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  • 1.
    Burger, Paul
    et al.
    Chalmers University of Technology, Sweden; Johannes Gutenberg University Mainz, Germany.
    Singh, G.
    Chalmers University of Technology, Sweden; Institute of Materials Science of Barcelona , Spain.
    Johansson, Christer
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Chalmers University of Technology, Sweden.
    Moya, Carlos
    Université Libre de Bruxelles, Belgium.
    Bruylants, Gilles
    Université Libre de Bruxelles, Belgium.
    Jakob, Gerhard
    Johannes Gutenberg University Mainz, Germany.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Atomic Force Manipulation of Single Magnetic Nanoparticles for Spin-Based Electronics2022In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 16, no 11, p. 19253-19260Article in journal (Refereed)
    Abstract [en]

    Magnetic nanoparticles (MNPs) are instrumental for fabrication of tailored nanomagnetic structures, especially where top-down lithographic patterning is not feasible. Here, we demonstrate precise and controllable manipulation of individual magnetite MNPs using the tip of an atomic force microscope. We verify our approach by placing a single MNP with a diameter of 50 nm on top of a 100 nm Hall bar fabricated in a quasi-two-dimensional electron gas (q2DEG) at the oxide interface between LaAlO3 and SrTiO3 (LAO/STO). A hysteresis loop due to the magnetic hysteresis properties of the magnetite MNPs was observed in the Hall resistance. Further, the effective coercivity of the Hall resistance hysteresis loop could be changed upon field cooling at different angles of the cooling field with respect to the measuring field. The effect is associated with the alignment of the MNP magnetic moment along the easy axis closest to the external field direction across the Verwey transition in magnetite. Our results can facilitate experimental realization of magnetic proximity devices using single MNPs and two-dimensional materials for spin-based nanoelectronics. © 2022 The Authors. 

  • 2.
    Faraz, S. M.
    et al.
    University of Engineering and Technology, Pakistan.
    Un Nabi Jafri, S. R.
    University of Engineering and Technology, Pakistan.
    Khan, H. R.
    University of Engineering and Technology, Pakistan.
    Shah, W.
    University of Engineering and Technology, Pakistan.
    Ul Hassan Alvi, Naveed
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Ul Wahab, Q.
    Linköping University, Sweden.
    Nur, O.
    Linköping University, Sweden.
    Effect of annealing temperature on the interface state density of n-ZnO nanorod/p-Si heterojunction diodes2021In: Open Physics, ISSN 2391-5471, Vol. 19, no 1, p. 467-476Article in journal (Refereed)
    Abstract [en]

    The effect of post-growth annealing treatment of zinc oxide (ZnO) nanorods on the electrical properties of their heterojunction diodes (HJDs) is investigated. ZnO nanorods are synthesized by the low-temperature aqueous solution growth technique and annealed at temperatures of 400 and 600°C. The as-grown and annealed nanorods are studied by scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electrical characterization of the ZnO/Si heterojunction diode is done by current–voltage (I–V) and capacitance–voltage (C–V) measurements at room temperature. The barrier height (ϕB), ideality factor (n), doping concentration and density of interface states (NSS) are extracted. All HJDs exhibited a nonlinear behavior with rectification factors of 23, 1,596 and 309 at ±5 V for the as-grown, 400 and 600°C-annealed nanorod HJDs, respectively. Barrier heights of 0.81 and 0.63 V are obtained for HJDs of 400 and 600°C-annealed nanorods, respectively. The energy distribution of the interface state density has been investigated and found to be in the range 0.70 × 1010 to 1.05 × 1012 eV/cm2 below the conduction band from EC = 0.03 to EC = 0.58 eV. The highest density of interface states is observed in HJDs of 600°C-annealed nanorods. Overall improved behavior is observed for the heterojunctions diodes of 400°C-annealed ZnO nanorods. © 2021 Sadia Muniza Faraz et al.

