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  • 1.
    Alam, Md Khorshed
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest.

    Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls.

    The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively. 

  • 2.
    Annamalai, Alagappan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Division of Biotechnology, Advanced Institute of Environmental and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Republic of Korea.
    Lee, Hyun Hwi
    Choi, Sun Hee
    Lee, Su Yong
    Gracia-Espino, Eduardo
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Subramanian, Arunprabaharan
    Park, Jaedeuk
    Kong, Ki-jeong
    Jang, Jum Suk
    Sn/Be Sequentially co-doped Hematite Photoanodes for Enhanced Photoelectrochemical Water Oxidation: Effect of Be2+ as co-dopant2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 23183Article in journal (Refereed)
    Abstract [en]

    For ex-situ co-doping methods, sintering at high temperatures enables rapid diffusion of Sn4+ and Be2+ dopants into hematite (alpha-Fe2O3) lattices, without altering the nanorod morphology or damaging their crystallinity. Sn/Be co-doping results in a remarkable enhancement in photocurrent (1.7 mA/cm(2)) compared to pristine alpha-Fe2O3 (0.7 mA/cm(2)), and Sn4+ mono-doped alpha-Fe2O3 photoanodes (1.0 mA/cm(2)). From first-principles calculations, we found that Sn4+ doping induced a shallow donor level below the conduction band minimum, which does not contribute to increase electrical conductivity and photocurrent because of its localized nature. Additionally, Sn4+-doping induce local micro-strain and a decreased Fe-O bond ordering. When Be2+ was co-doped with Sn4+-doped alpha-Fe2O3 photoanodes, the conduction band recovered its original state, without localized impurities peaks, also a reduction in micro-strain and increased Fe-O bond ordering is observed. Also the sequence in which the ex-situ co-doping is carried out is very crucial, as Be/Sn co-doping sequence induces many under-coordinated O atoms resulting in a higher micro-strain and lower charge separation efficiency resulting undesired electron recombination. Here, we perform a detailed systematic characterization using XRD, FESEM, XPS and comprehensive electrochemical and photoelectrochemical studies, along with sophisticated synchrotron diffraction studies and extended X-ray absorption fine structure.

  • 3.
    Asadpoordarvish, Amir
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Functional and Flexible Light-Emitting Electrochemical Cells2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The introduction of artificial illumination has brought extensive benefits to mankind, and during the last years we have seen a tremendous progress in this field with the introduction of the energy-efficient light-emitting diode (LED) and the high-contrast organic LED display. These high-end technologies are, however, produced using costly and complex processes, and it is anticipated that the next big thing in the field will be the advent of a low-cost and “green” illumination technology, which can be fabricated in a cost- and material-efficient manner using non-toxic and abundant raw materials, and which features attractive form factors such as flexibility, robustness and light-weight. The light-emitting electrochemical cell (LEC) is a newly invented illumination technology, and in this thesis we present results that imply that it can turn the above vision into reality.

    The thin-film LEC comprises an active material sandwiched between a cathode and an anode as its key constituent parts. With the aid of a handheld air-brush, we show that functional large-area LECs can be fabricated by simply spraying three layers of solution -- forming the anode, active material, and cathode -- on top of a substrate. We also demonstrate that such “spray-sintered” LECs can feature multicolored emission patterns, and be fabricated directly on complex-shaped surfaces, with one notable example being the realization of a light-emission fork!

    Almost all LECs up-to-date have been fabricated on glass substrates, but for a flexible and light-weight emissive device, it is obviously relevant to identify more appropriate substrate materials. For this end, we show that it is possible to spray-coat the entire LEC directly on conventional copy paper, and that such paper-LECs feature uniform light-emission even under heavy bending and flexing.

    We have further looked into the fundamental aspects of the LEC operation and demonstrated that the in-situ doping formation, which is a characteristic and heralded feature of LECs, can bring problems in the form of doping-induced self-absorption. By quantitatively analyzing this phenomenon, we provided straightforward guidelines on how future efficiency-optimized LEC devices should be designed.

    The in-situ doping formation process brings the important advantage that LECs can be fabricated from solely air-stabile materials, but during light emission the device needs to be protected from the ambient air. We have therefore developed a functional glass/epoxy encapsulation procedure for the attainment of LEC devices that feature a record-long ambient-air operational lifetime of 5600 h. For the light-emission device of the future, it is however critical that the encapsulation is flexible, and in our last study, we show that the use of multi-layer barrier can result in high-performance flexible LECs.

  • 4.
    Asadpoordarvish, Amir
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sandström, Andreas
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    A Flexible Encapsulation Structure for Ambient-Air Operation of Light-Emitting Electrochemical Cells2016In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 18, no 1, p. 105-110Article in journal (Other academic)
    Abstract [en]

    The emerging field of organic electronics is heralded because it promises low-cost and flexible devices, and it was recently demonstrated that a light-emitting electrochemical cell (LEC) can be fabricated with cost-efficient methods under ambient air. However, the LEC turns sensitive to oxygen and water during light-emission, and it is therefore timely to identify flexible encapsulation structures. Here, we demonstrate that a multilayer film, featuring a water and oxygen barrier property of ≈1 × 10–3 g/m2/day and ≈1 × 10–3 cm3/m2/bar/day respectively, is fit for this task. By sandwiching an LEC between such multilayer barriers, as attached by a UV-curable epoxy, we realize flexible LECs with performance on par with identical glass-encapsulated devices, and which remain functional after one year storage under air.

  • 5.
    Asadpoordarvish, Amir
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. LunaLEC, Umeå, Sweden.
    Sandström, Andreas
    Larsen, Christian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Bollström, Roger
    Toivakka, Martti
    Österbacka, Ronald
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Light-Emitting Paper2015In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 25, no 21, p. 3238-3245Article in journal (Refereed)
    Abstract [en]

    A solution-based fabrication of flexible and light-weight light-emitting devices on paper substrates is reported. Two different types of paper substrates are coated with a surface-emitting light-emitting electrochemical cell (LEC) device: a multilayer-coated specialty paper with an intermediate surface roughness of 0.4 μm and a low-end and low-cost copy paper with a large surface roughness of 5 μm. The entire device fabrication is executed using a handheld airbrush, and it is notable that all of the constituent layers are deposited from solution under ambient air. The top-emitting paper-LECs are highly flexible, and display a uniform light emission with a luminance of 200 cd m−2 at a current conversion efficacy of 1.4 cd A−1.

  • 6. Bandyopadhyay, Sulalit
    et al.
    Singh, Gurvinder
    Sandvig, Ioanna
    Sandvig, Axel
    MI Lab and Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Mathieu, Roland
    Kumar, P. Anil
    Glomm, Wilhelm Robert
    Synthesis and in vitro cellular interactions of superparamagnetic iron nanoparticles with a crystalline gold shell2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 316, p. 171-178Article in journal (Refereed)
    Abstract [en]

    Fe@Au core-shell nanoparticles (NPs) exhibit multiple functionalities enabling their effective use in applications such as medical imaging and drug delivery. In this work, a novel synthetic method was developed and optimized for the synthesis of highly stable, monodisperse Fe@Au NPs of average diameter similar to 24 nm exhibiting magneto-plasmonic characteristics. Fe@Au NPs were characterized by a wide range of experimental techniques, including scanning (transmission) electron microscopy (S(T)EM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and UV-vis spectroscopy. The formed particles comprise an amorphous iron core with a crystalline Au shell of tunable thickness, and retain the superparamagnetic properties at room temperature after formation of a crystalline Au shell. After surface modification, PEGylated Fe@Au NPs were used for in vitro studies on olfactory ensheathing cells (OECs) and human neural stem cells (hNSCs). No adverse effects of the Fe@Au particles were observed post-labeling, both cell types retaining normal morphology, viability, proliferation, and motility. It can be concluded that no appreciable toxic effects on both cell types, coupled with multifunctionality and chemical stability make them ideal candidates for therapeutic as well as diagnostic applications.

