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  • 1.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. DESY, Photon Sci, Hamburg, Germany.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ohm, Wiebke
    DESY, Photon Sci, Hamburg, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. DESY, Photon Sci, Hamburg, Germany..
    In situ self-assembly study in bio-based thin films2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 2. Chang, B.
    et al.
    Schneider, K.
    Patil, N.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. DESY, Hamburg, Germany.
    Heinrich, G.
    Microstructure characterization in a single isotactic polypropylene spherulite by synchrotron microfocus wide angle X-ray scattering2018In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 142, p. 387-393Article in journal (Refereed)
    Abstract [en]

    Position-resolved microstructure in a single spherulite of iPP is quantitatively studied by synchrotron microfocus wide angle X-ray scattering. The results show that the normal of mother lamellae in a spherulite is aligned mainly perpendicular to the radius, and the subsidiary daughter lamellae are inclined 80.75° with respect to that of the dominant mother lamellae. The crystallinity in the spherulite is in the range of 46%–56%, which is rarely influenced by the crystallization temperature. The ratio between the daughter lamellae and the mother lamellae is 0.18 when iPP crystallizes at 138 °C and it decreases to 0.11 as the crystallization temperature is decreased to 130 °C. The b-axis and c-axis in the mother lamellae tend to orient perpendicular to the radius direction, and the a-axis prefers to align in the radius direction.

  • 3.
    Chang, Baobao
    et al.
    Leibniz Inst Polymer Res Dresden, Dresden, Germany.;Tech Univ Dresden, Inst Werkstoffwissensch, Dresden, Germany..
    Schneider, Konrad
    Leibniz Inst Polymer Res Dresden, Dresden, Germany..
    Patil, Nilesh
    Leibniz Inst Polymer Res Dresden, Dresden, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. DESY, Hamburg, Germany.
    Heinrich, Gert
    Leibniz Inst Polymer Res Dresden, Dresden, Germany.;Tech Univ Dresden, Inst Text Maschinen & Text Hochleistungswerkstof, Dresden, Germany..
    Microstructure characterization in a single isotactic polypropylene spherulite by synchrotron microfocus wide angle X-ray scattering2018In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 142, p. 387-393Article in journal (Refereed)
    Abstract [en]

    Position-resolved microstructure in a single spherulite of iPP is quantitatively studied by synchrotron microfocus wide angle X-ray scattering. The results show that the normal of mother lamellae in a spherulite is aligned mainly perpendicular to the radius, and the subsidiary daughter lamellae are inclined 80.75 degrees with respect to that of the dominant mother lamellae. The crystallinity in the spherulite is in the range of 46%-56%, which is rarely influenced by the crystallization temperature. The ratio between the daughter lamellae and the mother lamellae is 0.18 when iPP crystallizes at 138 degrees C and it decreases to 0.11 as the crystallization temperature is decreased to 130 degrees C. The b-axis and c-axis in the mother lamellae tend to orient perpendicular to the radius direction, and the a-axis prefers to align in the radius direction.

  • 4. Dev, A. S.
    et al.
    Kumar, D.
    Potdar, S.
    Pandit, P.
    Roth, Stephan Volkher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Photon Science, DESY, Notkestrasse 85, Hamburg, Germany.
    Gupta, A.
    Portable mini-chamber for temperature dependent studies using small angle and wide angle x-ray scattering2018In: DAE Solid State Physics Symposium 2017, American Institute of Physics (AIP), 2018, Vol. 1942, article id 080057Conference paper (Refereed)
    Abstract [en]

    The present work describes the design and performance of a vacuum compatible portable mini chamber for temperature dependent GISAXS and GIWAXS studies of thin films and multilayer structures. The water cooled body of the chamber allows sample annealing up to 900 K using ultra high vacuum compatible (UHV) pyrolytic boron nitride heater, thus making it possible to study the temperature dependent evolution of structure and morphology of two-dimensional nanostructured materials. Due to its light weight and small size, the chamber is portable and can be accommodated at synchrotron facilities worldwide. A systematic illustration of the versatility of the chamber has been demonstrated at beamline P03, PETRA-III, DESY, Hamburg, Germany. Temperature dependent grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) measurements were performed on oblique angle deposited Co/Ag multilayer structure, which jointly revealed that the surface diffusion in Co columns in Co/Ag multilayer enhances by increasing temperature from RT to ∼573 K. This results in a morphology change from columnar tilted structure to densely packed morphological isotropic multilayer