  • 3.
    Faraz, Sadia
    et al.
    NED University of Engineering and Technology, Pakistan.
    Jafri, Syed
    NED University of Engineering and Technology, Pakistan.
    Tajvar, Zarreen
    NED University of Engineering and Technology, Pakistan.
    Ul Hassan Alvi, Naveed
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Wahab, Qamar
    Linkoping University, Sweden.
    Nur, Omer
    Linkoping University, Sweden.
    Effect of annealing atmosphere on the diode behaviourof zno/si heterojunction2021In: Elektronika ir Elektrotechnika, ISSN 1392-1215, Vol. 27, no 4, p. 49-54Article in journal (Refereed)
    Abstract [en]

    The effect of thermal annealing atmosphere on the electrical characteristics of Zinc oxide (ZnO) nanorods/p-Silicon (Si) diodes is investigated. ZnO nanorods are grown by low-temperature aqueous solution growth method and annealed in Nitrogen and Oxygen atmosphere. As-grown and annealed nanorods are studied by scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electrical characteristics of ZnO/Si heterojunction diodes are studied by current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. Improvements in rectifying behaviour, ideality factor, carrier concentration, and series resistance are observed after annealing. The ideality factor of 4.4 for as-grown improved to 3.8 and for Nitrogen and Oxygen annealed improved to 3.5 nanorods diodes. The series resistances decreased from 1.6 to 1.8 times after annealing. An overall improved behaviour is observed for oxygen annealed heterojunction diodes. The study suggests that by controlling the ZnO nanorods annealing temperatures and atmospheres the electronic and optoelectronic properties of ZnO devices can be improved.

  • 4.
    He, Hans
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Cedergren, Karin
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Shetty, Naveen
    Chalmers University of Technology, Sweden.
    Lara-Avila, Samuel
    Chalmers University of Technology, Sweden; NPL, UK.
    Kubatkin, Sergey
    Chalmers University of Technology, Sweden.
    Bergsten, Tobias
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Eklund, Gunnar
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Accurate graphene quantum Hall arrays for the new International System of Units2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 6933Article in journal (Refereed)
    Abstract [en]

    Graphene quantum Hall effect (QHE) resistance standards have the potential to provide superior realizations of three key units in the new International System of Units (SI): the ohm, the ampere, and the kilogram (Kibble Balance). However, these prospects require different resistance values than practically achievable in single graphene devices (~12.9 kΩ), and they need bias currents two orders of magnitude higher than typical breakdown currents IC ~ 100 μA. Here we present experiments on quantization accuracy of a 236-element quantum Hall array (QHA), demonstrating RK/236 ≈ 109 Ω with 0.2 part-per-billion (nΩ/Ω) accuracy with IC ≥ 5 mA (~1 nΩ/Ω accuracy for IC = 8.5 mA), using epitaxial graphene on silicon carbide (epigraphene). The array accuracy, comparable to the most precise universality tests of QHE, together with the scalability and reliability of this approach, pave the road for wider use of graphene in the new SI and beyond. © 2022, The Author(s).

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  • 5.
    Heydari, Golrokh
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sedighi Moghaddam, Maziar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. KTH Royal Institute of Technology, Sweden.
    Tuominen, Mikko
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Fielden, Matthew
    KTH Royal Institute of Technology, Sweden.
    Haapanen, Janne
    TUT Tampere University of Technology, Finland.
    Mäkelä, Jyrki M.
    TUT Tampere University of Technology, Finland.
    Claesson, Per M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. KTH Royal Institute of Technology, Sweden.
    Wetting hysteresis induced by temperature changes: Supercooled water on hydrophobic surfaces2016In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 468, p. 21-33Article in journal (Refereed)
    Abstract [en]

    The state and stability of supercooled water on (super)hydrophobic surfaces is crucial for low temperature applications and it will affect anti-icing and de-icing properties. Surface characteristics such as topography and chemistry are expected to affect wetting hysteresis during temperature cycling experiments, and also the freezing delay of supercooled water. We utilized stochastically rough wood surfaces that were further modified to render them hydrophobic or superhydrophobic. Liquid flame spraying (LFS) was utilized to create a multi-scale roughness by depositing titanium dioxide nanoparticles. The coating was subsequently made non-polar by applying a thin plasma polymer layer. As flat reference samples modified silica surfaces with similar chemistries were utilized. With these substrates we test the hypothesis that superhydrophobic surfaces also should retard ice formation. Wetting hysteresis was evaluated using contact angle measurements during a freeze-thaw cycle from room temperature to freezing occurrence at -7 °C, and then back to room temperature. Further, the delay in freezing of supercooled water droplets was studied at temperatures of -4 °C and -7 °C. The hysteresis in contact angle observed during a cooling-heating cycle is found to be small on flat hydrophobic surfaces. However, significant changes in contact angles during a cooling-heating cycle are observed on the rough surfaces, with a higher contact angle observed on cooling compared to during the subsequent heating. Condensation and subsequent frost formation at sub-zero temperatures induce the hysteresis. The freezing delay data show that the flat surface is more efficient in enhancing the freezing delay than the rougher surfaces, which can be rationalized considering heterogeneous nucleation theory. Thus, our data suggests that molecular flat surfaces, rather than rough superhydrophobic surfaces, are beneficial for retarding ice formation under conditions that allow condensation and frost formation to occur.

