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CFRP laser texturing to increase the adhesive bonding: morphological analysis of treated surfaces
摘要： Surface roughness of the adherends represents an important factor for manufacturing a reliable bonded joint in structural applications. In case of bonding of parts in carbon fibre reinforced polymer (CFRP), an increase of roughness parameters can be obtained with various techniques. In this paper, the morphology obtained from a CO2 laser texturing on CFRP laminates were investigated. CFRP laminates were manufactured and subjected to laser texturing with various densities. In particular, the densities of treatment have been defined as a function of the grid dimensions of the texture. Subsequently, non-contact measurements were carried out to evaluate the evolution of the surface roughness parameters as a function of the density of the laser treatment. Results showed a strong correlation between surface roughness and density of treatment. In conclusion, these results were compared with experimental tests, which showed that the mechanical performance for ENF bonded joints was limited only by the flexural mechanical resistance of the CFRP adherends. As a result of this work, the developed laser texturing approach is potentially able to increase the mechanical resistance in the function of the real local load acting on the complex bonded joint, optimizing time and cost process.
关键词： surface modification,surface roughness/morphology,Composites,adhesion by mechanical interlocking
更新于2025-09-23 15:21:01
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Role of shell composition and morphology in achieving single-emitter photostability for green-emitting a??gianta?? quantum dots
摘要： The use of the varied chemical reactivity of precursors to drive the production of a desired nanocrystal architecture has become a common method to grow thick-shell graded alloy quantum dots (QDs) with robust optical properties. Conclusions on their behavior assume the ideal chemical gradation and uniform particle composition. Here, advanced analytical electron microscopy (high-resolution scanning transmission electron microscopy coupled with energy dispersive spectroscopy) is used to confirm the nature and extent of compositional gradation and these data are compared with performance behavior obtained from single-nanocrystal spectroscopy to elucidate structure, chemical-composition, and optical-property correlations. Specifically, the evolution of the chemical structure and single-nanocrystal luminescence was determined for a time-series of graded-alloy “CdZnSSe/ZnS” core/shell QDs prepared in a single-pot reaction. In a separate step, thick (～6 monolayers) to giant (>14 monolayers) shells of ZnS were added to the alloyed QDs via a successive ionic layer adsorption and reaction (SILAR) process, and the impact of this shell on the optical performance was also assessed. By determining the degree of alloying for each component element on a per-particle basis, we observe that the actual product from the single-pot reaction is less “graded” in Cd and more so in Se than anticipated, with Se extending throughout the structure. The latter suggests much slower Se reaction kinetics than expected or an ability of Se to diffuse away from the initially nucleated core. It was also found that the subsequent growth of thick phase-pure ZnS shells by the SILAR method was required to significantly reduce blinking and photobleaching. However, correlated single-nanocrystal optical characterization and electron microscopy further revealed that these beneficial properties are only achieved if the thick ZnS shell is complete and without large lattice discontinuities. In this way, we identify the necessary structural design features that are required for ideal light emission properties in these green-visible emitting QDs.
关键词： green-emitting,photostability,quantum dots,morphology,giant quantum dots,shell composition
更新于2025-09-23 15:21:01
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Structural and Electrical Investigation of Cobalt-Doped NiOx/Perovskite Interface for Efficient Inverted Solar Cells
摘要： Inorganic hole-transporting materials (HTMs) for stable and cheap inverted perovskite-based solar cells are highly desired. In this context, NiOx, with low synthesis temperature, has been employed. However, the low conductivity and the large number of defects limit the boost of the e?ciency. An approach to improve the conductivity is metal doping. In this work, we have synthesized cobalt-doped NiOx nanoparticles containing 0.75, 1, 1.25, 2.5, and 5 mol% cobalt (Co) ions to be used for the inverted planar perovskite solar cells. The best e?ciency of the devices utilizing the low temperature-deposited Co-doped NiOx HTM obtained a champion photoconversion e?ciency of 16.42%, with 0.75 mol% of doping. Interestingly, we demonstrated that the improvement is not from an increase of the conductivity of the NiOx ?lm, but due to the improvement of the perovskite layer morphology. We observe that the Co-doping raises the interfacial recombination of the device but more importantly improves the perovskite morphology, enlarging grain size and reducing the density of bulk defects and the bulk recombination. In the case of 0.75 mol% of doping, the bene?cial e?ects do not just compensate for the deleterious one but increase performance further. Therefore, 0.75 mol% Co doping results in a signi?cant improvement in the performance of NiOx-based inverted planar perovskite solar cells, and represents a good compromise to synthesize, and deposit, the inorganic material at low temperature, without losing the performance, due to the strong impact on the structural properties of the perovskite. This work highlights the importance of the interface from two di?erent points of view, electrical and structural, recognizing the role of a low doping Co concentration, as a key to improve the inverted perovskite-based solar cells’ performance.
