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Exciton states in InGaAsP/InP core–shell quantum dots under an external electric field
摘要： The effect of an external electric field on the exciton states of InGaAsP/InP core–shell quantum dots is investigated through the variational method. The effect of the shell thickness, core radius, electric field strength, and material components on the exciton states are analyzed in detail. The numerical results show that the electron and hole energies decrease as the shell thickness or core radius is increased. The Bohr radius is a nonmonotonic function of the shell thickness or core radius, and the change of the exciton binding energy is nonlinear as the shell thickness or core radius is increased. With increasing electric field strength, the Bohr radius increases while the exciton binding energy decreases. The exciton binding energy decreases (increases) as the Ga (As) component is increased.
关键词： Electric field,Core–shell quantum dot,Exciton binding energy
更新于2025-09-16 10:30:52
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Plasmonic and nonlinear optical behavior of nanostructures in glass matrix for photonics application
摘要： There is a growing interest in bimetallic core shell nanostructures that comprised out of noble metals due to their fascinating plasmonic properties, leading to a wide range of applications in future nanotechnology. Here we report on Ag/Cu core shell nanostructures in a glass matrix. It includes novel approaches for characterizing embedded core shell nanostructures with a detailed study on the nanosize effect in tuning their optical and nonlinear optical properties along with biomedical applications. Annealing the Ag/Cu as- exchanged samples resulted in the formation of core-shell nanostructures, which were confirmed using UV–vis absorption spectroscopy and high-resolution transmission electron microscopy. The prepared plasmonic nanostructures were further studied using X-ray diffraction, Rutherford backscattering, photoluminescence, Raman, X-ray photoelectron spectroscopy and Z scan techniques. The nonlinear optical properties of the glasses containing bimetallic nanoparticles have been studied at a non-resonant wavelength using femtosecond laser pulses and a possible mechanism for the observed nonlinearity have been explained.
关键词： Soda-lime glass,Core-shell nanostructures,Surface plasmon resonance
更新于2025-09-16 10:30:52
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Development of InP Quantum Dot-based Light Emitting Diodes
摘要： High performance quantum dot light emitting diode (QLED) is being considered as the next generation technology for energy efficient solid-state lighting and displays. InP QLED is the most promising alternative of the toxic CdSe QLED. Unlike the problems of poor hole injection in CdSe-based QLED, highly delocalized electrons and parasitic emissions are serious problems in green-emitting InP QLED. The loss mechanism and device physics in InP QLED have not been sufficiently studied since the first report of InP QLED in 2011. This review summarized the recent efforts on improving the performance of InP QLED, from the perspectives of core/shell structures to optimization of carrier transport layers. It is our intention to conduct a review as well as clarify some previous misunderstandings on the device physics in InP QLED, and provide some insights for the possible solutions of the challenging problems in InP QLED.
关键词： InP quantum dots,carrier transport layers,parasitic emissions,core/shell structures,QLED
更新于2025-09-16 10:30:52
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New Strategy to Achieve Laser Direct Writing of Polymers: Fabrication of the Color-Changing Microcapsule with Core-Shell Structure
摘要： This paper proposed an efficient and environmentally friendly strategy to prepare a new color-changing microcapsule with core-shell structure for laser direct writing of polymers, and only the physical melt blending of polymers was employed. The laser absorber (SnO2) and the easily carbonized polymer (PC) were designed as the “core” and the “shell” of the microcapsule, respectively. The microcapsules were in situ formed during melt blending. SEM, TEM, and EDS confirmed the successful preparation of SnO2/PC microcapsules with core-shell structure. Its average diameter was 2.2 μm, and the “shell” thickness was 0.21?0.24 μm. As expected, this SnO2/PC microcapsule endowed polymers with an outstanding performance of NIR laser direct writing. The Raman spectroscopy and XPS indicated that the color change ascribed to the polymer carbonization due to the instantaneous high temperature caused by the SnO2 absorption of NIR laser energy. Optical microscopy observed a thick carbonization layer of 234 μm. Moreover, Raman depth imaging revealed the carbonization distribution, confirming that the amorphous carbon produced by the carbonization of the PC “shell” is the key factor of SnO2/PC microcapsules to provide polymers an outstanding performance of laser direct writing. This color-changing microcapsule has no selectivity to polymers due to providing a black color source (the carbonization of PC) itself, ensuring the high contrast and precision of patterns or texts after laser direct writing for all general-purpose polymers. We believe that this novel strategy to achieve laser direct writing of polymers will have broad application prospects.