  • 6.
    Hjalmarsson, Nicklas
    et al.
    KTH The Royal Institute of Technology, Sweden.
    Atkin, Rob
    University of Newcastle, Australia.
    Rutland, Mark W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, Sweden.
    Is the boundary layer of an ionic liquid equally lubricating at higher temperature?2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 13, p. 9232-9239Article in journal (Refereed)
    Abstract [en]

    Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system.

  • 7.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Stormvinter, Albin
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Andersson, Pär
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Lundin, Per
    Ludin Stress Service AB, Sweden.
    Influence of Local Electropolishing Conditions on Ferritic–Pearlitic Steel on X-Ray Diffraction Residual Stress Profiling2023In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Article in journal (Refereed)
    Abstract [en]

    Layer removal with electropolishing is a well-established method when measuring residual stress profiles with lab-XRD. This is done to measure the depth impact from processes such as shot peening, heat treatment, or machining. Electropolishing is used to minimize the influence on the inherent residual stresses of the material during layer removal, performed successively in incremental steps to specific depths followed by measurement. Great control of the material removal is critical for the measured stresses at each depth. Therefore, the selection of size of the measurement spot and electropolishing parameters is essential. The main objective in this work is to investigate how different electrolytes and electropolishing equipment affect the resulting surface roughness, geometry, microstructure, and consequently the measured residual stress. A second objective has been to establish a methodology of assessing the acquired electropolished depth. The aim has been to get a better understanding of the influence of the layer removal method on the accuracy of the acquired depth. Evaluation has been done by electropolishing one ground and one shot peened sample of a low-alloy carbon steel, grade 1.1730, with different methods. The results showed a difference in stresses depending on the electrolyte used where the perchloric acid had better ability to retain the stresses compared to the saturated salt. Electropolishing with saturated salt is fast and results in evenly distributed material removal but has high surface roughness, which is due to a difference in electropolishing of the two phases, ferrite, and pearlite. Perchloric acid electropolishing is slower but generates a smooth surface as both ferrite and pearlite have the same material removal rates but may cause an increased material removal for the center of the electropolished area. In this work, it is suggested to use perchloric acid electropolishing for the final layer removal step. © 2023, The Author(s).

  • 8.
    Jakubek, Ryan S.
    et al.
    NASA Johnson Space Center, USA.
    Bhartia, Rohit
    Photon Systems Incorporated, USA.
    Uckert, Kyle
    California Institution of Technology, USA.
    Asher, Sanford A.
    University of Pittsburgh, USA.
    Czaja, Andrew D.
    University of Cincinnati, USA.
    Fries, Marc D.
    NASA Johnson Space Center, USA.
    Hand, Kevin
    California Institution of Technology, USA.
    Haney, Nikole C.
    NASA Johnson Space Center, USA.
    Razzell Hollis, Joseph
    The Natural History Museum, UK.
    Minitti, Michelle
    Framework, USA.
    Sharma, Shiv K.
    University of Hawaii, USA.
    Sharma, Sunanda
    California Institution of Technology, USA.
    Siljeström, Sandra
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Calibration of Raman Bandwidths on the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Deep Ultraviolet Raman and Fluorescence Instrument Aboard the Perseverance Rover2023In: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530Article in journal (Refereed)
    Abstract [en]

