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Site-controlled formation of single Si nanocrystals in a buried SiO <sub/>2</sub> matrix using ion beam mixing
摘要： For future nanoelectronic devices – such as room-temperature single electron transistors – the site-controlled formation of single Si nanocrystals (NCs) is a crucial prerequisite. Here, we report an approach to fabricate single Si NCs via medium-energy Si+ or Ne+ ion beam mixing of Si into a buried SiO2 layer followed by thermally activated phase separation. Binary collision approximation and kinetic Monte Carlo methods are conducted to gain atomistic insight into the influence of relevant experimental parameters on the Si NC formation process. Energy-filtered transmission electron microscopy is performed to obtain quantitative values on the Si NC size and distribution in dependence of the layer stack geometry, ion fluence and thermal budget. Employing a focused Ne+ beam from a helium ion microscope, we demonstrate site-controlled self-assembly of single Si NCs. Line irradiation with a fluence of 3000 Ne+/nm2 and a line width of 4 nm leads to the formation of a chain of Si NCs, and a single NC with 2.2 nm diameter is subsequently isolated and visualized in a few nanometer thin lamella prepared by a focused ion beam (FIB). The Si NC is centered between the SiO2 layers and perpendicular to the incident Ne+ beam.
关键词： phase separation,Monte Carlo simulations,single electron transistor,ion beam mixing,helium ion microscopy
更新于2025-11-21 11:20:48
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[IEEE 2018 Eleventh International Conference "Management of large-scale system development" (MLSD 2018) - Moscow (2018.10.1-2018.10.3)] 2018 Eleventh International Conference "Management of large-scale system development" (MLSD - Optimization of the Structure and Parameters of the Light Cycle Aimed at Improving Traffic Safety at an Intersection
摘要： Formulas for evaluating structural safety for an arbitrary scheme of the road network segment are proposed. On their basis the problem of structural optimization of the traffic light cycle aimed at improving traffic safety is set. The similar optimization problem with respect to traffic intensity is set as well. Approaches to their solution are offered.
关键词： scheme of phase separation,microscopic models of traffic flows,optimization,safety of the road network segment,controlled intersection,computational experiments
更新于2025-09-23 15:22:29
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Sharp phase-separated interface of 6,13-bis(triisopropylsilylethynyl) pentacene/polystyrene blend films prepared by electrostatic spray deposition
摘要： In this study, organic field-effect transistors (OFETs) based on blend films comprising 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) and polystyrene (PS) were fabricated. The blend films were prepared by electrostatic spray deposition (ESD). A vertically phase-separated structure (TIPS pentacene (top)/PS (bottom)) can be spontaneously formed without additional treatments such as solvent-vapor annealing, which is significantly different from the blend with poly(methyl methacrylate) (PMMA). Due to the sharp phase-separated interface, OFETs based on the TIPS pentacene/PS blend films exhibited superior characteristics and operational stability.
关键词： Organic field-effect transistor,Small molecule/polymer blend,Electrostatic spray deposition,Vertical phase separation
更新于2025-09-23 15:22:29
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Formation of Polymer Wall Structure on Plastic Substrate by Transfer Method of Fluororesin for Flexible Liquid Crystal Displays
摘要： In this paper, we examined the transfer method of fluororesin as the novel formation method of polymer wall in order to realize the lattice-shaped polymer walls without patterned light irradiation using photomask. We clarified that the transfer method was effective for formation of polymer wall structure on flexible substrate.