  • 5. Hohn, N.
    et al.
    Schlosser, S. J.
    Bießmann, L.
    Grott, S.
    Xia, S.
    Wang, K.
    Schwartzkopf, M.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. Deutsches Elektronen-Synchrotron, Germany.
    Müller-Buschbaum, P.
    Readily available titania nanostructuring routines based on mobility and polarity controlled phase separation of an amphiphilic diblock copolymer2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 11, p. 5325-5334Article in journal (Refereed)
    Abstract [en]

    The amphiphilic diblock copolymer polystyrene-block-polyethylene oxide is combined with sol-gel chemistry to control the structure formation of blade-coated foam-like titania thin films. The influence of evaporation time before immersion into a poor solvent bath and polarity of the poor solvent bath are studied. Resulting morphological changes are quantified by scanning electron microscopy (SEM) and grazing incidence small angle X-ray scattering (GISAXS) measurements. SEM images surface structures while GISAXS accesses inner film structures. Due to the correlation of evaporation time and mobility of the polymer template during the phase separation process, a decrease in the distances of neighboring titania nanostructures from 50 nm to 22 nm is achieved. Furthermore, through an increase of polarity of an immersion bath the energetic incompatibility of the hydrophobic block and the solvent can be enhanced, leading to an increase of titania nanostructure distances from 35 nm to 55 nm. Thus, a simple approach is presented to control titania nanostructure in foam-like films prepared via blade coating, which enables an easy upscaling of film preparation.

  • 6.
    Kamada, Ayaka
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ingverud, Tobias
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ohm, Wiebke
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Photon Science, Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg, Germany.
    Lundell, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    Lendel, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Flow-assisted assembly of nanostructured protein microfibers2017In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 6, p. 1232-1237Article in journal (Refereed)
    Abstract [en]

    Some of the most remarkable materials in nature are made from proteins. The properties of these materials are closely connected to the hierarchical assembly of the protein building blocks. In this perspective, amyloid-like protein nanofibrils (PNFs) have emerged as a promising foundation for the synthesis of novel bio-based materials for a variety of applications. Whereas recent advances have revealed the molecular structure of PNFs, the mechanisms associated with fibril-fibril interactions and their assembly into macroscale structures remain largely unexplored. Here, we show that whey PNFs can be assembled into microfibers using a flow-focusing approach and without the addition of plasticizers or cross-linkers. Microfocus small-angle X-ray scattering allows us to monitor the fibril orientation in the microchannel and compare the assembly processes of PNFs of distinct morphologies. We find that the strongest fiber is obtained with a sufficient balance between ordered nanostructure and fibril entanglement. The results provide insights in the behavior of protein nanostructures under laminar flow conditions and their assembly mechanism into hierarchical macroscopic structures.

  • 7. Kim, Young Yong
    et al.
    Kim, Kyungtae
    Jung, Sungmin
    Kim, Changsub
    Kim, Jehan
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sprung, Michael
    Vartanyants, Ivan A.
    Ree, Moonhor
    Synchrotron X-ray scattering and photon correlation spectroscopy studies on thin film morphology details and structural changes of an amorphous-crystalline brush diblock copolymer2016In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 105, p. 472-486Article in journal (Refereed)
    Abstract [en]

