- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Electrostatic Directed Assembly of Colloidal Microparticles Assisted by Convective Flow
摘要： Electrostatic directed assembly of colloidal particles on charged patterns, i.e. nanoxerography, has proven to find innovative applications in plasmonics, anticounterfeiting or particle sorting. However, this technique was restricted to dispersions of nanoparticles whose diameters are typically below 100nm. The combination of experiments and simulations shows that this limitation is due to an uncontrolled dewetting of the substrate and to the small mobility of large particles. The “convective nanoxerography” process developed in this work overcomes this limit and allows making selective and dense assemblies of micron-sized particles, expanding by a factor 40 the size range foreseeable.
关键词： colloidal microparticles,Electrostatic directed assembly,nanoxerography,micron-sized particles,convective flow
更新于2025-09-09 09:28:46
-
Giant Modal Gain Coefficients in Colloidal II-VI Nanoplatelets
摘要： Modal gain coefficient is a key figure of merit for a laser material. Previously, net modal gain coefficients larger than a few thousand cm-1 were achieved in II-VI and III-V semiconductor gain media, but this required operation at cryogenic temperatures. In this work, using pump-fluence-dependent variable-stripe-length measurements, we show that colloidal CdSe nanoplatelets enable giant modal gain coefficients at room temperature, up to 6,600 cm-1 under pulsed optical excitation. Furthermore, we show that exceptional gain performance is common to the family of CdSe nanoplatelets, as shown by examining samples having different vertical thicknesses and lateral areas. Overall, colloidal II-VI nanoplatelets with superior optical gain properties are promising for a broad range of applications, including high speed light amplification and loss compensation in plasmonic photonic circuits.
关键词： colloidal nanoplatelets,optical gain,variable stripe-length method,CdSe,modal gain coefficient,colloidal quantum wells
更新于2025-09-04 15:30:14
-
Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique
摘要： This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures—in this case, hexagonally arranged nanopillars—printed in a layer of directly photopatternable sol-gel TiO2. Firstly, to increase the achievable structure height the photosensitive layer underneath the microspheres is deposited on a re?ective layer instead of the usual transparent substrate. Secondly, an increased width of the pillars is achieved by tilting the incident wave and using multiple exposures or substrate rotation, additionally allowing to better control the shape of the pillar’s cross section. The theoretical analysis is carried out by rigorous modelling of the photonics nanojet underneath the microspheres and by optimizing the experimental conditions. Aspect ratios (structure height/lateral structure size) greater than 2 are predicted and demonstrated experimentally for structure dimensions in the sub micrometer range, as well as line/space ratios (lateral pillar size/distance between pillars) greater than 1. These nanostructures could lead for example to materials exhibiting ef?cient light trapping in the visible and near-infrared range, as well as improved hydrophobic or photocatalytic properties for numerous applications in environmental and photovoltaic systems.
关键词： TiO2,sub-wavelength structures,sol-gel,colloidal photolithography
更新于2025-09-04 15:30:14
-
Silver-Nanowire-Based Interferometric Optical Tweezers for Enhanced Optical Trapping and Binding of Nanoparticles
摘要： Light-induced self-assembly offers a new route to build mesoscale optical matter arrays from nanoparticles (NPs), yet the low stability of optical matter systems limits the assembly of large-scale NP arrays. Here it is shown that the interferometric optical fields created by illuminating a single Ag nanowire deposited on a coverslip can enhance the electrodynamic interactions among NPs. The Ag nanowire serves as a plasmonic antenna to shape the incident laser beam and guide the optical assembly of colloidal metal (Ag and Au) and dielectric (polystyrene) NPs in solution. By controlling the laser polarization direction, both the mesoscale interactions among multiple NPs and the near-field coupling between the NPs and nanowire can be tuned, leading to large-scale and stable optical matter arrays consisting of up to 60 NPs. These results demonstrate that single Ag nanowires can serve as multifunctional antennas to guide the optical trapping and binding of multiple NPs and provide a new strategy to control electrodynamic interactions using hybrid nanostructures.
