Publications by authors named "Schwartzkopf M"

Article Synopsis
  • Mesoporous titania thin films have potential applications in various fields such as sensors, batteries, and solar cells, but traditional methods of creating these films often require high temperatures that can damage the structures.
  • A new approach using UV irradiation is presented as a low-temperature, energy-efficient alternative that achieves comparable crystallinity and size to conventional methods, without the drawbacks of high-temperature calcination.
  • This UV method allows for the creation of diverse film morphologies and maintains consistent optical properties, demonstrating its adaptability with different titanium precursors for thin film fabrication.
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Ternary hybrid thin films composed of a diblock copolymer templating two types of nanoparticles (NPs) expand the functionality of binary systems, which renders them interesting for magnetic sensing or magnetic data storage applications. Herein, one-pot slot-die printed hybrid polystyrene--poly(methyl methacrylate) (PS--PMMA) thin films are prepared with iron oxide (magnetite, FeO, = 20 nm) and nickel NPs (Ni, = 46 nm) in one step by the advanced slot-die coating technique, which facilitates upscaling of fabrication. The evolution of the hybrid film morphology is probed with in situ grazing-incidence small-angle X-ray scattering and compared to that of a PS--PMMA thin film without NPs.

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  • - The study investigates defects in carbon fiber-reinforced polymers (CFRPs) after low-velocity impacts using X-ray techniques, noting that practical monitoring in the field is challenging.
  • - The research identifies and categorizes defects ranging from 1 nm to 1 mm, correlating these with material properties like fiber orientation and density, using machine learning to analyze the data.
  • - Three damage domains are found: severe damage with visible dents, intact areas with no defects, and transition zones with detectable defects, highlighting the relationship between parameters from different measurement techniques.
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Introducing metallic nanoparticles, such as Au, on a substrate as a surfactant or wetting inducer has been demonstrated as a simple but effective way to facilitate the formation of ultra-thin silver layers (UTSLs) during the subsequent Ag deposition. However, most studies have paid much attention to the applications of UTSLs assisted by metallic surfactants but neglected the underlying mechanisms of how the metallic surfactant affects the formation of UTSL. Herein, we have applied grazing-incidence wide-/small-angle X-ray scattering to reveal the effects of the Au surfactant or seed layer (pre-deposited Au nanoparticles) on the formation of UTSL by high-power impulse magnetron sputter deposition (HiPIMS) on a zinc oxide (ZnO) thin film.

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Plasmons have facilitated diverse analytical applications due to the boosting signal detectability by hot spots. In practical applications, it is crucial to fabricate straightforward, large-scale, and reproducible plasmonic substrates. Dewetting treatment, applying direct thermal annealing of metal films, has been used as a straightforward method in the fabrication of such plasmonic nanostructures.

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Titanium dioxide (TiO) shows significant potential as a self-cleaning material to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and prevent virus transmission. This study provides insights into the impact of UV-A light on the photocatalytic inactivation of adsorbed SARS-CoV-2 virus-like particles (VLPs) on a TiO surface at the molecular and atomic levels. X-ray photoelectron spectroscopy, combined with density functional theory calculations, reveals that spike proteins can adsorb on TiO predominantly via their amine and amide functional groups in their amino acids blocks.

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  • Poly(ethylene oxide) (PEO)-based composite electrolytes (PCEs) are important for making safer and better lithium-metal batteries.
  • Researchers used special X-ray techniques to study how these PCEs change when used in batteries, focusing on their structure and arrangement.
  • They found that certain chemical reactions change the structure of the PCE, and that lithium movement inside the battery affects the size and distance of certain areas in the material, helping to improve battery performance.
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Multimodal in situ experiments during slot-die coating of thin films pioneer the way to kinetic studies on thin-film formation. They establish a powerful tool to understand and optimize the formation and properties of thin-film devices, e.g.

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Multilayer neutron optics require precise control of interface morphology for optimal performance. In this work, we investigate the effects of different growth conditions on the interface morphology of Ni/Ti-based multilayers, with a focus on incorporating low-neutron-absorbing BC and using different ion assistance schemes. Grazing-incidence small-angle X-ray scattering was used to probe the structural and morphological details of buried interfaces, revealing that the layers become more strongly correlated and the interfaces form mounds with increasing amounts of BC.

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The utilization of polarized neutrons is of great importance in scientific disciplines spanning materials science, physics, biology, and chemistry. However, state-of-the-art multilayer polarizing neutron optics have limitations, particularly low specular reflectivity and polarization at higher scattering vectors/angles, and the requirement of high external magnetic fields to saturate the polarizer magnetization. Here, we show that, by incorporating BC into Fe/Si multilayers, amorphization and smooth interfaces can be achieved, yielding higher neutron reflectivity, less diffuse scattering, and higher polarization.

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Humidity sensors play a critical role in monitoring human activities, environmental health, food processing and storage, and many other fields. Recently, some 2D materials, particularly MXenes, have been considered as promising candidates for creating humidity sensors because of their high surface area, surface-to-bulk ratio, and excellent conductivity, arising from the high concentration and mobility of free electrons. In this work, we propose the plasmon-assisted surface modification and termination tuning of common MXene (TiCT) to enhance their response to humidity and increase their stability against oxidation.

