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[IEEE 2020 International SAUPEC/RobMech/PRASA Conference - Cape Town, South Africa (2020.1.29-2020.1.31)] 2020 International SAUPEC/RobMech/PRASA Conference - Thin film photovoltaic module characterisation based in indoor and outdoor methods
摘要： This paper is the fifth in a series of articles on the basic physics of light yield nonproportionality in scintillators. Here, we compare and contrast the nonproportionality as registered by gamma rays and high-energy electrons. As has been noted in the past, these two types of data have different curve shapes (for plots of the light yield against electron or gamma energy). Herein, we show how the experimental gamma nonproportionality curve can be calculated from the electron response by accounting for the distribution of high energy electrons created by the gamma photon via the photoelectric interaction. Similarly, we measure and model the gamma-induced resolution as a function of energy and compare this data to predictions from our model. The utility of the model is explored using data acquired with the scintillators (Eu), GYGAG(Ce) and CsI(Na).
关键词： Gamma ray detectors,solid scintillation detectors,luminescence
更新于2025-09-23 15:21:01
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Synthesis and photoluminescent properties of Ba2+ ions doped europium formate phosphors for white light-emitting diodes
摘要： We report on the synthesis and photoluminescent performance of the Ba2+ ions doped Eu(HCOO)3 phosphors as well as their promising applications in indoor illumination. The thermal stability of the synthesized sample with microparticles was characterized by the thermogravimetric analysis. Irradiated by 396 nm light, the unique emissions of Eu3+ ions originating from the 5D0 → 7FJ (J ? 1, 2, 3, 4) transitions were observed. With the aid of the Judd-Ofelt theory, the local symmetry properties of the Eu3+ ions in the selected host were studied, revealing that the sites taken by the Eu3+ ions possessed low symmetry with non-inversion center. An enhanced luminescent intensity was seen in the resultant phosphors when the Ba2+ ions were introduced and the optimal doping content was 10 mol%. The studied samples can exhibit bright visible red emission with high color purity of 93.3% upon 396 nm excitation. Moreover, the resistance of the emission intensity to the temperature was also explored and the activation energy was 0.188 eV. Furthermore, the internal quantum efficiency of the resultant samples was 67% when excited by 396 nm. Ultimately, a light-emitting diode (LED) lamp, which emitted warm white light with high color rendering index of 80.7 and low color correlated temperature of 4715 K, was constructed, indicating the feasibility of the synthesized phosphors for white-LED.
关键词： Phosphors,White-LED,Luminescence,Rare-earth ion
更新于2025-09-23 15:21:01
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Non-classically Controlled Sign in a 1.6 Tesla Magnetic Circularly Polarized Luminescence of Three Pyrenes in a Chloroform and a PMMA Film
摘要： Molecular pyrene, 1-hydroxylpyrene, and 2-hydroxypyrene in chloroform and embedded in poly(methyl methacrylate) film reveal mirror-image magnetic circularly polarized luminescence (MCPL) when south (S)-up or north (N)-up direction of the longitudinal external magnetic field of 1.6 T to unpolarized incident light (Faraday geometry) is employed. The |gMCPL| magnitude is on the order of 10–3 T–1 in 374–416 nm. The sign of MCPL is controlled by the S-up and N-up geometry and by the position (1- or 2-) of the hydroxy group.
关键词： magnetic circularly polarized luminescence,pyrene,chirality,fluorescence
更新于2025-09-23 15:21:01
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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) - The Influence of Al <sub/>2</sub> O <sub/>3</sub> Passivation of III-V on Ge Multijunction Solar Cells to the Spatial Distribution of Luminescent Coupling Effect
摘要： The nonuniformity of luminescent coupling (LC) effect in III-V based multijunction solar cells (MJSCs) is partly ascribed to recombination at perimeter defects. An attempt to solve this was done by sidewall passivation of InGaP/GaAs/Ge triple junction solar cells through atomic layer deposition of thin Al2O3. Results revealed that sidewall passivation of a complete MJSC can increase LC current collection in a limiting GaAs middle cell by 21.9% and enhance its uniformity by 7.2%; hence, demonstrating a non-invasive way to improve current matching among subcells.
关键词： photovoltaic cells,luminescence coupling,current mapping,atomic layer deposition,laser beam-induced passivation
更新于2025-09-23 15:21:01
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[IEEE 2019 8th International Congress on Advanced Applied Informatics (IIAI-AAI) - Toyama, Japan (2019.7.7-2019.7.11)] 2019 8th International Congress on Advanced Applied Informatics (IIAI-AAI) - Phase Type Special-Purpose Computer for Electroholography in Embedded Systems
摘要： This paper is the fifth in a series of articles on the basic physics of light yield nonproportionality in scintillators. Here, we compare and contrast the nonproportionality as registered by gamma rays and high-energy electrons. As has been noted in the past, these two types of data have different curve shapes (for plots of the light yield against electron or gamma energy). Herein, we show how the experimental gamma nonproportionality curve can be calculated from the electron response by accounting for the distribution of high energy electrons created by the gamma photon via the photoelectric interaction. Similarly, we measure and model the gamma-induced resolution as a function of energy and compare this data to predictions from our model. The utility of the model is explored using data acquired with the scintillators (Eu), GYGAG(Ce) and CsI(Na).
