Silicon/Si structure. This sensitivity surpasses previous observations several to hundreds of times and even outperforms many other structures in the short-wavelength spectrum, further emphasizing its significance in this field. The use of a unique fluoro-amino electrolysis technique ensures consistent porosity, mitigating the adverse effects of photoluminescence. Combined with surface Ag, it induces local surface plasmon resonance and efficient plasmon coupling, markedly increasing electron density. This highly sensitive structure propels advancements in near-infrared photodetectors and Raman signal enhancement, establishing a robust foundation for potential applications in highly sensitive photodetectors and biological sensors.

Graphene is a kind of two-dimensional material with a single-layer carbon structure and has been investigated in many high-performance photodetectors. The lateral photovoltaic effect (LPE) is widely used in the position-sensitive detectors (PSDs) owing to its linear response of photovoltage to the light position. In this Letter, a type of graphene-enhanced LPE is observed in the Ag nanoparticle-covered graphene/n-type Si. The LPE sensitivity can reach 97.3 mV/mm, much higher than the sensitivity of 1.3 mV/mm in the control sample of Ag/Si and 5.2 mV/mm of graphene/Si. Based on the photocarriers' diffusion mechanism, tailoring a photocarrier transfer at the interface of a heterojunction plays a key role for the enhancement. These findings exhibit great application potential of graphene in the field of PSDs and offer an effective method for the optimization of LPE devices.

Attaining highly uniform operations in a disordered system presents a persistent challenge. The utilization of ion migration in amorphous materials to trigger the resistive switching process of the material usually results in inferior uniformity of the memristive device. Here, we demonstrate that the resistive switching behavior can be activated through carrier doping in the disorder system, and highly ordered resistance modulation is achieved in Ag-doped albumen. By manipulating the doping level of the carrier, the localization of the free electron wavefunction can be tuned, leading to multi-level variations in resistance. This memristive switching behavior is in all electronic and displays excellent switching uniformity, holding great potential for applications in high-density memories and neuromorphic computing chips.