    In this work, we derive a simple method for calibrating Raman bandwidths for the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument onboard NASA’s Perseverance rover. Raman bandwidths and shapes reported by an instrument contain contributions from both the intrinsic Raman band (IRB) and instrumental artifacts. To directly correlate bandwidth to sample properties and to compare bandwidths across instruments, the IRB width needs to be separated from instrumental effects. Here, we use the ubiquitous bandwidth calibration method of modeling the observed Raman bands as a convolution of a Lorentzian IRB and a Gaussian instrument slit function. Using calibration target data, we calculate that SHERLOC has a slit function width of 34.1 cm–1. With a measure of the instrument slit function, we can deconvolve the IRB from the observed band, providing the width of the Raman band unobscured by instrumental artifact. We present the correlation between observed Raman bandwidth and intrinsic Raman bandwidth in table form for the quick estimation of SHERLOC Raman intrinsic bandwidths. We discuss the limitations of using this model to calibrate Raman bandwidth and derive a quantitative method for calculating the errors associated with the calibration. We demonstrate the utility of this method of bandwidth calibration by examining the intrinsic bandwidths of SHERLOC sulfate spectra and by modeling the SHERLOC spectrum of olivine. 

  • 9.
    Karlsson, Stefan
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Functional cover glass materials for solar energy applications2023Conference paper (Other academic)
    Abstract [en]

    Glass materials are essential in everyone’s life by enabling daylight to reach the interior of our buildings,being the primary component for communication via optical fibers and a key component in electronic devices as protective cover and/or dielectric material. It is also an essential component in solar energy applications which comprise, e.g., photovoltaics , solar thermal collectors, greenhouses and algae reactors, by acting as a protective and light transmitting barrier. Adding functionalities to glass in an intelligent way creates opportunities to enhance the properties of the glass material for its use. There are several possibilities to add functionalities and the wider concept Transparent Intelligence will be briefly introduced and how it can aid our efforts to overcome today’s societal challenges. Glass as a cover material for solar energy applications constitutes a significant part of the costs and isan important component for efficient light capture and protection to the environment. The research and development of cover glass for solar energy applications have so far received limited attention eventhough it is an important material for our future sustainable development. Recent research efforts have provided knowledge of which properties that needs to be optimized ‐ balancing efficiency, service lifetime and cost. The challenges of cover glass for different solar energy applications differs somewhat but all have in common the efficient solar light capture and protection to the environment. Thus, theknow‐how can be used in several different industrial sectors. The fundamentals of cover glasses for solarenergy applications as well as previous and on‐going project concepts will be presented. This includes i) state‐of‐the‐art of cover materials for greenhouses, ii) results on optimization of cover glass for photovoltaics, iii) initial results on how to provide both anti‐reflective and anti‐soiling properties,iv) results on broadband antireflective coatings for solar thermal energy, and v) other promising concepts. At last will some future challenges and needs be discussed, e.g., in relation to the concept ofideal material choices for PV.

  • 10.
    Karlsson, Stefan
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Eklund, Per
    Linköping University, Sweden.
    Österlund, Lars
    Uppsala University, Sweden.
    Birch, Jens
    Linköping University, Sweden.
    Ali, Sharafat
    Linnæus University, Sweden.
    Effects of deposition temperature on the mechanical and structural properties of amorphous Al-Si-O thin films prepared by radio frequency magnetron sputtering2023In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 787, article id 140135Article in journal (Refereed)
    Abstract [en]

    Aluminosilicate (Al–Si–O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 °C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al–O–Al vibrational band (at 1050 cm−1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hardness. The same Al–O–Al vibrational band (at 1050 cm−1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

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  • 11.
    Karlsson, Stefan
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Järn, Mikael
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Zäll, Erik
    Umeå University, Sweden.
    Antireflektiv beläggning i världsklass ger effektivare solfångare2023In: GLAS, no 4, p. 36-37Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    I ett nyligen avslutat forskningsprojekt har Absolicon Solar Collector tillsammans med RISE Research Institutes of Sweden och Umeå universitet utvecklat en ny toppmodern antireflektiv beläggning som kan göra Absolicons solfångare än mer effektiva. Nu siktar man på ett nytt projekt för att skala upp metoden.

