Charge Emission Research Articles

Light‐emitting diodes enabled by two‐dimensional semiconductors: Architectures, optimization, and functional advances

Abstract Two‐dimensional (2D) semiconductors offer unique advantages for light‐emitting diodes (LEDs) due to their atomic‐scale thickness, strong excitonic effects, tunable band structures, and compatibility with Van Der Waals heterostructures. These properties enable fine control over carrier injection, exciton recombination, and light–matter interactions, facilitating functionalities not easily achieved in bulk semiconductors. This review provides a comprehensive overview of 2D material‐based LEDs, with emphasis on device architectures, performance modulation, and emerging applications. Key configurations, such as p–n junctions, Schottky contacts, and quantum well heterostructures, are examined in terms of charge transport and emission behavior. Strategies to tailor emission properties are discussed, focusing on band structure engineering, interface optimization, and photonic field control. Additionally, unique electroluminescence phenomena arising from spin–valley coupling, in‐plane anisotropy, and multi‐exciton dynamics are highlighted, enabling polarized, valley‐resolved, and dynamically tunable emission. These capabilities open up opportunities for integration into quantum light sources, neuromorphic vision, and reconfigurable photonic platforms. To advance toward practical applications, improvements are needed in spectral tunability, light‐extraction efficiency, and scalable fabrication. Continued progress in materials synthesis, device engineering, and photonic integration is expected to accelerate the development of high‐performance, application‐oriented 2D optoelectronic systems.

Stochastic Nature of Voltage-Controlled Charge Dynamics in AlOx Magnetic Tunnel Junctions.

Spintronic memristors based on ferromagnetic metal/oxide heterostructures have recently enabled reversible manipulation of both magnetic properties and resistive switching (RS), offering promising prospects for multibit memory and neuromorphic computing. In this study, we investigate the stochastic nature and relaxation processes of charge dynamics induced by localized oxygen vacancy (VO) in AlOx-based magnetic tunnel junctions (MTJs). We observe that random telegraph noise (RTN) exhibits charge stochasticity at specific bias voltages in the low resistance state (LRS), reflecting the competition and transition between charge capture and emission states against the thermal energy. This behavior reveals that the thermally unstable charge stochasticity originates from localized traps in the AlOx barrier. In contrast, the high resistance state (HRS) favors the RTN emission states, indicating the dominance of direct tunneling effects. Through numerical calculations based on the tight-binding (TB) model and experimental results, we demonstrate that voltage-driven shifts in the VO position within the AlOx barrier, associated with RS, govern the charge dynamics of the MTJs investigated. These findings provide valuable insights and practical implications for the development of next-generation devices leveraging charge stochasticity in AlOx-based MTJs.

Synergetic Spin-Crossover and Luminescence in a Fe(II) Complex with Aggregation-Induced Emission and Twisted Intramolecular Charge Transfer

Synergetic Spin-Crossover and Luminescence in a Fe(II) Complex with Aggregation-Induced Emission and Twisted Intramolecular Charge Transfer

Physics-based analytical models for p-GaN/AlGaN/GaN HEMTs considering gate charge emission

Abstract In this article, physics-based analytical models of channel charge density (2DEG: Two-Dimensional Electron Gas), gate capacitance and drain current have been proposed for normally-OFF p-GaN/AlGaN/GaN High Electron Mobility Transistors (HEMTs). The models incorporate key physical phenomena, such as charge emission from the gate terminal via thermionic field emission (TFE) and thermionic emission (TE), as observed in prior studies on these devices. Notably, for the first time, the channel charge density is expressed explicitly as a function of gate voltage for p-GaN gated HEMTs, accounting for gate charge emission effects. This channel charge expression is subsequently employed to model gate capacitance and drain current for p-GaN gated HEMTs. Finally, the accuracy of the proposed models is rigorously validated using experimental and/or TCAD data for multiple p-GaN/AlGaN/GaN HEMT structures having diverse device parameters and for the reported range of gate and drain voltages. The robustness of the drain current model is further assessed under elevated temperature conditions. Moreover, the applicability of the proposed models is demonstrated for p-GaN gated HEMTs exhibiting low gate charge emission characteristics.

