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Development of InP Quantum Dot-based Light Emitting Diodes
摘要： High performance quantum dot light emitting diode (QLED) is being considered as the next generation technology for energy efficient solid-state lighting and displays. InP QLED is the most promising alternative of the toxic CdSe QLED. Unlike the problems of poor hole injection in CdSe-based QLED, highly delocalized electrons and parasitic emissions are serious problems in green-emitting InP QLED. The loss mechanism and device physics in InP QLED have not been sufficiently studied since the first report of InP QLED in 2011. This review summarized the recent efforts on improving the performance of InP QLED, from the perspectives of core/shell structures to optimization of carrier transport layers. It is our intention to conduct a review as well as clarify some previous misunderstandings on the device physics in InP QLED, and provide some insights for the possible solutions of the challenging problems in InP QLED.
关键词： InP quantum dots,carrier transport layers,parasitic emissions,core/shell structures,QLED
更新于2025-09-16 10:30:52
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A new strategy for structuring white organic light-emitting diodes by combining complementary emissions in the same interface
摘要： In this work, we proposed a new strategy for structuring white organic light-emitting diodes (WOLEDs) using all exciplex emissions, where the white devices can be fabricated by simply depositing several exciplex acceptor layers on the same exciplex donor layer in a vertical direction, and complementary exciplex emissions can be realized in the same exciplex donor layer interface for forming white emission. Based on this new strategy, a series of WOLEDs with different array arrangements of different exciplex acceptor layers on the same exciplex donor layer were demonstrated. The device with a bisected blue-yellow exciplex acceptor layer on the same exciplex donor layer realizes good two-color white emission with a high color rendering index of 71, and also achieves a high current efficiency of 3.17 cd A?1. Moreover, the emission spectra and device performance of white devices can be adjusted and improved by simply changing the array arrangements of different exciplex acceptor layers on the same exciplex donor layer. More importantly, the proposed new strategy can effectively solve the interface problem induced by employing interface exciplexes to realize multi-color white emission, which provides a new approach to accomplish all exciplex emission WOLEDs.
关键词： exciplex emissions,device performance,color rendering index,white organic light-emitting diodes,current efficiency
更新于2025-09-16 10:30:52
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White-light/tunable emissions in single-phased BaLa2Si3O10:Eu3+, Bi3+ phosphor for the simultaneous applications in white light-emitting diodes and luminous cement
摘要： In this work, we report the single-phased BaLa2Si3O10:Eu3+, Bi3+ phosphor with white-light/tunable emissions under UV excitations. We find the emissions of Bi3+-doped BaLa2Si3O10 samples are dependent on the excitation spectral wavelength, where exciting by the wavelength from 240 to 410 nm range can lead to the tunable Bi3+ emissions owing to the intensity change of three emission bands (i.e., 367 nm, 423 nm, and 516 nm). After co-doping the Eu3+ ions into Bi3+-doped BaLa2Si3O10, the energy transfer from Bi3+ to Eu3+ ions dominated by a dipole–quadrupole (d–q) interaction mechanism is proved. Typically, by exciting with 365 nm and varying the Eu3+ content, the tunable emissions from blue, white to red are observable in the BaLa2Si3O10:Eu3+, Bi3+. By coating the white BaLa2Si3O10:Eu3+, Bi3+ sample with a commercial 365-nm UV LED chip or mixing it with the cement, we not only achieve the white-light LEDs device with the desirable color rendering index (CRI) of 95, excellent luminescent efficiency of 80 lm/W, and good excellent color temperature (CT) of 4215 K at the CIE chromaticity of (0.338, 0.357), but also achieve the luminous cement.
关键词： white light-emitting diodes,single-phased phosphor,white-light/tunable emissions,luminous cement,BaLa2Si3O10:Eu3+,Bi3+
更新于2025-09-12 10:27:22
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A New Co-Substitution Strategy as a Model to Study a Rare-Earth-Free Spinel-Type Phosphor with Red Emissions and Its Application in Light-Emitting Diodes
摘要： The substitution of metal sites in Mg2TiO4 substrate leads to charge imbalance that will be closely related to a variety of changes including lattice structure, cell distortion, and photophysical properties. Herein, the co-substitution strategy of [Ga3+?Ga3+] for [Mg2+?Ti4+] and Sn4+ for Ti4+ achieves for the first time the novel Mg3Ga2SnO8 (MGS):xMn4+ (x = 0?3%) phosphors with efficient red emissions. In terms of X-ray powder diffraction (XRD) and Rietveld refinement analysis, MGS:Mn4+ possesses a structure isotypic of Mg2TiO4 in the cubic space group Fd3?m (227). There are two types of octahedra for Mn4+ ions in this structure, where Ga3+ ions completely occupy a group of octahedral sites and Mg2+/Sn4+ has been randomly distributed over another group of octahedral sites. A strong excitation band in the broad spectral range (220?550 nm) has been identified, thus facilitating the commercial uses for blue LED chips excitation. An intense red emission band at 680 nm has been observed due to the characteristic 2Eg?4A2g transition of Mn4+ ions. A concentration quenching effect occurs when the Mn4+ content exceeds 1.5%, and the quenching mechanism is demonstrated to be dipole?quadrupole interactions. Temperature-dependent luminescence measurements support its good thermal stability, and the corresponding activation energy Ea is determined to be 0.2552 eV. The possible luminous mechanism of the Mn4+ ion is explained by the Tanabe?Sugano energy level diagram. The crystal field strength and the Racah parameters together with the nephelauxetic ratio are also determined for Mn4+ in the MGS lattice. High color rendition warm white-light-emitting diodes (WLEDs) based on the optimal phosphor MGS:1.5%Mn4+,1.5%Li+ possess a color rendering index and color temperature of 85.6 and 3658 K, respectively. Its feasibility for application in solid-state white lighting has been verified.