  • 7.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Electric Field Assisted Nano-patterning: A New Approach to Produce Ordered Arrays of High Aspect Ratio Nanostructures Inexpensively2014Conference paper (Refereed)
  • 8.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Formation of well defined 3D continuous networks of SWNTs into polystyrene and P3HT nanocomposites2012Conference paper (Other academic)
  • 9.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Formation of well defined percolated arrays of SWNTs into micropatterns of P3HT for solar cell applications2012Conference paper (Refereed)
  • 10.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lithographic Method2012Patent (Other (popular science, discussion, etc.))
  • 11.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nano-engineered Nanotube Networks for Enhanced Vertical Charge Transport at Ultralow Nanotube Loading in a P3HT Nanocomposite Film2014Other (Refereed)
  • 12.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sun Seekers2014In: Pan European Networks: Science and Technology, ISSN 2049-2405, Vol. 11, p. 74-75Article in journal (Other (popular science, discussion, etc.))
  • 13.
    Barbero, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    SWNT networks art cover2014Other (Other (popular science, discussion, etc.))
  • 14.
    Barbero, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Yu, Junchun
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Carbon nanotube networks: nano-engineering of SWNT networks for enhanced charge transport at ultralow nanotube loading2014In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 26, no 19, p. 3164-Article in journal (Refereed)
    Abstract [en]

    Arrays of nano-engineered carbon nanotube networks embedded in nanoscale polymer structures enable highly efficient charge transport as demonstrated by D. R. Barbero and co-workers on page 3111. An increase in charge transport by several orders of magnitude is recorded at low nanotube loading compared to traditional random networks in either insulating (polystyrene) or semiconducting (polythiophene) polymers. These novel networks are expected to enhance the performance of next generation hybrid and carbon based photovoltaic devices.

  • 15.
    Barbero, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Yu, Junchun
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nano-engineering of SWNT networks for enhanced charge transport at ultralow nanotube loading2014In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 26, no 19, p. 3111-3117Article in journal (Refereed)
    Abstract [en]

    We demonstrate a simple and controllable method to form periodic arrays of highly conductive nano-engineered single wall carbon nanotube networks from solution. These networks increase the conductivity of a polymer composite by as much as eight orders of magnitude compared to a traditional random network. These nano-engineered networks are demonstrated in both polystyrene and polythiophene polymers.

  • 16.
    Barbero, David R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ultralow Percolation Threshold in Nanoconfined Domains2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 10, p. 9906-9913Article in journal (Refereed)
    Abstract [en]

    Self-assembled percolated networks play an important role in many advanced electronic materials and devices. In nanocarbon composites, decreasing the percolation threshold phi(c) is of paramount importance to reduce nanotube bundling, minimize material resources and costs, and enhance charge transport. Here we demonstrate that three-dimensional nanoconfinement in single-wall carbon nanotube/polymer nanocomposites produces a strong reduction in phi(c) reaching the lowest value ever reported in this system of phi(c) approximate to 1.8 X 10(-5) wt % and 4-5 orders of magnitude lower than the theoretical statistical percolation threshold oh phi(stat) Moreover, a change in network resistivity and electrical conduction was observed with increased confinement, and a simple resistive model is used to accurately estimate the difference in is in the confined networks. These results are explained in terms of networks' size, confinement, and tube orientation as determined by atomic force microscopy, electrical conductivity measurements, and polarized Raman spectroscopy. Our findings provide important insight into nanoscale percolated networks and should find application in electronic nanocomposites and devices.

  • 17.
    Barzegar, Hamid R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nitze, Florian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sharifi, Tiva
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tai, Cheuk W.
    Malolepszy, Artur
    Stobinski, Leszek
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Simple Dip-Coating Process for the Synthesis of Small Diameter Single-Walled Carbon Nanotubes-Effect of Catalyst Composition and Catalyst Particle Size on Chirality and Diameter2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 22, p. 12232-12239Article in journal (Refereed)
    Abstract [en]

    We report on a dip-coating method to prepare catalyst particles (mixture of iron and cobalt) with a controlled diameter distribution on silicon wafer substrates by changing the solution's concentration and withdrawal velocity. The size and distribution of the prepared catalyst particles were analyzed by atomic force microscopy. Carbon nanotubes were grown by chemical vapor deposition on the substrates with the prepared catalyst particles. By decreasing the catalyst particle size to below 10 nm, the growth of carbon nanotubes can be tuned from few-walled carbon nanotubes, with homogeneous diameter, to highly pure single-walled carbon nanotubes. Analysis of the Raman radial breathing modes, using three different Raman excitation wavelengths (488, 633, and 785 nm), showed a relatively broad diameter distribution (0.8-1.4 nm) of single-walled carbon nanotubes with different chiralities. However, by changing the composition of the catalyst particles while maintaining the growth parameters, the chiralities of single-walled carbon nanotubes were reduced to mainly four different types, (12, 1), (12, 0), (8, 5), and (7, 5), accounting for about 70% of all nanotubes.

  • 18.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Larsen, Christian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Jia, Xueen
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Palladium nanocrystals supported on photo-transformed C-60 nanorods: effect of crystal morphology and electron mobility on the electrocatalytic activity towards ethanol oxidation2014In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 73, p. 34-40Article in journal (Refereed)
    Abstract [en]

    We report on the synthesis and decoration of high-aspect-ratio crystalline C-60 nanorods (NRs) by functionalized palladium nanoparticles with an average size of 4.78 +/- 0.66 nm. In their pristine form, C-60 NRs suffer from partial damage in the solution-based decoration process resulting in poor crystallinity. However, by modifying the NR surface via in situ photochemical transformation in the liquid state, we are able to prepare highly stable NRs that retain their crystalline structure during the decoration process. Our method thus opens up for the synthesis of highly crystalline nanocomposite hybrids comprising Pd nanoparticles and C-60 NRs. Bys measuring the electron mobility of different C-60 NRs, we relate both the effect of electron mobility and crystallinity to the final electrocatalytic performance of the synthesized hybrid structures. We show that the photo-transformed C-60 NRs exhibit highly advantageous properties for ethanol oxidation based on both a better crystallinity and a higher bulk conductivity. These findings give important information in the search for efficient catalyst support.