关键词： self-assembly,colloidal nanoparticles,optical binding,interferometric optical tweezers
更新于2025-09-04 15:30:14
-
Preparation of monolayer hollow spherical tungsten oxide films with enhanced near infrared electrochromic performances
摘要： In this study, monolayer hollow spherical tungsten oxide (WO3) films have been prepared for the first time by magnetron sputtering combined with the colloidal crystal template method. Due to the large specific surface area, short ion diffusion distances, and weak scattering of the monolayer hollow structure, the hollow spherical WO3 film exhibits excellent electrochromic performance. This includes high transmittance modulation in the near-infrared spectral range (78.8% at l ? 1000 nm), fast switching (cid:2)1) response time (2.41 s for coloration and 1.28 s for bleaching), and high coloring efficiency (102.9 cm2 C at 1000 nm. The results show that the hollow spherical WO3 film can effectively regulate incident light, especially in the near infrared band, which is not visible but has significant thermal effects.
关键词： Electrochromics,Hollow spherical tungsten oxide,Colloidal crystal template,Magnetron sputtering
更新于2025-09-04 15:30:14
-
Water-dispersible Copper Sulfide Nanocrystals via Ligand Exchange of 1-dodecanethiol
摘要： In colloidal Cu2-xS nanocrystal synthesis, thiols are often used as organic ligands and sulfur source, as they yield high-quality nanocrystals. However, thiol ligands on Cu2-xS nanocrystals are difficult to exchange, limiting the applications of these nanocrystals in photovoltaics, biomedical sensing and photocatalysis. Here, we present an effective and facile procedure to exchange native 1-dodecanethiol on Cu2-xS nanocrystals by 3-mercaptopropionic acid, 11-mercaptoundecanoic acid, and S2- in formamide under inert atmosphere. The product hydrophilic Cu2-xS nanocrystals have excellent colloidal stability in formamide. Furthermore, the size, shape and optical properties of the nanocrystals are not significantly affected by the ligand exchange. Water-dispersible Cu2-xS nanocrystals are easily obtained by precipitation of the nanocrystals capped by S2-, 3-mercaptopropionate or 11-mercaptoundecanoate from formamide, followed by redispersion in water. Interestingly, the ligand exchange rates for Cu2-xS nanocrystals capped with 1-dodecanethiol are observed to depend on the preparation method, being much slower for Cu2-xS nanocrystals prepared through heating-up than through hot-injection synthesis protocols. XPS studies reveal that the differences in the ligand exchange rates are due to the surface chemistry of the Cu2-xS nanocrystals, where the nanocrystals prepared via hot-injection synthesis have a less dense ligand layer due to the presence of trioctylphosphine oxide during synthesis. A model is proposed that explains the observed differences in the ligand exchange rates. The facile ligand exchange procedures reported here enable the use of high-quality colloidal Cu2-xS nanocrystals prepared in the presence of 1-dodecanethiol in various applications.
关键词： thiol ligands,surface chemistry,ligand exchange,colloidal Cu2-xS nanocrystals,water-dispersible
更新于2025-09-04 15:30:14
-
The self-assembly of DyF3 nanoparticles synthesized by chloride-based route
摘要： The series of DyF3 nanoparticles was synthesized for the first time by a chloride-based route, using the water-soluble dysprosium chloride hexahydrate as a precursor. The synthesized nanoparticles have sizes of 3 to 7 nm, which is the smallest reported size for DyF3 nanoparticles. The influence of precursor concentration in an aqueous solution prior to the chemical reaction on the size of nanoparticles was studied. The influence of microwave-assisted hydrothermal treatment was also studied. The analysis of transmission electron microscopy (TEM) data revealed no correlation between the size of synthesized nanoparticles and the concentration of the aqueous solution. The AC/DC magnetic susceptibility of DyF3 nanoparticles was measured. The dipolar ferromagnetic transition for this sample was not observed down to 1.8 K that can be possibly explained by onset of superparamagnetism. The self-assembly of DyF3 nanoparticles was observed for the first time by analysis of XRD and TEM data and the evidence of superlattice formation along (020) and (210) lattice planes over the size of 20–30 nm (4–5 nanoparticles) was obtained.
