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Tunable bluea??greena??emitting Na4CaSi3O9:Ce3+,Li+,Tb3+ phosphor with energy transfer for near-UV white LEDs
摘要： Phosphor-converted white light emitting diodes (w-LEDs), with high luminous ef?ciency, low energy consumption, extended lifetime, and eco-friendly nature, have revolutionized various industries. Among them, an alkaline earth silicate-based phosphor host, Na4CaSi3O9, shows good crystal structure stability and ?exible properties for diverse application. Here, Ce3t/Lit and Tb3t/Lit co-doped Na4CaSi3O9 phosphors are fabricated by the standard solid-state reaction approach. The Ce3t/Lit-activated phosphors show strong absorption within 200e400 nm and exhibit a blue emission centered at 423 nm. The quenching concentration of Ce3t appears at x ? 0.05 and can be attributed to the dipoleequadrupole interaction. When Tb3t ions are co-doped, the Na4CaSi3O9:Ce3t/Lit phosphor emission can be adjusted from blue to green under the irradiation of 365 nm through the dipoleedipole interaction induced energy transfer from Ce3t to Tb3t ions with a maximum value of 28.32%. This study highlights the Na4CaSi3O9:Ce3t/Lit,Tb3t/Lit phosphors as a new and ef?cient material for w-LED applications.
关键词： Phosphor,Solid-state reaction,Luminescence,LED,Energy transfer
更新于2025-09-23 15:21:01
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Photovoltaic-Driven SiC MOSFET Circuit Breaker with Latching and Current Limiting Capability
摘要： This paper introduces a Solid State Circuit Breaker with Latching and Current Limiting capabilities for DC distribution systems. The proposed circuit uses very few electronic parts and it is fully analog. A SiC N-MOSFET driven by a photovoltaic driver and a maximum current detector circuit are the core elements of the system. This work details circuit operation under different conditions and includes experimental validation at 1 kVdc. Wide versatility, highly configurable, and very fast response, less than 1 μs in the case of short-circuit, are the most remarkable outcomes.
关键词： SiC MOSFET,Solid State Circuit Breaker (SSCB),fault current limiter,WBG semiconductors,DC power distribution
更新于2025-09-23 15:21:01
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New approach to raising the resolution of position sensitive detector with moving current-voltage characteristic
摘要： Position sensitive detectors (PSD) are widely applied for determining the coordinate of an optical signal and continuously tracking it. Currently, studies concerned with the possibility of further raising the spatial resolution of PSDs remain topical. In this paper, we present the results obtained in reaching an ultrahigh resolution for a device based on the PSD Multiscan with an integral operation principle which fundamentally differs from that of the lateral PSD. The PSD Multiscan design is based on an array of back-to-back photodiodes. Its optical signal coordinate read-out is formed via the moving current-voltage characteristic of the sensor directly on the PSD as an output potential proportional to the coordinate of the optical spot median. This measurement principle provides a continuous comparison of near-equal photocurrents, which maintains a high signal-to-noise ratio over the whole sensing area. The absence of computational operations in electronic circuits of the PSD Multiscan makes it possible to introduce a nonlinear amplifier element, which substantially improves the resolution of the device based on the sensor developed in the study (as good as 0.05 μm). It has been shown that the resolution remains high for detectors with different lengths and is independent of the position of the optical spot on the sensing area.
关键词： Analogue electronic circuits,Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc),Optical detector readout concepts
更新于2025-09-23 15:21:01
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A study on structural, spectral, and magnetic properties of Pr–Bi co-doped M-type barium–strontium hexaferrites via the solid-state reaction method
摘要： Pr–Bi co-doped M-type Ba–Sr hexaferrites with nominal compositions Ba0.35Sr0.65?xPrxFe12.0?xBixO19 (0.00 ≤ x ≤ 0.40) were synthesized for the first time by the solid-state reaction method. These hexaferrites were characterized by X-ray diffractometer (XRD), Fourier transformer infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and thermogravimetric analyzer (TGA). XRD patterns showed that the single M-type hexaferrite phase was obtained only if Pr–Bi content (x) ≤ 0.24. FT-IR frequency bands in the range (608–610) cm?1 and (445–447) cm?1 correspond to the formation of tetrahedral and octahedral clusters of metal oxides in the hexaferrites, respectively. FE-SEM micrographs indicated that the grains were of platelet-like shapes. The saturation magnetization (Ms), remanent magnetization (Mr), magnetic anisotropy field (Ha), first anisotropy constant (K1) and coercivity (Hc) first increased with Pr–Bi content (x) from 0.00 to 0.08, and then decreased when Pr–Bi content (x) ≥ 0.08. The Curie temperature (Tc) decreased with increasing Pr–Bi content (x) from 0.00 to 0.40.
