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Improved luminescence properties of a novel red dodec-fluoride phosphor Ba <sub/>3</sub> Sc <sub/>2</sub> F <sub/>12</sub> :Mn <sup>4+</sup> with extraordinary thermal stability for WLED application
摘要： Mn4+-activated red phosphors have recently attracted tremendous attention for their fascinating performance in white light emitting diodes (WLEDs) application to achieve warm white light, while the thermal stability of fluoride is still considered as a drawback. Herein, we report a novel red phosphor composed of Ba3Sc2F12:Mn4+ (BSF:Mn), in which, the emitting centers of Mn4+ ions are locating in the sites of Sc3+ ions. The photoluminescence of BSF:Mn varies with the concentration of K2MnF6, reaction temperature, and the concentrations of NH3·H2O in reaction system. Partly substituting Ba2+ with Ca2+ decreases the luminescent intensity of BSF:Mn. By employing the as-prepared phosphor BSF:Mn as a red component, a high-performance WLED with a correlated color temperature (CCT) at 4796 K and a color rendering index (CRI) of 85.2 was obtained. The phosphor BSF:Mn keeps undecomposed up to 800 oC, therefore, this work exhibits a strategy to explore a novel Mn4+-doped fluoride with particularly thermal stability.
关键词： luminescent properties,thermal stability,Ba3Sc2F12:Mn4+,Mn4+-activated red phosphors,WLEDs
更新于2025-09-19 17:13:59
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Luminescent Down‐Conversion Semiconductor Quantum Dots and Aligned Quantum Rods for Liquid Crystal Displays
摘要： Herein, emerging applications of luminescent semiconductor nanocrystals are addressed, such as quantum dots and quantum rods as down-conversion materials used in liquid crystal displays (LCD). Their precisely tunable emission wavelengths and narrow emission bandwidths offer high color purity resulting in a wide color gamut with vivid colors for LCDs. Anisotropic materials, such as quantum rods, have the additional advantage of polarized emission, which can bring a significant improvement to the efficiency of LCD displays. The basic optical properties of these nanomaterials are considered, with a focus on quantum rods, and the challenges and progress in their assembly are discussed. Different techniques for quantum rod alignment are introduced such as shear-oriented, electric field and magnetic field assisted assembly, mechanical rubbing, stretching, and electrospinning. The photoalignment approach allows for an easy arrangement of quantum rods in-plane, and the implications of this method to patterning are considered. Different configurations of LCDs utilizing semiconductor quantum dots and quantum rods as down-conversion layers are also presented, and the potential applications that are enabled by the wide range of emerging materials are highlighted.
关键词： quantum dots,liquid crystal displays,photoalignment,quantum rods,luminescent semiconductor nanocrystals,down-conversion materials,polarized emission
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Luminescent Solar Concentrator Tandem-on-Silicon with above 700mV Passivated Contact Silicon Bottom Cell
摘要： Luminescent solar concentrator (LSC) tandem-on-silicon (Si) provides a route towards achieving higher than 30% overall efficiency which can overcome the theoretical efficiency limit of a single junction Si cell. Here, we present optical coupling and performance of high Voc passivated contact Si bottom cell for LSC tandem-on-Si where the top module consists of highly efficient luminophores and an array of micro InGaP cells embedded in a poly (lauryl methacrylate) waveguide. In this device configuration, InGaP cell area coverage is only ~0.5% of the total LSC area which significantly reduces the high cost III-V material usage. The performance of Si sub-cell is investigated under LSC spectrum and is compared against the measurement done under 1 μm thick InGaP filter which mimics the spectrum seen by Si bottom cell in a conventional III-V/Si tandem. Voc of greater than 700 mV has been observed for the passivated contact Si bottom cell in these tandem applications.
关键词： passivated contact cells,luminescent solar concentrator,silicon
更新于2025-09-19 17:13:59
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Green fluorescent carbon quantum dots functionalized with polyethyleneimine, and their application to aptamer-based determination of thrombin and ATP
摘要： Brightly fluorescent carbon quantum dots coated with polyethylenimine (PEI-CDs) were prepared using malic acid and PEI as the precursors. The PEI-CDs have a high quantum yield (41%) and green emission (peaking at 502 nm under 430 nm excitation), both of which are not affected by high ionic strength. The PEI-CDs have a positive charge at physiological pH values and can electrostatically bind aptamers with their negative charge. This is shown for aptamers binding thrombin or ATP. Binding of aptamers results in quenching of fluorescence. If thrombin or ATP are introduced, the respective aptamer will bind them, and the complex is then released from the PEI-CDs. Fluorescence increases in proportion to the analyte concentration. Under optimized conditions, thrombin and ATP can be sensitively and selectively detected by fluorometry with lower detection limits of 1.2 and 13 nM, respectively. The assay was successfully applied to the determination of thrombin and of ATP in spiked serum samples.