  • 19.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Larsen, Christian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Solution-Based Phototransformation of C-60 Nanorods: Towards Improved Electronic Devices2013In: Particle & particle systems characterization, ISSN 0934-0866, E-ISSN 1521-4117, Vol. 30, no 8, p. 715-720Article in journal (Refereed)
    Abstract [en]

    A modified liquid-liquid interface precipitation synthesis of C-60 nanorods, effects and opportunities following an in situ photochemical transformation in the liquid state, and an electronic characterization using a field-effect transistor (FET) geometry are reported. The nanorods feature a high aspect ratio of approximate to 10(3) and a notably small average diameter of 172 nm. Interestingly, it is found that a decreased nanorod diameter appears to correlate with distinctly improved electronic properties, and an average electron mobility of 0.30 cm(2) V-1 s(-1), as measured in a FET geometry, is reported for as-grown nanorods, with the peak value being an impressive 1.0 cm(2) V-1 s(-1). A photoexposure using green laser light ( = 532 nm) is demonstrated to result in the formation of a polymer-C-60 shell encapsulating a monomer-C-60 bulk; such photo-transformed nanorods exhibit an electron mobility of 4.7 x 10(-3) cm(2) V-1 s(-1). It is notable that the utilized FET geometry only probes the polymer-C-60 nanorod surface shell, and that the monomer-C-60 bulk is anticipated to exhibit a higher mobility. Importantly, photoexposed nanorods can be conveniently processed as a stabile dispersion in common hydrophobic solvents, and this finding is attributed to the insoluble character of the polymer-C-60 shell.

  • 20.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Department of Physics, University of California, Berkeley, USA.
    Pham, Thang
    Talyzin, Alexandr V.
    Zettl, Alex
    Synthesis of graphene nanoribbons inside boron nitride nanotubes2016In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 253, no 12, p. 2377-2379Article in journal (Refereed)
    Abstract [en]

    We report on bottom-up synthesis of graphene nanoribbons inside boron nitride nanotubes, using coronene molecules as building blocks. The synthesized ribbons are one or two coronene molecules wide, depending on the diameter of the host nanotube. The encapsulated carbon nanostructures can be eliminated from the inner cavity of the filled boron nitride nanotube via oxidation without any damage to the nanotube structure.

  • 21.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA; Lawrence Berkeley Natl Lab, Div Mat Sci, Berkeley, CA 94720 USA; Univ Calif Berkeley, Kavli Energy NanoSci Inst, Berkeley, CA 94720 USA; Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA.
    Yan, Aiming
    Coh, Sinisa
    Gracia-Espino, Eduardo
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Dunn, Gabriel
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Louie, Steven G.
    Cohen, Marvin L.
    Zettl, Alex
    Electrostatically Driven Nanoballoon Actuator2016In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 16, no 11, p. 6787-6791Article in journal (Refereed)
    Abstract [en]

    We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.

  • 22.
    Beaton, Stephen
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Verktyg för utveckling av terrängparker inom skidanläggningar.: Shaper2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today we can create digital 3D models which can be realised almost instantly through production methods such as 3D printing and computer controlled milling.

    What if this same technology could be applied to the development and construction of terrain parks?

    With snow as the material tools could be developed using similar principles to design and sculpt the surface, only on a larger scale.

    How would terrain park designers adapt their process to use this new technology? In this Industrial design thesis I explore how the ideas of the terrain park designer can be expressed through such a system with focus on the designers knowledge and skill without the need to learn complicated 3D programs.

    Sketch, create, ride. 

  • 23. Bouhrara, M.
    et al.
    Abou-Hamad, E.
    Alabedi, G.
    Al-Taie, I.
    Kim, Y.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Goze-Bac, C.
    Electromagnetic Properties of Inner Double Walled Carbon Nanotubes Investigated by Nuclear Magnetic Resonance2013In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2013, p. 713475-Article in journal (Refereed)
    Abstract [en]

    The nuclear magnetic resonance (NMR) analytical technique was used to investigate the double walled carbon nanotubes (DWNTs) electromagnetic properties of inner walls. The local magnetic and electronic properties of inner nanotubes in DWNTs were analyzed using 25% (13) C enriched C-60 by which the effect of dipolar coupling could be minimized. The diamagnetic shielding was determined due to the ring currents on outer nanotubes in DWNTs. The NMR chemical shift anisotropy (CSA) spectra and spin-lattice relaxation studies reveal the metallic properties of the inner nanotubes with a signature of the spin-gap opening below 70 K.

  • 24.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Carbon nanotubes and graphene polymer composites for opto-electronic applications2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbon nanotubes are carbon based structures with outstanding electronical and mechanical properties. They are used in a wide range of applications, usually embedded in polymer in the form of composites, in order to affect the electronic behavior of the matrix material. However, as the nanotubes properties are directly dependent on their intrinsic structure, it is necessary to select specific nanotubes depending on the application, which can be a complicated and inefficient process. This makes it attractive to be able to reduce the amount of material used in the composites.

    In this thesis, focus is placed on the electrical properties of the composites. A simple patterning method is presented which allows the use of extremely low amounts of nanotubes in order to increase the electrical conductivity of diverse polymers such as polystyrene (PS) or poly(3-hexylthiophene) (P3HT). This method is called nanoimprint lithography and uses a flexible mold in order to pattern composite films, leading to the creation of conducting nanotube networks, resulting in vertically conducting samples (from the bottom of the film to the top of the imprinted patterns).

    In parallel, X-ray diffraction measurements have been conducted on thin P3HT polymer films. These were prepared on either silicon substrate or on graphene, and the influence of the processing conditions as well as of the substrate on the crystallinity of the polymer have been investigated. The knowledge of the crystalline structure of P3HT is of great importance as it influences its electronic properties. Establishing a link between the processing conditions and the resulting crystallinity is therefore vital in order to be able to make opto-electronic devices such as transistor or photovoltaic cells.

  • 25.
    Boulanger, Nicolas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nano-engineered Nanotube Networks for Enhanced Vertical Charge Transport at Ultralow Nanotube Loading in a P3HT Nanocomposite Film2014Conference paper (Refereed)
    Abstract [en]

    Due to their exceptional charge transport properties, single wall carbon nanotubes (SWNTs) are expected to enhance the performance of organic based photovoltaic (PV) solar cells through an ultrafast charge transfer process when placed in contact with a semiconducting organic interface such as poly-3-hexylthiophene (P3HT)1.

     

    However, in order to produce efficient charge transport through the active layer, a percolated network of interconnected tubes must be formed. Typical methods (e.g. spin-coating, drop-casting) do not form an efficient pathway for charges, and they often result in randomly organized networks and nanotube aggregates which have been shown to lower conductivity2,3.

     

    Here, we present a new concept where nanoscale nano-engineered SWNT networks are formed in a composite film made of >90% semi-conducting nanotubes in a P3HT matrix.4 These nanoscale networks result in several orders of magnitude increase in charge transport through the composite layer made of P3HT, and compared to an identical composite film simply spun or drop-cast. These nano-networks also result in a strong effective decrease of the percolation threshold, thereby offering the possibility to use much lower amounts of nanotubes in devices. We discuss these results and the mechanisms of charge transport enhancement.

