Lucas P. Kreuzer

Lucas P. Kreuzer
German Aerospace Center (DLR) | DLR · Institute of Material Physics in Space

Doctor of Philosophy

About

41
Publications
5,210
Reads
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465
Citations
Citations since 2016
41 Research Items
464 Citations
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2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
Introduction
During my PhD, I investigated the behavior of multi-responsive polymer thin films (mainly with neutron scattering). Currently, I am studying the relationship of dynamics and structure in liquid metal alloys (sometimes in µ-gravity environment). My research aims to develop improved alloys for lightweight constructions. In addition, the experimentally obtained data contributes to the generation of advanced algorithms that are used in simulations of complex multicomponent systems.

Publications

Publications (41)
Article
The water swelling and subsequent solvent exchange including co-nonsolvency behavior of thin films of a doubly thermo-responsive diblock copolymer (DBC) are studied via spectral reflectance, time-of-flight neutron reflectometry, and Fourier transform infrared spectroscopy. The DBC consists of a thermo-responsive zwitterionic (poly(4-((3-methacrylam...
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Peter Müller-Buschbaum and co-workers show in their article number 2100191 that ternary nanoswitches can be realized when combining multi-responsive block copolymer films with mixed vapor atmospheres. The combination of amphiphilicity and the co-nonsolvency effect is used to prepare three distinctly different film thicknesses as analyzed with neutr...
Article
The water vapor-induced swelling, as well as subsequent phase-transition kinetics, of thin films of a diblock copolymer (DBC) loaded with different amounts of the salt NaBr, is investigated in situ. In dilute aqueous solution, the DBC features an orthogonally thermoresponsive behavior. It consists of a zwitterionic poly(sulfobetaine) block, namely,...
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The structure degradation process of a PbS quantum dot-ink based solar cell is investigated during the device operation with advanced X-ray scattering methods and a spontaneous decrease of the quantum dot inter-dot distance is observed with an increase in the spatial disorder in the active layer. These findings elucidate the origin of light-soaking...
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The European Spallation Source (ESS), which is under construction in Lund (Sweden), will be the leading and most brilliant neutron source and aims at starting user operation at the end of 2023. Among others, two small angle neutron scattering (SANS) machines will be operated. Due to the high brilliance of the source, it is important to minimize the...
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In times where research focuses on the use of organic polymers as a base for complex organic electronic applications and improving device efficiencies, degradation is still less intensively addressed in fundamental studies. Hence, advanced neutron scattering methods are applied to investigate a model system for organic electronics composed of the w...
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To systematically add functionality to nanoscale polymer switches, an understanding of their responsive behavior is crucial. Herein, solvent vapor stimuli are applied to thin films of a diblock copolymer consisting of a short poly(methyl methacrylate) (PMMA) block and a long poly(N‐isopropylmethacrylamide) (PNIPMAM) block for realizing ternary nano...
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The FlexiProb project is a joint effort of three soft matter groups at the Universities of Bielefeld, Darmstadt, and Munich with scientific support from the European Spallation Source (ESS), the small-K advanced diffractometer (SKADI) beamline development group of the Jülich Centre for Neutron Science (JCNS), and the Heinz Maier-Leibnitz Zentrum (M...
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As part of the development of the new European Spallation Source (ESS) in Lund (Sweden), which will provide the most brilliant neutron beams worldwide, it is necessary to provide different sample environments with which the potential of the new source can be exploited as soon as possible from the start of operation. The overarching goal of the proj...
Article
A long-range order shifting to a short-range order of the QDs is found at the burn-in stage of solar cell.
Article
We demonstrate that the cononsolvency effect strongly affects the responsive behavior of PMMA-b-PNIPAM films in the polymer-rich part of the phase diagram. Thin films equilibrated in water vapor show a swelling and contraction at the exchange of the surrounding atmosphere to mixed vapor of water and methanol. The film kinetics are investigated in-s...
Article
Abnormal fast dehydration and rehydration of light- and thermo- dual-responsive copolymer films of poly(oligo(ethylene glycol) methyl ether methacrylate-co-6-(4-phenylazophenoxy)hexyl acrylate), abbreviated as P(OEGMA300-co-PAHA), are triggered by UV radiation. Both rapid kinetic processes are probed by in-situ neutron reflectivity (NR). The transi...
Article
Spray deposition is a scalable and cost-effective technique for the fabrication of magnetic hybrid films containing diblock copolymers (DBCs) and magnetic nanoparticles. However, it is challenging to obtain spray-deposited anisotropic magnetic hybrid films without using external magnetic fields. In the present work, spray deposition is applied to p...
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Perovskite solar cells (PSCs) have been developed as a promising photovoltaic technology because of their excellent photovoltaic performance. However, interfacial recombination and charge carrier transport losses at the surface greatly limit the performance and stability of PSCs. In this work, the fabrication of high-quality PSCs based on methylamm...
Article
The cyclic swelling and collapse behavior of a doubly thermoresponsive diblock copolymer thin film, consisting of a zwitterionic poly(sulfobetaine), poly(N,N-dimethyl-N-(3-methacrylamidopropyl)-ammoniopropane sulfonate) (PSPP), and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block, is investigated in situ at three characteristic temperatur...
Article
In neutron scattering on soft matter, an important concern is the control and stability of environmental conditions surrounding the sample. Complex sample environment setups are often expensive to fabricate or simply not achievable by conventional workshop manufacturing. We make use of state-of-the-art 3D metal-printing technology to realize a samp...
Article