关键词： Aptamer sensor,Thrombin detection,Serum analysis,Green luminescent,PEI-CDs,Malic acid,Polyethylenimine,Fluorescence assay,ATP detection,Hydrothermal reaction
更新于2025-09-19 17:13:59
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Bi-Activated Glasses and their Potential Covering Spectral Region as Active Media for Tunable near Infrared Lasers
摘要： To obtain the near infrared luminescence Bi-activated phosphate-aluminum-natrium glasses were synthesized and treated under reduction conditions. The reduction conditions were achieved by different methods: treatment in graphite atmosphere, hydrogen atmosphere, and X-ray irradiation. The spectral-luminescent properties of glass samples were measured and analyzed. Bi-activated phosphate-aluminum-natrium glasses after reduction treatment have shown wide near infrared luminescence with two peaks at the telecommunication windows region. The nature of the luminescent centers in Bi-activated phosphate-aluminum-natrium glasses are discussed. The spectral-luminescent properties of synthesized glasses were studied at the context of Bi-activated glass as the active media for tunable near infrared lasers operating in 1050-1500 nm region. The demonstrated properties of Bi-activated phosphate-aluminum-natrium glass are promising to fill the gap in near infrared lasers operating range.
关键词： Tunable infrared lasers,near infrared luminescence,Bi-doped glasses,spectral-luminescent properties of bismuth in glass matrix
更新于2025-09-16 10:30:52
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Enhancing Photovoltaic Performance of GaAs Single-Junction Solar Cells by Applying a Spectral Conversion Layer Containing Eu-Doped and Yb/Er-Doped Phosphors
摘要： In this study, we examined e?orts to increase the photovoltaic performance of GaAs single-junction solar cells using spectral conversion layers, respectively, composed of europium-doped (Eu-doped) phosphors, ytterbium/erbium-doped (Yb/Er-doped) phosphors, and a combination of Eu-doped and Yb/Er-doped phosphors. Spin-on ?lm deposition was used to apply the conversion layers, all of which had a total phosphor concentration of 3 wt%. The chemical compositions of the phosphors were examined by energy-dispersive X-ray spectroscopy. The ?uorescence emissions of the phosphors were con?rmed by using photoluminescence measurements. Under laser diode excitation at 405 nm, we observed green luminescent downshift (LDS) emissions by Eu-doped phosphors at wavelengths of 479 nm to 557 nm, and under excitation at 980 nm, we observed red up-conversion (UC) emissions by Yb/Er-doped phosphors at wavelengths of 647 nm to 672 nm. The spectral conversion layers were characterized in terms of optical re?ectance, external quantum e?ciency, and photovoltaic current and voltage under AM 1.5 G simulations. The conversion e?ciency of the cell combining Eu-doped and Yb/Er-doped phosphors (23.84%) exceeded that of the cell coated with Yb/Er-doped phosphors (23.72%), the cell coated with Eu-doped phosphors (23.19%), and the cell coated without phosphors (22.91%).
关键词： ytterbium/erbium-doped (Yb/Er-doped),europium-doped (Eu-doped),up-conversion,phosphors,GaAs solar cell,luminescent downshift
更新于2025-09-16 10:30:52
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A quantum dot-silica composite as an efficient spectral converter in a luminescent down-shifting layer of organic photovoltaic devices
摘要： We developed a gradient quantum dot (QD)@polyvinylpyrrolidone (PVP)-silica composite as a spectral converter to improve light harvesting of the photoactive layer in organic photovoltaic (OPV) devices. The spectral converter prepared by a simple sol–gel method served as a luminescent down-shifting (LDS) layer that absorbed ultraviolet and emitted visible light. Re-emitted light energy from the LDS layer appeared within the absorption range of the photoactive donor material of P3HT in the OPV devices. We investigated how the light harvesting ability was affected by the concentration of QD@PVP and the thickness of the LDS layer. The OPV devices with the LDS layer showed increased power conversion efficiency (PCE) from 3.38% to 3.68% compared to pristine OPV devices due to improved incident light transmittance and increased light harvesting.