    1. Stranks, S. D. ; Weisspfennig, C.; Parkinson, P.; Johnston, M. B. ; Herz, L. M. ; Nicholas, R. J.  Nano Lett. 2011, 11(1), 66–72.
    2. Nirmalraj, P. N. ; Lyons, P. E. ; Coleman, J. N. ; Boland, J. J. Nano Lett. 2009, 9(11), 3890–3895.
    3. Kymakis, E.; Amaratunga, G. A. J.  J. Appl. Phys. 2006, 99 (8), 084302.
    4. Barbero, D. R. ; Boulanger, N.; Ramstedt; M., Yu, J. , Advanced Materials 2014, 21, 3111.
  • 26.
    Boulanger, Nicolas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Yu, Junchun
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    SWNT nano-engineered networks strongly increase charge transport in P3HT2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 20, p. 11633-11636Article in journal (Refereed)
    Abstract [en]

    We demonstrate the formation of arrays of 3D nano- sized networks of interconnected single-wall carbon nanotubes (SWNT) with well defined dimensions in a poly-3- hexylthiophene (P3HT) thin film. These novel nanotube nano-networks produce efficient ohmic charge transport, even at very low nanotube loadings and low voltages. An increase in conductivity between one and two orders of magnitude is observed compared to a random network. The formation of these nano-engineered networks is compatible with large area imprinting and roll to roll processes, which makes it highly desirable for opto-electronic and energy conversion applications using carbon nanotubes.

  • 27. Ekeroth, Sebastian
    et al.
    Münger, E. Peter
    Boyd, Robert
    Ekspong, Joakim
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brenning, Nils
    Helmersson, Ulf
    Catalytic nanotruss structures realized by magnetic self-assembly in pulsed plasma2018In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 5, p. 3132-3137Article in journal (Refereed)
    Abstract [en]

    Tunable nanostructures that feature a high surface area are firmly attached to a conducting substrate and can be fabricated efficiently over significant areas, which are of interest for a wide variety of applications in, for instance, energy storage and catalysis. We present a novel approach to fabricate Fe nanoparticles using a pulsed-plasma process and their subsequent guidance and self-organization into well-defined nanostructures on a substrate of choice by the use of an external magnetic field. A systematic analysis and study of the growth procedure demonstrate that nondesired nanoparticle agglomeration in the plasma phase is hindered by electrostatic repulsion, that a polydisperse nanoparticle distribution is a consequence of the magnetic collection, and that the formation of highly networked nanotruss structures is a direct result of the polydisperse nanoparticle distribution. The nanoparticles in the nanotruss are strongly connected, and their outer surfaces are covered with a 2 nm layer of iron oxide. A 10 μm thick nanotruss structure was grown on a lightweight, flexible and conducting carbon-paper substrate, which enabled the efficient production of H2 gas from water splitting at a low overpotential of 210 mV and at a current density of 10 mA/cm2.

  • 28.
    Elhaj, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Monolithic space-filling porous materials from engineering plastics by thermally induced phase separation2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 18, p. 15653-15666Article in journal (Refereed)
    Abstract [en]

    Six different uncompounded engineering and commodity polymers were evaluated for their ability to produce space-filling monolithic entities by thermally induced phase separation (TIPS) from 22 different solvents. Attempts were first made to dissolve the polymers at elevated temperatures, selected below the boiling point of each solvent. Then the solutions of polymers that were homogeneous dissolved underwent a controlled temperature decrease to induce a phase separation as the upper critical solution temperature was passed. Twelve of the solvents gave monolithic entities by this procedure, materials that were characterized with regard to their specific surface area and pore size distribution. These measured parameters were then correlated with their macroporous morphology, assessed by scanning electron microscopy. Monolithic materials with widely different mesoporous properties were obtained with specific surface areas ranging from 169 m(2)/g to structures with essentially nonporous skeletons and distinct mesopore size distribution modes from 6 to 15 nm. The materials furthermore had a wide variation in their macroporous morphologies-among the same polymer processed in different solvents and between different polymers dissolved in the same solvent. TIPS processing therefore appears to be a viable route to prepare space-filling meso- and macroporous support materials for a wide variety of purposes in separation science and heterogeneous chemistry.

  • 29.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Barzegar, Hamid Reza
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sharifi, Tiva
    Yan, Aiming
    Zettl, Alex
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabrication of One-Dimensional Zigzag [6,6]-Phenyl-C-61-Butyric Acid Methyl Ester Nanoribbons from Two-Dimensional Nanosheets2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 10, p. 10516-10522Article in journal (Refereed)
    Abstract [en]

    One-dimensional (10) zigzag [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoribbons are produced by folding two-dimensional ultrathin PCBM nanosheets in a simple solvent process. The unique 1D PCBM nanostructures exhibit uniform width of 3.8 +/- 0.3 nm, equivalent to four PCBM molecules, and lengths of 20-400 nm. These nanoribbons show well-defined crystalline structure, comprising PCBM molecules in a hexagonal arrangement without trapped solvent molecules. First-principle calculations and detailed experimental characterization provide an insight into the structure and formation mechanism of the 1D PCBM nanoribbons. Given their dimensions and physical properties, we foresee that these nanostructures should be ideal as acceptor material in organic solar cells.

  • 30.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Understanding the Interface of Six-Shell Cuboctahedral and Icosahedral Palladium Clusters on Reduced Graphene Oxide: Experimental and Theoretical Study2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 18, p. 6626-6633Article in journal (Refereed)
    Abstract [en]

    Studies on noble-metal-decorated carbon nanostructures are reported almost on a daily basis, but detailed studies on the nanoscale interactions for well-defined systems are very rare. Here we report a study of reduced graphene oxide (rGOx) homogeneously decorated with palladium (Pd) nanoclusters with well-defined shape and size (2.3 +/- 0.3 nm). The rGOx was modified with benzyl mercaptan (BnSH) to improve the interaction with Pd clusters, and N,N-dimethylformamide was used as solvent and capping agent during the decoration process. The resulting Pd nanoparticles anchored to the rGOx-surface exhibit high crystallinity and are fully consistent with six-shell cuboctahedral and icosahedral clusters containing similar to 600 Pd atoms, where 45% of these are located at the surface. According to X-ray photoelectron spectroscopy analysis, the Pd clusters exhibit an oxidized surface forming a PdOx shell. Given the well-defined experimental system, as verified by electron microscopy data and theoretical simulations, we performed ab initio simulations using 10 functionalized graphenes (with vacancies or pyridine, amine, hydroxyl, carboxyl, or epoxy groups) to understand the adsorption process of BnSH, their further role in the Pd cluster formation, and the electronic properties of the graphene-nanoparticle hybrid system. Both the experimental and theoretical results suggest that Pd clusters interact with fiinctionalized graphene by a sulfur bridge while the remaining Pd surface is oxidized. Our study is of significant importance for all work related to anchoring of nanoparticles on nanocarbon-based supports, which are used in a variety of applications.

  • 31.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Science and Technology, Department of Physics.
    Jia, Xueen
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Improved oxygen reduction performance of Pt–Ni nanoparticles by adhesion on nitrogen-doped graphene2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 5, p. 2804-2811Article in journal (Refereed)
    Abstract [en]

    Graphene and its derivatives hold great potential as support for nanocatalyst in various energy applications, such as fuel cells, batteries, and capacitors. In this work, we used density functional theory to analyze substrate effect on the electrocatalytic activity of Pt–Ni bimetallic nanoparticles for oxygen reduction reaction (ORR). The dissociative mechanism is used to evaluate the ORR performance (energy barrier for O2 dissociation, free energy of intermediates, d-band center, overpotential, and electrochemical activity) for a Pt–Ni core–shell-like nanoparticle (PtNiCS) deposited on nondefective graphene (GS) or nitrogen-doped graphene (N-GS). The electronic and catalytic properties of PtNiCS on N-GS designate N-doped graphene as the best substrate to use for ORR, showing better interaction with the bimetallic cluster, improved charge transfer between constitutes, and a superior ORR performance when compared to PtNiCS on GS. The N-GS has a significant effect in reducing the energy barrier for O2 dissociation and decrease the energetic stability of HO* intermediates, resulting in enhanced ORR activity compared with the PtNiCS on GS. In addition, the strong interaction between PtNiCS cluster and N-GS substrate may lead to an improved long-term stability of the catalytic particle during ORR cycles.

