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Fluorescence spectra of colloidal self-assembled CdSe nano-wire on substrate of porous Al <sub/>2</sub> O <sub/>3</sub> /Au nanoparticles
摘要： We present a self-assembly method to prepare array nano-wires of colloidal CdSe quantum dots on a substrate of porous Al2O3 film modified by gold nanoparticles. The photoluminescence (PL) spectra of nanowires are in situ measured by using a scanning near-field optical microscopy (SNOM) probe tip with 100-nm aperture on the scanning near-field optical microscope. The results show that the binding sites from the edge of porous Al2O3 nanopores are combined with the carboxyl of CdSe quantum dots’ surface to form an array of CdSe nanowires in the process of losing background solvent because of the gold nanoparticles filling the nano-holes of porous Al2O3 film. Compared with the area of non-self-assembled nano-wire, the fluorescence on the Al2O3/Au/CdSe interface is significantly enhanced in the self-assembly nano-wire regions due to the electron transfer conductor effect of the gold nanoparticles’ surface. In addition, its full width at half maximum (FWHM) is also obviously widened. The method of enhancing fluorescence and energy transfer can widely be applied to photodetector, photocatalysis, optical display, optical sensing, and biomedical imaging, and so on.
关键词： porous Al2O3 film,colloidal self-assembled method,CdSe nano-wire,enhanced photoluminescence
更新于2025-11-25 10:30:42
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Building Intermixed Donor-Acceptor Architectures for Water-Processable Organic Photovoltaics
摘要： A modified synthesis method for aqueous nanoparticle printing inks, based upon vacuum-assisted solvent removal, is reported. Poly(3-hexylthiophene) : phenyl C61 butyric acid methyl ester nanoparticle inks were prepared via this modified miniemulsion method; leading to both an improvement in photoactive layer morphology and a substantial reduction in the ink fabrication time. A combination of UV-visible spectroscopy, photoluminescence spectroscopy and scanning transmission X-ray microscopy measurements revealed a nanoparticle morphology comprised of highly intermixed donor-acceptor domains. Consistent with these measurements, dynamic mechanical thermal analysis of the nanoparticles showed a glass transition temperature (Tg) of 104 °C, rather than a pure polymer phase or pure fullerene phase Tg. Together the spectroscopy, microscopy and thermomechanical data indicate that rapid solvent removal generates a more blended nanoparticle morphology. As such, this study highlights a new experimental lever for optimising nanostructure in the photoactive layer of nanoparticulate organic photovoltaic devices by enabling highly intermixed donor-acceptor architectures to be built from customised nanoparticulate inks.
关键词： organic photovoltaic,scanning transmission X-ray microscopy,morphology,colloidal inks,exciton dissociation,Nanostructure,eco-friendly processing
更新于2025-11-19 16:46:39
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Latent fingermark detection using functionalised silicon oxide nanoparticles: Method optimisation and evaluation
摘要： The application of nanoparticles for latent fingermark detection has been reported in the literature over the past two decades. One of the nanoparticles that shows promise to become a routine technique is functionalised silicon oxide nanoparticles (SiO2 NPs). In a recent optimisation of the technique, the use of carboxyl-functionalised SiO2 NPs doped with luminescent ruthenium complex was proposed as a breakthrough for latent fingermark detection. In this study, the aforementioned functionalised SiO2 NPs were extensively evaluated. Modification and optimisation of the original detection parameters were performed to enhance detection quality and improve applicability. Various detection parameters were evaluated and assessed. A lower concentration of the functionalised nanoparticles used in the colloidal dispersion was determined to offer improved detection effectiveness. A combination of increased bath temperature and reduced immersion time was found to produce good overall results. A set of modified detection parameters was suggested for the use of the functionalised SiO2 NPs to detect latent fingermarks. Performance of the modified detection parameters was compared against that of the published detection method. Comparison experiments were carried out on fingermark specimens deposited on aluminium foil, transparent polypropylene plastic and green polyethylene plastic. Three donors (weak, average and strong) and two age intervals (ten days and three months) were considered in the comparison study. Evaluation of the results suggested that the overall performance of the modified method for latent fingermark detection was superior to that obtained using the previously published detection parameters.
关键词： Bath temperature,Detection effectiveness,Method modification,Colloidal,Surface functionalisation,Luminescence technique
更新于2025-11-19 16:46:39
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Controlling colloidal processing of (K,Na)NbO3-based materials in aqueous medium
摘要： K0.5Na0.5NbO3-based materials are serious candidates to replace lead-based piezoceramics since they show excellent electrical and piezoelectric properties. The tape casting technique can be used to obtain highly textured KNN-based ceramics; however, despite industrial and environmental advantages of water-based processing, there are not reports about the control of colloidal processing conditions to obtain optimized K0.5Na0.5NbO3-based slurries in aqueous medium. This paper reports a procedure for controlling colloidal processing conditions to obtain optimized (K0.5Na0.5)0.97Li0.03Nb0.8Ta0.2O3 suspensions. Zeta potential and cationic solubility measurements as a function of pH showed that pH 8.5 is adequate for controlling colloidal stability and rheological behavior of aqueous suspensions, while flow curves analysis allowed optimizing processing parameters, such as, powder content, amount of deflocculant and binder, and sonication time. Optimized colloidal suspensions were prepared and used to obtain high quality tapes. Processed ceramics from these stacked tapes show equivalent properties to those processed directly from powders, which demonstrates the effectiveness of the colloidal route reported here.