关键词： silicone elastomer,phase separation,fluororesin,plastic substrate,polymer wall
更新于2025-09-23 15:22:29
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Self-structuring in Zr1?xAlxN films as a function of composition and growth temperature
摘要： Nanostructure formation via surface-diffusion-mediated segregation of ZrN and AlN in Zr1?xAlxN films during high mobility growth conditions is investigated for 0 ≤ × ≤ 1. The large immiscibility combined with interfacial surface and strain energy balance resulted in a hard nanolabyrinthine lamellar structure with well-defined (semi) coherent c-ZrN and w-AlN domains of sub-nm to ~4 nm in 0.2 ≤ × ≤ 0.4 films, as controlled by atom mobility. For high AlN contents (x > 0.49) Al-rich ZrN domains attain wurtzite structure within fine equiaxed nanocomposite wurtzite lattice. Slow diffusion in wurtzite films points towards crystal structure dependent driving force for decomposition. The findings of unlikelihood of iso-structural decomposition in c-Zr1?xAlxN, and stability of w-Zr1?xAlxN (in large × films) is complemented with first principles calculations.
关键词： phase separation,nanostructure,thin films,self-organization,ZrAlN
更新于2025-09-23 15:21:21
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Ideal alloys of two donor isomers with non-covalently conformational locking for ternary organic solar cells
摘要： Ternary organic solar cells (OSCs) based on the alloy model have great potential in maximizing the improvement of device performance due to the probability of simultaneously enhancing the photocurrent through morphology optimization and improving open circuit voltage (Voc) by energy level adjustment. However, rationally designing compatible materials and constructing an effective alloy remain difficult. In this manuscript, two donor isomers, BT-TO-ID and BT-OT-ID with non-covalently conformational locking of alkoxy groups at different position, were designed and synthesized to obtain an ‘‘ideal alloy’’. A linearly tunable Voc was observed between the Voc limitation of binary blends with the changes of the composition across the full range, indicating the behavior of an ideal alloy in the ternary blends. A face-on molecular packing and an appropriate phase separation was observed in the ternary blends due to the strong interactions between the two isomers, which facilitated charge transport and charge recombination suppression. Notable improvements of 76% and 29% in device performance were obtained for the ternary blends compared with BT-OT-ID based and BT-OT-ID based binary devices, respectively. Therefore, this work provided a probable molecular design strategy to guide the construction of an effective alloy in ternary OSCs.
关键词： Open circuit voltage,Non-covalently conformational locking,Alloy model,Device performance,Molecular packing,Phase separation,Ternary organic solar cells,Donor isomers
更新于2025-09-23 15:21:01
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A molecular dynamics approach to nanostructuring of particles produced via aerosol cationic photopolymerization
摘要： Structuring of particles obtained by aerosol photopolymerization is here described from both the experimental and the simulation point of view. Transport phenomena occurring within aerosol droplets are studied in order to identify the key issues that must be carefully designed when considering particles structuring. In particular, phase separation and diffusion of the reacting species were evaluated using molecular dynamics simulations, allowing the identification of a series of formulation parameters such as the composition of a mixed solvent (hexadecane and 2-octanone) or the addition of a chain transfer reagent, which are crucial for the control of phase separation and, thus, of the final morphology of the microparticles. The results were compared with morphology analyses obtained from the experimental work. We also found that molecular simulations were useful for the decoupling of the effects of different solvents which were thus treated separately. The interplay between phase separation and gelation rates was also found to be crucial in the structuring process. For example, the ratio between hexadecane and a chain transfer reagent seemed to strongly affect the final morphology of micro-particles.
关键词： Photopolymerization,Nanoparticles,Nano-structuring,Phase separation,Molecular dynamics
更新于2025-09-23 15:21:01
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Appropriate Molecular Interaction Enabling Perfect Balance Between Induced Crystallinity and Phase Separation for Efficient Photovoltaic Blends
摘要： Fluorination is a promising modification method to adjust the photophysical profiles of organic semiconductors. Notably, the fluorine modification on donor or acceptor materials could impact the molecular interaction, which is strongly related to the morphology of bulk heterojunction (BHJ) blends and the resultant device performance. Therefore, it’s essential to investigate how the molecular interaction affect the morphology of BHJ films. In this study, a new fluorinated polymer PBDB-PSF is synthesized to investigate the molecular interaction in both nonfluorinated (ITIC) and fluorinated (IT-4F) systems. The results reveal that the F-F interaction in PBDB-PSF:IT-4F system could effectively induce the crystallization of IT-4F while retaining ideal phase separation scale, resulting in outstanding charge transport. On the contrary, poor morphology can be observed in PBDB-PSF:ITIC system due to the unbalanced molecular interaction. As a consequence, the PBDB-PSF:IT-4F device delivers an excellent PCE of 13.63%, which greatly exceeds PBDB-PSF:ITIC device (9.84%). These results highlight manipulating the micromorphology in regard of molecular interaction.