  • 32.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Science and Technology, Department of Physics.
    López-Urías, F
    Kim, YA
    Hayashi, T
    Muramatsu, H
    Endo, M
    Terrones, H
    Terrones, Mauricio
    Dresselhaus, Mildred S
    Novel carbon-based nanomaterials: graphene and graphitic nanoribbons2013In: Handbook of advanced ceramics: materials; applications; processing; and properties; second edition / [ed] Shigeyuki Somiya, Oxford: Elsevier, 2013, p. 61-87Chapter in book (Other academic)
    Abstract [en]

    The fascinating characteristic of carbon atoms to create multiple orbital hybridizations (e.g., sp, sp2, or sp3) provides the possibility to synthesize one-, two-, and three-dimensional carbon nanostructures with unique physical–chemical properties. In this way, the two-dimensional (2D) carbon-atomic layered crystal (graphene) and graphitic nanoribbons have attracted the attention of several scientific groups around the world due to their novel and unusual physicochemical properties. The relative simplicity of the Novoselov–Geim method to extract a single graphene layer along with the fascinating properties of graphene, such as the linear E(k) electronic structure in monolayer graphene, has stimulated extensive experimental and theoretical studies. This chapter reviews experimental and theoretical work on graphene with special attention to graphene nanoribbons. We focus on the role of topological defects, edge chirality, and chemical doping on the electronic, transport, and structural properties of graphene and graphene nanoribbons. We also review different synthesis techniques, such as chemical vapor deposition, chemical routes, and nanotube exfoliation, to obtain carbon nanoribbons. We also summarize common characterization techniques used for graphene materials, such as scanning electron microscopy, high resolution electron microscopy, scanning tunneling spectroscopy, near edge X-ray absorption fine structure, electron spin resonance, and Raman spectroscopy techniques. Edge-state characterization and the special magnetic properties of edges are also reviewed. In addition, first-principles density functional theory calculations of the electronic and transport properties of doped armchair nanoribbons are described. Finally, we discuss the future perspectives of these graphene-like materials, including applications in electronic devices, composites, catalysts, and energy storage devices.

  • 33.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry. Advanced Materials Department, IPICYT, México.
    López-Urías, Florentino
    Terrones, Humberto
    Terrones, Mauricio
    Self-assembly synthesis of decorated nitrogen-doped carbon nanotubes with ZnO nanoparticles: anchoring mechanism and the effects of sulfur2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 1, p. 741-747Article in journal (Refereed)
    Abstract [en]

    Hybrid systems consisting of ZnO nanoparticles (ZnO-NPs) anchored on the surface of nitrogen-doped multiwalled carbon nanotubes (CNX-MWNTs) have been synthesized. The anchoring process consists of a self-assembly method involving the mixing of CNX-MWNTs in a solution with N,N-dimethylformamide, zinc acetylacetonate, and thiophene. Thiophene is used as a capping agent for controlling the size and distribution of ZnO-NPs, as well as an anchoring element between the NPs and the nanotube walls. Scanning and transmission electron microscopy characterization revealed that the ZnO-NPs are homogeneously deposited on the surface of CNX-MWNTs. X-ray powder diffraction analysis demonstrated that the ZnO-NPs exhibit a Wurtzite-type crystal structure with an average particle diameter of 5 nm. We also show that the ZnO-NPs do not exhibit a preferential growth direction with respect to the nanotube surface, and their formation is simply controlled by the concentration of the passivating agent. Density functional theory (DFT) calculations confirm that sulfur (from thiophene) is an effective passivating agent for ZnO by preferentially binding low-coordinated Zn atoms. However, the ZnO-NPs could be chemically bonded to the nanotubes through oxygen atoms close to the nitrogenated sites of the tubes. Our results also demonstrate that isolated and sulfur passivated ZnO-NPs become magnetic and exhibit half-metallicity (electronic states with only one spin component are present at the Fermi level). Sulfur-passivated ZnO retains these properties even after forming ZnO/CNX-MWNT hybrid materials.

  • 34.
    Gracia-Espino, Eduardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry. Advanced Materials Department, IPICYT, Mexico.
    Rebollo-Plata, Bernabe
    Martinez-Gutierrez, Hugo
    Munoz-Sandoval, Emilio
    Lopez-Urias, Florentino
    Endo, Morinobu
    Terrones, Humberto
    Terrones, Mauricio
    Temperature Dependence of Sensors Based on Silver-Decorated Nitrogen-Doped Multiwalled Carbon Nanotubes2016In: Journal of Sensors, ISSN 1687-725X, E-ISSN 1687-7268, article id 4319498Article in journal (Refereed)
    Abstract [en]

    Vapor sensors are easily fabricated onto alumina substrates using foils of silver-decorated nitrogen-doped multiwalled carbon nanotubes (CNX-MWNTs-Ag) as active sensing material. The vapor sensors are tested using carbon disulfide, acetone, ethanol, and chloroform vapors. The CNX-MWNTs are produced by chemical vapor deposition process and then decorated with 14 nm Ag nanoparticles (Ag-NPs). The samples are characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Our results demonstrate that Ag-decorated CNX-MWNTs exhibit a better response and sensitivity when compared with pristine CNX-MWNTs based sensors, making them promising candidates for air-pollutants environmental monitoring. The temperature effect on the sensor performance is also studied; we found that the detection mechanism could be tuned from physisorption, at room temperature, to chemisorption at higher working temperature. Finally, first-principles density functional calculations are carried out to understand the interactions between the systems involved in the sensors, finding good agreement between experimental results and the theoretical approach.

  • 35.
    Hu, Guangzhi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nitze, Florian
    Chalmers University of Technology.
    Jia, Xueen
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sharifi, Tiva
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barzegar, Hamid Reza
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Gracia-Espino, Eduardo
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Reduction free room temperature synthesis of a durable and efficient Pd/ordered mesoporous carbon composite electrocatalyst for alkaline direct alcohols fuel cell2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 2, p. 676-682Article in journal (Refereed)
    Abstract [en]

    The development of easy and environmentally benign synthesis methods of efficient electrocatalysts for use in energy conversion applications motivates researchers all over the world. Here we report a novel and versatile method to synthesize well-dispersed palladium-functionalized ordered mesoporous carbons (Pd/OMCs) at room temperature without any reducing agent by one-pot mixing of tri(dibenzylideneacetone)palladium(0) (Pd2DBA3) and OMCs together in a common N,N-dimethylformamide (DMF) solution. The formation of Pd nanoparticles and their crystallization on the OMC is catalyzed by protons in the solution and can thus be controlled by the solution pH. The complete process and the as-prepared nanocomposite was characterized by UV-spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (HTEM), X-ray photoelectron spectrum (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The electrocatalytic property of the as-decorated material was examined with cyclic voltammetry (CV). The Pd/OMC composite shows up to two times higher electrocatalytic ability with a significantly better durability towards ethanol and methanol oxidation in alkaline media compared to commercial high surface area conductive carbon black Vulcan XC-72 decorated with equivalent Pd nanoparticles. Our described method provides new insight for the development of highly efficient carbon based nanocatalysts by simple and environmentally sound methods.