关键词： hole transport material,inverted planar perovskite solar cell,perovskite morphology,Co-doped NiOx,electrical conductivity
更新于2025-09-23 15:21:01
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Diastereoisomer-Induced Morphology Tunable Self-Assembled Organic Microcrystals of Conjugated Molecules for Ultraviolet Laser
摘要： Precisely controlling self-assembly behavior and micro/nanostructure morphology of conjugated materials is significant for constructing optoelectronic devices. Inspired by natural functional materials, molecular stereoisomerism strategy (MSS) is an effective and convenient means to tune their molecular arrangement and macroscopic property of conjugated materials. Herein, a supramolecular chiral difluorenols, 9,9′-diphenyl-9H,9′H-[2,2′-bifluorene]-9,9′-diol (DPFOH), is set as a desirable model to reveal the diastereomeric effects of conjugated molecules toward controlling the micro/nanostructure morphology and optoelectronic behavior for deep-blue organic laser. Two diastereomers, raceme (rac)- and mesomer (meso)-DPFOH, are obtained and unambiguously elucidated by X-ray crystallography. It is common sense to observe the slight diastereomeric effects on photophysical properties and electrochemical characteristics in solution or pristine film state for the isotropic phase. Interestingly, as a consequent of the disparate multi-dimensional intermolecular interaction, rac-DPFOH molecule can self-assemble into 1D rod-shaped but rectangular plate-shaped microcrystals for meso-DPFOH. Impressively, rac-DPFOH microrod presents a well-defined emission with an excellent ultraviolet microlasing behavior at 398 nm, whereas the 2D microplate of meso-DPFOH show a broad emission centered at 420 nm without gain processing. Therefore, MSS provides a new approach to design conjugated molecules and tune superstructure morphology for optoelectronic applications.
关键词： optical properties,tunable morphology,organic ultraviolet microlasers,diastereoisomer effect,microcrystals
更新于2025-09-23 15:21:01
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Laser fabrication of structural bone: surface morphology and biomineralization assessment
摘要： The current work explores the surface morphology of the laser-ablated bone using Yb-fiber coupled Nd:YAG laser (λ = 1064 nm) in continuous wave mode. As the laser-ablated region contains physiochemically modified carbonized and nonstructural region, it becomes unknown material for the body. Thus, biomineralization on such a laser-ablated region was assessed by in vitro immersion test in noncellular simulated body fluid. The presence of hydroxyapatite was detected in the precipitated mineral product using scanning electron microscopy equipped with energy dispersive spectroscopy, and X-ray diffraction analysis. The effect of varying laser parameters on distribution of surface morphology features was identified and its corresponding effect on biomineralization was studied.
关键词： Laser-bone interaction,Surface morphology,Finite element method (FEM) modeling,Laser ablation
更新于2025-09-23 15:21:01
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Stepped morphology on vicinal 3C- and 4H-SiC (0001) faces: A Kinetic Monte Carlo study
摘要： Stepped morphologies on vicinal 3C- and 4H-SiC (0001) surfaces with the miscut toward [1100] or [1120] directions have been studied with a three-dimensional kinetic Monte Carlo model. In the model, a three-dimensional lattice mesh was established based on the crystal lattice of 3C-and 4H-SiC to fix the positions of atoms and interatomic bonding. Periodic boundary conditions were applied in the lateral direction while helicoidal boundary conditions were used in the direction of crystal growth. Events, such as adatoms attachment, detachment and interlayer transport at the step edges, and adatoms adsorption and diffusion on the terraces were considered in the model. Effects of Ehrlich-Schwoebel barriers at downward step edges and incorporation barriers at upwards step edges were also considered. Moreover, the atoms of silicon and carbon were treated as the minimal diffusing species independently to achieve more elaborate information for the behavior of atoms in the crystal surface. The simulation results showed that multiple-height steps were formed on the vicinal 4H-SiC (0001) surfaces, whereas single bilayer-height stepped morphologies were observed on the vicinal 3C-SiC (0001) surfaces. Furthermore, zigzag shaped edges were observed for both of 3C- and 4H-SiC (0001) surfaces with the miscut toward [1120] direction. At last, the formation mechanism of the stepped morphology was also analyzed.
关键词： Computer simulation,Crystal morphology,Silicon Carbide,Surfaces,Kinetic Monte Carlo Model
更新于2025-09-23 15:21:01
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Chiral Helical Polymer Nanomaterials with Tunable Morphology: Prepared with Chiral Solvent To Induce Helix-Sense-Selective Precipitation Polymerization
摘要： We report an unprecedented strategy for using achiral monomer to construct chiral helical polymer nanomaterials with tunable morphology—helix-sense-selective precipitation polymerization induced by a chiral solvent (HSSPP-CS). CHCl3, chiral α-pinene, and an alkanol were employed to constitute a solvent mixture for performing HSSPP-CS. (R)- or (S)-α-pinene worked as chiral source and transferred its chirality to the resulting helical polyacetylenes derived from achiral monomer in the course of polymerization, thereby forming chiral helical polymers and endowing the nanomaterials thereof with optical activity. Simply changing solvent composition provided chiral polymer products varying in morphology from fibrous to rod-like and finally to spherical morphology. This is the first report dealing with chirality transfer from chiral solvent to induce helix-sense-selective precipitation polymerizations. The study establishes a straightforward and effective alternative for making use of achiral monomers to construct chiral helical polymer nanomaterials with diverse morphology.