关键词： microcapsule,core-shell structure,carbonization,polymer,laser direct writing,near-infrared pulsed laser
更新于2025-09-16 10:30:52
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Synthesis of N-doped TiO <sub/>2</sub> /SiO <sub/>2</sub> /Fe <sub/>3</sub> O <sub/>4</sub> magnetic nanocomposites as a novel purple LED illumination-driven photocatalyst for photocatalytic and photoelectrocatalytic degradation of naproxen: optimization and different scavenger agents study
摘要： N-doped TiO2/SiO2/Fe3O4 as a new magnetic photocatalyst that is active in visible light has been prepared by simple sol–gel method. The prepared samples were characterized by XRD, FESEM, EDX, TEM, BET, BJH, VSM, XPS, FT-IR, and DRS–UV/Vis analysis. The photocatalytic effect of synthesized samples on naproxen degradation was studied. The operational parameters were optimized through central composite design to achieve maximum efficiency. The optimum values for maximum efficiency were obtained at pH of 4.29, catalyst mass of 0.06 g, naproxen concentration of 9.33 mg L(cid:1)1, and irradiation time of 217.06 min. At these optimum conditions, the maximum photocatalytic degradation percentages of naproxen were found to be 96.32% at desirability function value of 1.0. Coupling the electrical current with the photocatalytic process proved that the electrical current was considerably efficient in decreasing the degradation time of removing the naproxen from aqueous solutions. The photocatalytic activity of the nanoparticles was also studied under sunlight. Considering the results provided by UV–Vis spectrophotometry and total organic carbon, it was found that the prepared samples are extraordinarily efficient to degrade naproxen under both purple LED and solar lights. Furthermore, the effect of different scavenger agents on naproxen degradation has been studied.
关键词： pharmaceutical compound,experimental design,Photodegradation,core–shell nanocomposite,titanium dioxide
更新于2025-09-16 10:30:52
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Strategy for performance enhancement of Cd1-XZnXTe/CdS core/shell quantum dot sensitized solar cells through band adjustment
摘要： Novel type-II core/shell structure quantum dos have been synthesized for solar cell photoelectrode material. Cd0.64Zn0.36Te and CdS were chosen as a core and shell, respectively, to generate type-II core/shell structure quantum dos (QDs). Density functional theory was employed to explore the energy structure of Cd1-xZnxTe/CdS core/shell QDs, revealing that introduction of Zn element is a feasible strategy to prepare CdTe/CdS based QDs with type-II core/shell structure. Then, Cd0.64Zn0.36Te/CdS core/shell QDs were synthesized by aqueous phase method. Microscopic measurements showed that Cd0.64Zn0.36Te/CdS core/shell QDs have high crystalline quality. Ultraviolet photoelectron spectroscopy together with optical spectra indicated an upward shift of the Cd0.64Zn0.36Te conduction band edge compared with CdTe, as also evidenced by systematic density functional theory based first principle calculation. Photoluminescence decay measurement also indicated the enhanced electron injection rate and decreased charge recombination of Cd0.64Zn0.36Te/CdS QD sensitized TiO2 films. In addition, by optimizing the deposition cycles of the CdS shell, the power conversion efficiency of Cd0.64Zn0.36Te/CdS QDs sensitized solar cells was enhanced.
关键词： Quantum dots,Solar cells,Core/shell,Cd0.64Zn0.36Te
更新于2025-09-16 10:30:52
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Preparation and Photocatalytic Activity of Ag-Modified SnO2@TiO2 Core- Shell Composites
摘要： Photocatalytic degradation is an important method to mediate organic pollution in the environment. This article reports Ag-modified SnO2@TiO2 core-shell composite photocatalysts prepared via a hydrothermal method. The composite materials were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetry, X-ray photoelectron spectrometry, and UV-vis diffuse reflectance spectroscopy. The Ag modification and core structure in the composite enhanced the photocatalytic activity and stability of TiO2 for Rhodamine B degradation under visible light irradiation. The composite modified in 0.15 M AgNO3 showed an optimal level of photocatalytic activity, as it degraded 99.14% of Rhodamine B in 60 min while pure TiO2 only degraded 45.7% during the same time.