  • 36.
    Huuva, Ivan
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Polymer structures for photovoltaics using colloidal self-assembly, thermal nanoimprinting and electrohydrodynamic annealing2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The efficiency of an organic photovoltaic cell depends mainly on its morphology where an exciton has to migrate to a p-n junction to create a photocurrent. Therefore the distance from the bulk of the cell to a junction interface should not exceed the diffusion length of the exciton. In this thesis, two novel lithographical methods, to produce specific polymer morphologies, were developed and evaluated. In the first method, called embedded annealing, self-assembled polystyrene colloids were embedded in a polydimethylsiloxane (PDMS) film and annealed under an electric field to produce a bi-polymer structure consisting of polymer columns in a thin film of PDMS. Polymer colloids were successfully assembled into two dimensional hexagonally close packed arrays. However, the annealing process was unsuccessful. The second method, imprint annealing, aimed to increase the aspect ratio (height/width) of thermally imprinted micrometer sized polystyrene features by annealing them in uniform electric fields. The results showed that the aspect ratio of imprinted features can be significantly increased, 21-fold, while maintaining the periodicity of the original imprint. This is in contrast to previous results where smooth polymer films annealed in uniform fields where the periodicity of the resulting structures cannot be independently controlled, and are highly sensitive to the electrode spacing. Feature sizes down to 1 µm and aspect ratios up to 4.5 were achieved using imprint annealing.

  • 37. Jehova Gonzalez, Viviana
    et al.
    Gracia-Espino, Eduardo
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Morelos-Gomez, Aaron
    Lopez-Urias, Florentino
    Terrones, Humberto
    Terrones, Mauricio
    Biotin molecules on nitrogen-doped carbon nanotubes enhance the uniform anchoring and formation of Ag nanoparticles2015In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 88, p. 51-59Article in journal (Refereed)
    Abstract [en]

    An efficient method for anchoring silver nanoparticles (Ag-NPs) on the surface of nitrogendoped multi-walled carbon nanotubes (CNx-MWCNTs) is reported. The process involves the attachment of biotin molecules on the surface of CNx-MWCNTs (both, pristine and acid treated) that act as a reducing agent for AgNO3, thus generating an efficient and homogeneous coating of Ag-NPs (similar to 3 nm in diameter). The reduction of AgNO3 on either pristine CNx-MWCNTs or acid treated CNx-MWCNTs (without biotin) results in Ag-NPs of large diameters and size distribution, in addition to a low anchoring efficiency. We confirmed that the use of biotin substantially improves the Ag-NPs anchoring efficiency, especially on acid treated CNx-MWCNTs. In order to elucidate the mechanism whereby Ag-NPs strongly bind to the surface of CNx-MWCNTs, density functional theory (DFT) calculations were carried out. These revealed the existence of covalent bonds established between one side of the biotin molecule and the CNx-MWCNT surface through oxygen atoms, leaving accessible the exposed sulfur atoms at the other end, which further provided an excellent interaction with the Ag-NPs via S Ag bonds. Finally, we demonstrate that these Ag-NPs coated CNx-MWCNTs could be used as efficient sensors of CS2. (c) 2015 Elsevier Ltd. All rights reserved.

  • 38.
    Jia, Xueen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nitze, Florian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barzegar, Hamid Reza
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sharifi, Tiva
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Tai, Cheuk-Wai
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Synthesis of Palladium/Helical Carbon Nanofiber Hybrid Nanostructures and Their Application for Hydrogen Peroxide and Glucose Detection2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 22, p. 12017-12022Article in journal (Refereed)
    Abstract [en]

    We report on a novel sensing platform for H2O2 and glucose based on immobilization of palladium-helical carbon nanofiber (Pd-HCNF) hybrid nanostnictures and glucose oxidase (GOx) with Nafion on a glassy carbon electrode (GCE). HCNFs were synthesized by a chemical vapor deposition process on a C-60-supported Pd catalyst. Pd-HCNF nanocomposites were prepared by a one-step reduction free method in dimethylformamide (DMF). The prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The Nafion/Pd-HCNF/GCE sensor exhibits excellent electrocatalytic sensitivity toward H2O2 (315 mA M-1 cm(-2)) as probed by cyclic voltammetry (CV) and chronoamperometry. We show that Pd-HCNF-modified electrodes significantly reduce the overpotential and enhance the electron transfer rate. A linear range from 5.0 mu M to 2.1 mM with a detection limit of 3.0 mu M (based on the S/N = 3) and good reproducibility were obtained. Furthermore, a sensing platform for glucose was prepared by immobilizing the Pd-HCNFs and glucose oxidase (GOx) with Nafion on a glassy carbon electrode. The resulting biosensor exhibits a good response to glucose with a wide linear range (0.06-6.0 mM) with a detection limit of 0.03 mM and a sensitivity of 13 mA M-1 cm(-2). We show that small size and homogeneous distribution of the Pd nanoparticles in combination with good conductivity and large surface area of the HCNFs lead to a H2O2 and glucose sensing platform that performs in the top range of the herein reported sensor platforms.

  • 39. Jiang, Linhai
    et al.
    Yao, Mingguang
    Liu, Bo
    Li, Quanjun
    Liu, Ran
    Lv, Hang
    Lu, Shuangchen
    Gong, Chen
    Zou, Bo
    Cui, Tian
    Liu, Bingbing
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Controlled Synthesis of CeO2/Graphene Nanocomposites with Highly Enhanced Optical and Catalytic Properties2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 21, p. 11741-11745Article in journal (Refereed)
    Abstract [en]

    In this paper, CeO2 nanocubes with the (200)-terminated surface/graphene sheet composites have been prepared successfully by a simple hydrothermal method. It is found that the CeO2 nanocubes with high crystallinity and specific exposed surface are well dispersed on well-exfoliated graphene surface. The (200)-terminated surface/graphene sheet composites modified electrode showed much higher sensitivity and excellent selectivity in its catalytic performance compared to a CeO2 nanoparticle-modified electrode. The photoluminescence intensity of the CeO2 anchored on graphene is about 30 times higher than that of pristine CeO2 crystals in air. The higher oxygen vacancy concentration in CeO2 is supposed to be an important cause for the higher photoluminescence and better electrochemical catalytic performance observed in the (200)-terminated surface/graphene sheet composites. Such ingenious design of supported well-dispersed catalysts in nanostructured ceria catalysts, synthesized in one step with an exposed high-activity surface, is important for technical applications and theoretical investigations.

