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  • 1
    Language: English
    In: Advanced materials (Deerfield Beach, Fla.), 10 December 2014, Vol.26(46), pp.7692-709
    Description: Grazing incidence X-ray scattering (GIXS) provides unique insights into the morphology of active materials and thin film layers used in organic photovoltaic devices. With grazing incidence wide angle X-ray scattering (GIWAXS) the molecular arrangement of the material is probed. GIWAXS is sensitive to the crystalline parts and allows for the determination of the crystal structure and the orientation of the crystalline regions with respect to the electrodes. With grazing incidence small angle X-ray scattering (GISAXS) the nano-scale structure inside the films is probed. As GISAXS is sensitive to length scales from nanometers to several hundred nanometers, all relevant length scales of organic solar cells are detectable. After an introduction to GISAXS and GIWAXS, selected examples for application of both techniques to active layer materials are reviewed. The particular focus is on conjugated polymers, such as poly(3-hexylthiophene) (P3HT).
    Keywords: Gisaxs ; Giwaxs ; Gixs ; Morphology ; Organic Photovoltaics
    ISSN: 09359648
    E-ISSN: 1521-4095
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  • 2
    In: Advanced Materials, December 2014, Vol.26(46), pp.7692-7709
    Description: Grazing incidence X‐ray scattering (GIXS) provides unique insights into the morphology of active materials and thin film layers used in organic photovoltaic devices. With grazing incidence wide angle X‐ray scattering (GIWAXS) the molecular arrangement of the material is probed. GIWAXS is sensitive to the crystalline parts and allows for the determination of the crystal structure and the orientation of the crystalline regions with respect to the electrodes. With grazing incidence small angle X‐ray scattering (GISAXS) the nano‐scale structure inside the films is probed. As GISAXS is sensitive to length scales from nanometers to several hundred nanometers, all relevant length scales of organic solar cells are detectable. After an introduction to GISAXS and GIWAXS, selected examples for application of both techniques to active layer materials are reviewed. The particular focus is on conjugated polymers, such as poly(3‐hexylthiophene) (P3HT). grazing incidence small angle X‐ray scattering (GISAXS) and grazing incidence wide angle X‐ray scattering (GIWAXS) are reviewed. Basics of both scattering techniques are explained and selected examples from application of GISAXS and for the use of GIWAXS in the analysis OPV device relevant structures are presented.
    Keywords: Organic Photovoltaics ; Gisaxs ; Giwaxs ; Gixs ; Morphology
    ISSN: 0935-9648
    E-ISSN: 1521-4095
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  • 3
    Language: English
    In: Journal of Physics: Condensed Matter, 2011, Vol.23(25), p.250301 (1pp)
    Description: Neutron and x-ray scattering have emerged as powerful methods for the determination of structure and dynamics. Driven by emerging new, powerful neutron and synchrotron radiation sources, the continuous development of new instrumentation and novel scattering techniques gives rise to exciting possibilities. For example, in situ observations become possible via a high neutron or x-ray flux at the sample and, as a consequence, morphological transitions with small time constants can be detected. This special issue covers a broad range of different materials from soft to hard condensed matter. Hence, different material classes such as colloids, polymers, alloys, oxides and metals are addressed. The issue is dedicated to the 60 th birthday of Professor Winfried Petry, scientific director of the Research Neutron Source Heinz Maier-Leibnitz (FRM-II), Germany, advisor at the physics department for the Bayerische Elite-Akademie, chair person of the Arbeitsgemeinschaft Metall- und Materialphysik of the German Physical Society (DPG) and a member of the professional council of the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG). We would like to acknowledge and thank all contributors for their submissions, which made this special issue possible in the first place. Moreover, we would like to thank the staff at IOP Publishing for helping us with the administrative aspects and for coordinating the refereeing process, and Valeria Lauter for the beautiful