关键词： Co-substitution strategy,Light-emitting diodes,Red emissions,Spinel-type phosphor,Rare-earth-free
更新于2025-09-12 10:27:22
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Analysis and Modeling of Conducted EMI From an AC–DC Power Supply in LED TV up to 1 MHz
摘要： Critical conduction mode (CRM) boost power factor correction (PFC) converter is widely used in ac–dc power supplies to achieve high power factor. The switching frequency varies in a half-line cycle. In this article, both the differential-mode (DM) and common-mode (CM) electromagnetic interference (EMI) noises below 1 MHz from the ac–dc power supply in a LED TV are analyzed and modeled. The power supply consists of two parts: CRM boost PFC converter and LLC resonant converter. The conducted EMI noise and noise source voltages are measured in the time domain and then converted to the frequency domain via short-time fast Fourier transform (STFFT). Through the joint time-frequency analysis using STFFT, the drain-to-source voltage of the power MOSFET in the PFC converter is identified as the dominant noise source of both CM and DM EMI below 1 MHz from the power supply. The EMI current path changes during different periods of a cycle of the line voltage. During most time of a cycle, two diodes of the bridge rectifier are forward biased, and the bridge rectifier can be treated as short circuit. The current paths of DM and CM EMI are explained and modeled by a linear equivalent circuit model. Three parasitic capacitances need to be considered to model the CM EMI noise in this device under test. From the circuit model, transfer functions relating DM and CM EMI spectra to noise source voltage spectrum are obtained. The conducted EMI spectra is predicted by multiplying the spectrum of noise source voltage by the transfer functions. The prediction matches with measurement. The effects of parasitic capacitances on CM EMI noise are analyzed by simulation and then validated by measurement. The analysis can help with EMI design to reduce the CM EMI.
关键词： conducted emissions (CE),differential mode (DM),Common mode (CM),electromagnetic interference (EMI),switched-mode power supply (SMPS),critical conduction mode (CRM),power factor correction (PFC)
更新于2025-09-12 10:27:22
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The role of photovoltaics in a sustainable European energy system under variable CO <sub/>2</sub> emissions targets, transmission capacities, and costs assumptions
摘要： PyPSA-Eur-Sec-30 is an open-source, hourly resolved, networked model of the European energy system that includes one node per country as well as electricity, heating, and transport sectors. The capacity and dispatch of generation and storage technologies in every country can be cost optimized under different CO2 emissions constraints. This paper presents an overview of the most relevant results previously obtained with the model, highlighting the influence of solar photovoltaic (PV) generation on them. For 95% CO2 emissions reduction, relative to 1990 level, PV generation supplies in average 33% of the electricity demand. Southern European countries install large PV capacities together with electric batteries, while northern countries install onshore and offshore wind capacities and use hydrogen storage and reinforced interconnections to deal with wind fluctuations. The strong daily generation profile of solar PV heavily impacts the dispatch time series of backup generation and storage technologies. The optimal PV and wind capacities are investigated for variable CO2 emissions, transmission interconnection among neighbouring countries, and cost assumptions.
关键词： energy system modelling,CO2 emissions targets,sector coupling,storage,grid integration,transmission grid
更新于2025-09-12 10:27:22
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Imaging of X-Ray-Excited Emissions from Quantum Dots and Biological Tissue in Whole Mouse
摘要： optical imaging in clinical and preclinical settings can provide a wealth of biological information, particularly when coupled with targetted nanoparticles, but optical scattering and absorption limit the depth and resolution in both animal and human subjects. two new hybrid approaches are presented, using the penetrating power of X-rays to increase the depth of optical imaging. foremost, we demonstrate the excitation by X-rays of quantum-dots (QD) emitting in the near-infrared (niR), using a clinical X-ray system to map the distribution of QDs at depth in whole mouse. We elicit a clear, spatially-resolved NIR signal from deep organs (brain, liver and kidney) with short (1 second) exposures and tolerable radiation doses that will permit future in vivo applications. furthermore, X-ray-excited endogenous emission is also detected from whole mouse. the use of keV X-rays to excite emission from QDs and tissue represent novel biomedical imaging technologies, and exploit emerging QDs as optical probes for spatial-temporal molecular imaging at greater depth than previously possible.