    We investigated structural details and temperature-induced structural changes of an amorphous-crystalline brush diblock copolymer, poly(3-((6-((7-(9H-carbazol-9-yl)heptanoyl)oxy)hexyl)thio)propylglycidyl ether)(60)-b-poly(glycidyl 12-((3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)oxy)-12oxododecanoate)(20) (PGK(60)-PGF(20)) in nanoscale thin films using synchrotron grazing incidence X-ray scattering (GIXS) and X-ray photon correlation spectroscopy (XPCS). Interestingly, the diblock copolymer was found to form a mixture of two different hexagonal cylinder structures (HEX1 and HEX2) where the PGF cylinders were aligned in the film plane. HEX1 was composed of PGF cylinders with higher population of crystals while HEX2 consisted of PGF cylinders with lower population of crystals. Surprisingly, the PGF block chains favorably self-assembled because of strong lateral interactions in the bristles, forming vertical multibilayer structure with partial interdigitation even in the highly confined cylindrical geometry. In heating run up to 340 K, some fraction of HEX2 was transformed to HEX1 via cold crystallization. In contrast, HEX1 was transformed to HEX2 above 340 K because of melting of the PGF crystals. The XPCS analysis found that the HEX structural changes associated with the cold crystallization in the PGF cylinder domains took place with relatively fast dynamics. The HEX structural changes associated with melting of the PGF crystals in the cylinder domains occurred with relatively slow dynamics; this unusual dynamics of structural changes might be attributed to a high energy melting process of PGF crystals against strong lateral interactions of the bristles.

  • 8.
    Rosén, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. SUNY Stony Brook.
    Brouzet, Christophe
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. DESY.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Three-Dimensional Orientation of Nanofibrils in Axially Symmetric Systems Using Small-Angle X-ray Scattering2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 12, p. 6889-6899Article in journal (Refereed)
    Abstract [en]

    The increased availability and brilliance of new X-ray facilities have in the recent years opened up the possibility to characterize the alignment of dispersed anisotropic nanoparticles in various microfluidic applications, from hydrodynamic self-assemblies to flows in complex geometries. In such applications, it is vital to study the alignment of the nanoparticles in the flow, as this in turn affects the final properties of the self-assembled superstructures or those of the flow itself. Small-angle X-ray scattering (SAXS) is a well-suited characterization technique for this but typically provides the alignment in a projected plane perpendicular to the beam direction. In this work, we demonstrate a simple method to reconstruct the full three-dimensional orientation distribution function from a SAXS experiment through the assumption that the azimuthal angle of the nanoparticles around the flow direction is distributed uniformly, an assumption that is valid for a large range of nanoparticle flow processes. For demonstration purposes, the experimental results from previous works on hydrodynamic self-assembly of cellulose nanofibrils (CNFs) into filaments have been revised, resulting in a small correction to the presented order parameters. The results are then directly compared with simple numerical models to describe the increased alignment of CNFs both in the flowing system and during the drying of the filament. The proposed reconstruction method will allow for further improvements of theoretical or numerical simulations and consequently open up new possibilities for optimizing assembly processes, which include flow alignment of elongated nanoparticles.

  • 9.
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Deutsches Elektronen-Synchrotron (DESY), Germany.
    A deep look into the spray coating process in real-time-the crucial role of x-rays2016In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 28, no 40, article id 403003Article, review/survey (Refereed)
    Abstract [en]

    Tailoring functional thin films and coating by rapid solvent-based processes is the basis for the fabrication of large scale high-end applications in nanotechnology. Due to solvent loss of the solution or dispersion inherent in the installation of functional thin films and multilayers the spraying and drying processes are strongly governed by non-equilibrium kinetics, often passing through transient states, until the final structure is installed. Therefore, the challenge is to observe the structural build-up during these coating processes in a spatially and time-resolved manner on multiple time and length scales, from the nanostructure to macroscopic length scales. During installation, the interaction of solid-fluid interfaces and between the different layers, the flow and evaporation themselves determine the structure of the coating. Advanced x-ray scattering methods open a powerful pathway for observing the involved processes in situ, from the spray to the coating, and allow for gaining deep insight in the nanostructuring processes. This review first provides an overview over these rapidly evolving methods, with main focus on functional coatings, organic photovoltaics and organic electronics. Secondly the role and decisive advantage of x-rays is outlined. Thirdly, focusing on spray deposition as a rapidly emerging method, recent advances in investigations of spray deposition of functional materials and devices via advanced x-ray scattering methods are presented.