Tuning of charge state and wavelength in InAs/GaAs quantum dots through p-i-p+-i-n heterostructure engineering

We present a p-i-p+-i-n AlAs/GaAs heterostructure device that enables independent tuning of quantum dot (QD) charge states and emission wavelength, addressing a key challenge in quantum light source integration. Utilizing quantum tunneling and the quantum-confined Stark effect, this device achieves precise modulation of QD emission with asymmetric AlAs barriers facilitating hole injection while suppressing electron tunneling. Photoluminescence measurements confirm a broad wavelength tuning range (7 meV) and stabilization of the single-hole X+ state, with second-order correlation g2(0) = 0.042(2), validating single-photon purity. This platform offers robust control for spin-photon entanglement and quantum network applications, paving the way for scalable quantum technologies.

Does Intermediate Input Trade Liberalization Reduce Firm Air Pollution? Evidence From China's Accession to the WTO

ABSTRACTTrade and environmental protection are significant issues concerning sustainable development. This paper merges the Chinese enterprise pollution database from 1998 to 2007 with industry input tariffs. Utilizing China's accession to the World Trade Organization (WTO) as a quasi‐natural experiment, we employ a differences‐in‐differences strategy to examine the effects and mechanisms of intermediate input trade liberalization on firm air pollution. Our findings indicate that trade liberalization significantly reduces the total sulfur dioxide emissions and per unit output sulfur dioxide emissions of firms. In terms of mechanisms, we find that factor substitution and technology spillover effects of imported intermediate inputs play a crucial role. Trade liberalization increases the importation of intermediate inputs by enterprises, substituting for the consumption of fossil fuels. Furthermore, technology spillover effects lead to capital‐biased technological progress for firms. We also observe that the emission reduction effects of trade liberalization are more pronounced for high‐productivity, low‐energy‐consumption, and capital‐intensive firms. Finally, our empirical evidence shows that environmental regulations and trade liberalization interact, and imposing high emission charges on firms enhances the emission reduction effects of imported intermediate inputs. This paper emphasizes the importance of developing countries implementing trade liberalization reforms for environmental protection.

Size matters: quantum confinement-driven dynamics in CsPbI3 quantum dot light-emitting diodes

The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots (QDs), making them versatile building blocks for next-generation light-emitting diodes (LEDs). This study investigates how quantum confinement governs the charge transport, exciton dynamics, and emission efficiency in QD-LEDs, using CsPbI3 QDs as a model system. By systematically varying QD sizes, we reveal size-dependent trade-offs in LED performance, such as enhanced efficiency for smaller QDs but increased brightness and stability for larger QDs under high current densities. Our findings offer critical insights into the design of high-performance QD-LEDs, paving the way for scalable and energy-efficient optoelectronic devices.

Real-World Vehicle Estimation and Control of Indirect Emissions Control and Performance Evaluation of Electric Vehicles with In-Wheel Motors

<div>The growing number of automobiles on the road has raised awareness about environmental sustainability and transportation alternatives, sparking ideas about future transportation. Few short-term alternatives meet consumer needs and enable mass production. Because they do not accurately reflect real-world driving. Current models are unable to estimate vehicle emissions. However, the purpose of this research is to present an application of an adaptive neuro-fuzzy inference system for managing the various factors contributing to vehicle gasoline engine exhaust emissions. It examines how well the three known standardized driving cycles (DSCs). Accurately reflect real-world driving and evaluate the impact of real-world driving on vehicle emissions. Indirect emissions are inversely proportional to the vehicle’s fuel consumption. The methodology used is Eco-score methodology to calculate indirect emissions of light vehicles. Expected emission charge estimates for different using styles. Emission rates range substantially between battery classes. The vehicle’s gasoline efficiency is four times better than a similar automobile, but neither mass nor charge multiplied appreciably. The range of this car is not restrained by the battery length, which increases driver comfort, while automobile meets customer expectations in addition to environmental worries and advantages. Despite the fact that they continue to be affordable, they offer a possibility for mass manufacturing reducing overall environmental effects. In keeping with the consequences, the adaptive neuro-fuzzy inference system works nicely to simulate and regulate vehicle engine exhaust emissions.</div> <div>However, the final objective of a regulatory-oriented studies software that focuses on air pollution from mobile sources is to identify and quantify any outcomes that the emissions may have on human fitness.</div> <div>However, before we invest highbrow and economic sources, we need to first recognize the restrictions of modern information and methodologies that preclude accurate estimates of risk to human health. Destiny research packages should be justified by way of their promise to triumph over these boundaries. The goal of this extent, then, is to identify troubles and pick out a studies schedule with a purpose to be only in advancing our potential to quantify the fitness dangers related to air pollution.</div>

