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LiF based scintillation neutron detector at high counting rates
摘要： In this work we revisit the problem of the restricted count rate capability of thermal neutron detectors utilizing the ZnS scintillator. The effect of the long afterglow of the scintillator on the detector performance at high counting rates is studied. A count rate capability substantially above values currently regarded as feasible is demonstrated.
关键词： thermal neutron detector,SiPM,ZnS:6LiF scintillator,count rate capability
更新于2025-09-23 15:21:01
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Inorganic Functionalization of CdSe <sub/><i>x</i> </sub> S <sub/> 1a?? <i>x</i> </sub> /ZnS Corea??Shell Quantum Dots and Their Photoelectric Properties
摘要： In this paper, different CdSexS1-x quantum dots (QDs) with stearic acid as ligands were synthesized, and then the outer ZnS shell was coated with oleylamine (OLA) as ligands using a single molecular source method. The surface ligand exchange of CdSe0.6S0.4 and CdSe0.6S0.4/ZnS quantum dots was carried out with ammonium zinc chloride ((NH4)2ZnCl4) inorganic ligands. The morphology, crystal form, and group of QDs were examined using a high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). Under the condition of simulated sunlight irradiation, the photoelectrochemical properties were tested with an electrochemical workstation. The results showed that the distance between QDs decreased after ligand exchange. The photocurrent density of CdSe0.6S0.4/ZnS QDs films after ligand exchange can reach 7.23 mA?cm-2, which is 11 times that of the photocurrent density before ligand exchange. The reason may be that ZnCl42- has strong ligand electron donor capacity, which increases the probability of non-radiative transition.
关键词： Inorganic functionalization,(NH4)2ZnCl4,CdSexS1-x/ZnS quantum dots
更新于2025-09-23 15:19:57
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Novel ultraviolet photodetector with ultrahigh photosensitivity employing SILAR-deposited ZnS film on MgZnO
摘要： A novel MgZnO/ZnS heterojunction-based ultraviolet (UV) photodetector (PD) with high performance is fabricated by a facile sol-gel process and a successive ionic layer adsorption and reaction (SILAR) method. ZnS is coated onto the MgZnO film as an interface modification layer, which overcomes the drawbacks of the pristine MgZnO photosensitive layer, such as lower carrier mobility and more traps in the material, and greatly enhances UV-light absorption. The type-II heterostructure constructed by work function differences near the interface facilitate the separation of photogenerated carriers. Compared with the MgZnO PD, the optimized heterojunction PD (MgZnO/ZnS-10) yields a dramatically decreased dark current (z1 nA), a remarkable responsivity (900 A/W) and an ultrahigh photo-to-dark current ratio (up to 2.3 (cid:1) 105) under 325 nm light illumination at 5 V bias. These results provide a cost-efficient means for improving the properties of MgZnO PDs, and show the advantages of MgZnO/ZnS heterojunction PDs in UV detection. This study demonstrates that rational construction of novel heterojunctions holds great potential for fabricating high-performance photodetectors.
关键词： Type-II heterostructure,MgZnO,Ultraviolet (UV) photodetector (PD),ZnS
更新于2025-09-23 15:19:57
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Development of a ZnCdS@ZnS quantum dotsa??based label-free electrochemiluminescence immunosensor for sensitive determination of aflatoxin B1 in lotus seed
摘要： In this study, we designed a ZnCdS@ZnS quantum dots (QDs)–based label-free electrochemiluminescence (ECL) immunosensor for sensitive determination of aflatoxin B1 (AFB1). A Nafion solution assembled abundant QDs on the surface of a Au electrode as ECL signal probes, with specially coupled anti-AFB1 antibodies as the capturing element. As the reduction reaction between S2O8 2? in the electrolyte and QDs on the electrode led to ECL emission, the decreased ECL signals resulting from target AFB1 in the samples were recorded for quantification. We evaluated electrochemical impedance spectroscopy and ECL measurements along each step in the construction of the proposed immunosensor. After systematic optimization of crucial parameters, the ECL immunosensor exhibited a good sensitivity, with a low detection limit of 0.01 ng/mL for AFB1 in a wide concentration range of 0.05–100 ng/mL. Testing with lotus seed samples confirmed the satisfactory selectivity, stability, and reproducibility of the developed ECL immunosensor for rapid, efficient, and sensitive detection of AFB1 at trace levels in complex matrices. This study provides a powerful and universal analytical platform for a variety of analytes that can be used in broad applications for real-time analysis, such as food and traditional Chinese medicine safety testing, environmental pollution monitoring, and disease diagnostics.