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  • 12.
    Karlsson, Stefan
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Österlund, Lars
    Uppsala University, Sweden.
    Anand, Srinivasan
    KTH Royal Institute of Technology, Sweden.
    Multifunktionella glasytor för solceller2023In: GLAS, no 4, p. 38-39Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    I ett forskningsprojekt som kommer avslutas vid årsskiftet har framtidens multifunktionella glasytor för solceller utvecklats. Antireflektiva, UV-skyddande, fotokatalytiska och lättrengörliga glasytor är egenskaperna som glasytorna kommer att få. Forskningsidén baseras på tidigare kunskap ifrån forskning vid RISE, Uppsala universitet och KTH och förväntas leda till effektiva solceller med längre livslängd.

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  • 13.
    Kumar, Ashutosh
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Berg, Martin
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Wang, Qin
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Uzuhashi, Jun
    National Institute for Materials Science, Japan.
    Ohkubo, Tadakatsu
    National Institute for Materials Science, Japan.
    Salter, Michael
    RISE Research Institutes of Sweden.
    Ramvall, Peter
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Acceptor activation of Mg-doped GaN—Effects of N2/O2 vs N2 as ambient gas during annealing2023In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 134, no 3, article id 035701Article in journal (Refereed)
    Abstract [en]

    Here, we investigate the effects of O2:N2 (1:1) as ambient gas as compared with pure N2 during activation annealing of Mg as p-type doping in GaN layers grown by MOCVD. The purpose is to understand the impact of O2 on the resulting free hole concentration and hole mobility using SIMS, XRD, STEM, AFM, and Hall effect measurements. Even though the presence of O2 in the ambient gas during annealing is very effective in reducing the H level of the Mg-doped GaN layers, the maximum achievable hole concentration and mobility is still higher with pure N2. The differences are explained by an in-diffusion of O to the GaN layer acting as n-dopant and, thus, giving rise to a compensation effect. The Mg-H complexes at substitutional (MgGa), i.e., the electrically active acceptor sites that provide free holes, are preferentially activated by annealing with N2 only as ambient gas, while annealing with O2:N2 (1:1) also dissociates electrically inactive Mg-H complexes resulting in much less residual H. At the lower growth pressure of 150 mbar compared to higher growth pressure of 300 mbar, an increasing carbon incorporation leads to a compensation effect drastically reducing the free hole concentration while the mobility is unaffected. © 2023 Author(s).

  • 14.
    Lindgren, Mikael
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Nord, Stefan
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Characterization of visual and IR reflectivity for soft car targets2018Conference paper (Other academic)
    Abstract [en]

    Advanced Driver Assistance Systems (ADAS) and Automated Driving (AD) vehicles rely heavily on optical sensors. Extensive testing of optical sensors is required and typically performed at test tracks like AstaZero. Soft surrogate targets are used for safety reasons, but the optical characteristics of surrogate targets may differ considerably from that of real vehicles. During tests the quality of the soft surrogate targets deteriorates due to repeated impacts and reassembly of the targets, and there is a need for methods to secure the quality of the soft surrogate targets over time.

    RISE has conducted a project together with Volvo Cars and Veoneer to develop and validate accurate and repeatable measurement methods of the optical characteristics of 3D soft car targets. The goal is to support international standardisation (ISO) with standard methods enabling future verification and calibration of optical characteristics of active safety 3D soft car targets.

    The poster presents results from optical measurements on soft car targets and real cars, performed in the project. One target was subjected to 100 rear-end collisions during which the reflectivity was measured.

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    Characterization of visual and IR reflectivity for soft car targets
  • 15.
    Lobov, Gleb S.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Zhao, Yichen
    KTH Royal Institute of Technology, Sweden.
    Marinins, Alexandrs
    KTH Royal Institute of Technology, Sweden.
    Yan, Min
    KTH Royal Institute of Technology, Sweden.
    Li, Jiantong
    KTH Royal Institute of Technology, Sweden.
    Sugunan, Abhilash
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Thylén, Lars
    Hewlett-Packard Laboratories, US; KTH Royal Institute of Technology, Sweden.
    Wosinski, Lech
    KTH Royal Institute of Technology, Sweden.
    Östling, Mikael
    KTH Royal Institute of Technology, Sweden.
    Toprak, Muhammet S.
    KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Dynamic manipulation of optical anisotropy of suspended Poly-3-hexylthiophene nanofibers2016In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 4, no 10, p. 1651-1656Article in journal (Refereed)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications.​.