  • 40.
    Johansson, Linus
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A transparent conductive electrode (TCE) is an important component in many of our modern optoelectronic devices like photovoltaics, light emitting diodes and touch screens. These devices require good current injection and spreading as well as a high transparency. In this thesis we explore the use of graphene as an alternative to the current widely used indium tin oxide (ITO) as TCE in gallium nitride (GaN) based light emitting diodes (LEDs). Monolayer crystalline graphene can be produced on copper foils using chemical vapor deposition (CVD), where metals (especially copper) has a catalysing effect on the formation of graphene. However, transfer of graphene from copper foils is not suitable for an industrial scale and it results in a poor contact with the target substrate. We investigate the possibility of directly integrating graphene on GaN-based LEDs by using plasma-enhanced chemical vapor deposition (PECVD). We try to obtain the optimal conditions under these catalyst-free circumstances and propose a recipe adapted for the setup that we used. We will also study ideas of using a metal (we tried copper and nickel) to assist the direct growth that could help to increase the fraction of sp2 carbon bonds and reduce the sheet resistance. The metals are evaporated onto our samples either before or after we grow a carbon film to either assist the growth or rearrange the carbon respectively. The focus was not on trying to optimize the conditions for one metal treatment but rather to briefly explore multiple methods to find a suitable path for further studies. The direct grown pristine carbon films shows indications from Raman measurements of being nanocrystalline graphene with a sheet resistance ranging from about 20-50 kΩ/sq having a transmittance of approximately 96 % at 550 nm. A transmittance at this level is closely related to the value of an ideal monolayer graphene, which indicates that our carbon films could be close to one atom in thickness while being visually homogeneous and complete in coverage. Due to the use of a temperature close to the melting point of copper we struggled to keep the assisting copper from evaporating too fast or staying homogeneous after the treatment. Nickel has a higher melting temperature, but it appears as if this metal might be diffusing into the GaN substrate which changes the properties of both the GaN and carbon film. Even though the metal treatments that we tested did not provide any noticeable improvements, there is need for further investigations to obtain suitable treatment conditions. We suggest that the treatments involving copper are a more promising path to pursue as nickel seem to cause unavoidable intermixing problems.

  • 41. Johansson, Staffan B.
    et al.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Stemme, Göran
    Roxhed, Niclas
    A MEMS-based passive hydrocephalus shunt for body position controlled intracranial pressure regulation2014In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 16, no 4, p. 529-536Article in journal (Refereed)
    Abstract [en]

    This paper reports a novel micro electro mechanical system (MEMS) valve with posture controlled flow characteristics for improved treatment of hydrocephalus, a disease that is characterized by elevated pressure in the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. In contrast to conventional differential pressure CSF valves, the CSF valve presented here features a third port which utilizes hydrostatic pressure from a pressure compensating catheter to adapt CSF drainage to optimized levels irrespective of body position. Prototypes have been fabricated using standard MEMS manufacturing processes and the experimental evaluation successfully showed that the flow rate was adjustable with a varying hydrostatic pressure on the third port. Measured data showed that flow rate was at near ideal values at laying body position and that the flow rate can be adjusted to optimal values at standing body position by selecting an appropriate length of the pressure compensating catheter. This is the first pressure balanced CSF valve intended for body position controlled CSF pressure regulation.

  • 42.
    Klechikov, Alexey
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Comment on "Nanohole-Structured and Palladium-Embedded 3D Porous Graphene for Ultrahigh Hydrogen Storage and CO Oxidation Multifunctionalities"2016In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, no 10, p. 9055-9056Article in journal (Refereed)
  • 43. Kordás, Krisztián
    et al.
    Kukkola, Jarmo
    Tóth, Géza
    Jantunen, Heli
    Szabó, Mária
    Sápi, András
    Kukovecz, Ákos
    Kónya, Zoltán
    Mikkola, Jyri-Pekka
    Department of Chemical Engineering, Åbo Akademi University, Åbo-Turku, Finland.
    Nanoparticle Dispersions2013In: Springer Handbook of Nanomaterials / [ed] Robert Vajtai, Springer Berlin/Heidelberg, 2013, p. 729-776Chapter in book (Refereed)
    Abstract [en]

    This chapter aims to provide an insight into the physics and chemistry of nanoparticle–liquid systems. The first part of the chapter discusses parameters and effects that influence dispersion stability (Sect. 20.1), including particle size and shape as well as the interactions at the interface between the solid and liquid phases. Section 20.2 summarizes the practical aspects of making a dispersion, collecting and listing hundreds of examples from contemporary literature. Because of the broad spectrum of materials in question, the survey is limited to dispersions of inorganic nanoparticles including metals, their oxides/sulfides, some (compound) semiconductors, as well as nanostructured carbon particles such as fullerenes, nanotubes, and graphene/graphite (Sect. 20.3). Dispersions of polymers of either synthetic or biological origin lie beyond the scope of this work. Since a very large fraction of applications are related to various surface coatings using dispersions as the source of nanoparticles, Sect. 20.4 is devoted to drying phenomena and particle self-ordering.

  • 44. Kumar, Abhinav
    et al.
    Bicer, Elif Melis
    Morgan, Anna Babin
    Pfeffer, Paul E.
    Monopoli, Marco
    Dawson, Kenneth A.
    Eriksson, Jonny
    Edwards, Katarina
    Lynham, Steven
    Arno, Matthew
    Behndig, Annelie F.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Somers, Graham
    Hassall, Dave
    Dailey, Lea Ann
    Forbes, Ben
    Mudway, Ian S.
    Enrichment of immunoregulatory proteins in the biomolecular corona of nanoparticles within human respiratory tract lining fluid2016In: Nanomedicine: Nanotechnology, Biology and Medicine, ISSN 1549-9634, E-ISSN 1549-9642, Vol. 12, no 4, p. 1033-1043Article in journal (Refereed)
    Abstract [en]

    When inhaled nanoparticles deposit in the lungs, they transit through respiratory tract lining fluid (RTLF) acquiring a biomolecular corona reflecting the interaction of the RTLF with the nanomaterial surface. Label-free snapshot proteomics was used to generate semiquantitative profiles of corona proteins formed around silica (SiO2) and poly(vinyl) acetate (PVAc) nanoparticles in RTLF, the latter employed as an archetype drug delivery vehicle. The evolved PVAc corona was significantly enriched compared to that observed on SiO2 nanoparticles (698 vs. 429 proteins identified); however both coronas contained a substantial contribution from innate immunity proteins, including surfactant protein A, napsin A and complement (C1q and C3) proteins. Functional protein classification supports the hypothesis that corona formation in RTLF constitutes opsonisation, preparing particles for phagocytosis and clearance from the lungs. These data highlight how an understanding of the evolved corona is necessary for the design of inhaled nanomedicines with acceptable safety and tailored clearance profiles. From the Clinical Editor: Inhaled nanoparticles often acquire a layer of protein corona while they go through the respiratory tract. Here, the authors investigated the identity of these proteins. The proper identification would improve the understanding of the use of inhaled nanoparticles in future therapeutics. (C) 2016 Published by Elsevier Inc.

  • 45.
    Lappalainen, Reijo
    et al.
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Korhonen, Hannu
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Kaitainen, Salla
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Myllymaa, Sami
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Qu, Chengjuan
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Lammi, Mikko J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nanostructured coatings for biomedical applications by ultra short pulsed laser deposition2015In: Comprehensive guide for nanocoatings technology: Volume 3, Properties and development / [ed] Mahmoud Aliofkhadzraei, Nova Science Publishers, Inc., 2015, 3, p. 309-323Chapter in book (Refereed)
    Abstract [en]

    Ultra short pulsed laser deposition (USPLD) technique is a novel, well-controlled physical vapour deposition method to deposit a wide variety of nanocoatings on solid substrate materials with good adhesion and various surface nanotopographies. Coating materials include ceramics, like Al2O3, TiO2, carbon nitride and amorphous diamond, metals, such as platinum, titanium and Ti6Al4V, as well as polymers, composite materials and so on. In this chapter, we demonstrate and review the possibilities of USPLD for modified biomaterial surfaces in medical applications, such as cell culture plates, electrodes or implants used in orthopaedics and dentistry. The coatings are used to control, e.g., cell growth and proliferation, bacterial adhesion, bioelectrical properties, corrosion, friction and wear.