关键词： Electrochemiluminescence immunosensor,Nafion,Lotus seed,Aflatoxin B1,ZnCdS@ZnS quantum dots,Label-free
更新于2025-09-23 15:19:57
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Impact of Hydrogen flow rate on physical properties of ZnS thin films: As potential buffer layer in solar cells
摘要： The exceptional need of potential Cd-free buffer layer in thin film solar cell devices motivated us to study the role of post-deposition Hydrogen annealing for the optimization of physical properties of ZnS thin films. The deposited films of thickness 200 nm were hydrogenated within the flow rate range of 50.0–150.0 sccm at 200°C. XRD analysis revealed transformation of amorphous into cubic phase with maximum crystallinity at 150.0 sccm for films deposited on glass substrate while into wurtzite structure for films on ITO substrate with enhanced crystallinity. A mixed phase (cubic and hexagonal) at 150.0 sccm also appeared. Electrical behaviour (I–V) exhibits ohmic nature with maximum carrier concentration at 100.0 sccm. The blue shift in absorption edge and maximum of 95% transmittance were recorded in the visible region with optical energy band gap of 3.41 eV at 150.0 sccm. The reduction in surface roughness is observed in surface topographical analysis while the photoluminescence (PL) study indicated a sharp peak at 2.95 eV with strongest emission for 150.0 sccm attributed to reduction of defects at interstitial sites and passivation of grain boundaries. These results are useful to understand the Hydrogen related impurities in ZnS films and the improvement caused by hydrogenation to physical properties suited for buffer layer in solar cells.
关键词： Buffer layer,ZnS thin films,Hydrogenation,Physical properties,e-beam evaporation
更新于2025-09-23 15:19:57
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Microwave activated synthesis of Ag2S and Ag2S@ZnS nanocrystals and their application in well-performing quantum dot sensitized solar cells
摘要： Incident photon-to-current conversion e?ciency (IPCE) of CdS based quantum dot sensitized solar cells (QDSCs) is a major drawback in their low e?ciency. Here we report a new trend in fabrication of QDSC with enhanced IPCE with application of as prepared Ag2S and Ag2S@ZnS QDs as a co sensitizer. Ag2S and Ag2S@ZnS QDs were synthesized ?rst using a microwave method and were examined by means of XRD, TEM and UV–Vis spectroscopy. Then the prepared QDs were applied for the fabrication of QDSCs using a novel drop casting method. The results revealed a signi?cant enhancement of IPCE as well as short current density (12.5 mA·cm?2) and cell e?ciency (3%). The enhancement is directly related to well absorption of Ag2S with low band gap in the visible range and e?ective injection of photo-excited electrons to CdS compact layer according to suggested band diagram. Ag2S@ZnS co-sensitizer showed an enhancement in photocurrent density due to successful passivation of Ag2S QDs and suppressing recombination on their surface.
关键词： Ag2S@ZnS quantum dots,QD sensitized solar cells,IPCE,Drop casting
更新于2025-09-23 15:19:57
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Neural network modeling and simulation of the synthesis of CuInS <sub/>2</sub> /ZnS quantum dots
摘要： The development of recipes for synthesis of quantum dots (QDs), a novel semi-conductor material for application in optoelectronic devices, is currently purely based on experiments. Since the quality of QDs represented by quantum yield (QY) and emission peak strongly depends on a number of different parameters (route, precursors, conditions, etc), a large number of experiments is necessary. In this article, we show that data-driven modeling can be used as a supporting tool for optimization and a better understanding of the synthesis process. By using the results collected during the development of CuInS2/ZnS (CIS/ZnS) QDs, a neural network model has been established. The model is able to predict the optical properties (QY and emission peak) of CIS/ZnS QDs as a function of the most important synthesis parameters, such as reaction temperature, time of CIS core formation and ZnS shell growth, feed molar ratio of Cu/In and Zn/Cu, various starting precursors, and types of ligands. Finally, a model analysis under various effects influencing the quality of QDs is performed.