  • 16.
    Pang, Xiaodan
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Industrial Systems. KTH Royal Institute of Technology, Sweden.
    Ozolins, Oskars
    RISE Research Institutes of Sweden, Digital Systems, Industrial Systems. KTH Royal Institute of Technology, Sweden.
    Jia, S
    DTU Technical University of Denmark, Denmark.
    Zhang, L
    Zhejiang University, China.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Udalcovs, Aleksejs
    RISE Research Institutes of Sweden.
    Bobrovs, V.
    Riga Technical University, Latvia.
    Hu, H.
    DTU Technical University of Denmark, Denmark.
    Morioka, T.
    DTU Technical University of Denmark, Denmark.
    Sun, Y. -T
    KTH Royal Institute of Technology, Sweden.
    Chen, J.
    Chalmers University of Technology, Sweden.
    Lourdudoss, S.
    KTH Royal Institute of Technology, Sweden.
    Oxenløwe, L. K.
    DTU Technical University of Denmark, Denmark.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Yu, X.
    Zhejiang University, China.
    Free-Space Transmissions in the Upper- and Lower-THz Bands Assisted with Photonics2021In: 2021 European Conference on Optical Communication (ECOC), 2021, p. 1-4Conference paper (Refereed)
    Abstract [en]

    We report our recent studies in photonics-assisted free-space transmissions in both the lower (0.3-0.5 THz) and upper- (~64.5 THz) terahertz bands. We adopt the hybrid electro-optical approach for the lower-THz signal transmission, whereas a directly modulated quantum cascade laser is used for the upper-THz band.

  • 17.
    Razzell Hollis, J.
    et al.
    California Institute of Technology, USA;The Natural History Museum, UK.
    Siljeström, Sandra
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Yanchilina, A.
    Impossible Sensing LLC, USA.
    The power of paired proximity science observations: Co-located data from SHERLOC and PIXL on Mars2022In: Icarus, ISSN 0019-1035, E-ISSN 1090-2643, Vol. 387, article id 115179Article in journal (Refereed)
    Abstract [en]

    We present a synthesis of PIXL elemental data and SHERLOC Raman spectra collected on two targets investigated by the Perseverance rover during the first year of its exploration of Jezero Crater, Mars. The Bellegarde target (in the Máaz formation) and Dourbes target (in the Séítah formation) exhibit distinctive mineralogies that are an ideal case study for in situ analysis by SHERLOC and PIXL. Each instrument alone produces valuable data about the chemistry and spatial distribution of mineral phases at the sub-millimeter scale. However, combining data from both instruments provides a more robust interpretation that overcomes the limitations of either instrument, for example: 1) Detection of correlated calcium and sulfur in Bellegarde by PIXL is corroborated by the co-located detection of calcium sulfate by SHERLOC. 2) Detection of sodium and chlorine in Dourbes is consistent with either chloride or oxychlorine salts, but SHERLOC does not detect perchlorate or chlorate. 3) A Raman peak at 1120 cm−1 in Dourbes could be sulfate or pyroxene, but elemental abundances from PIXL at that location are a better match to pyroxene. This study emphasizes the importance of analyzing co-located data from both instruments together, to obtain a more complete picture of sub-millimeter-scale mineralogy measured in situ in Jezero crater, Mars, by the Perseverance rover. © 2022 The Authors

  • 18.
    Ràfols-Ribé, Joan
    et al.
    Umeå University, Sweden.
    Zhang, X.
    Umeå University, Sweden.
    Larsen, Christian
    Umeå University, Sweden.
    Lundberg, Petter
    Umeå University, Sweden.
    Lindh, E. Mattias
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Mai, Cuc
    Uppsala University, Sweden.
    Mindemark, Jonas
    Uppsala University, Sweden.
    Gracia-Espino, Eduardo
    Umeå University, Sweden.
    Edman, Ludvig
    Umeå University, Sweden.
    Controlling the Emission Zone by Additives for Improved Light-Emitting Electrochemical Cells2022In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 34, no 8, article id 2107849Article in journal (Refereed)
    Abstract [en]

    The position of the emission zone (EZ) in the active material of a light-emitting electrochemical cell (LEC) has a profound influence on its performance because of microcavity effects and doping- and electrode-induced quenching. Previous attempts of EZ control have focused on the two principal constituents in the active material—the organic semiconductor (OSC) and the mobile ions—but this study demonstrates that it is possible to effectively control the EZ position through the inclusion of an appropriate additive into the active material. More specifically, it is shown that a mere modification of the end group on an added neutral compound, which also functions as an ion transporter, results in a shifted EZ from close to the anode to the center of the active material, which translates into a 60% improvement of the power efficiency. This particular finding is rationalized by a lowering of the effective electron mobility of the OSC through specific additive: OSC interactions, but the more important generic conclusion is that it is possible to control the EZ position, and thereby the LEC performance, by the straightforward inclusion of an easily tuned additive in the active material. © 2022 The Authors.