  • 46.
    Larsen, Christian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabricating designed fullerene nanostructures for functional electronic devices2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A long-term goal within the field of organic electronics has been to developflexible and functional devices, which can be processed and patterned withlow-cost and energy-efficient solution-based methods. This thesis presents anumber of functional paths towards the attainment of this goal via thedevelopment and demonstration of novel fabrication and patterningmethods involving the important organic-semiconductor family termedfullerenes.Fullerenes are soccer-shaped small molecules, with two often-employedexamples being the symmetric C60 molecule and its more soluble derivative[6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We show that PCBM canbe photochemically transformed into a dimeric state in a bi-excited reactionprocess, and that the exposed material features a significantly reducedsolubility in common solvents as well as an effectively retained electronmobility. This attractive combination of material properties allows for adirect and resist-free lithographic patterning of electronic PCBM films downto a smallest feature size of 1 µm, using a simple and scalable two-stepprocess constituting light exposure and solution development. In a furtherdevelopment, it was shown that the two-step method was useful also in thearea-selective transformation of fullerene/conjugated-polymer blend films,as demonstrated through the realization of a functional complementary logiccircuit comprising a 5-stage ring oscillator.In another project, we have synthesized highly flexible, single-crystal C60nanorods with a solution-based self-assembly process termed liquid-liquidinterfacial precipitation. The 1-dimensional nanorods can be deposited fromtheir synthesis solution and employed as the active material in field-effecttransistor devices. Here, it was revealed that the as-fabricated nanorods canfeature an impressive electron mobility of 1.0 cm2 V-1 s-1, which is on par withthe performance of a work horse in the transistor field, viz. vacuumdeposited amorphous Si. We further demonstrated that the processability ofthe nanorods can be improved by a tuned light-exposure treatment, duringwhich the nanorod shell is polymerized while the high-mobility interior bulkis left intact. This has the desired consequence that stabile nanoroddispersions can be prepared in a wide range of solvents, and we anticipatethat functional electronic devices based on solution-processable nanorodscan be realized in a near future.

  • 47. Louw, Andrew M
    et al.
    Kolar, Mallappa K
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Novikova, Liudmila N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Kjems, Jørgen
    Novikov, Lev N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Chitosan polyplex mediated delivery of miRNA-124 reduces activation of microglial cells in vitro and in rat models of spinal cord injury2016In: Nanomedicine: Nanotechnology, Biology and Medicine, ISSN 1549-9634, E-ISSN 1549-9642, Vol. 12, no 3, p. 643-653Article in journal (Refereed)
    Abstract [en]

    Traumatic injury to the central nervous system (CNS) is further complicated by an increase in secondary neuronal damage imposed by activated microglia/macrophages. MicroRNA-124 (miR-124) is responsible for mouse monocyte quiescence and reduction of their inflammatory cytokine production. We describe the formulation and ex vivo transfection of chitosan/miR-124 polyplex particles into rat microglia and the resulting reduction of reactive oxygen species (ROS) and TNF-α and lower expression of MHC-II. Upon microinjection into uninjured rat spinal cords, particles formed with Cy3-labeled control sequence RNA, were specifically internalized by OX42 positive macrophages and microglia cells. Alternatively particles injected in the peritoneum were transported by macrophages to the site of spinal cord injury 72h post injection. Microinjections of chitosan/miR-124 particles significantly reduced the number of ED-1 positive macrophages in the injured spinal cord. Taken together, these data present a potential treatment technique to reduce inflammation for a multitude of CNS neurodegenerative conditions.

  • 48.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nanomagnetism in otherwise nonmagnetic materials2010In: Handbook of Nanophysics: Vol. 1. Principles and Methods / [ed] Sattler, Klaus D., Boca Raton, Fla.: Taylor and Francis , 2010, p. 25-30Chapter in book (Other academic)
  • 49. McDonagh, Birgitte H.
    et al.
    Volden, Sondre
    Lystvet, Sina M.
    Singh, Gurvinder
    Ese, Marit-Helen G.
    Ryan, Joseph A.
    Lindgren, Mikael
    Sandvig, Axel
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Norwegian Univ Sci & Technol NTNU, Fac Med, Dept Neurosci, N-7491 Trondheim, Norway.
    Sandvig, Ioanna
    Glomm, Wilhelm R.
    Self-assembly and characterization of transferrin-gold nanoconstructs and their interaction with bio-interfaces2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 17, p. 8062-8070Article in journal (Refereed)
    Abstract [en]

    Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein's site-specific receptor targeting capabilities with the optical properties imparted by the nano-sized gold. We have described two different synthesis protocols, one yielding fluorescent Tf-stabilized gold nanoclusters (AuNCs) and one yielding Tf-stabilized gold nanoparticles that exhibit localized surface plasmon resonance. We demonstrate that the synthetic route employed has a large influence both on the gold nanostructure formed, and also on the structural integrity of the protein. A slight protein unfolding allows stronger interaction with lipids, and was found to significantly perturb lipid monolayers. Interactions between the protein-gold nanostructures and three different cell types were also assessed, indicating that the enhanced membrane affinity may be attributed to intercellular membrane differences.

  • 50.
    Moberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Creating nanopatterned polymer films for use in light-emitting electrochemical cells2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Thermal nanoimprint lithography (T-NIL) is a cheap and fast technique to produce nanopatterns in polymeric materials. It creates these patterns by pressing a stamp down into a polymer film that has been heated above its glass transition temperature. These nanopatterned polymer films can be used in a wide variety of scientific fields, not the least the organic semiconductor industry. There the nanopatterned films have, among else, been used to improve the efficiency of organic light-emitting diodes (OLEDs). The light-emitting electrochemical cell (LEC), which is similar in structure to an OLED, also uses polymer films in their device structure but the light emitting layer also contains an electrolyte. However, it has not been shown if nanopatterns can improve LECs as well or if it is even possible to make an imprint in their polymer films that are mixed with an electrolyte.

    This thesis shows that T-NIL can be used to imprint nanopatterns in films made of poly(ethylene oxide) and the conjugated polymer Super Yellow. The best nanopatterns were produced by setting the imprint parameters to  85 °C, 10 bar, 1800 s for poly(ethylene oxide) and 115 °C, 20 bar, 1800 s for Super Yellow. Imprints were also performed on polystyrene but no nanopatterns could be produced. This was most likely because the stamp could not handle the high temperature that is required to make a nanopattern in polystyrene.

    The best imprint parameters of Super Yellow were then used to produce a pattern in a film made of Super Yellow mixed with the salt tetrahexylammonium tetrafluoroborate (THABF4) in order to be able to produce one imprinted and one reference LEC. The imprinted LEC had a luminosity of 139 cd/m2, an improvement of 20% compared to the reference’s 115 cd/m2 when operated under identical conditions.  The forward direction and the angular dependent electroluminescence spectrum of the imprinted LEC clearly showed an effect not observed in the reference.

    These findings show that the polymer films used in a LEC can be imprinted with a nanopattern by using T-NIL. The imprinted films can be used to create functional LECs that show different behavior and a higher luminosity compared to a non-imprinted reference. If these results can be repeated it might be the starting point of a brighter future.

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