关键词： CuInS2/ZnS,optimization,simulation,neural network,quantum dots
更新于2025-09-23 15:19:57
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CuInS <sub/>2</sub> -Doped ZnS Quantum Dots Obtained via Non-Injection Cation Exchange Show Reduced but Heterogeneous Blinking and Provide Insights into Their Structurea??Optical Property Relationships
摘要： Cadmium-free CuInS2-doped ZnS quantum dots (QDs) are synthesized through a 2-step non-injection synthetic method. The resulting QDs are small (8 nm or less) and relatively isotropic with photoluminescence quantum yields (PL QY) up to almost 70% and emission peaks in the 560-600 nm window, depending on the amount of Zn precursor added. The results indicate small CuInS2 ‘clusters’ within a zinc-blende ZnS lattice are the radiative recombination centers in the nanoparticle. Interestingly, higher ensemble photoluminescence quantum yields (PL QY) result when cation exchange is less extensive (~80 % ZnS composition), while a reduction in blinking is observed when ZnS composition exceeds 99%. A wide heterogeneity in blinking behavior from QD-to-QD is evident and a subpopulation statistical analysis shows that the on-state dwell times change from multiexponential (or inverse power law) behavior towards more mono-exponential behavior for particles that spend more of their time in the on-state. These results indicate that, as the number of CuInS2 emitting centers is reduced, the number of pathways leading to the off-state decreases, and a model is proposed to relate this behavior to the QD structure. These results provide a novel route towards CuInS2-doped visible-light emitting ZnS QDs with high quantum yield and reduced blinking and provides insight into how the composition of dopant and host matrix affects the radiative recombination mechanisms in single particles.
关键词： non-injection cation exchange,CuInS2-doped ZnS,blinking,structure-optical property relationships,quantum dots
更新于2025-09-23 15:19:57
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Effect of Polymer Capping on Photonic Multi-Corea??Shell Quantum Dots CdSe/CdS/ZnS: Impact of Sunlight and Antibacterial Activity
摘要： The highly luminescent CdSe/CdS/ZnS core?multi-shell quantum dots (QDs) were prepared without a protective atmosphere through the precursor injection method (phosphine free) in paraffin liquid and oleic acid. Polymers (PEG, PVA, PVP, and PAA) were coated to CdSe/CdS/ZnS core?multi-shell quantum dots to increase stability. However, core?multi-shell structured QDs reveal enhanced emission in the range 355?410 nm by suppressing the defect sensitive cores and nonradioactive recombination in PL spectra. The cubic zinc blended quantum dots with crystallite size in the range 22?44 nm, as confirmed by XRD, were obtained. The resultant absorption spectra of all the samples showed that the samples were absorbent in the UV region over the 302?380 nm range. In the FT-IR spectrum 712, 731, and 400?700 cm?1 band values were assigned to CdSe, CdS, and ZnS band stretching, respectively. Images of CdSe, CdSe/CdS, and CdSe/CdS/ZnS quantum dots obtained from the SEM were spherical whereas QDs capped with different polymers (PEG, PVA, PVP, and PAA) showed nanofibers that were linear and homogeneous size ranged between 12 and 38 nm. These as prepared QDs were placed under visible light for 48 h. After absorbing UV light, the range of UV?vis intensity was enhanced until 389?464 nm and emission intensity enhanced until 492?509 nm, which was confirmed by UV and PL spectra. CdSe/CdS/ZnS QDs with organic ligands revealed antibacterial activity over a broad range against Klebsiella Pneumoniae and Pseudomonas aeruginosa.
关键词： CdSe/CdS/ZnS,Photoluminescence,Polymer capping,Quantum dots,Antibacterial activity
更新于2025-09-23 15:19:57
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Double-Emission Ratiometric Fluorescent Sensors Composed of Rare-Earth-Doped ZnS Quantum Dots for Hg <sup>2+</sup> Detection
摘要： Quantum dots (QDs) are a class of zero-dimensional nanocrystal materials, whose lengths are limited to 2?10 nm. Their unique advantages such as wide excitation spectra, narrow emission spectra, and high quantum yield make their application possible in ?uorescence sensing, wherein QDs such as CdSe, CdTe, and CdS are used. Indeed, QDs have a wide range of applications in ?uorescence sensing, and there have been many reports of applications based on QDs as ion probes. The emission spectra of QDs can be adjusted by changing the size of the QDs or doping them with other ions/elements. However, the high toxicity of Cd and the poor anti-interference ability of single-emission ?uorescent probes greatly limit the applications of QDs in many ?elds. In this paper, ZnS QDs are doped with the rare-earth element Ce to form a low-toxicity double-emission ratiometric ?uorescent sensor, ZnS:Ce, for Hg2+ detection. The results of transmission electron microscopy (TEM), X-ray di?ractometry, X-ray photoelectron spectroscopy, and optical spectroscopy show that ZnS:Ce QDs were successfully synthesized. Under the optimal conditions, the concentration of Hg2+ was in the range of 10?100 μM, which had a linear relationship with the ?uorescence intensity of the ZnS:Ce QDs: the linear correlation coe?cient was 0.998, and the detection limit was 0.82 μM L?1. In addition, the ?uorescent sensor had good selectivity for Hg2+, and it was successfully applied to the detection of Hg2+ in laboratory water samples.
关键词： ZnS:Ce,Hg2+ detection,Quantum dots,ratiometric fluorescent sensor,double-emission
更新于2025-09-23 15:19:57