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Low-temperature dark anneal as pre-treatment for LeTID in multicrystalline silicon
摘要： Light and elevated temperature induced degradation (LeTID) is currently a severe issue in crystalline silicon photovoltaics, which has led to numerous efforts to both understand the mechanism and to mitigate it. Here we show that a low-temperature dark anneal performed as the last step in typical solar cell processing influences greatly LeTID characteristics, both the strength of the degradation and the degradation kinetics. While a relatively short anneal in the temperature range of 200–240 °C can be detrimental to LeTID by doubling the degradation intensity, an optimized anneal at 300 °C shows the opposite trend providing an efficient means to eliminate LeTID. Furthermore, we show that the simulated recombination activity of metal precipitation and dissolution during the dark anneal correlates with the experiments, suggesting a possible explanation for the LeTID mechanism.
关键词： PERC,Precipitation,Multicrystalline silicon,Minority-carrier lifetime,LeTID,Copper in silicon
更新于2025-09-23 15:23:52
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Pressure effect on phosphor thermometry using Mg <sub/>4</sub> FGeO <sub/>6</sub> :Mn
摘要： This study examined the effect of ambient pressure on the luminescent lifetime of Mg4FGeO6:Mn phosphors in different morphologies. To evaluate the pressure sensitivity of phosphor in the form of particle, agglomerated particle and chemically bonded coating, samples including phosphor powder, pressed phosphor disc, and chemically bonded phosphor coating were fabricated and calibrated using a PMT-based measurement system for a pressure range of 20-200 kPa and a temperature range of 298-873 K. The results showed no obvious pressure effect on the lifetime of the chemically bonded Mg4FGeO6:Mn coating. However, the lifetime of the phosphor powder and pressed phosphor disc decreased as pressure increased. This pressure effect was most obvious for the pressed phosphor disc, which was further aggravated at higher temperatures. The atomic distance between manganese ion and other atomics reduced as pressure increased, which induced the movement of excited state in the configuration coordinate. Considering this dependency of pressure sensitivity on phosphor morphology, it is important to adopt the same fabrication procedure for calibration and temperature measurement using Mg4FGeO6:Mn. In addition, for in-flow measurement using Mg4FGeO6:Mn tracer particles, the influence of environmental pressure must be considered.
关键词： Phosphor thermometry,Lifetime,Mg4FGeO6:Mn,Pressure effect
更新于2025-09-23 15:23:52
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Fabrication and mid-infrared property of Er:CaF2 transparent ceramics
摘要： High doped Er:CaF2 transparent ceramics (up to 10.0 at.%) were fabricated by hot pressing nanopowders which were synthesized by co-precipitation method. The composition and micrographs of the powders were characterized. The mid-infrared emission spectra and lifetimes of the 4I13/2 energy level of Er:CaF2 transparent ceramics were investigated for the first time. The mechanisms of energy transfer processes based on the emission spectra of different wavelengths were discussed. The enhanced 2.7 μm emission intensity and the reductions of near-infrared fluorescence lifetimes were observed indicating that the high concentrations of Er3+ ions are beneficial to overcome the self-termination effect and realize 2.7 μm laser output. It can be seen from these results that high concentrations Er-doped CaF2 transparent ceramics can be considered as promising host materials for the applications of mid-infrared lasers.
关键词： Transparent ceramic,Mid-infrared,Luminescence lifetime,Nanoparticle
更新于2025-09-23 15:23:52
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Effect of Fixation and Mounting on Fluorescence Lifetime of Cellular Autofluorescence
摘要： Fluorescence lifetime measurements are often performed on live as well as fixed cells and tissues. Fixation and mounting processes are routinely used in cellular research or clinical diagnosis. In this study, the effects of fixation and mounting on the fluorescence lifetime of cellular autofluorescence were studied by fluorescence lifetime imaging microscopy over fluorophores, reduced fluorescent time. Two endogenous nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), showed different results between live cells and fixed cells. The average lifetime of NADH in live HeLa cells was about 1.02 ns, while maintained about 1.57 ns during the fixation periods of 14 days. The average lifetimes of FAD in live and fixed HeLa cells within 11 days were similar around 1.75 ns but increased to 2.10 ns after 12 days. The free and bound states of the two kinds of fluorophores were further analyzed. It was found that the bound-FAD had two different groups, which was related to the cell division cycle. The effect of mounting medium on fluorescence lifetimes was also studied, indicating glycerol has a negative impact on the fluorescence lifetime compared with neutral balsam.