Minimizing Interfacial Energy Losses with Carbon Dot Bifacial Modification Layers for High‐Efficiency and Stable Perovskite LEDs

Abstract Perovskite light‐emitting diodes (PeLEDs) have reached near‐unity photoluminescent quantum yields (PLQYs), but further improvements in electroluminescent efficiency are constrained by interfacial energy losses between the emissive layer and charge transport layers. In this study, multifunctional carbon dot organic frameworks (CDOFs) are introduced as a dual‐interface modification material for perovskite layer. This approach effectively passivates both the upper and buried interfaces, boosting the PLQY to nearly 100% and enabling an external quantum efficiency of 28.0%. The CDOFs also facilitate balanced charge injection, achieving a low turn‐on voltage of only 1.9 V, significantly below the bandgap voltage. Additionally, the exceptional defect passivation imparted by CDOFs significantly bolsters structural stability, achieving a T50 operational lifetime of 81.7 min at an initial ultrahigh luminance of 10 000 cd m−2, with no detectable Joule heating. This study underscores the potential of CDOFs in significantly advancing PeLED performance.

Bright "D-A-D" semiconducting small molecule aggregates for NIR-II fluorescence bioimaging guiding photothermal therapy.

Donor-acceptor-donor (D-A-D) semiconducting small molecule nanoparticles have emerged as high-performance NIR-II fluorophores for real-time bioimaging. However, due to their intrinsic defects in aggregation-caused quenching (ACQ) and "energy gap law", D-A-D semiconducting small molecule nanoparticles typically exhibit low NIR-II fluorescence quantum yields (QYs). Herein, both the strategies of aggregation induced emission (AIE) and intermolecular charge transfer (CT) have been incorporated into the design of new D-A-D semiconducting small molecules. AIE enhances the NIR-II fluorescence intensity of NIR-II fluorophore aggregates in nanoparticles, while intermolecular CT increases both NIR absorption and NIR-II emission, thereby further improving their NIR-II fluorescence QYs. Four D-A-D semiconducting small molecules (TD, TT, TC, and TCD) were designed. Due to the combination of intermolecular CT and AIE of TCD aggregates, the NIR absorption and NIR-II fluorescence signals of TCD NPs were stronger than those of TD NPs and TT NPs with a single AIE property or TC NPs with strong intermolecular CT. Furthermore, TCD NPs demonstrated excellent performance in in vivo NIR-II fluorescence bioimaging guiding photothermal therapy.

Aromatic cation–π induced multifluorescence tunable two-dimensional co-assemblies for encoded information security†

The field of light-emitting two-dimensional co-assemblies (2DCAs) is extending rapidly. Nevertheless, multifluorescence tunable 2DCAs are relatively underdeveloped, because the exploration of novel assembly strategies and noncovalent interactions to realize desirable photophysical features is still difficult. Herein, we present the first implementation of an aromatic cation–π interaction induced emissive charge transfer strategy for multifluorescence tunable 2DCAs, which are derived from fluorophore anthracene-based monomers and planar aromatic cations (pyrylium and tropylium). Benefiting from the aromatic cation–π interactions between anthracene and cationic guests, well-regulated 2DCAs are thus successfully obtained. The resultant 2DCAs exhibit a broadened fluorescence tunable range between blue-green and red emission colors, which is simply realized by varying the solvent ratio to turn on/off the aromatic cation–π emission charge transfer in the assembly/disassembly state of 2DCAs. On this basis, the programmable numbers, letters, patterns, and 3D codes with co-assembly encoded information security functions are successfully fabricated on papers, which would have a positive impact on developing supramolecular encryption materials.

Recent Progress in Atomically Precise Cu-M Alloy Nanoclusters.