关键词： Pr–Bi co-doped,structural properties,solid-state reaction method,spectral properties,magnetic properties,M-type barium–strontium hexaferrites
更新于2025-09-23 15:21:01
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Weak Coupling, Strong Coupling, Critical Coupling and Fano Resonances: A Unifying Vision
摘要： The transversal concepts of weak, strong and critical coupling, and of Fano resonances, are analyzed within a unified framework which relies on a simple classical model of driven-dissipative coupled oscillators. A careful exploration of the system’s parameter space has led to the emergence of certain intriguing phenomena, which we named lineshape inheritance, universal absorption lineshape, and strong critical coupling. These concepts may be of relevance when attempting to understand the response of a diversity of systems, especially in the fields of (quantum) light-matter coupling, and of solid-state nanophysics, where the basic scheme of multi-oscillator dissipative resonances is often encountered.
关键词： strong coupling,Fano resonances,critical coupling,solid-state nanophysics,weak coupling,light-matter coupling
更新于2025-09-23 15:21:01
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Aryl substitution of pentacenes
摘要： A series of 11 new pentacene derivatives has been synthesized, with unsymmetrical substitution based on a trialkylsilylethynyl group at the 6-position and various aryl groups appended to the 13-position. The electronic and physical properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films), thermoanalytical methods (DSC and TGA), cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives). X-ray crystallography has been specifically used to study the influence of unsymmetrical substitution on the solid-state packing of the pentacene derivatives. The obtained results add to our ability to better predict substitution patterns that might be helpful for designing new semiconductors for use in solid-state devices.
关键词： organic semiconductor,pentacene,π-stacking,solid-state structure,carbon-nanomaterials,polycyclic aromatic hydrocarbon
更新于2025-09-23 15:21:01
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Above 800 mV Open-Circuit Voltage in Solid-State Photovoltaic Devices Using Phosphonium Cation-Based Solid Ionic Conductors
摘要： Here, we report phosphonium based two solid ionic conductors (SICs) named as triphenylphosphonium methyl iodide (TPPMeI) and triphenylphosphonium iodide (TPPHI) prepared via simple protocol at room temperature and were used as an electrolyte for solid state photovoltaic devices (ss-PVDs) showing the open circuit voltage (Voc) exceeding to 800 mV. Here, very first time, detailed electrochemical investigations with theoretical aspects of phosphonium electrolytes were taken into account, where PVDs prepared from these SICs, TPPMeI resulted into the highest power conversion efficiency (PCE) of 4.08 % with Voc of 810 mV. However, this performance was further enhanced up to the PCE of 6.71% with 824 mV of Voc in the presence of additives like LiI and tert-butyl pyridine. This work leads to find the best alternative of liquid and quaternary ammonium ion based electrolytes which suffers from problems like lower Voc (< 800 mV), stability, leakage etc.