cover artwork. Finally, to the readers, we hope that you find this special issue a valuable resource that provides insights into the present possibilities of neutron and x-ray scattering as powerful tools for the investigation of structure and dynamics. Structure and dynamics determined by neutron and x-ray scattering contents In situ studies of mass transport in liquid alloys by means of neutron radiography F Kargl, M Engelhardt, F Yang, H Weis, P Schmakat, B Schillinger, A Griesche and A Meyer Magnetic spin structure of pyroxene-type MnGeO 3 G J Redhammer, A Senyshyn, G Tippelt and G Roth Nanostructured diblock copolymer films with embedded magnetic nanoparticles Xin Xia, Ezzeldin Metwalli, Matthias A Ruderer, Volker Körstgens, Peter Busch, Peter Böni and Peter Müller-Buschbaum Thermal expansion of a La-based bulk metallic glass: insight from in situ high-energy x-ray diffraction J Bednarcik, S Michalik, M Sikorski, C Curfs, X D Wang, J Z Jiang and H Franz The slow short-time motions of phospholipid molecules with a focus on the influence of multiple scattering and fitting artefacts Sebastian Busch and Tobias Unruh Quasi-elastic scattering under short-range order: the linear regime and beyond Michael Leitner and Gero Vogl Structural relaxation as seen by quasielastic neutron scattering on viscous ZrTiCuNiBe droplets F Yang, T Kordel, D Holland-Moritz, T Unruh and A Meyer In situ observation of cluster formation during nanoparticle solution casting on a colloidal film S V Roth, G Herzog, V Körstgens, A Buffet, M Schwartzkopf, J Perlich, M M Abul Kashem, R Döhrmann, R Gehrke, A Rothkirch, K Stassig, W Wurth, G Benecke, C Li, P Fratzl, M Rawolle and P Müller-Buschbaum Inelastic neutron and x-ray scattering from incommensurate magnetic systems Peter Böni, Bertrand Roessli and Klaudia Hradil Development of magnetic moments in Fe 1-x Ni x -alloys Benjamin Glaubitz, Stefan Buschhorn, Frank Brüssing, Radu Abrudan and Hartmut Zabel Modified mode-coupling theory for the collective dynamics of simple liquids B Schmid and W Schirmacher Inelastic neutron and low-frequency Raman scattering in niobium-phosphate glasses: the role of spatially fluctuating elastic and elasto-optic constants A Schulte, W Schirmacher, B Schmid and T Unruh The effect of heat treatment on the internal structure of nanostructured block copolymer films A Sepe, E T Hoppe, S Jaksch, D Magerl, Q Zhong, J Perlich, D Posselt, D-M Smilgies and C M Papadakis Hydrogen release from sodium alanate observed by time-resolved neutron backscattering Aline Léon and Joachim Wuttke Morphology of thin nanocomposite films of asymmetric diblock copolymer and magnetite nanoparticles Valeria Lauter, Peter Müller-Buschbaum, Hans Lauter and Winfried Petry Structural characterization of casein micelles: shape changes during film formation R Gebhardt, C Vendrely and U Kulozik
    Keywords: Physics;
    ISSN: 0953-8984
    E-ISSN: 1361-648X
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  • 4
    Language: English
    In: Polymer, 14 July 2017, Vol.121, pp.173-182
    Description: Thin blend films of the diblock copolymer poly(3-hexylthiophene-2,5-diyl)- -polystyrene (P3HT- -PS) and phenyl-C61-butyric acid methyl ester (PCBM) are prepared and investigated. The morphology of films with 9, 25, 33, 50, 58 and 67% PCBM weight fraction is determined. The surface topography is probed with optical microscopy and atomic force microscopy whereas the lateral inner structures are determined using grazing incidence small angle neutron scattering (GISANS). Grazing incidence X-ray diffraction (GI-XRD) shows a blend ratio dependence of the P3HT crystallites orientation within the block copolymer films. The thermodynamically favoured P3HT edge-on orientation is suppressed upon increasing the PCBM content from 9% till 33% while it recovers in samples with a PCBM weight fraction above 50%. PCBM tends to interact with the PS block at low PCBM fractions and forms segregated domains at a PCBM weight fraction higher than 50%. The addition of PCBM decreases the degree of lamellar structure order and well-ordered hexagonal packed cylindrical structures emerge in at a PCBM weight fraction of 67%. Absorbance and photoluminescence measurements show the relationship between morphology transformation and optoelectronic properties. The phenomena reported here could provide an alternative view for potential nanotechnology applications.