  • 10. Schaffer, C. J.
    et al.
    Palumbiny, C. M.
    Niedermeier, M. A.
    Burger, C.
    Santoro, G.
    Roth, Stephan Volkher
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Deutsches Elektronen-Synchrotron DESY, Germany.
    Müller-Buschbaum, P.
    Morphological Degradation in Low Bandgap Polymer Solar Cells: An In Operando Study2016In: Advanced Energy Materials, ISSN 1614-6832, Vol. 6, no 19, article id 1600712Article in journal (Refereed)
  • 11. Schwartzkopf, M.
    et al.
    Hinz, A.
    Polonskyi, O.
    Strunskus, T.
    Löhrer, F. C.
    Körstgens, V.
    Müller-Buschbaum, P.
    Faupel, F.
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Photon Science, Deutsches Elektronen-Synchrotron (DESY), Germany.
    Role of Sputter Deposition Rate in Tailoring Nanogranular Gold Structures on Polymer Surfaces2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 6, p. 5629-5637Article in journal (Refereed)
    Abstract [en]

    The reproducible low-cost fabrication of functional polymer-metal interfaces via self-assembly is of crucial importance in organic electronics and organic photovoltaics. In particular, submonolayer and nanogranular systems expose highly interesting electrical, plasmonic, and catalytic properties. The exploitation of their great potential requires tailoring of the structure on the nanometer scale and below. To obtain full control over the complex nanostructural evolution at the polymer-metal interface, we monitor the evolution of the metallic layer morphology with in situ time-resolved grazing-incidence small-angle X-ray scattering during sputter deposition. We identify the impact of different deposition rates on the growth regimes: the deposition rate affects primarily the nucleation process and the adsorption-mediated growth, whereas rather small effects on diffusion-mediated growth processes are observed. Only at higher rates are initial particle densities higher due to an increasing influence of random nucleation, and an earlier onset of thin film percolation occurs. The obtained results are discussed to identify optimized morphological parameters of the gold cluster ensemble relevant for various applications as a function of the effective layer thickness and deposition rate. Our study opens up new opportunities to improve the fabrication of tailored metal-polymer nanostructures for plasmonic-enhanced applications such as organic photovoltaics and sensors.

  • 12. Schwartzkopf, Matthias
    et al.
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Investigating Polymer-Metal Interfaces by Grazing Incidence Small-Angle X-Ray Scattering from Gradients to Real-Time Studies2016In: NANOMATERIALS, ISSN 2079-4991, Vol. 6, no 12, article id 239Article, review/survey (Refereed)
    Abstract [en]

    Tailoring the polymer-metal interface is crucial for advanced material design. Vacuum deposition methods for metal layer coating are widely used in industry and research. They allow for installing a variety of nanostructures, often making use of the selective interaction of the metal atoms with the underlying polymer thin film. The polymer thin film may eventually be nanostructured, too, in order to create a hierarchy in length scales. Grazing incidence X-ray scattering is an advanced method to characterize and investigate polymer-metal interfaces. Being non-destructive and yielding statistically relevant results, it allows for deducing the detailed polymer-metal interaction. We review the use of grazing incidence X-ray scattering to elucidate the polymer-metal interface, making use of the modern synchrotron radiation facilities, allowing for very local studies via in situ (so-called stop-sputter) experiments as well as studies observing the nanostructured metal nanoparticle layer growth in real time.

  • 13. Song, Lin
    et al.
    Wang, Weijia
    Koerstgens, Volker
    Gonzalez, Daniel Mosegui
    Loehrer, Franziska C.
    Schaffer, Christoph J.
    Schlipf, Johannes
    Peters, Kristina
    Bein, Thomas
    Fattakhova-Rohlfing, Dina
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Photon Science, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    In situ study of spray deposited titania photoanodes for scalable fabrication of solid-state dye-sensitized solar cells2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 40, p. 317-326Article in journal (Refereed)
    Abstract [en]

    Spray coating, a cost-effective and scalable technique, has been employed for fabricating titania films for solidstate dye-sensitized solar cells (ssDSSCs). The spray deposition of films is inherently based on kinetic processes with great complexity, which poses great challenges in its understanding. In the present work, the kinetics of the structure evolution of deposited films are investigated by in situ grazing-incidence small-angle x-ray scattering during spray deposition. The spray-solution is prepared via a polystyrene-block-polyethylene oxide (PS-b-PEO) template assisted sol-gel synthesis. It is turned into nanostructured titania/PS-b-PEO composite films via spray deposition. The information about nanostructure length scales of the composite film is obtained in real-time and in situ, revealing the morphological evolution during the spray deposition. The resulting mesoporous titania films serve as photoanodes of ssDSSCs, which couple with the solution-cast hole transport layer to form the active layers. The well working ssDSSCs demonstrate the successful use of spray deposition as a large-scale manufacturing process for photoanodes.