关键词： biomedical imaging,Biological tissue,Whole Mouse,Quantum Dots,NIR signal,X-ray-excited emissions
更新于2025-09-12 10:27:22
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Multi C–C/ C–N Coupled Light‐Emitting Aliphatic Terpolymers: N–H Functionalized Fluorophore‐Monomers and High‐Performance Applications
摘要： For circumventing the costly fluorescent labelling, nonconventional multifunctional intrinsically fluorescent aliphatic-terpolymers, i.e., 1, 2, 3, 4, and 5, were synthesized via C–C/ C–N coupled in situ protrusions of fluorophore-monomers in solution polymerization of two non-emissive monomers. These scalable terpolymers were suitable for sensing and high-performance exclusion of Cu(II), logic-function, and bioimaging. The structures of terpolymers, fluorescent monomers, aggregation-induced enhanced emissions, bioimaging abilities, and the superadsorption were understood using 1H/ 13C NMR, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, atomic absorption spectroscopy, thermogravimetric analysis, high-resolution transmission electron microscopy, dynamic light scattering, electron paramagnetic resonance spectroscopy, solid-state fluorescence, fluorescence imaging, and fluorescence lifetime, along with isotherms, kinetics, and thermodynamic studies. The geometries and electronic structures of fluorophores and absorption-emission properties of terpolymers were examined using density functional theory, time-dependent DFT, and natural transition orbital analyses. For 1, 2, and 5, the limit of detection values were 1.03 × 10?7, 1.65 × 10?7, and 1.77 × 10?7 M, respectively. The maximum adsorption capacities were 1575.21, 1433.70, and 1472.21 mg g?1 for 1, 2, and 5, respectively.
关键词： aliphatic,aggregation-induced enhanced emissions,light-emitting,logic-gates,superadsorption,Nonconventional,bioimaging,Cu(II)-sensors,DFT-TDDFT-NTO,terpolymers
更新于2025-09-11 14:15:04
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Assessment of 50?kWp rooftop solar photovoltaic plant at The ICFAI University, Jaipur: A case study
摘要： Currently, India is espousing nonconventional energy sources at an express rate owing to concerns about climate change, emission of harmful greenhouse gases (GHG), and exhausting conventional energy sources. The solar photovoltaic (SPV) plants are, hence, expected to play a noteworthy role to meet energy security and sustainability goals. Contemporary studies reveal substantial ecological concerns associated with installing the ground mounted SPV plants in urban locations. Further observations depict that aforementioned plants need additional land, transmission, and distribution infrastructures. Consequently, rooftop SPV plants are the best solution to produce energy in urban locations, owing to the availability of a large number of empty rooftop spaces with least capacity expenditure. The present article discusses the techno-economic and ecological aspects of a 50 kWp rooftop SPV plant installed at ICFAI University, Jaipur. The plant has produced around 64.149 MWh in the year 2017. The technical assessment focuses on the effects of the meteorological parameters upon energy generation factors. The annual average final yield, reference yield, capacity utilization factor, and performance ratio found to be 106.9 kWh/kWp/month, 149.7 kWh/kWp/month, 14.64 and 70%, respectively. The economic parameters like net present value, internal rate of return, profitability index, and payback period are computed with 0–50% subsidy rates, which supports the financial viability of the plant. The plant contributed significantly to reducing GHG emissions by mitigating 102 t CO2, 128 kg SO2, 268 kg NOx, and 7,033 kg ash in the year 2017 as evident from the ecological investigation.
关键词： rooftop solar photovoltaic plant,GHG emissions,meteorological parameters,pay back period,capacity utilization factor,performance ratio
更新于2025-09-11 14:15:04
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Life cycle analysis of a building integrated photovoltaic system operating in Bogotá, Colombia
摘要： In this study, the environmental behavior was characterized for a 840 Wp building-integrated photovoltaic (BIPV) system installed in the Department of Physics of the Faculty of Sciences at the National University of Colombia, Bogota campus. The methodology focused on the application of the international technical standards for Life Cycle Analysis (LCA) from cradle to grave based on the NTC ISO 14040 and NTC ISO 1404 standards, which regulate the methodological procedure. This article is based on comparing the potential of environmental impacts of five power generation scenarios, taking as reference the installation of the photovoltaic system (PV) at the University. During the analysis it was possible to determine that energy generation with coal has a greatest environmental impact compared with photovoltaics: 84% and 6% respectively. This represents 1138.8 gCO2eq/kWh for coal, compared to 35 gCO2eq/kWh for the PV system.
关键词： Solar energy,Solar cells,Greenhouse emissions,Photovoltaic systems,Life cycle analysis
更新于2025-09-11 14:15:04