    Keywords: Block Copolymer ; Self-Assembly ; Morphology ; Gisans ; Engineering ; Chemistry
    ISSN: 0032-3861
    E-ISSN: 1873-2291
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  • 5
    Language: English
    In: Polymer, 22 November 2016, Vol.105, pp.357-367
    Description: Grazing incidence small angle X-ray scattering (GISAXS) methods are frequently very successfully utilized for morphological investigations of thin polymer blend films used in organic photovoltaics. However, conventional GISAXS does no longer provide material sensitivity when the blend consists of more than two components due to the contrast conditions. In case of multi-component blends the use of grazing incidence resonant soft X-ray scattering (GI-RSoXS) can overcome such problems. In this work we exemplarily apply GI-RSoXS to investigate simultaneously the vertical and lateral morphology of polymer-fullerene bulk heterojunction layers made from poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2,6-diyl]] (PCPDTBT) and [6,6]-penyl-C 61 butyric acid methyl ester (PCBM) with added photosensitizer perylene diimide (PDI) with and without use of the solvent additive 1,8-octanedithiol (ODT). The investigation reveals that films without solvent additive ODT tend to show only vertical phase separation while films prepared with solvent additive also phase separate laterally. PDI seems to assist lateral phase separation between PCPDTBT and PCBM by expelling PCBM from the amorphous polymer matrix.
    Keywords: GI-Rsoxs ; Gisaxs ; Polymer Blend ; Conducting Polymer ; Organic Photovoltaics ; Engineering ; Chemistry
    ISSN: 0032-3861
    E-ISSN: 1873-2291
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  • 6
    Language: English
    In: Journal of Materials Chemistry, 2011, Vol.22(1), p.192
    Description: We report the fabrication of structured polymer films viaa novel imprinting routine, which additionally allows for entire surface coverage by an underlying homogeneous polymer film. The imprinting method is based on an inverted micromolding in capillaries (MIMIC) approach and in combination with master molds made of bisphenol-A-polycarbonate (PC) sample sizes of up to 20 30 mm super(2) were perfectly structured. Nanoscopic channel structures made of the conducting poly(3,4-ethylenedioxy-thiophene):poly(styrene sulfonate) (PEDOT:PSS) and the thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) also prove the wide application possibilities of this structuring method. For PEDOT:PSS structures the film thickness of the homogeneous supporting polymer layer can be controlled between 0 and 80 nm by an externally applied pressure during imprinting. In addition, conducting polymer blend films as they are used for organic solar cells have a reduced optical reflection if spin cast onto such structured PEDOT:PSS films. For channel structures made of PNIPAM it is shown that their macroscopic optical grating effect responds to the environmental humidity. Due to water inclusion in the PNIPAM network unifying of adjacent channels occurs already in the early stages of the swelling process and results in a homogeneous polymer film. Finally a first batch processing device for the structuring routine is demonstrated, which also guarantees constant lift-off conditions.
    Keywords: Addition Polymerization ; Channels ; Conducting Polymers ; Film Thickness ; Nanocomposites ; Nanomaterials ; Nanostructure ; Routines ; Thin Films, Surfaces, and Interfaces (So) ; Chemical and Electrochemical Properties (MD) ; Chemical and Electrochemical Properties (Ep) ; Chemical and Electrochemical Properties (Ed) ; Chemical and Electrochemical Properties (EC);
    ISSN: 0959-9428
    E-ISSN: 1364-5501
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  • 7
    Language: English
    In: Journal of Physics: Condensed Matter, 2011, Vol.23(25), p.254215 (6pp)
    Description: Thin self-assembled nanocomposite films of an asymmetric diblock copolymer and nanoparticles are fabricated. The morphologies of the films of the diblock copolymer poly(styrene- block -n-butyl methacrylate), P(Sd- b -BMA), with different volume fractions of large magnetite Fe 3 O 4 nanoparticles are studied before and after annealing. Neutron reflectometry reveals remarkable evidence that confining asymmetric copolymer to a limit of two layers forces the film, after the annealing, to form a mixed cylindricallamellar two-layer structure. This complex morphology is very stable and is preserved after the incorporation of nanoparticles up to 10% volume fraction. The other striking result is that the monodispersed nanoparticles with affinity to the polystyrene (PS) domain and with a size of 10 nm, which is close to the size of the PS chains, are assembled by the diblock copolymer matrix, so the distribution of the nanoparticles is reduced solely to the PS domain of the film. Our studies demonstrate that for asymmetric block copolymers in thin film geometry the self-assembly is strongly influenced by the interfacial and surface energies of the blocks and substrate.
