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A graphene quantum dots-Pb2+ based fluorescent switch for selective and sensitive determination of D-penicillamine
摘要： Taking consideration of metal-induced fluorescence quenching and excellent coordination effect of D-penicillamine (D-PA), a graphene quantum dots (GQDs)-based fluorescent switch for D-PA detection was designed and established firstly with the help of lead ions. GQDs obtained from citric acids made them rich in carboxyl and hydroxyl groups, giving GQDs the ability to combine with lead ions. As anticipated, the fluorescence intensity was quenched by Pb2+ through electron transfer process. Further, the addition of D-PA effectively recovered the fluorescence due to the departure of Pb2+ from GQDs aroused by the strong coordination between D-PA and Pb2+. Thus, a fluorescent switch was activated for D-PA detection. The fluorescence recovery efficiencies were found to be proportional to the concentration of D-PA in the range of 0.6–50 μmol L-1 and the detection limit was 0.47 μmol L-1. The real sample detection was performed in human urea sample and satisfactory recoveries of 96.84%-102.13% were obtained. The GQDs-Pb2+ based fluorescent switch sensing method was firstly established with low detection limit and wide linear range, making it a supplement and improvement for D-PA detection.
关键词： lead ions,graphene quantum dots,D-penicillamine,fluorescent switch
更新于2025-09-12 10:27:22
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Visualizing the Impact of Light Soaking on Morphological Domains in an Operational Cesium Lead Halide Perovskite Solar Cell
摘要： The dynamics of photogenerated carriers and mobile ions in an operational cesium lead halide (CsPbI3) perovskite solar cells (PSC) under working conditions are studied using nanoscale resolved photoluminescence (PL) lifetime imaging microscopy. The temporally and spatially resolved PL changes in the perovskite film during and after bias light soaking are dynamically monitored. By analyzing the dynamic variations of PL intensity and PL lifetime of an open-circuited PSC, the impacts of light soaking are revealed by a dynamic model of photogenerated charge carrier and mobile ions. We confirmed the different behavior from morphological domains interiors and domains boundaries during light soaking, which shed light on the engineering of the domain interiors in additions to the commonly considered domain boundary strategies. This work provides a full picture of the photogenerated process in an operating PSC and therefore guides the design and operation of perovskite-based optoelectronic devices.
关键词： charge carriers,perovskite solar cells,mobile ions,light soaking,photoluminescence
更新于2025-09-12 10:27:22
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Effect of up-conversion luminescence in Er3+ doped phosphate glasses for developing Erbium-Doped Fibre Amplifiers (EDFA) and G-LED's
摘要： The (NPbPEr) glasses of the composition (20-x) Na2SO4-20PbO-60P2O5-xEr2O3 (x= 0.1, 0.3, 0.5, 0.7, 1.0 mol %) are synthesized by melt quenching process. The basic characterization studies like XRD and EDS have confirmed amorphous nature and contents of the samples. The spectroscopic studies viz., optical absorption, photoluminescence (PL) and decay profiles were carried out. The PL spectra exhibited an intense sharp green emission peak at 544 nm due to 4S3/2 → 4I15/2 transition of Er3+ ions both in down-conversion (DC, l exc = 377 nm) and up-conversion (UC, l exc = 977 nm) PL spectra. The spectra also exhibited a broad intense NIR band at 1532 nm ascribed to 4I13/2→4I15/2 transition of Er3+ ions at l exc = 977 nm. The analysis of the spectra indicated 0.5 mol% of Er2O3 is the optimal concentration for achieving maximal PL output both in the green and in NIR regions. The CIE color coordinates and the corresponding CCT (K) values were estimated from both UC and DC emission spectra. Overall analysis of the results suggested that the investigated glasses are potential candidates for getting intense green light emission and are quite suitable as optical fibre amplifiers in the green and NIR (around 1.5 m m) regions.
关键词： Er3+ ions,Green and NIR emission,sodium sulfo-phosphate glasses
更新于2025-09-12 10:27:22
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The Impact of Mobile Ions on the Steady State Performance of Perovskite Solar Cells
摘要： Mobile ions in perovskite solar cells induce many unique transient phenomena, while their influence under steady-state, the primary operating condition, has received little attention. Therefore, in this work we employ ionic-drift diffusion models to assess how the steady-state distribution of mobile ions affects the photogenerated carrier collection, and their redistribution due to dopants and energy band alignment. We demonstrate that mobile ions can transform the carrier transport mechanism from a combination of drift and diffusion to transport by diffusion only, which only impacts the device efficiency if the carrier mobility-lifetime product is limited due to increased transport losses and changed recombination dynamics. A high concentration of dopants is also required in perovskite devices for such doping to have a measurable impact while the energy alignment of the transport layers, on the other hand, can in principle result in a doping-like effect, which generally causes adverse consequences for cell efficiency.
关键词： dopants,steady-state performance,perovskite solar cells,energy band alignment,mobile ions,carrier transport
更新于2025-09-12 10:27:22
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Detection of lead Using Thioglycolic Acid Capped ZnSe and ZnSe@ZnS core-shell Quantum Dots
摘要： Herein, we proffer a sensitive and selective sensor using ZnSe and ZnSe@ZnS quantum dots (QDs), for detection of toxic metal ions at nm level. It has been found that the TGA capped ZnSe and ZnSe@ZnS QDs were apparently sensitive to Pb2+ ions as perceptible from their fluorescence quenching measurements. However, in case of few common heavy metal ions such as Zn2+, Co2+, Fe2+, , Mg2+, Cu2+, Ni2+ and Cd2+ ions, negligible quenching compared to Pb2+ ions was noted. Hence, we have successfully detected Pb2+ ions in aqueous solutions based on the photoluminescence (PL) spectroscopy. The observed linearity range was from 10 NM to 100 nM for both Pb2+ ions. An alternative QD based sensor for the spectroscopic detection, and concentration quantification of Pb2+ ions is proposed.