关键词： induced crystalline,molecular interaction,phase separation,fluorination,synergistic effect
更新于2025-09-23 15:21:01
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Application of Atom Probe Tomography to Complex Microstructures of Laser Additively Manufactured Samples
摘要： Additive Manufacturing (AM) technologies have gained increasing interest across multiple industrial sectors ranging from biomedical to aerospace. AM is not only used for prototyping, but also for tooling as well as for final part production. The computer-controlled, layer-by-layer building up process allows for increased design freedom enabling to produce almost any shape. Additional benefits are potential resource efficiency, increased product customization and lightweight design. Two prominent metal-based laser AM (LAM) techniques are laser powder bed fusion (LPBF) and laser metal deposition (LMD). In LPBF, a focused laser beam is scanned over a bed filled with metal powder to locally melt and fuse the powder to produce fully dense metal parts. The next layer of powder is then distributed and the laser scans again. LMD is a nozzle-based AM process in which a focused laser beam creates a melt pool in the build’s surface. Metallic powder is then injected into the melt pool through a nozzle. The 3D part is built by moving the nozzle/laser assembly forward track by track and layer by layer. Material produced by LAM exhibits a unique thermal history: initially, the material is cooled rapidly from the liquid state in the meltpool. Subsequently, the material experiences a cyclic reheating, the so-called intrinsic heat treatment (IHT), as neighboring tracks and further layers are deposited during the LAM process. Consequences of this thermal history are very complex, sometimes hierarchical microstructures with inhomogeneities at scales ranging from nanometers up millimeters. Fully understanding and characterizing these microstructures is challenging and requires the combination of methods spanning a similar range: from light optical microscopy (LOM) to electron microscopy to atom probe tomography (APT). Here we present examples how APT can deliver valuable information on complex microstructures to better understand the IHT, rapid solidification as well as phase separation in different metallic alloys. Here I will discuss examples in steel, Al- and Ni-based superalloys, and high entropy alloys (HEA).
关键词： Laser Additive Manufacturing,Additive Manufacturing,Phase Separation,Microstructures,Atom Probe Tomography,Rapid Solidification,Intrinsic Heat Treatment
更新于2025-09-23 15:19:57
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Molecular Stacking Effect on Small-Molecular Organic Light-Emitting Diodes Prepared with Solution Process
摘要： The light emitting layer (EML) is generally prepared by mixing host and dopant to realize organic light emitting diode (OLED). However, phase separation is often observed during the fabrication process to prepare OLEDs depending on the structure of the host materials. In particular, phase separation due to π-π stacking is frequently observed during thermal annealing for the solution process. The annealing process is required for solvent removal and complete relaxation of the molecule. Hence, the materials with a high glass transition temperature (Tg) are ideal because phase separation occurs due to π-π stacking during annealing process if Tg is too low. To understand this phenomenon, we compared two host materials with similar molecular weights but different three-dimensional connectivity, which causes different rotational freedom. Then, we investigated the effect on the device properties depending on the annealing conditions. In both materials, when the annealing temperature rises above 120 °C, the dopant completely escaped from the EML. However, the material that does not disturb the molecular stacking order by annealing due to its limited free rotation through internal bond shows much better device characteristics even after annealing at a higher temperature than Tg. The results show that interdiffusion at the interface and unstable internal density distribution with annealing temperature are responsible for the device degradation behavior.
关键词： X-ray reflectivity,Depth profile,Free volume,Phase separation,Segmental motion,Small molecule,Solution process
更新于2025-09-23 15:19:57