    Keywords: Polystyrene Resins ; Magnetite ; Self Assembly ; Morphology ; Asymmetry ; Copolymers ; Nanoparticles ; Thin Films ; Condensed Matter Physics (General) (So);
    ISSN: 0953-8984
    E-ISSN: 1361-648X
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  • 8
    Language: English
    In: Physical Review B, 11/2011, Vol.84(17)
    ISSN: 1098-0121
    E-ISSN: 1550-235X
    Source: American Physical Society (APS) (via CrossRef)
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  • 9
    Language: English
    In: Langmuir : the ACS journal of surfaces and colloids, 12 June 2012, Vol.28(23), pp.8791-8
    Description: The phase separation mechanism in semidilute aqueous poly(N-isopropylacrylamide) (PNIPAM) solutions is investigated with small-angle neutron scattering (SANS). The nature of the phase transition is probed in static SANS measurements and with time-dependent SANS measurements after a temperature jump. The observed critical exponents of the phase transition describing the temperature dependence of the Ornstein-Zernike amplitude and correlation length are smaller than values from mean-field theory. Time-dependent SANS measurements show that the specific surface decreases with increasing time after a temperature jump above the phase transition. Thus, the formation of additional hydrogen bonds in the collapsed state is a kinetic effect: A certain fraction of water remains as bound water in the system. Moreover, H-D exchange reactions observed in PNIPAM have to be taken into account.
    Keywords: Acrylamides -- Chemistry ; Polymers -- Chemistry ; Water -- Chemistry
    ISSN: 07437463
    E-ISSN: 1520-5827
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  • 10
    Language: English
    In: Langmuir : the ACS journal of surfaces and colloids, 06 March 2012, Vol.28(9), pp.4479-90
    Description: A series of symmetrical, thermo-responsive triblock copolymers was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, and studied in aqueous solution with respect to their ability to form hydrogels. Triblock copolymers were composed of two identical, permanently hydrophobic outer blocks, made of low molar mass polystyrene, and of a hydrophilic inner block of variable length, consisting of poly(methoxy diethylene glycol acrylate) PMDEGA. The polymers exhibited a LCST-type phase transition in the range of 20-40 °C, which markedly depended on molar mass and concentration. Accordingly, the triblock copolymers behaved as amphiphiles at low temperatures, but became water-insoluble at high temperatures. The temperature dependent self-assembly of the amphiphilic block copolymers in aqueous solution was studied by turbidimetry and rheology at concentrations up to 30 wt %, to elucidate the impact of the inner thermoresponsive block on the gel properties. Additionally, small-angle X-ray scattering (SAXS) was performed to access the structural changes in the gel with temperature. For all polymers a gel phase was obtained at low temperatures, which underwent a gel-sol transition at intermediate temperatures, well below the cloud point where phase separation occurred. With increasing length of the PMDEGA inner block, the gel-sol transition shifts to markedly lower concentrations, as well as to higher transition temperatures. For the longest PMDEGA block studied (DP(n) about 450), gels had already formed at 3.5 wt % at low temperatures. The gel-sol transition of the hydrogels and the LCST-type phase transition of the hydrophilic inner block were found to be independent of each other.
    ISSN: 07437463
    E-ISSN: 1520-5827
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