关键词： Metal ions,Photoluminescence,Thioglycolic acid,Quantum dots,Core-shell QDs
更新于2025-09-12 10:27:22
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Two-Dimensional Fluorescent Strategy Based on Porous Silicon Quantum Dots for Metal-Ion Detection and Recognition
摘要： A two-dimensional photoluminescent (2D PL) detection strategy was established based on luminescent porous silicon (LuPSi) with wide-size-distributed silicon quantum dots and abundant surface chemistry. Owing to the intrinsic nature of LuPSi, interaction or reaction between analytes and LuPSi may cause static, dynamic, oxidation-induced, and deposition-induced quenching. By monitoring of both the PL intensity change and peak shift of LuPSi, the 2D PL detection strategy could discriminate di?erent analytes. Detection and recognition of di?erent metal ions in real water samples using a single peak were realized. Compared with the existing array-based methods, the 2D PL approach signi?cantly simpli?ed the sensing element and detection process.
关键词： metal ions,quantum dot array,two-dimensional photoluminescence,luminescent porous silicon,recognition
更新于2025-09-12 10:27:22
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Dramatic Spectral Broadening of Ultrafast Laser Pulses in Molecular Nitrogen Ions <sup>*</sup>
摘要： We investigate nonlinear interaction of nitrogen molecules with a two-color laser field composed by an intense 800 nm laser pulse and a weak 400 nm laser pulse. It is demonstrated that the spectrum of 400 nm pulses is dramatically broadened when the two beams temporally overlap. In comparison, the spectral broadening in argon is less pronounced, although argon atoms and nitrogen molecules have comparable ionization potentials. We reveal that the dramatic spectral broadening originates from the greatly enhanced nonlinear optical effects in the near-resonant condition of interaction between the 400 nm pulses and the nitrogen molecular ions.
关键词： two-color laser field,spectral broadening,nonlinear interaction,nitrogen molecular ions
更新于2025-09-12 10:27:22
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Carbon multicharged ions emission from femtosecond laser plume
摘要： Carbon ion emission from femtosecond laser ablation of a glassy carbon target is studied. A Ti:sapphire laser (pulse duration τ ~ 150 fs, wavelength λ = 800 nm, laser fluence F ≤ 6.4 J cm?2) is used to ablate the carbon target while ion emission is detected by a time-of-flight detector equipped with a three-grid retarding field analyzer. A strong effect of the laser pulse fluence on the yield of carbon ions is observed. Up to C6+ ions are detected. The carbon ion time-of-flight signal is fit to a shifted Maxwell-Boltzmann distribution and used to extrapolate the effective plasma ion temperature Tieff = 6.9 eV. Applying an external electric field along the plasma expansion direction increases ion extraction, possibly due to the retrograde motion of the plasma-vacuum edge.
关键词： Femtosecond laser ablation,Time-of-flight,Plasma ion temperature,Carbon multicharged ions,Shifted Maxwell-Boltzmann distribution
更新于2025-09-12 10:27:22
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Polarization of fluorescence radiation following electron impact excitation of ions immersed in strongly coupled plasmas
摘要： An investigation on the electron impact excitation and subsequent radiative decay process of He-like Fe24t ions immersed in strongly coupled plasmas is made, using the 1s2p 3;1P1 ! 1s2 1S0 characteristic lines as an example. The shielded nuclear potential of the uniform electron gas model (UEGM) type experienced by the electron is parameterized by the ion-sphere radius. For the target structure, accuracies of wave functions are justified by evaluating the energies of the relevant states. To serve as an independent check of the results, self-consistent calculations are carried out using the multiconfiguration Dirac-Fock relativistic configuration interaction method incorporating the same potential. For the impact excitation process, the UEGM potential is also employed to screen the projectile electron from the nucleus and target electrons. A distorted-wave method in the framework of the relativistic theory is developed to include the effect of plasma background, in which the continuum wave function of the projectile electron is evaluated by solving numerically the modified Dirac equations. The plasma effects on the total excitation cross section, magnetic sublevel cross section, and linear polarization of fluorescence radiation are investigated. The comparison with the available theoretical and experimental results is satisfactory.
关键词： UEGM potential,linear polarization,He-like Fe24t ions,electron impact excitation,strongly coupled plasmas,radiative decay
更新于2025-09-12 10:27:22
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Dual Functions of Crystallization Control and Defect Passivation Enabled by an Ionic Compensation Strategy for Stable and High-Efficient Perovskite Solar Cells
摘要： The fabrication of perovskite films with high crystallization quality, less defects and fewer grain boundaries (uncoordinated ions), is one critical step to obtain excellent power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In this work, we develop a novel method to control the perovskite growth toward better crystallinity and less defects using I- and thiourea as additives for the first time (we define ITU for I- and thiourea). Grain boundaries in the perovskite films are significantly reduced compared with the traditional method. Moreover, concentration of the defects in perovskite films is decreased by nearly one-half. Based on high-quality films, the PSCs with a champion PCE of 20.39% present a stabilized output efficiency of 19.26% under one sun illumination compared with that of the control devices (17.75%). The devices also exhibit small hysteresis and excellent long-term and light stability. The devices can retain 80% of the initial PCE after 100 h of light soaking or 30 days of aging in ambient atmosphere. This work not only demonstrates a novel approach to passivate the defects by balancing iodide ions, but also offers a strategy to control the perovskite film growth, which can be widely used in photoelectric devices.
关键词： iodide ions,crystallinity,defect states,perovskite solar cells,light stability
更新于2025-09-12 10:27:22