Metal nanoclusters (NCs) with dimensions of approximately 3 nm serve as a crucial link between metal-organic complexes and metal nanoparticles, garnering significant interest due to their distinctive molecule-like characteristics. These include well-defined molecular structures, clear HOMO-LUMO transitions, quantized charge, and robust luminescence emission. Atomically precise alloy NCs, in contrast to homometallic NCs, exhibit a wealth of structures and intriguing properties, with their novel attributes often intricately tied to the positions of alloyed elements within the structure, facilitating the exploration of structure-property relationships. A notable subgroup within this category comprises Cu-M (where M represents metals such as Au, Ag, Rh, Ir, Pd, Pt, Zn, Al etc.) alloy NCs. In this review, we initially outline recent advancements in the development of efficient synthetic techniques for Cu-M alloy NCs, emphasizing the underlying physical and chemical properties that enable precise control over their sizes and surface characteristics. Subsequently, we delve into recent progress in structural elucidation techniques for Cu-M alloy NCs. This structural insight is instrumental in comprehensively understanding the structure-property correlations at the molecular level. Finally, we showcase various examples of Cu-M alloy NCs to illustrate their photoluminescent and catalytic properties, shedding light on their diverse functionalities and potential applications.

Influence of Sn2+ doping to improve the charge transport and light-emitting properties of CsPbCl3 perovskites

Doping B-site with metal ions is an emerging strategy to reduce lead toxicity and enhance the optoelectronic performance of lead halide perovskites. Also, the concentration of metal dopants plays an important role in achieving the desired electrical and optical properties of these halide perovskites. This work presents a simple chemical approach to synthesize pure and Sn2+doped CsPbCl3perovskites at room temperature. The dopant concentration was varied from 1 to 9 mol%. The structural, morphological, optical, thermal, and electrical properties of prepared perovskites are studied in order to check the optimal doping concentration along with to know the improvement in the optoelectronic properties required for LEDs and photovoltaic cells. It was observed that CsPbCl3perovskites exhibit high photoluminescence intensity, blue/violet emission, and high charge carrier mobility (up to 56.3 cm2V s-1) with a reduction in bandgap (up to 2.865 eV) after Sn2+doping.

Carbon emission controls and optimal carbon related regulation in oligopoly: Examination of policy effects on competitiveness and entry deterrence

Carbon emission controls and optimal carbon related regulation in oligopoly: Examination of policy effects on competitiveness and entry deterrence

Molecular simulation methods of evaporating electrosprayed droplets

Molecular simulation methods of evaporating electrosprayed droplets

Carborane-based BODIPY dyes: synthesis, structural analysis, photophysics and applications.

Icosahedral boron clusters-based BODIPY dyes represent a cutting-edge class of compounds that merge the unique properties of boron clusters with the exceptional fluorescence characteristics of BODIPY dyes. These kinds of molecules have garnered substantial interest due to their potential applications across various fields, mainly including optoelectronics, bioimaging, and potential use as boron carriers for Boron Neutron Capture Therapy (BNCT). Carborane clusters are known for their exceptional stability, rigid geometry, and 3D-aromaticity, while BODIPY dyes are renowned for their strong absorption, high fluorescence quantum yields, and photostability. The integration of carborane into BODIPY structures leverages the stability and versatility of carboranes while enhancing the photophysical properties of BODIPY-based fluorophores. This review explores the synthesis and structural diversity of boron clusters-based BODIPY dyes, highlighting how carborane incorporation can lead to significant changes in the electronic and optical properties of the dyes. We discuss the enhanced photophysical characteristics, such as red-shifted absorption and emission poperties, charge and electronic transfer effects, and improved cellular uptake, resulting from carborane substitution. The review also delves into the diverse applications of these compounds. In bioimaging, carborane-BODIPY dyes offer superior fluorescence properties and cellular internalization, making them ideal for cell tracking. In photodynamic therapy, (PDT) these dyes can act as potent photosensitizers capable of generating reactive oxygen species (ROS) for targeted cancer treatment making them excellent candidates for PDT. Additionally, their unique electronic properties make them suitable candidates for optoelectronic applications, including organic light-emitting diodes (OLEDs) and sensors. Overall, carborane-BODIPY dyes represent a versatile and promising class of materials with significant potential for innovation in scientific and technological applications. This review aims to provide a comprehensive overview of the current state of research on carborane-BODIPY dyes, highlighting their synthesis, properties, and broad application spectrum.