关键词： tunable morphology,chiral solvent,achiral monomer,chiral helical polymer nanomaterials,helix-sense-selective precipitation polymerization
更新于2025-09-23 15:21:01
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Unraveling the Complex Nanomorphology of Ternary Organic Solar Cells with Multimodal Analytical Transmission Electron Microscopy
摘要： Elucidating the complex materials distribution in the active layers of ternary organic solar cells is one of the greatest challenges in the field of organic photovoltaics. Knowledge of the nanomorphology is key to understanding photophysical processes (e.g. charge separation, adjustment of the recombination mechanism as well as suppression of the radiationless and energetic losses) and thus improving the device performance. Here, we demonstrate for the first time the successful discrimination and spatial mapping of the active layer components of a ternary organic solar cell using analytical transmission electron microscopy. The material distribution of all three organic components was successfully visualized by multimodal imaging using complementary electron energy loss signals. A complete picture of the morphological aspects could be gained by studying the lateral and cross-sectional morphology as well as the morphology evolution as a function of the mixing ratio of the polymers. Finally, a correlation between the morphology, photophysical processes and device performance of the ternary and the reference binary system was achieved, explaining the differences of the power conversion efficiency (PCE) between the two systems.
关键词： device performance,EFTEM,morphology,TEM,Ternary organic solar cells
更新于2025-09-23 15:21:01
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Direct Electrochemical Preparation of Nanostructured Silicon Carbide and Its Nitridation Behavior
摘要： Silicon carbide was synthesized from mixtures of SiO2 and graphite by applying the concept of the FFC-Cambridge process and several fundamental aspects of the synthesis route were investigated. Porous disks composed of powders of SiO2 and graphite in molar ratios of 1:0.5, 1:1 and 1:1.5 were prepared by sintering in inert atmosphere and subjected to electro-deoxidation in molten CaCl2 at 1173 K under a range of experimental conditions. Disks of molar ratio 1:1.5, reduced at an applied voltage of 2.8 V for a duration of 6 h, yielded exclusively phase-pure SiC of nanowire morphology as the reaction product, while the other precursor compositions provided significant amounts of calcium silicides. Voltages lower than 2.8 V gave mixtures of SiC with elemental Si and graphite, and voltages higher than that gave CaSi alone. Shorter electro-deoxidation times led to incomplete reduction and allowed for the identification of CaSiO3 as a transient phase. Based on the experimental results a multipath reaction mechanism is proposed, consisting of the electrochemical reduction of SiO2 and CaSiO3 to Si and the subsequent in-situ carbonization of the Si formed to SiC. The effect of N2 at high temperature on the electrochemically synthesized SiC was investigated and the formation of nanowire Si2N2O was observed. Overall, the process presented is a facile single-step and low-temperature method for the synthesis of SiC with possible commercial prospects.
关键词： electro-deoxidation,Silicon carbide,Si2N2O,molten CaCl2,FFC-Cambridge process,nanowire morphology
更新于2025-09-23 15:21:01
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Modulation of donor alkyl terminal chains with shifting branching point leads to optimized morphology and efficient all-small-molecule organic solar cells
摘要： Terminal group modification is one of the most influential factors for small molecular donors compared with their polymer counterparts, resulting in an opportunity to optimize the morphology of all-small-molecule organic solar cells (ASM-OSCs). In this manuscript, we report three novel small molecular donors with branching points at the 1-, 2-, and 3-positions in alkyl terminal chains, called BSCl-C1, BSCl-C2 and BSCl-C3, respectively. Using IDIC-4Cl as acceptor, the subtle branching position shift achieves a dramatic disparity in photovoltaic parameters, as indicated by the short circuit current (Jsc) changing from 4.90 mA cm?2 to 20.1 mA cm?2 to 14.2 mA cm?2 and the fill factor varying from 33.9% to 71.3% to 67.0% for BSCl-C1, BSCl-C2, and BSCl-C3, respectively. The best device performance of 12.4% is obtained by the BSCl-C2:IDIC-4Cl system, which not only ranks among the top values reported to date, but also exhibits low energy loss in systems that use IDIC as acceptors. The notable device performance based on BSCl-C2 is attributed to the optimized phase morphology caused by the strong molecular crystallinity and suitable intermolecular interaction with IDIC-4Cl. These results demonstrate that suitably tuning the branching position of terminal groups could promote the high performance of ASM-OSCs.
关键词： branching point,phase morphology,crystallinity,intermolecular interaction,all-small-molecule
更新于2025-09-23 15:21:01