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Plasmonic Evolution and Arrested Development for Silver Nanoscale Colloids: A Classroom Demonstration
摘要： A vivid demonstration visualizing the colloidal behavior of silver nanocrystals is described. An aqueous?ethanol silver ion solution becomes yellow upon initial chemical reduction (using sodium borohydride, NaBH4), which is followed by chromatic evolution to orange, red, violet, and ?nally blue over the course of approximately 3 min because of the predictable growth and evolution of the nanocrystals. This undergraduate-level classroom demonstration is useful for illustrating the protective e?ect of a passivating ligand, such as polyvinylpyrrolidone (PVP), by showing the ability of PVP to halt the growth and coalescence of silver colloids at a desired stage, arresting the color transition at a particular hue. This demonstration can also be extended to highlight the bifurcated impact of such passivation on colloid behavior (e.g., improved long-term colloid stability coupled with worsened nanocatalytic performance).
关键词： First-Year Undergraduate/General,Inquiry-Based/Discovery Learning,Colloids,Second-Year Undergraduate,Demonstrations,Metals
更新于2025-09-16 10:30:52
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Electrostatically controlled surface boundary conditions in nematic liquid crystals and colloids
摘要： Differing from isotropic fluids, liquid crystals exhibit highly anisotropic interactions with surfaces, which define boundary conditions for the alignment of constituent rod-like molecules at interfaces with colloidal inclusions and confining substrates. We show that surface alignment of the nematic molecules can be controlled by harnessing the competing aligning effects of surface functionalization and electric field arising from surface charging and bulk counterions. The control of ionic content in the bulk and at surfaces allows for tuning orientations of shape-anisotropic particles like platelets within an aligned nematic host and for changing the orientation of director relative to confining substrates. The ensuing anisotropic elastic and electrostatic interactions enable colloidal crystals with reconfigurable symmetries and orientations of inclusions.
关键词： colloids,nematic alignment,liquid crystals,surface boundary conditions,electrostatic control
更新于2025-09-12 10:27:22
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Binary ionic liquid electrolytes for copper indium sulfide quantum dot sensitized-TiO2 solar cell to achieve long-term durability
摘要： This work demonstrates a straightforward strategy to develop the copper-indium-sul?de (CIS) quantum dot-sensitized solar cells (QDSSCs) consisting of ionic liquids (ILs) as electrolyte instead of any volatile solvent. The power conversion ef?ciency (PCE) of the solar cell yielded with 0.36% in the presence of 1-butyl-3-methylimidazolium sul?de ([BMIm][S2?/Sn2?]) and 1-butyl-3-methylimidazolium thiocyanate ([BMIm][SCN]) exhibited an improvement of JSC and FF yielding with 0.75% (JSC: 8.69 mA cm?2, VOC: 0.32 V, FF 26.8%). It exhibited long-term stability within 20% drops after 72 h-continuous photo-irradiation and subsequent storage for more than 1300 h in dark. It is due to suppression of the volatilization of solvent and decomposition of sul?de/polysul?de (S2?/Sn2?) anions. The solar cell performances were found to promote as an increase of interfacial charge transfer ef?ciency between electrolyte and electrodes by means of electrochemical impedance spectroscopy.
关键词： Electrochemical impedance spectroscopy (EIS),Power-conversion ef?ciency (PCE),Ionic liquid electrolyte,Quantum dot-sensitized solar cell,Copper indium-sul?de (CIS) colloids
更新于2025-09-12 10:27:22
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Aqueous Carbon Quantum Dot-Embedded PC60-PC <sub/>61</sub> BM Nanospheres for Ecological Fluorescent Printing: Contrasting Fluorescence Resonance Energy-Transfer Signals between Watermelon-like and Random Morphologies
摘要： To go beyond the PC60 surfactant structure, the double-layer micelle morphology in water motivates exploration of altered protocols to produce new morphologies. Furthermore, the low photoluminescence quantum yield of aqueous fullerene-based particles encourages high fluorescence to create a light-emitting display. With this in mind, we established new hybrid n-type nanospheres with carbon quantum dot (CQD)-embedded PC60-PC61BM particles, processed using two different protocols. The homogenizer-assisted PC60-CQD-PC61BM resulted in a watermelon-shaped spherical particle, whereas a circular morphology with randomly embedded CQDs was observed in the microwave-treated hybrids. More surprisingly, the watermelon-shaped colloid induced efficient fluorescence resonance energy transfer (FRET) between the CQD and C60 molecules of PC61BM, and the FRET-mediated emission signature diminished gradually as the stripe patterns collapsed. This phenomenon allowed different fluorescent colors in the colloidal printing film. We thereby provided the new carrier dynamics of the particle photonic activities of the developed aqueous PC60-based colloids with the possibility of ecological utilization.