Catastrophic emission of charges from near-extremal Nariai black holes

Using both the in-out formalism and the monodromy method, we study the emission of charges from near-extremal charged Nariai black holes with the black hole event and cosmological horizons close to each other, whose near-horizon geometry is dS2×S2. The emission becomes catastrophic for a charge with energy greater than its chemical potential, whose leading exponential factor increases inversely proportional to the separation of two horizons. This effect may prevent near-extremal Nariai black holes with large charges that evaporate dominantly through the charge emission from evolving to black holes with a naked singularity, in analog to near-extremal RN-dS black holes that have the Breitenlohner-Friedman bound, below which they become stable against Hawking radiation and Schwinger effect of charge emission. The near-extremal Nariai black holes with small charges, which are close to near-extremal Schwarzschild-de Sitter black holes, emit dominantly charge-neutral particles and evolve to black holes with increasing charge to mass ratio. We illuminate the origin of the catastrophic emission in the phase-integral formulation and monodromy method by comparing near-extremal charged Nariai black holes with near-extremal Reissner-Nordtröm-dS black holes. Published by the American Physical Society 2024

Experimental-Modeling Framework for Identifying Defects Responsible for Reliability Issues in 2D FETs.

In this work, a self-consistent method is used to identify and describe defects plaguing 300 mm integrated 2D field-effect transistors. This method requires measurements of the transfer characteristic hysteresis combined with physics-based modeling of charge carrier capture and emission processes using technology computer aided design (TCAD) tools. The interconnection of experiments and simulations allows one to thoroughly characterize charge trapping/detrapping by/from defects, depending on their energy position. Once the trap energy distribution is extracted, it is used as input in transient TCAD simulations to reproduce the experimental hysteretic transfer characteristics. Our method is widely applicable to any 2D channel/gate stack combination. Here, it is demonstrated on FAB-integrated devices with AlOx/HfO2 gate oxide. A Gaussian-approximated defect band in the AlOx interlayer centered at a position of about 0.1 eV below the conduction band minimum of WS2 is obtained. Based on this energy position, it is concluded that aluminum interstitial and oxygen vacancies are the defects giving rise to the observed hysteresis. These defects are detrimental to the stability of the studied devices as they are easily accessible by channel carriers during on-state operation. A prominent hysteresis obtained during measurements is consistent with this conclusion.

Unravelling the Optoelectronic and Biological Properties of Phenanthroimidazo [1,2‐c] Quinazoline‐Based Donor‐Acceptor Materials

Abstract Imidazo[1,2‐c]quinazoline, a class of fused imidazole and quinazoline acceptor units, is widely established as biologically and broadly spectral active materials, while their optoelectronic properties were seldom investigated in the literature. In this context, this research work introduced two donors of varying strength, such as triphenylamine (TP) and phenothiazine (PZ) units, into the phenanthroimidazo [1,2‐c] quinazoline acceptor unit to form donor‐acceptor type luminescence materials such as TPQZ and PZQZ, respectively and were characterized by NMR and mass spectroscopy. Both these materials exhibited intramolecular charge transfer (ICT) type absorption (∼380–450 nm) and emission (∼540–600 nm) characteristics, which attributed to the electronic transition occurring from the HOMO of the TP/PZ donor to the LUMO+1 and LUMO+2 of the imidazo [1,2‐c] quinazoline acceptor unit, as predicted using DFT calculations. Increasing the electron donor strength was not only limited to fine‐tuning the π→π* based localized (∼400–450 nm) to ICT (∼450–650 nm) emission characteristics in both the solution and solid‐state conditions but also found to improve the zone of inhibition to 16 mm against Staphylococcus aureus/Bacillus subtilis bacterial species. The scope of realizing the luminescence nature of this acceptor unit is further expanded towards tagging biological samples such as E. coli. Overall, this work opens up a new paradigm in developing luminescent materials utilizing imidazo[1,2‐c]quinazoline acceptor unit for optoelectronic and biological applications.

Providing charge emission for cloud seeding aircraft

Releasing charge into natural droplet systems such as fog and clouds offers a route to influence their properties. To facilitate charge release across a wide range of altitudes and meteorological circumstances—such as developing clouds—a charge emitter has been developed for integration with the conventional cloud-seeding flares carried by crewed cloud-seeding aircraft. This allows charge emitters to be used alongside, or instead of, conventional particle releasing flares. The charge emitter flare system is self-contained and self-powered, and includes internal monitoring and recording of its operating parameters. Using this “flare emitter” approach, successful charge emission has been demonstrated in level flight, at 3 km altitude, likely to have exceeded natural ion concentrations by several orders of magnitude. This quantitative verification of successful charge emission can underpin further physically based experiments on the effectiveness of charge release in cloud seeding.