关键词： Aqueous tape casting,KNN,Lead-free,Rheological properties,Colloidal suspensions
更新于2025-11-14 17:28:48
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Direct Hot-Injection Synthesis of Lead Halide Perovskite Nanocubes in Acrylic Monomers for Ultrastable and Bright Nanocrystal–Polymer Composite Films
摘要： In recent years, lead halide perovskite nanocrystals (NCs) have attracted significant attention in both fundamental research and commercial applications due to their excellent optical and optoelectrical properties. However, the protective ligands on the surface of the perovskites NCs could be easily removed after the tedious process of centrifugation, separation, and dispersion, which greatly hampers their stability against light, heat, moisture, and oxygen and limits their practical applications. Here we report a new post-processing-free strategy (i.e., without centrifugation, separation, and dispersion process) of using an UV-polymerizable acrylic monomer of lauryl methacrylate (LMA) as the solvent to synthesize CsPbBr3 NCs, and then adding polyester polyurethane acrylates oligomer, monomer (IBOA) and initiator for directly UV polymerization to fabricate NC-polymer composite films. These films exhibited an improved photoluminescence quantum yield (85-90%) than classic NC-film (40-50%), which were processed using octadecene (ODE) as the solvent for NC synthesis and post-processed for UV polymerization. Significantly, the as-fabricated films by post-processing-free strategy exhibited excellent photostability against strong Xe lamp illumination; while the other films using classic methods were quickly photo-degraded. Meanwhile, these NC-polymer composite films showed good stability against moisture and heating when aging in water at 50oC for over 200 hours. These films, along with K2SiF6:Mn4+ (KSF) phosphor emitters, were used as downconverters for blue LEDs in liquid crystal displays with a wide color gamut of 115% in the International Commission on Illumination (CIE) 1931 color space. This work provides a facile and effective strategy for the preparation of ultrastable and bright color-conversion NC films for the development of the next-generation wide color gamut displays.
关键词： display backlight,lead halide perovskite,colloidal nanocrystals,color-conversion optical films,photostability
更新于2025-11-14 17:03:37
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Enhancing light absorption by colloidal metal chalcogenide quantum dots <i>via</i> chalcogenol(ate) surface ligands
摘要： Chemical species at the surface (ligands) of colloidal inorganic semiconductor nanocrystals (QDs) markedly impact the optoelectronic properties of the resulting systems. Here, post-synthesis surface chemistry modification of colloidal metal chalcogenide QDs is demonstrated to induce both broadband absorption enhancement and band gap reduction. A comprehensive library of chalcogenol(ate) ligands is exploited to infer the role of surface chemistry on the QD optical absorption: the ligand chalcogenol(ate) binding group mainly determines the narrowing of the optical band gap, which is attributed to the np occupied orbital contribution to the valence band edge, and mediates the absorption enhancement, which is related to the π-conjugation of the ligand pendant moiety, with further contribution from electron donor substituents. These findings point to a description of colloidal QDs that may conceive ligands as part of the overall QD electronic structure, beyond models derived from analogies with core/shell heterostructures, which consider ligands as mere perturbation to the core properties. The enhanced light absorption achieved via surface chemistry modification may be exploited for QD-based applications in which an efficient light-harvesting initiates charge carrier separation or redox processes.
关键词： colloidal metal chalcogenide quantum dots,light absorption,optoelectronic properties,surface ligands,band gap reduction
更新于2025-10-22 19:40:53
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Oxygen Plasma-Induced p-type Doping Improves Performance and Stability of PbS Quantum Dot Solar Cells
摘要： PbS quantum dots (QDs) have been extensively studied for photovoltaic applications thanks to their facile and low-cost fabrication processing and interesting physical properties such as size-dependent and tunable bandgap. However, the performance of PbS QDs based solar cells is highly sensitive to the humidity level in the ambient air, which is a serious obstacle toward its practical applications. Although it has been previously revealed that oxygen doping of the hole transporting layer (HTL) can mitigate the cause of this issue, the suggested methods to recover the device performance are time-consuming and relatively costly. Here, we report on a low-power oxygen plasma treatment as a rapid and cost-effective method to effectively recover the device performance and stability. Our optimization results show that a 10 min treatment is the best condition, resulting in an enhanced power conversion efficiency (PCE) from 6.9% for the as-prepared device to 9% for the plasma treated one. Moreover, our modified device shows long-term shelf-life stability.