关键词： water-processable organic semiconductor colloids,fullerene-based nanoparticles,fluorescence resonance energy transfer,ecological fluorescent printing,carbon quantum dots
更新于2025-09-11 14:15:04
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Drag Controlled Formation of Polymeric Colloids with Optical Traps
摘要： Optical trapping is a powerful optical manipulation technique for controlling various mesoscopic systems that allows formation of tailor-made polymeric micro-sized colloids by directed coalescence of nucleation sites. However, control over the size of a single colloid requires constant monitoring of the growth process and deactivation of the optical trap once it reaches the required dimensions. Moreover, producing more than one colloid requires moving the sample to a pristine location where the process must be repeated. Here, we present a novel method for continuous control over formation of polydimethylsiloxane colloids based on directed coalescence induced by optical traps under flow inside micro-fluidic channels. Once the drag force on a growing colloid exceeds the trapping force, it leaves the optical trap, and a new colloid starts to form at the same location. We demonstrate repeatability of the process and selectively produce colloids with radii of ~1–14 μm by controlling the laser intensity and flow rate. In addition, holographic optical tweezers are used to show how multiple optical traps in 3D could be used to influence a significant cross section of the micro-channel, thus forming a light-controlled assembly line for colloidal formation.
关键词： optical trapping,micro-fluidic channels,polymeric colloids,holographic optical tweezers,drag force
更新于2025-09-11 14:15:04
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109 Evaluation of the Efficacy and Safety of Fractional Picosecond 1064-nm Laser Treatment for Skin Rejuvenation
摘要： Gold (Au) colloids are becoming ubiquitous across biomedical engineering, solar energy conversion, and nano-optics. Such universality has originated from the exotic plasmonic effect of Au colloids (i.e., localized surface plasmon resonance (LSPRs)) in conjunction with the versatile access to their synthetic routes. Herein, we introduce a previously undiscovered usage of Au colloids for advancing cryoprotectants with significant ice recrystallization inhibition (IRI). Oligopeptides inspired by the antifreeze protein (AFP) and antifreeze glycoprotein (AFGP) are attached onto the surface of well-defined Au colloids with the same sizes but different shapes. These AF(G)P-inspired Au colloids can directly adsorb onto a growing ice crystal via the synergistic interplay between hydrogen bonding and hydrophobic groups, in stark contrast to their bare Au counterparts. Dark-field optical microscopy analyses, benefitting from LSPR, allow us to individually trace the in situ movement of the antifreezing Au colloids during ice growth/recrystallization and clearly evidence their direct adsorption onto the growing ice crystal, which is consistent with theoretical predictions. With the assistance of molecular dynamics (MD) simulations, we evidently attribute the IRI of AF(G)P-inspired Au colloids to the Kelvin effect. We also exploit the IRI dependence on the Au colloidal shapes; indeed, the facet contacts between ice and Au colloids can be better than the point-like counterparts in terms of IRI. The design principles and predictive theory outlined in this work will be of broad interest not only for the fundamental exploration of the inhibition of ice growth but also for enriching the application of Au colloids.
关键词： gold colloids,antifreezing proteins,dark-field microspectroscopy,oligopeptides,Ice recrystallization inhibition
更新于2025-09-11 14:15:04
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Synthesis of Hollow Silica Nanocubes with Tuneable Size and Shape, Suitable for Light Scattering Studies
摘要： We present a preparation method for hollow silica nanocubes with tuneable size and shape in the range required for light scattering studies. Cuprous oxide nanocubes are prepared by a water-assisted polyol method. By adjusting the water content, the size of the nanocubes can be tuned in the range of 40–120 nm. These cubes function as a shape template in the subsequent coating with St?ber silica, resulting in core-shell nanocubes. Dissolving the core with nitric acid results in hollow silica nanocubes with sizes ranging from 80–120 nm and cubicity shape parameters between 3 and 6.5.
