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General Synthesis of Ordered Mesoporous Rare-Earth Orthovanadate Thin Films and Their Use as Photocatalysts and Phosphors for Lighting Applications
摘要： Herein, the block copolymer templating sol-gel synthesis of a novel class of ternary oxide nanomaterials is reported. NdVO4, EuVO4, GdVO4, DyVO4, YVO4, and TmVO4 have been prepared as open mesoporous films by the dip-coating method using hydrated rare-earth nitrate salt precursors along with vanadium oxytrichloride. All materials crystallize in the tetragonal ZrSiO4-type structure with space-group I41/amd. Short-term treatment at 550 °C is found sufficient to initiate crystallization. Characterization via X-ray and electron diffraction, Raman and X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry confirms the single-phase nature and uniformity of the different orthovanadates with tailorable crystallite sizes. The integrated results from electron and atomic force microscopy, Kr-physisorption as well as in-situ and ex-situ synchrotron-based small-angle X-ray scattering reveal that the porosity persists throughout the thickness of films and the mesoscopic ordering is retained even after heating in air at 700 °C. Photobleaching experiments indicate that the sol-gel derived materials, showing an indirect band gap transition at (3.8±0.1) eV, exhibit good photocatalytic properties—the activity is highly superior to that of bulk films of the same nominal composition. Moreover, when doping GdVO4, YVO4, and solid solution GdVO4-YVO4 with trivalent rare-earth ions such as Eu3+, Dy3+, Er3+, or Tm3+ ions, the films hold promise as phosphors for lighting applications, which might pave the way toward development of (3-dimensional) intricate nanocomposites with unprecedented functionalities.
关键词： Block copolymer templating,ternary metal oxide nanostructure,photocatalyst,phosphor,sol-gel chemistry
更新于2025-11-21 10:59:37
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Improving performance and stability of planar perovskite solar cells through grain boundary passivation with block copolymer
摘要： Organic-inorganic metal halide perovskite solar cells (PSCs) exhibit excellent photovoltaic performance but suffer from instabilities against moisture and heat due to the inherent hydroscopic nature and volatility of their organic components. Herein, we report that employing block copolymer F127 as the passivation reagent in conjunction with solvent annealing process can efficiently improve the performance and stability of corresponding organic-inorganic PSCs. It is anticipated that the hydrophilic poly(ethylene oxide) tails of F127 polymers connect with contiguous perovskite crystals and passivate defects at perovskite grain boundaries, whereas the dangling hydrophobic poly(phenyl oxide) centers suppress perovskite decomposition caused by moisture and heat. After the optimization of the F127 additive, the planar PSCs with champion power conversion efficiencies of 21.01% and 18.71% were achieved on rigid and flexible substrates, respectively. The F127 passivation strategy provides an effective approach for fabricating high-efficiency and stable PSCs.
关键词： flexible solar cells,block copolymer,perovskite solar cells,interface passivation,stability
更新于2025-10-22 19:40:53
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Block copolymer brush layer-templated gold nanoparticles on nanofibers for surface-enhanced Raman scattering optophysiology
摘要： A nanothin block copolymer (BCP) brush-layer film adsorbed on glass nanofibers is shown to address the long-standing challenge of forming a template for the deposition of dense and well dispersed nanoparticles on highly curved surfaces, allowing the development of an improved nanosensor for neurotransmitters. We employed a polystyrene-block-poly(4-vinylpyridine) BCP and plasmonic gold nanoparticles (AuNPs) of 52 nm in diameter for the fabrication of the nanosensor on pulled fibers with diameters down to 200 nm. The method is simple, using only solution processes and a plasma cleaning step. The templating of the AuNPs on the nanofiber surprisingly gave rise to more than one order of magnitude improvement in the surface-enhanced Raman scattering (SERS) performance for 4-mercaptobenzoic acid compared to the same AuNPs aggregated on identical fibers without the use of a template. We hypothesize that a wavelength-scale lens formed by the nanofiber contributes to enhancing the SERS performance, to the extent that it can melt the glass nanofiber under moderate laser power. We then show the capability of this nanosensor to detect the co-release of the neurotransmitters dopamine and glutamate from living mouse brain dopaminergic neurons with a sensitivity one order of magnitude greater than with aggregated AuNPs. The simplicity of fabrication and the far superior performance of the BCP-templated nanofiber demonstrates the potential of this method to efficiently pattern nanoparticles on highly curved surfaces and its application as molecular nanosensors for cell physiology.