关键词： Phosphonium cation based solid organic ionic conductors,Solid ionic conductors,Solid state photovoltaic device,Triphenylphosphonium cation,Organic Electrolytes
更新于2025-09-23 15:19:57
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The Phase Behavior in the Active Layer of Small Molecule Organic Photovoltaics: The State Diagram of p-DTS(FBTTh <sub/>2</sub> ) <sub/>2</sub> :PC <sub/>71</sub> BM
摘要： A comprehensive study was undertaken to obtain a more fundamental understanding of the phase behavior of the p-DTS(FBTTh2)2:PC71BM system, used in small molecule organic solar cells, with a strong focus on the amorphous phase and its influence on crystallinity. Three dedicated thermal protocols were used in combination with advanced thermal analysis, solid-state NMR, and wide angle X-ray diffraction. Rapid cooling, to avoid structure formation and gain insight in the amorphous phase, and slow cooling, to promote structure formation, were used as limiting cases to explain the intermediate behavior after device processing from solution. A complete state diagram was developed and the glass transition (Tg) - composition relationship was determined. In the case of slow cooling and the procedure used for device processing, the rapid crystallization of p-DTS(FBTTh2)2 leads to an enrichment of the amorphous phase in PC71BM, increasing its Tg and causing vitrification of the mixed amorphous phase before crystallization when the total amount of PC71BM exceeds 70 wt%. The common processing additive 1,8-diiodooctane (DIO) was found to lead to a lower p-DTS(FBTTh2)2 crystallinity and smaller average crystal size. More importantly, it acts as a strong plasticizer, lowering Tg significantly and thus reducing the morphological stability of the p-DTS(FBTTh2)2:PC71BM mixtures.
关键词： p-DTS(FBTTh2)2:PC71BM,glass transition temperature,wide angle X-ray diffraction,phase behavior,crystallinity,amorphous phase,small molecule organic photovoltaics,thermal analysis,solid-state NMR,1,8-diiodooctane (DIO)
更新于2025-09-23 15:19:57
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Ytterbium-doped fibre femtosecond laser offers robust operation with deep and precise microsurgery of C. elegans neurons
摘要： Laser microsurgery is a powerful tool for neurobiology, used to ablate cells and sever neurites in-vivo. We compare a relatively new laser source to two well-established designs. Rare-earth-doped mode-locked fibre lasers that produce high power pulses recently gained popularity for industrial uses. Such systems are manufactured to high standards of robustness and low maintenance requirements typical of solid-state lasers. We demonstrate that an Ytterbium-doped fibre femtosecond laser is comparable in precision to a Ti:Sapphire femtosecond laser (1–2 micrometres), but with added operational reliability. Due to the lower pulse energy required to ablate, it is more precise than a solid-state nanosecond laser. Due to reduced scattering of near infrared light, it can lesion deeper (more than 100 micrometres) in tissue. These advantages are not specific to the model system ablated for our demonstration, namely neurites in the nematode C. elegans, but are applicable to other systems and transparent tissue where a precise micron-resolution dissection is required.
关键词： Ytterbium-doped fibre femtosecond laser,Laser microsurgery,neuronal regeneration,Ti:Sapphire femtosecond laser,solid-state nanosecond laser,C. elegans
更新于2025-09-23 15:19:57
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Illuminating homes with LEDs in India: Rapid market creation towards low-carbon technology transition in a developing country
摘要： Near-term climate change mitigation calls for technological innovation and widespread implementation of appropriate technologies. This is salient in emerging economies, where impending socio-economic and infrastructural transitions hold immense potential for locking-in low-carbon development pathways. Yet, little is understood about how developing countries can scale appropriate technology transitions, given their often underdeveloped technological innovation capabilities and supporting infrastructures and finances. This paper examines a recent, rapid, and ongoing transition of India's lighting market to light emitting diode (LED) technology, from a negligible market share to LEDs becoming the dominant lighting products within five years, despite the country's otherwise limited visibility in the global solid-state lighting industry. Annual sales of LED bulbs grew more than 130 times to over 650 million bulbs between 2014–2018, with over 30 billion kWh of estimated annual energy savings. Focusing on this striking story of technology transition, this paper analyzes India's LED uptake using semi-structured interviews and drawing on the technology innovation systems literature. The results show that the success of transition coexists with its share of shortfalls, and that there is an important tension between the lowering of upfront costs of low-carbon technologies and the efforts to enhance domestic technological capabilities. The paper discusses the results for the Indian LED case and emphasizes the importance of consistent strategic action taking into account all (and not limited) parts of the technology innovation system, while also providing insights on how mitigation technologies can be developed and deployed in developing countries.
关键词： Technology innovation systems,Light emitting diode (LED),Developing countries,India,Solid state lighting,Climate change mitigation,Energy efficiency
更新于2025-09-23 15:19:57