关键词： colloids,nanocubes,microscopy,silica,superballs,synthesis
更新于2025-09-10 09:29:36
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Control of Shell Morphology in p-n Heterostructured Water-Processable Semiconductor Colloids: Toward Extremely Efficient Charge Separation
摘要： This article describes p–n heterostructured water-borne semiconductor nanoparticles (NPs) with unique surface structures via control of shell morphology. The shell particles, comprising PC60–[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) composite, having n-type semiconductor characteristics, notably influence the charge carrier behavior in the core–shell NPs. A one- or two-phase methodology based on a PC60 surfactant-water phase and PC61BM n-type semiconductor-organic phase provides highly specific control over the shell structure of the NPs, which promote their superior charge separation ability when combined with poly-3-hexyl-thiophene (P3HT). Moreover, the resulting water-borne NP exhibits shell morphology-dependent carrier quenching and stability, which is characterized via luminescence studies paired with structural analysis. Corresponding to the results, outstanding performances of photovoltaic cells with over 5% efficiency are achieved. The results suggest that the surrounding shell environments, such as the shell structure, and its electronic charge density, are crucial in determining the overall activity of the core–shell p–n heterostructured NPs. Thus, this work provides a new protocol in the current fields of water-based organic semiconductor colloids.
关键词： p–n heterostructure,charge separation,water-borne colloids,water-processable nanoparticles,organic semiconducting nanoparticles
更新于2025-09-10 09:29:36
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Particulate Coatings with Optimized Haze Properties
摘要： The haze factor, which describes the fraction of light that is scattered when passing through a transparent material, is of general importance for any optical device, from milk glass shielding visibility while providing ambient lighting to solar cells that are optimized by sophisticated light management layers. Often, such active layers are fabricated from particulate materials that are deposited as thin films on a substrate. Here, the effect of structural arrangement, position, and orientation of particles on the resulting haze factor is investigated. A mathematical optimization model that iteratively alters the particle layer structure to maximize or minimize the haze factor for a range of optimization scenarios is designed. Colloidal self-assembly techniques are then used to replicate typical particle structures found in the optimized designs and correlate the macroscopically measured haze values to the predictions of the optimization. The results indicate general design rules that control the haze value in particle layers. Non close-packed structures with distributed scatterers and high degrees of order provide minimal haze values while chain-like arrangements and small clusters maximize the haze of a particle layer. Finally, the findings are transferred to metal nanohole films as model transparent electrodes with controlled haze values.
关键词： haze factor,electromagnetic scattering,thin films,colloidal lithography,colloids,mathematical optimization
更新于2025-09-10 09:29:36
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Scalable, Highly Uniform, and Robust Colloidal Mie Resonators for All-Dielectric Soft Meta-Optics
摘要： All-dielectric nanoparticles (NPs) with high (>3.0) or moderate (1.7–3.0) refractive indices have become fundamental to meta-optics, as they enable low-loss, low-heating, and quenching-free magnetodielectric Mie resonances, which are difficult to achieve by use of plasmonic counterparts. However, a scalable and versatile synthetic route for such magnetodielectric NPs retaining high uniformity, roundness, and robustness has remained elusive. Thus, soft self-assembly still represents an underutilized method in the optical engineer’s toolset, which in turn limits the accessible range of meta-optics. Herein, a gram-scale and versatile synthesis of dielectric colloidal Mie resonators is presented, in which selenous acid precursors are converted into highly uniform, crystalline colloids by a low demand reaction. These crystalline selenium (c-Se) colloids enable strong electric and magnetic resonances due to their moderate refractive index (2.8–3.2 at optical frequencies), while simultaneously satisfying the requirements of high uniformity, roundness, and robustness. Even with these exotic properties, c-Se colloids are successfully self-assembled into various all-dielectric meta-optics systems including (i) metafluids exhibiting directional scattering, (ii) metamolecules with nanogap-dielectric resonances, and (iii) metacrystals with magnetodielectric bandgaps. The design space of all-dielectric meta-optics will be greatly expanded by utilizing soft self-assembly of c-Se colloids.
关键词： soft nanophotonics,self-assembly,colloids,selenium,3D all-dielectric meta-optics
更新于2025-09-10 09:29:36