关键词： colloidal quantum dots,plasma,lead sulfide,photovoltaics,stability
更新于2025-10-22 19:40:53
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Colloidally Stable Monolayer Nanosheets with Colorimetric Responses
摘要： Despite the discovery of chromogenic-layered materials for decades of years, fabrication of colloidally stable monolayer organic 2D nanosheets in aqueous media with colorimetric responses is still challenging. Herein reported is the first solution synthesis of chromic monolayer nanosheets via the topochemical polymerization of self-assembled amphiphilic diacetylenes in aqueous media. The polydiacetylene (PDA) nanosheets are ≈3–4 nm thick in solution and only ≈1.9 nm thick in the dried state, while the lateral size can reach several micrometers. Moreover, the aqueous stability endows PDA nanosheets with excellent processability, which can further assemble into films via vacuum filtration or act as an ink for high-resolution inkjet printing. The filtrated films and printed patterns exhibit fully reversible blue-to-red thermochromism, and the film also displays an interesting reversible colorimetric transition in response to near-infrared light, which is not reported for other PDA-only systems. The present colloidal PDA nanosheets should represent a new kind of chromic organic 2D nanomaterials that may be applied as novel building blocks for developing intelligent hybrid materials and may also find diverse sensing, display and/or anticounterfeiting applications.
关键词： colorimetric responses,monolayer nanosheets,colloidal stability,polydiacetylene
更新于2025-09-23 15:23:52
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Electrostatically Directed Assembly of Nanostructured Composites for Enhanced Photocatalysis
摘要： It is well established that the activity of photocatalysts can be improved by deposition of redox catalysts, which can effectively extract the photogenerated charge carriers, enhance the rate of interfacial reactions, and thus suppress undesired recombination processes. For optimum performance, a high degree of control over the loading, size, and surface catalytic properties of redox catalyst particles is desirable. Herein, a novel, highly controllable, and versatile method for preparation of TiO2 catalyst composites is reported. It starts with the generation of “naked” (ligand-free) nanoparticles of CuOx or FeOx by pulsed laser ablation of metal oxide targets in water. In the next step, a nearly quantitative colloidal deposition of CuOx and FeOx nanoparticles onto anatase TiO2 substrate is achieved by adjusting the pH in order to establish electrostatic attraction between the colloids and the substrate. The resulting TiO2–CuOx and TiO2–FeOx assemblies with optimum catalyst amount (≈0.5 wt%) exhibit photocatalytic rates in degradation of 2,4-dichlorophenoxyacetic acid enhanced by a factor of ≈1.5 as compared to pristine TiO2 under simulated solar irradiation. The electrostatically directed assembly of TiO2 with ligand-free catalyst nanoparticles generated by pulsed laser ablation is thus demonstrated as a viable tool for preparation of composites with enhanced photocatalytic performance.
关键词： photocatalysis,titanium dioxide,laser ablation,colloidal deposition,nanoparticles
更新于2025-09-23 15:23:52
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Quantum and Dielectric Confinement Effects in Lower-Dimensional Hybrid Perovskite Semiconductors
摘要： Hybrid halide perovskites are now superstar materials leading the field of low-cost thin film photovoltaics technologies. Following the surge for more efficient and stable 3D bulk alloys, multilayered halide perovskites and colloidal perovskite nanostructures appeared in 2016 as viable alternative solutions to this challenge, largely exceeding the original proof of concept made in 2009 and 2014, respectively. This triggered renewed interest in lower-dimensional hybrid halide perovskites and at the same time increasingly more numerous and differentiated applications. The present paper is a review of the past and present literature on both colloidal nanostructures and multilayered compounds, emphasizing that availability of accurate structural information is of dramatic importance to reach a fair understanding of quantum and dielectric confinement effects. Layered halide perovskites occupy a special place in the history of halide perovskites, with a large number of seminal papers in the 1980s and 1990s. In recent years, the rationalization of structure–properties relationship has greatly benefited from new theoretical approaches dedicated to their electronic structures and optoelectronic properties, as well as a growing number of contributions based on modern experimental techniques. This is a necessary step to provide in-depth tools to decipher their extensive chemical engineering possibilities which surpass the ones of their 3D bulk counterparts. Comparisons to classical semiconductor nanostructures and 2D van der Waals heterostructures are also stressed. Since 2015, colloidal nanostructures have undergone a quick development for applications based on light emission. Although intensively studied in the last two years by various spectroscopy techniques, the description of quantum and dielectric confinement effects on their optoelectronic properties is still in its infancy.
关键词： quantum confinement,multilayered perovskites,structural engineering,colloidal nanostructures,hybrid halide perovskites,optoelectronic properties,2D materials,dielectric confinement
更新于2025-09-23 15:23:52