关键词： block copolymer brush,neurosciences,SERS optophysiology,nanofiber,neurotransmitters
更新于2025-09-23 15:23:52
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Low-density PMMA/MAM nanocellular polymers using low MAM contents: Production and characterization
摘要： Low-density nanocellular polymers are required to take advantage of the full potential of these materials as high efficient thermal insulators. However, their production is still a challenging task. One promising approach is the use of nanostructured polymer blends of poly(methyl methacrylate) (PMMA) and a block copolymer poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) (MAM), which are useful for promoting nucleation but seem to present a severe drawback, as apparently avoid low relative densities. In this work, new strategies to overcome this limitation and produce low-density nanocellular materials based on these blends are investigated. First, the effect of very low amounts of the MAM copolymer is analysed. It is detected that nanostructuration can be prevented using low copolymer contents, but nucleation is still enhanced as a result of the copolymer molecules with high CO2 affinity dispersed in the matrix, so nanocellular polymers are obtained using very low percentages of the copolymer. Second, the influence of the foaming temperature is studied. Results show that for systems in which there is not a clear nanostructuration, cells can grow more freely and smaller relative densities can be achieved. For these studies, blends of PMMA with MAM with copolymer contents from 10 wt% and as low as 0.1 wt% are used. For the first time, the production strategies proposed in this work have allowed obtaining low density (relative density 0.23) nanocellular polymers based on PMMA/MAM blends.
关键词： nanostructuration,gas dissolution foaming,PMMA,MAM,block copolymer,nanocellular polymer,nanocellular foam
更新于2025-09-23 15:23:52
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A novel luminescent sensor for disaccharide detection in food: Synthesis and application of a water-soluble rod-coil ionic block copolymer
摘要： A simple and low cost method for detecting disaccharide in food product is important for people who need control the consumption of saccharides in daily life. In this study, a water soluble rod-coil ionic block copolymer poly[2,7-(9,9-dihexyl-fuorene)]-b-cationic quaternized-poly[2-(dimethylamino)ethyl methacrylate] (PF-b-PDI) was employed as luminescent sensor for detection of lactose, sucrose and maltose in food. It was found that the PF-b-PDI could emit vision fluorescence with the existence of hydroquinone (HQ) in aqueous, but would be quenched by the oxidization of hydrogen peroxide (H2O2). The glucose oxidase (GOx) could be used for catalyzing the glucose to generate the H2O2. And the sucrase, maltase and lactase could respectively catalyze sucrose, maltose and lactose to glucose. With the selectivity and catalyst of enzyme, the PF-b-PDI aqueous blend with HQ showed fluorescence sensitive to sucrose, maltose and lactose with detection limit value of 1.36 μM, 1.09 μM and 3.08 μM, respectively. Moreover, the detection of lactose in milk samples by this method just revealed 0.44% of average deviation compared to standard lactose solution, which mean this method was suitable for detecting lactose in milk.
关键词： maltose,rod-coil ionic block copolymer,lactose,sucrose,luminescent sensor
更新于2025-09-23 15:22:29
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Development of New Blue-Light Emitting PPV Block Copolymer: Synthesis, Characterization and Electro-Optical Studies
摘要： New soluble intense blue light emitting bulky ring substituted segmented PPV block copolymer was synthesized by synthesized condensation polymerization. Rigid cyclohexyl methoxy group substituted distyrylbenzene unit was the chromophore group present in the synthesized segmented block copolymer. The obtained copolymer was dissolved in all common organic solvents. The structure of the copolymer was characterized by using FT-IR, NMR techniques, and elemental analysis. GPC analysis shows that the copolymer has narrow polydispersity index. Thermal gravimetric analysis shows it has excellent thermal stability with maximum decomposition temperature obtained as 4220C. The HOMO and LUMO values of copolymer were estimated from the cyclic voltammograms. Photoluminescence studies show that copolymer gives blue emission. XRD and DSC studies give information about the semi-crystalline nature of the present copolymer. Overall results such as thermal properties, photoluminescence characteristics and low onset voltage from Voltage vs. Current data are confirmed the suitability of the copolymer for fabricating PLEDs.
关键词： polymer light emitting diodes,light emitting polymers,segmented block copolymer
更新于2025-09-23 15:21:01
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Block Copolymer Derived Vertically Coupled Plasmonic Arrays for Surface-Enhanced Raman Spectroscopy
摘要： A surface-enhanced Raman spectroscopy sensing template consisting of gold-covered nanopillars is developed. The plasmonic slab consists of a perforated gold film at the base of the nanopillars and a Babinet complementary dot array on top of the pillars. The nanopillars were fabricated by the incorporation of an iron salt precursor into a self-assembled block copolymer thin film and subsequent reactive ion etching. The preparation is easy, scalable, and cost-effective. We report on the increase in surface-enhanced Raman scattering efficiency for smaller pillar heights and stronger coupling between the dot array and perforated gold film with average enhancement factors as high as 107. In addition, the block copolymer-derived templates show an excellent relative standard deviation of 8% in the measurement of the Raman intensity. Finite difference time domain simulations were performed to investigate the nature of the electromagnetic near-field enhancement and to identify plasmonic hot spots.