  • 14. Su, Bo
    et al.
    Caller-Guanan, Herbert A.
    Koerstgens, Volker
    Rui, Yichuan
    Yao, Yuan
    Saxena, Nitin
    Santoro, Gonzalo
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Deutsch Elektronen Synchrotron DESY, Germany.
    Mueller-Buschbaum, Peter
    Macroscale and Nanoscale Morphology Evolution during in Situ Spray Coating of Titania Films for Perovskite Solar Cells2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 50, p. 43724-43732Article in journal (Refereed)
    Abstract [en]

    Mesoporous titania is a cheap and widely used material for photovoltaic applications. To enable a large-scale fabrication and a controllable pore size, we combined a block copolymer-assisted sol gel route with spray coating to fabricate titania films, in which the block copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) is used as a structure-directing template. Both the macroscale and nanoscale are studied. The kinetics and thermodynamics of the spray deposition processes are simulated on a macroscale, which shows a good agreement with the large-scale morphology of the spray-coated films obtained in practice. On the nanoscale, the structure evolution of the titania films is probed with in situ grazing incidence small-angle X-ray scattering (GISAXS) during the spray process. The changes of the PS domain size depend not "only on micellization but also on solvent evaporation during the spray coating. Perovskite (CH3NH3PbI3) solar cells (PSCs) based on sprayed titania film are fabricated, which showcases the suitability of spray-deposited titania films for PSCs.

  • 15. Vayalil, Sarathlal Koyiloth
    et al.
    Gupta, Ajay
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. DESY, Germany.
    Study of pattern transition in nanopatterned Si(100) produced by impurity-assisted low-energy ion-beam erosion2017In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 123, no 4, article id 225Article in journal (Refereed)
    Abstract [en]

    In this work, formation of self-organized Si nanostructures induced by pure Fe incorporation during normal incidence low-energy (1keV) Ar+ ion bombardment is presented. It has been observed that the incorporation of Fe affects the evolution of the surface topography. The addition of Fe generates pronounced nanopatterns, such as dots, ripples and combinations of dots and ripples. The orientation of the ripple wave vector of the patterns formed is found to be in a direction normal to the Fe flow. The nanoripples with wavelength of the order of 39 nm produced is expected to be the lowest wavelength of the patterns reported on ion-beam-eroded structures under the incorporation of metallic impurities as per our knowledge. From the AFM and GISAXS analysis, it has been confirmed that the ripples formed are asymmetric in nature. The effect of the concentration of the Fe on morphological transition of the patterns has been studied using Rutherford backscattering measurements.

  • 16. Wang, K.
    et al.
    Körstgens, V.
    Yang, D.
    Hohn, N.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
    Müller-Buschbaum, P.
    Morphology control of low temperature fabricated ZnO nanostructures for transparent active layers in all solid-state dye-sensitized solar cells2018In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 10, p. 4405-4415Article in journal (Refereed)
    Abstract [en]

    Based on a method using sol-gel chemistry combined with diblock copolymer templating, a low-temperature route to fabricate zinc oxide (ZnO) films with tunable morphologies including foam-like, worm-like and sphere-like structures is demonstrated. The morphologies are probed using scanning electron microscopy and grazing-incidence small-angle X-ray scattering. Based on controlled nanostructured ZnO films, all solid-state dye-sensitized solar cells (ssDSSCs) are prepared, for which every layer is deposited at low temperature to reduce the energy consumption of the manufacturing process. Transparent active layers for ssDSSCs are obtained, which demonstrates the possibility for building integrated solar cells. The ssDSSCs with a worm-like ZnO morphology, exhibiting relatively better ordered interconnected three-dimensional structures and larger meso-pore sizes, show the highest power conversion efficiencies and almost 100% efficiency of charge separation and collection for the absorbed photons. After 120 days, almost 80% of the initial power conversion efficiency is maintained in ambient air conditions, which demonstrates good long-term stability of the ssDSSCs even without special encapsulation. 