关键词： X-ray techniques,Self-assembly,Nanocrystalline materials,Colloidal processing,Crystal structure,Electron microscopy
更新于2025-09-04 15:30:14
-
Cs Oleate Precursor Preparation for Lead Halide Perovskite Nanocrystal Synthesis: The Influence of Excess Oleic Acid on Achieving Solubility, Conversion, and Reproducibility.
摘要： In the colloidal synthesis of inorganic perovskite materials, cesium oleate (CsOL) is the most commonly used Cs precursor. Yet despite its ubiquitous use in literature, CsOL has been observed to be insoluble at room temperature and leads to surprisingly inconsistent results in CsPbX3 nanocrystal synthesis depending on the Cs salt from which the precursor is derived. We show that under the conditions used in most reports, the amount of oleic acid (OA) added, while stoichiometrically sufficient, still leads to incomplete conversion of the Cs salts to CsOL. This results in a mixture of Cs sources being present during the reaction, causing decreased homogeneity and reproducibility. When a 1:5 Cs:OA ratio is used, complete conversion is readily obtained even under mild conditions, resulting in a precursor solution that is soluble at room temperature and yields identical synthetic results regardless of the initial Cs source. Further, 1H nuclear magnetic resonance (NMR) of solutions prepared using varying Cs:OA ratios shows that the maximum ratio of Cs:OA obtainable in solution is 1:5, with any excess Cs present in the precipitate. We believe the use of a soluble, fully converted CsOL reagent will improve reproducibility for Cs-based perovskite synthesis and directly benefit synthetic methods based on microfluidics.
关键词： reproducibility,inorganic perovskite materials,microfluidics,CsPbX3 nanocrystal synthesis,colloidal synthesis,oleic acid,solubility,cesium oleate
更新于2025-09-04 15:30:14
-
Highly Stable Luminous “Snakes” from CsPbX3 Perovskite Nanocrystals Anchored on Amine-Coated Silica Nanowires
摘要： CsPbX3 (X=Cl, Br and I) perovskite nanocrystals (NCs) are known for their exceptional optoelectronic properties, yet the material’s instability towards polar solvents, heat or UV irradiation greatly limits its further applications. Herein, an efficient in-situ growing strategy has been developed to give highly stable perovskite NC composites (abbr. CsPbX3@CA-SiO2) by anchoring CsPbX3 NCs onto silica nanowires (NWs), which effectively depresses the optical degradation of their photoluminescence (PL) and enhances stability. The preparation of surface-functionalized serpentine silica NWs is realized by a sol-gel process involving hydrolysis of a mixture of tetraethylorthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES) and trimethoxy(octadecyl)silane (TMODS) in a water/oil emulsion. The serpentine NWs are formed via an anisotropic growth with lengths up to 8 μm. The free amino groups are employed as surface ligands for growing perovskite NCs, yielding distributed monodisperse NCs (~8 nm) around the NW matrix. The emission wavelength is tunable by simple variation of the halide compositions (CsPbX3, X=Cl, Br or I) and the composites demonstrate a high photoluminescence quantum yield (PLQY 32-69%). Additionally, we have demonstrated the composites CsPbX3@CA-SiO2 can be self-woven to form a porous 3D hierarchical NWs membrane, giving rise to a superhydrophobic surface with hierarchical micro/nano structural features. The resulting composites exhibit high stability towards water, heat and UV irradiation. This work elucidates an effective strategy to incorporate perovskite nanocrystals onto functional matrices as multifunctional stable light sources.
关键词： colloidal CsPbX3 nanocrystal,superhydrophobic,photostability,assembled hierarchical membrane,serpentine silica nanowires
更新于2025-09-04 15:30:14