Nanostructured Ge is considered a highly promising material for Li-ion battery applications as Ge offers high specific capacity and Li-ion diffusivity, while inherent mesoporous nanostructures can contribute resistance against capacity fading as typically induced by high volume expansion in bulk Ge films. Mesoporous GeO x /Ge/C films are synthesize...
Article
For PbS quantum dots (QDs) based optoelectronic devices, gold is the most frequently used electrode material. In most device architectures gold is in direct contact with the QD solid. To better understand the formation of the interface between gold and a close-packed QD layer at an early stage, in situ grazing-incidence small-angle X-ray scattering...
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Colloidal PbS quantum dots (QDs) are promising candidates for various optoelectronic applications based on solution-processed thin-film techniques. In this work, a versatile layer-by-layer (LBL) spray deposition of the QDs is introduced aiming for a future large-scale fabrication process of optoelectronic devices. As compared to spin-coated QD soli...
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Efficient infiltration of a mesoporous titania matrix with conducting organic polymers or small molecules is one key challenge to overcome for hybrid photovoltaic devices. A quantitative analysis of the backfilling efficiency with time-of-flight grazing incidence small-angle neutron scattering (ToF-GISANS) and scanning electron microscopy (SEM) mea...
Article
The orientation of block copolymer (BCP) features in thin films can be obtained by spin-coating a BCP solution on a substrate surface functionalized by a polymer brush layer of the appropriate random copolymer (RCP). Although this approach is well-established, little work reporting the amount and the distribution of residual solvent in the polymer...
Article
The investigation of the response kinetics of smart colloidal microgel films is crucial for their optimization to enable advanced applications. We study the classical thermo-responsive microgel model system N-isopropylacrylamide (NIPAM) cross-linked with N,N’-methylenebisacrylamide (BIS). Without the typically used polyelectrolyte coating of the su...
Article
Tailoring optical and electronic properties of nanostructured polymer-metal-composites demonstrates great potential for an efficient fabrication of modern organic optical and electronic devices such as flexible sensors, transistors, diodes or photovoltaics. Self-assembled polymer-metal-nanocomposites offer an excellent perspective for creating hier...
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Many nanoscale biopolymer building blocks with defect-free molecular structure and exceptional mechanical properties have the potential to surpass the performance of existing fossil-based materials with respect to barrier properties, load-bearing substrates for advanced functionalities, as well as light-weight construction. Comprehension and contro...
Article
The humidity-induced swelling and exchange behavior of a block copolymer thin film, which consists of a zwitterionic poly(sulfobetaine) [poly(N,N-dimethyl-N-(3-(methacrylamido)propyl)ammoniopropanesulfonate) (PSPP)] block and a nonionic poly(N-isopropylacrylamide) (PNIPAM) block, are investigated by time-of-flight neutron reflectometry (TOF-NR). We...
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The ligand exchange process is a key step in fabrications of quantum dot (QD) optoelectronic devices. In this work, based on grazing incidence X-ray scattering techniques, we find that the ligand exchange process with halide ions changes the PbS QD superlattice from a face-centered cubic to body-centered cubic stacking, while the QD crystal lattice...
Article
Hybrid films of zinc oxide (ZnO) and poly(3-hexylthiophen-2,5-diyl) (P3HT) show promising characteristics for application in hybrid bulk heterojunction solar cells (HBSCs). However, the incompatibility of ZnO and P3HT may lead to a reduced interface area, thus reducing the probability of exciton separation and consequently lowering solar cells effi...
Article
Mesoporous ZnO films with large surface-area-to-volume-ratio show great promise in multiple applications, among which solid-state dye-sensitized solar cells (ssDSSCs) have attracted great attention in the field of photovoltaics. An appropriate mesopore size in the nanostructured ZnO films significantly plays an indispensable role in improving the d...
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Polysulfobetaines in aqueous solution show upper critical solution temperature (UCST) behavior. We investigate here the representative of this class of materials, poly (N,N-dimethyl-N-(3-methacrylamidopropyl) ammonio propane sulfonate) (PSPP), with respect to: (i) the dynamics in aqueous solution above the cloud point as function of NaBr concentrat...
Article
Polymer electrodes made of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) are used in many applications but are also sensitive to humidity. We study humidity induced changes of PEDOT:PSS electrodes as monitored with in situ time-of-flight neutron reflectivity (TOF-NR) measurements under high humidity conditions. The influence of...
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Enzyme-catalyzed controlled radical polymerization represents a powerful approach for the polymerization of a wide variety of water-soluble monomers. However, in such an enzyme-based polymerization system, the macromolecular catalyst (i.e., enzyme) has to be separated from the polymer product. Here, we present a compelling approach for the separati...
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In this work we show that different enzymes, such as horseradish peroxidase, glucose oxidase, laccase and catalase, can be directly immobilized onto plasmonic gold nanoparticles (NPs) and superparamagnetic iron oxide NPs simply via unspecific physical adsorption, yielding catalytically active and colloidally stable NP systems. The enzyme coating on...

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Projects

Projects (2)
Project
The FlexiProb project aims for a flexible and quickly interchangeable sample carrier system for small-angle neutron scattering (SANS) at the ESS beamlines SKADI and LOKI. In order to reduce downtimes of the instruments, three different sample environment systems are designed by soft matter groups at the University of Bielefeld, Darmstadt, and Munich, which share an identical base framework. This enables a fast plug-and-play exchange mechanism between the setups.
Project
We aim for a fundamental understanding of how external stimuli, including temperature, light, the composition of surrounding vapor, and salt additives, affect the behavior of polymer thin films. Mesoscopic parameters, e.g., film thickness and incorporated solvent content, and the thin film morphology are probed with neutron scattering techniques, while FTIR provides molecular information about polymer-polymer and polymer-solvent interactions.