关键词： spectral converter,organic photovoltaic devices,silica composite,quantum dot,luminescent down-shifting
更新于2025-09-16 10:30:52
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Rationally assembled nonanuclear lanthanide clusters: Dy <sub/>9</sub> displays slow relaxation of magnetization and Tb <sub/>9</sub> serves as luminescent sensor for Fe <sup>3+</sup> , CrO <sub/>4</sub><sup>2?</sup> and Cr <sub/>2</sub> O <sub/>7</sub><sup>2?</sup>
摘要： The utilization of a Schi? base ligand 2-((2-hydroxy-4-methoxy-benzylideneamino)methyl)phenol (H2L) a?orded five nonanuclear lanthanide(III) clusters of formula [Ln9L8(m3-OH)8(m5-O)2(DMF)8][H3O](cid:3)nH2O (Ln = Eu, n = 1 (1[H3O](cid:3)H2O); Ln = Gd, n = 4 (2[H3O](cid:3)4H2O); Ln = Tb, n = 3 (3[H3O](cid:3)3H2O); Ln = Dy, n = 6 (4[H3O](cid:3)6H2O); Ln = Ho, n = 2 (5[H3O](cid:3)2H2O)). Single-crystal X-ray di?raction analysis revealed that all of the complexes were isomorphous and had a diabolo-like topology. The intriguing Ln9 core was constructed by two square pyramidal units that shared a vertex metal centre. Variable-temperature dc magnetic susceptibility studies indicated weak antiferromagnetic interactions for 2[H3O](cid:3)4H2O, 3[H3O](cid:3)3H2O, 4[H3O](cid:3)6H2O and 5[H3O](cid:3)2H2O. The DyIII 9 cluster displayed a slow relaxation of magnetization. Fluorescence measurements revealed an intense green photoluminescence for the TbIII 9 compound. The luminescence tests showed that the TbIII 9 analogue could perform as a highly sensitive, selective and recyclable luminescence sensing material for Fe3+, CrO4 2(cid:2). In this work, the H2L ligand was derived by finely modifying the previously designed compounds (((2-hydroxy-3-methoxybenzyl)imino)- 2(cid:2) and Cr2O7 2(cid:2)? *a and methyl)-6-ethoxyphenol and (((2-hydroxy-3-methoxybenzyl)imino)methyl)-6-methoxyphenol, from which the Ln2 and Ln4 clusters were successfully prepared and reported. Noticeably, the decisive decrease in the steric hindrance of the predesigned ligands resulted in the expansion of the nuclearity. This work demonstrated the synthetic potential for assembling the large clusters by rationally decreasing the steric rsc.li/njc hindrance of the analogous ligands.
关键词： magnetization,Fe3+,CrO4 2(cid:2),luminescent sensor,Cr2O7 2(cid:2),lanthanide clusters
更新于2025-09-16 10:30:52
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Distarch Phosphate as a Matrix for the Generation of Quantum Dots
摘要： Generation of ZnS, CdS, CaS and MgS quantum dots (QDs) was attempted in the matrix of distarch phosphate, an anionic polysaccharide. Based on the analysis of FTIR spectra, thermograms and Differential Scanning Calorimetry, interactions of QDS with the matrix could be excluded. On generation of MgS QDs and also, to a certain extent, CaS QDs, hydrolysis of the salts generating these QDs took place. That process had an impact on the partial destruction of the matrix. Molecular weight and radii of gyration of the products showed that the generation of QDs was dependent on the properties of the matrix polysaccharide. The elasticity, plasticity and viscosity of the gels containing QDs were significantly lower than those of plain distarch phosphate. Generally these values changed with time similarly to gels free of QDs.
关键词： Biocomposites,Calcium sulfide,Cadmium sulfide,Magnesium sulfide,Zinc sulfide,Luminescent biodegradable foils
更新于2025-09-16 10:30:52
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Metallic Nanomaterials (Part B) || 5. Size-controlled atomically precise copper nanoclusters: Synthetic protocols, spectroscopic properties and applications
摘要： Noble metal nanoclusters (NCs) are a new class of nanomaterials which are considered being a missing link between isolated metal atoms and metal nanoparticles (NPs). The sizes of the NCs are comparable to the Fermi wavelength of the conduction electrons, and this renders them to be luminescent in nature. They exhibit size-dependent fluorescence properties spanning almost the entire breath of the visible spectrum. Among all the noble metal NCs being explored, copper NCs (CuNCs) are the most rarely investigated primarily because of their propensity of getting oxidised. In this chapter, we have given a comprehensive understanding as to why these NCs are luminescent in nature. We have also given a detailed overview regarding the various templates used for the synthesis of these CuNCs along with the respective protocols being followed. The various instrumental techniques used to characterize these CuNCs are discussed which provides an in-depth understanding as to how these CuNCs can be properly examined. Finally, we have highlighted some of the most recent applications of these CuNCs which make them unique to serve as the next-generation fluorophores.
关键词： nano-thermometry,bio-imaging,sensing,synthetic protocols,instrumentations,spectroscopic properties,templates,luminescent nanoclusters
更新于2025-09-16 10:30:52