  • 17.
    Wang, Kun
    et al.
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Biessmann, Lorenz
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrontron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsch Elektronen Synchrontron DESY, Notkestr 85, D-22603 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Tuning of the Morphology and Optoelectronic Properties of ZnO/P3HT/P3HT-b-PEO Hybrid Films via Spray Deposition Method2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 24, p. 20569-20577Article in journal (Refereed)
    Abstract [en]

    The self-assembly of amphiphilic diblock copolymers yields the possibility of using them as a template for tailoring the film morphologies of solgel chemistry-derived inorganic electron transport materials, such as mesoporous ZnO and TiO2. However, additional steps including etching and backfilling are required for the common bulk heterojunction fabrication process when using insulating diblock copolymers. Here, we use the conducting diblock copolymer poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) in which P3HT acts as charge carrier transport material and light absorber, whereas PEO serves as a template for ZnO synthesis. The initial solution is subsequently spray-coated to obtain the hybrid film. Scanning electron microscopy and grazing-incidence small-angle X-ray scattering measurements reveal a significant change in the morphology of the hybrid films during deposition. Optoelectronic properties illustrate the improved charge separation and charge transfer process. Both the amount of the diblock copolymer and the annealing temperature play an important role in tuning the morphology and the optoelectronic properties. Hybrid films being sprayed from a solution with the ratio of omega(ZnO), omega(P3HT), and omega(P3HT-b-PEO) of 2:1:1 and subsequent annealing at 80 degrees C show the most promising morphology combined with an optimal photoluminescence quenching. Thus, the presented simple, reagent- and energy-saving fabrication method provides a promising approach for a large-scale preparation of bulk heterojunction P3HT/ZnO films on flexible substrates.

  • 18.
    Yu, Shun
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chen, Fei
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wu, Qiong
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Deutsches Elektronen-Synchrotron (DESY), Germany.
    Bruning, Karsten
    Schneider, Konrad
    Kuktaite, Ramune
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Structural Changes of Gluten/Glycerol Plastics under Dry and Moist Conditions and during Tensile Tests2016In: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 4, no 6, p. 3388-3397Article in journal (Refereed)
    Abstract [en]

    The structures of wheat gluten-based materials are greatly influenced by plasticizer content, moisture content, and external mechanical loading. In this study, the effects of moisture on the structure of wheat gluten (WG) plasticized by glycerol were investigated by using in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), mechanical tensile testing, and thermal analyses. The materials were processed with additives of ammonium hydroxide/salicylic acid or urea and conditioned at 0, 50, and 100% relative humidity (RH). In general, water showed similar effects on the WG structure and mechanical properties regardless of the type of additive. It was observed that the known hexagonal close-packed (HCP) structure in WG was present mainly under moist conditions and swelled with an increase in water content. The absorbed water molecules hydrated the protein chains at 50% RH and further led to the formation of a separate water/glycerol phase at 100% RH. An interesting feature was observed by in situ SAXS during tensile deformation; both the HCP structure and other protein aggregates packed more densely in both the tensile and transverse directions. It is interpreted as follows: "randomly oriented" chains were drawn out and stretched in the tensile direction, which squeezes the self-assembled structures together, similar to "tightening a knot".

  • 19. Zhang, Peng
    et al.
    Santoro, Gonzalo
    Yu, Shun
    Vayalil, Sarathlal K.
    Bommel, Sebastian
    Roth, Stephan V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Manipulating the Assembly of Spray-Deposited Nanocolloids: In Situ Study and Monolayer Film Preparation2016In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 32, no 17, p. 4251-4258Article in journal (Refereed)
    Abstract [en]

    Fabrication of nanoparticle arrays on a substrate is one of the most concerned aspects for manipulating assembly of nanoparticles and preparing functional nanocomposites. Here, we studied in situ the assembly kinetics of polystyrene nanocolloids by using grazing incidence small-angle X-ray scattering. The structure formation of the nanoparticle film is monitored during air-brush spraying, which provides a rapid and scalable preparation. By optimizing the substrate temperature, the dispersion of the nanocolloids can be tailored to prepare monolayer film. The success of the monolayer preparations is attributed to the fast solvent evaporation which inhibits the aggregation of the nanocolloids. The present study may open a new avenue for the manufacture-friendly preparation of well-dispersed nanoparticle thin films.

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