关键词： Gamma ray detectors,solid scintillation detectors,luminescence
更新于2025-09-23 15:21:01
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Hybrid nanoparticle layers toward enhanced luminescence of phosphor plates for white LEDs
摘要： MgF2 porous nanoparticle-silica hybrid coating layers were utilized to enhance luminescence efficiency of phosphor plates for white light emitting diodes (wLEDs). Silica and chemically synthesized porous MgF2 nanoparticles were sequentially deposited by spin coating on the phosphor plate with phosphor-in-glass (PiG) configuration. Microscopic investigation the hybrid film suggested intermixing of silica and porous MgF2 nanoparticles. Numerical estimation based on transfer matrix method expected a significant reduction in reflectance and enhancement of transmission spectra by the hybrid coating. In accordance, the photoluminescence intensity of phosphor plates showed a drastic improvement and quantum yield were enhanced from 30% (for bare PiG plate) to 45% (for hybrid layer coated PiG plate). When assembled with blue LEDs, hybrid nanoparticle coating on the PiG phosphor plates improved luminescence efficacy from 40 lm/W to 49 lm/W without deterioration of chromaticity during operation. In addition, mechanical durability of the hybrid thin film was confirmed by abrasion test. Conformal coating of matching layer consisting of porous MgF2 nanoparticles and silica can provide an efficient route to highly luminescent white LEDs with mechanical stability.
关键词： refractive index,phosphor-in-glass,nanoparticles,Luminescence,Hybrid coating
更新于2025-09-23 15:21:01
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Aggregation-Induced Emission-Based Polymer Materials: Ratiometric Fluorescence Responses Controlled by Hydrostatic Pressure
摘要： Dual fluorescence materials that exhibit controllable ratiometric changes in response to various external stimuli have attracted much attention from the viewpoints of applied material science and sensing/imaging technologies in interfaces. In the present study, we found fluorescence polymers based on aggregation-induced emission (AIE) characters. The functional AIE polymers can be converted to ratiometric fluorophores upon electronic excitation, and subsequently, their optical/photophysical properties can also be regulated by hydrostatic pressure or isotropic mechanical force. The degree of substitution (DS) of AIE branches on the polymer backbone plays critical roles in influencing the pressure-induced ratiometric fluorescence responses. The present study provides significant guidelines for developing AIE-based smart applied materials to response in hydrostatic pressure.
关键词： fluorescence spectroscopy,excited-state behavior,polyethylene,hydrostatic pressure,aggregation-induced emission,luminescence materials
更新于2025-09-23 15:21:01
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Design of lanthanide-based metal-organic frameworks with enhanced near-infrared emission
摘要： A strategy based on the use of ligand steric hindrance and metal doping is reported for the design and synthesis of near-infrared (NIR) emitting lanthanide-based metal–organic frameworks (MOFs). The lanthanide ions are free of coordinated solvents, and the resulting NIR-MOFs are highly emissive and exhibit long luminescence lifetimes.
关键词： metal doping,ligand steric hindrance,lanthanide-based metal–organic frameworks,luminescence,near-infrared emission
更新于2025-09-23 15:21:01
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Quantum Dot-Based Sensitization System for Boosted Photon Absorption and Enhanced Second Near-Infrared Luminescence of Lanthanide-Doped Nanoparticle
摘要： Efficient energy transfer is a promising strategy in overcoming the inherent limits of narrow band and weak absorption of lanthanide ions due to the nature of 4f-4f transitions. Herein, we introduce a nanoparticle-sensitized nanoparticle system where a near-infrared-emitting quantum dot (QD) is used as a sensitizer with broadband photon absorption for lanthanide-doped nanoparticle (LNP) to generate second near-infrared (NIR-II) emission. The NIR-II luminescence of Er3+-doped LNP by Ag2S QD sensitization displays an enhancement of ~17-fold in intensity and ~10-fold in brightness over bare LNP because of increased absorptivity and overall broadening of the absorption spectrum of LNP. Furthermore, QD-sensitized LNP system exhibits excellent photostability, and is able to improve the signal to noise ratio of tumor NIR-II imaging via in situ crosslinking of QD and LNP. The QD-sensitized LNP system for luminescence enhancement opens a potential avenue for efficient energy transfer in complex nanoparticle-nanoparticle systems.
关键词： Lanthanide-Doped Nanoparticle,Photon Absorption,Second Near-Infrared Luminescence,Quantum Dot,Sensitization System
更新于2025-09-23 15:21:01
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Dual-mode light-emitting lanthanide metal-organic frameworks with high water and thermal stability and its application in white LEDs
摘要： It is well known that the up-conversion luminescence from lanthanide metal-organic frameworks (Ln-MOFs) is difficult to achieve, and thus, there are few reports on dual luminescence-based MOFs. Here, dual-mode light-emitting Ln-MOFs are synthesized using a low-cost hydrothermal method. Our results show that the obtained Ln-MOFs not only have high thermal stability (up to 420 degrees) but also are stable in deionized water. The dual-mode up and down-conversion luminescence is simultaneously observed from Er-Eu-MOFs. The temperature-dependent fluorescence decay time is calculated to be ranged from 0.46 ms to 0.36 ms for temperatures from100 K to 300 K. We suggested that this phenomenon was because the number of phonons participating in the MOF matrix increases with temperature during the luminescence process, and the phonons interact with the electrons in the material. The values of the J-O parameters calculated from the emission spectra indicated that the symmetry around Eu3+ ions in Eu-MOF is the highest, which was also higher than that of Er-Eu-MOF. To explore the potential applications of Eu-MOFs in white light-emitting diodes (LEDs), red emission from Eu-MOFs was combined with blue, green, and yellow emissions from metal halide perovskites to achieve white light emission. The white light with excellent color quality and vision performance was obtained. These findings demonstrate that the Ln-MOFs are potentially successful materials for the applications in white LEDs.
关键词： high thermal stability,Dual-mode luminescence,LEDs,MOFs,lanthanide
更新于2025-09-23 15:21:01