关键词： Hydrothermal method,Core-shell composites,Photocatalytic activity
更新于2025-09-16 10:30:52
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Core-shell hollow spheres of type C@MoS2 for use in surface-assisted laser desorption/ionization time of flight mass spectrometry of small molecules
摘要： Mesoporous carbon hollow spheres coated with MoS2 (C@MoS2) were synthesized to obtain a material with large specific surface area, fast electron transfer efficiency and good water dispersibility. The composite material was applied as a matrix for the analysis of small molecules by surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). The use of a core-shell C@MoS2 matrix strongly reduces matrix background interferences and increases signal intensity in the analysis of sulfonamides antibiotics (SAs), cationic dyes, emodin, as well as estrogen and amino acids. The composite material was applied to the SALDI-TOF MS analysis of selected molecules in (spiked) real samples. The ionization mechanism of the core-shell C@MoS2 as a matrix is discussed. The method exhibits low fragmentation interference, excellent ionization efficiency, high reproducibility and satisfactory salt tolerance.
关键词： Ionization mechanism,Core-shell C@MoS2,Emodin,Estrogen,Amino acids,Cationic dyes,Sulfonamides antibiotics,SALDI-TOF MS,Salt tolerance
更新于2025-09-12 10:27:22
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Synthesis of Anatase (Core)/Rutile (Shell) Nanostructured TiO <sub/>2</sub> Thin Films by Magnetron Sputtering Methods for Dye-Sensitized Solar Cell Applications
摘要： Currently, anatase/rutile core/shell structures are accepted as highly efficient building blocks for TiO2-based catalysts or photo-electrodes used in dye-sensitized solar cells (DSSCs). It is understood that a thin layer of rutile covering the core anatase pillar would improve the performance of DSSCs by retarding the charge recombination at the semiconductor/sensitizer/electrolyte interfaces. In this work, we report on the synthesis of core/shell nanostructured TiO2 thin films using reactive magnetron sputtering at a glancing angle with different power applying modes: well-separated pillars of pure anatase were synthesized using the DC mode, and then, high-pulse peak power was applied to the Ti target (high power impulse magnetron sputtering – HiPIMS) resulting in the covering of the anatase columns with a thin layer of rutile. The latter technique is well-known to increase the energy load during the growth of the film which is a key parameter to successfully obtain the TiO2 phase normally only achieved at high temperature, i.e. rutile. The peak current, the frequency and the pulse width were optimized in order to obtain the desired crystalline structure and thickness of the rutile top layer. Scanning Electron Microscopy (SEM) cross-section views of the synthesized films clearly show that the pillar-like structures are not affected by the energetic species striking the surface during the HiPIMS process. Grazing Incidence X-Ray Diffraction (GIXRD) suggests the presence of both anatase and rutile phases in the films. Further characterization of the anatase/rutile core/shell interface by electron transmission techniques such as Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS) mapping confirm the hypothesis and reveal that the anatase pillars are partly covered by a rutile crust.
关键词： EELS,Dye-Sensitized Solar Cells,TEM,TiO2,GLAD,Reactive Magnetron Sputtering,core/shell nanostructures,HiPIMS
更新于2025-09-12 10:27:22
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Plasmonically Enhanced Upconversion Luminescence via Holographically Formed Silver Nanogratings
摘要： Greatly enhanced upconversion luminescence was demonstrated by integrating the core-shell upconversion nanorods with the Ag nanogratings. Both the Ag nanogratings and upconversion nanorods were fabricated/synthesized in a facile, cost-effective, high throughput way. Experimental results showed that the upconversion luminescence intensity of Er3+ in the core-shell upconversion nanorods can be well tuned and enhanced by changing the shell thickness and the period of the Ag nanograting. The underlying physical mechanism for the upconversion luminescence enhancement was attributed to the plasmonically enhanced near infrared broadband absorption of the periodic Ag nanograting and the localized surface plasmon resonance of Ag nanocrystals. The maximum enhanced factors of 523 nm, 544 nm (green emission) and 658 nm (red emission) of Er3+ ions excited at 980 nm are 3.8, 5.5 and 4.6 folds, respectively. Our fabrication approach and results suggest that such a simple integration is potentially useful for biosensing/imaging and anticounterfeiting applications.
关键词： plasmonic enhancement,upconversion,core-shell nanorod,nanograting,Holographical synthesis
更新于2025-09-12 10:27:22