关键词： fluorescence lifetime,fixed cells,Autofluorescence,mounting medium
更新于2025-09-23 15:23:52
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Photoemission and thermoluminescence characteristics of Dy3+-doped zinc sodium bismuth borate glasses
摘要： The present study reports preparation and characterization of Dy3+-doped PbO free alkali-heavy-metal-borate glasses for luminescent applications. The amorphous nature of the glasses and the presence of various structural groups like BiO6, BO3 and BO4 were confirmed through XRD and FTIR measurements. The Oscillator strength of Dy3+ absorption transitions as well as the bond formed with the O2- ion in the glass network were determined using the absorption spectra. Radiative parameters extracted from Judd-Ofelt theory proved the degree of suitability of prepared glasses for lasing applications. The photoluminescence spectra exhibited the emission characteristics of Dy3+ ions and used to calculate the branching ratio, stimulated emission cross-section and radiative lifetime. Metastable lifetimes of Dy3+ ions were obtained through exponential fitting of respective decay profiles. The luminescence quenching phenomena was reasoned using Inokuti-Hirayama (I-H) model. The optical gain and quantum efficiency values clearly suggested Dy3+ doping at 0.3 mol% was optimum for 587 nm lasing action. Further, CIE chromaticity plot indicated the possible applications in solid state lighting devices. The thermoluminescence glow curves of 0.3 mol% Dy3+-doped glasses were considered for gamma irradiation and kinetic parameters of the same were evaluated using Computerized Glow Curve Deconvolution (CGCD) technique.
关键词： luminescence,kinetic order,Rare earth,Judd-Ofelt parameter,lifetime
更新于2025-09-23 15:23:52
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Contactless Optical Characterization of Carrier Dynamics in Free-Standing InAs-InAlAs Core-Shell Nanowires on Silicon
摘要： Contactless time-resolved pump-probe and external quantum efficiency measurements were performed on epitaxially grown free-standing wurtzite indium arsenide/indium aluminum arsenide (InAs-InAlAs) core-shell nanowires on Si (111) substrate from 77K to 293K. The first independent investigation of Shockley-Read-Hall, radiative and Auger recombination in InAs-based NWs is presented. Although the Shockley-Read Hall recombination coefficient was found to be at least two orders of magnitude larger than the average experimental values of other reported InAs materials, the Auger recombination coefficient was reported to be ten-fold smaller. The very low Auger and high radiative rates result in an estimated peak internal quantum efficiency of the core-shell nanowires as high as 22% at 77K, making these nanowires of potential interest for high efficiency mid-infrared emitters. A greater than two-fold enhancement in minority carrier lifetime was observed from capping nanowires with a thin InAlAs shell due to passivation of surface defects.
关键词： Auger recombination rate,radiative,Shockley-Read-Hall,Pump-probe spectroscopy,core-shell nanowires,surface/interface recombination velocity,minority carrier lifetime
更新于2025-09-23 15:23:52
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A robust and versatile platform for image scanning microscopy enabling super-resolution FLIM
摘要： Image scanning microscopy (ISM) can improve the effective spatial resolution of confocal microscopy to its theoretical limit. However, current implementations are not robust or versatile, and are incompatible with fluorescence lifetime imaging (FLIM). We describe an implementation of ISM based on a single-photon detector array that enables super-resolution FLIM and improves multicolor, live-cell and in-depth imaging, thereby paving the way for a massive transition from confocal microscopy to ISM.
关键词： super-resolution,SPAD array,fluorescence lifetime imaging,confocal microscopy,image scanning microscopy
更新于2025-09-23 15:23:52
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Electronic transition dipole moment and radiative lifetime calculations of lithium dimer ion-pair states
摘要： We present here a computational study of the lifetimes of the ion-pair n1Rt g , n = 3–6, states of lithium dimer. The lifetimes are calculated using ab initio electronic transition dipole moment functions and combination of experimental and ab initio potential curves. The ab initio calculations are carried out using the full configuration-interaction method. The lifetime calculations include the radiative contributions of all the allowed bound–bound and bound-free transitions to lower electronic states. In addition, to test the computational methods used in this work, we have calculated the lifetimes of levels of the lowest excited singlet, A1Rt u , state of lithium dimer.
关键词： Electronic transition dipole moment,Lithium dimer,Lifetime,Ion-pair states
更新于2025-09-23 15:22:29
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The investigation of a new fast timing system based on DRS4 waveform sampling system
摘要： In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excited states. In the paper, we have developed a new fast timing system, which is made up of two LaBr3:Ce detectors and a set of waveform sampling system. The sampling system based on domino ring sampler version 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smaller volume and higher timing accuracy, and the waveform data are performed by means of digital waveform analysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keV g photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in the large dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the t 152Gd-21 decay of 152Eu source is measured. The measured lifetime is 45.3(±5.0)ps, very close to the value of the National Nuclear Data Center (NNDC: 46.2((±3.9)ps). The experimental results indicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, the system can be widely used in the research of the fast timing technology.
关键词： Waveform sampling system,Excited state lifetime,LaBr3:Ce scintilator,Fast timing technique
更新于2025-09-23 15:22:29
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Luminescent TOP Nanosensors for Simultaneously Measuring Temperature, Oxygen, and pH at a Single Excitation Wavelength
摘要： Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pH-sensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands allowing for ratiometric intensity-based and time-resolved studies in the visible and near infrared wavelength region. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of these nanosensors for the sensitive fluorescence readout of TOP simultaneously at the same position.
关键词： lifetime,fluorescence,chromium(III) complex,oxygen/pH/temperature biosensor,optical multianalyte nanosensors,phosphorescence
更新于2025-09-23 15:22:29