关键词： block copolymer lithography,finite difference time domain simulation,SERS uniformity,plasmonic nanomaterials,surface-enhanced Raman spectroscopy,nanofabrication,4-aminothiophenol
更新于2025-09-23 15:21:01
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Molecular Simulations of Laser Spike Annealing of Block-Copolymer Lamellar Thin-Films
摘要： We use molecular dynamic simulations to study the phase behavior of a coarse-grained lamella-forming A-b-B di-block copolymer under thin-film soft confinement for different heating cycle lengths, film thicknesses, and substrate-polymer affinities. This model describes the effect on thin-film morphology with a free surface (air-polymer interface) and a solid substrate. Our simulation results were first validated by showing that they capture changes for the order-disorder transition temperature with annealing conditions consistent with those found in laser spike annealing experiments, when the vertical lamella phase formed on neutral substrates. In addition, simulations with a substrate selective for a particular block revealed the formation of other phases including a mixed vertical-horizontal lamella and a metastable island phase having horizontal but incomplete lamella layers. The nanoscale roughness features of this island phase, and hence its surface wettability, can be tuned with suitable choices of chemistry and annealing conditions.
关键词： thin-film,nanoscale roughness,order-disorder transition,phase behavior,laser spike annealing,molecular dynamic simulations,block copolymer
更新于2025-09-23 15:21:01
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Enhanced Ordering and Efficient Photoalignment of Nanostructures in Block Copolymers Enabled by Halogen Bond
摘要： Fabrication and manipulation of macroscopically ordered nanostructures in polymer ?lms via supramolecular self-organization are fascinating from the viewpoints of science and technology. Here, a halogen bond (XB) was introduced into a block copolymer to facilitate its microphase separation process upon XB-driven supramolecular self-assembly. To the best of our knowledge, this is an extremely rare example to elegantly maneuver nanostructures of polymers by the emerging supramolecular interaction, XB. The nonmesogenic block copolymer composed of poly(ethylene oxide) and azopyridine-containing polymethacrylate was transformed into a supramolecular liquid-crystalline polymer through the halogen-bonded interaction between 1,2-diiodo-3,4,5,6-tetra?uorobenzene and the azopyridine group with the optimal molar ratio of 1:1. For comparison, one hydrogen-bonded liquid-crystalline polymer was also fabricated but no such ordering enhancement was acquired, indicating that both the high directionality of XB and the resulting supramolecular mesogenic ordering played key roles in the enhanced ordering of nanostructures in polymer ?lms. In addition, e?cient photoalignment and photoreorientation of nanostructures coinciding with the oriented direction of the supramolecular mesogens were also obtained by manipulating photoirradiation of linearly polarized light for the present XB-involved liquid-crystalline block copolymer, which is promising for the development of a novel generation of advanced composite liquid crystal (LC) materials.
关键词： halogen bond,supramolecular self-assembly,photoalignment,block copolymer,nanostructures
更新于2025-09-23 15:19:57
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Cu Nanoparticle Array-Mediated III-V/Si Integration: Application in Series-Connected Tandem Solar Cells
摘要： The integration of III-V materials with crystalline Si (c-Si) is a promising pathway to design high-performance optoelectronic devices, including solar cells. We have previously reported high-efficiency III-V/Si tandem cells using our unique semiconductor bonding technique, termed smart stack. In the conventional smart stack cells, Pd nanoparticle (NP) arrays have been commonly employed as bonding mediators between III-V and c-Si; however, from an economical point of view, the use of other low-cost metals would be preferable. Therefore, this study focused on the possibility of Cu. A polystyrene-block-poly-2-vinylpyridine (PS-b-P2VP)-based block copolymer was utilized to prepare Cu NP arrays. Desired Cu NP arrays were achieved by starting with self-assembled PS-b-P2VP micelles preloaded with Cu2+ ions. Satisfying bonding properties (low-resistance interfaces) were confirmed when GaAs subcells were stacked on the Cu NP arrays formed on native oxide-removed c-Si subcells. Conversion efficiencies up to 25.9% have been demonstrated with triple-junction structures consisting of InGaP/GaAs top and c-Si bottom subcells. The long-term reliability of Cu NP array-mediated smart stack cells were also verified by the thermal cycle and damp heat tests. Hence, we have successfully confirmed that not only Pd but also Cu is available to realize high-efficiency smart stack cells.
关键词： III-V,Copper,block copolymer,solar cell,tandem,nanoparticle,silicon,self-assembly
更新于2025-09-23 15:19:57