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Article Synopsis
  • The study addresses the ongoing issue of replicability in perovskite solar cells (PSCs) due to trace impurities, particularly focusing on the effects of water contamination in lead iodide (PbI).
  • Researchers discovered that while adding water accelerates crystallization during film formation, it also causes imbalances in charge-carrier mobility, negatively affecting device performance.
  • The findings highlight that using anhydrous PbI enhances film growth and stability, leading to a high power conversion efficiency of 24.3%, emphasizing the need for careful water content management in PSC production.
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Solution processing of hybrid perovskite semiconductors is a highly promising approach for the fabrication of cost-effective electronic and optoelectronic devices. However, challenges with this approach lie in overcoming the controllability of the perovskite film morphology and the reproducibility of device efficiencies. Here, a facile and practical aging treatment (AT) strategy is reported to modulate the perovskite crystal growth to produce sufficiently high-quality perovskite thin films with improved homogeneity and full-coverage morphology.

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While gold nanoparticles (Au NPs) are widely used as surface-enhanced Raman spectroscopy (SERS) substrates, their agglomeration and dynamic movement under laser irradiation result in the major drawback in SERS applications, viz., the repeatability of SERS signals. We tune the optical and structural properties of size- and shape-modified Au NPs embedded in a thin silicon nitride (SiN) matrix by intense electronic excitation with swift heavy ion (SHI) irradiation with the aim of overcoming this classical SERS disadvantage.

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Thermal growth kinetics of embedded bimetallic (AuAg/SiO) nanoparticles are explored and compared with their monometallic (Au/SiO and Ag/SiO) counterparts, as their practical applicability demands stability and uniformity. The plasmonic properties of these nanoparticles (NPs) significantly improve when their size falls in the ultra-small region (diameter < 10 nm), owing to their large active surface area. Interestingly, the bimetallic NPs exhibit better optical properties and structural stability as compared to their monometallic counterparts.

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One of the major limitations of flexible sensors is the loss of conductivity upon multiple stretching and bending cycles. Conducting fillers with two different geometries, carbon black and carbon nanotubes, were introduced in polydimethylsiloxane (PDMS) for physical insights into the structure formation of nanofillers by the application of periodic tensile stress. The loading of the nanofillers was selected beyond the percolation threshold to determine the cyclic stability of the resulting network channels.

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Article Synopsis
  • A quantum dot film on a flexible substrate undergoes a phase transition from tetragonal to cubic and back to tetragonal as uniaxial strain is applied, which is observed using grazing-incidence small-angle X-ray scattering (GISAXS).
  • Changes in optoelectronic properties, indicated by photoluminescence (PL) measurements, correlate with the phase transitions and involve variations in inter-dot distances.
  • The study highlights the importance of understanding strain effects on quantum dot films for advancing flexible electronics and solar technologies.
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Ultrasmall nanoparticles (NPs) with a high active surface area are essential for optoelectronic and photovoltaic applications. However, the structural stability and sustainability of these ultrasmall NPs at higher temperatures remain a critical problem. Here, we have synthesized the nanocomposites (NCs) of Ag NPs inside the silica matrix using the atom beam co-sputtering technique.

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Fabrication of ultra-thin gold (Au) layers (UTGLs) has been regarded as the key technique to achieve applications with tunable optical response, flexible sensors and electronic devices. Various strategies have been developed to optimize the wetting process of Au, resulting in the formation of UTGLs at a minimum thickness. The related studies on UTGLs attracted huge attention in recent years.

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  • * To overcome these limitations, a new innovative process-aid solid (PAS) engineering approach is introduced, using an asymmetric 1,3-dibromo-5-chlorobenzene solid that improves dipole direction and interlaminar interactions.
  • * The implementation of PAS leads to better exciton splitting, charge transport, and reduced recombination losses, achieving a fill factor of 80.2% and a maximum power conversion efficiency (PCE) of 18.5%, with record efficiency for thick-film devices
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Natural high-performance materials have inspired the exploration of novel materials from protein building blocks. The ability of proteins to self-organize into amyloid-like nanofibrils has opened an avenue to new materials by hierarchical assembly processes. As the mechanisms by which proteins form nanofibrils are becoming clear, the challenge now is to understand how the nanofibrils can be designed to form larger structures with defined order.

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  • - The study explores how crystal orientations impact the behavior of charge carriers in perovskite solar cells, highlighting the importance of these orientations for optimizing their optoelectronic properties.
  • - Researchers used CsBr-doped mixed cation perovskite phases and advanced X-ray scattering to analyze how doping affected the arrangement of crystal lattice planes and the subsequent charge carrier dynamics.
  • - Results indicate that modifying the composition with CsBr can enhance the solar cell performance by improving the crystal structure, reducing trap states, and facilitating better transport of charge carriers.
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Mesoporous hematite (α-FeO) thin films with high surface-to-volume ratios show great potential as photoelectrodes or electrochemical electrodes in energy conversion and storage. In the present work, with the assistance of an up-scalable slot-die coating technique, locally highly ordered α-FeO thin films are successfully printed based on the amphiphilic diblock copolymer poly(styrene--4-vinylpyridine) (PS--P4VP) as a structure-directing agent. Pure PS--P4VP films are printed under the same conditions for comparison.

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Large-scale fabrication of metal cluster layers for usage in sensor applications and photovoltaics is a huge challenge. Physical vapor deposition offers large-scale fabrication of metal cluster layers on templates and polymer surfaces. In the case of aluminum (Al), only little is known about the formation and interaction of Al clusters during sputter deposition.

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