  • 19.
    Röding, Magnus
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Svensson, Peter
    RISE - Research Institutes of Sweden (2017-2019), Bioscience and Materials, Agrifood and Bioscience.
    Loren, Niklas
    RISE - Research Institutes of Sweden (2017-2019), Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Functional regression-based fluid permeability prediction in monodisperse sphere packings from isotropic two-point correlation functions2017In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 134, p. 126-131Article in journal (Refereed)
    Abstract [en]

    We study fluid permeability in random sphere packings consisting of impermeable monodisperse hard spheres. Several different pseudo-potential models are used to obtain varying degrees of microstructural heterogeneity. Systematically varying solid volume fraction and degree of heterogeneity, virtual screening of more than 10,000 material structures is performed, simulating fluid flow using a lattice Boltzmann framework and computing the permeability. We develop a well-performing functional regression model for permeability prediction based on using isotropic two-point correlation functions as microstructural descriptors. The performance is good over a large range of solid volume fractions and degrees of heterogeneity, and to our knowledge this is the first attempt at using two-point correlation functions as functional predictors in a nonparametric statistics/machine learning context for permeability prediction.

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  • 20.
    Shafa, Muhammad
    et al.
    Xi’an Jiaotong University, China; Yulin University, China.
    Wu, Di
    Xi’an Jiaotong University, China.
    Chen, Xi
    Xi’an Jiaotong University, China.
    Ul Hassan Alvi, Naveed
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Pan, Yi
    Xi’an Jiaotong University, China.
    Najar, Adel
    United Arab Emirates University United Arab Emirates.
    Flexible infrared photodetector based on indium antimonide nanowire arrays2021In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 32, no 27, article id 27LT01Article in journal (Refereed)
    Abstract [en]

    Narrow bandgap semiconductors like indium antimonide (InSb) are very suitable for high-performance room temperature infrared photodetectors, but the fragile nature of the wafer materials hinders their application as flexible/wearable devices. Here, we present a method to fabricate a photodetector device of assembled crystalline InSb nanowire (NW) arrays on a flexible substrate that balances high performance and flexibility, facilitating its application in wearable devices. The InSb NWs were synthesized by means of a vapor-liquid-solid technique, with gold nanoclusters as seeding particles. The morphological and crystal properties were investigated using scanning electron microscopy, x-ray diffraction and high-resolution transmission electron microscopy, which revealed the unique spike shape and high crystallinity with (111) and (220) planes of InSb NWs. The flexible infrared photodetector devices were fabricated by transferring the NWs onto transparent and stretchable polydimethylsiloxane substrate with pre-deposited gold electrodes. Current versus time measurement of the photodetector devices under light showed photoresponsivity and sensitivity to mid-infrared at bias as low as 0.1 V while attached to curved surfaces (suitable for skin implants). A high-performance NW device yielded efficient rise and decay times down to 1 s and short time lag for infrared detection. Based on dark current, calculated specific detectivity of the flexible photodetector was 1.4 × 1012Jones. The performance and durability render such devices promising for use as wearable infrared photodetectors.

  • 21.
    Shetty, Naveen
    et al.
    Chalmers University of Technology, Sweden.
    He, Hans
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology. Chalmers University of Technology, Sweden.
    Mitra, Richa
    Chalmers University of Technology, Sweden.
    Huhtasaari, Johanna
    Chalmers University of Technology, Sweden.
    Iordanidou, Konstantina
    Chalmers University of Technology, Sweden.
    Wiktor, Julia
    Chalmers University of Technology, Sweden.
    Kubatkin, Sergey
    Chalmers University of Technology, Sweden.
    Dash, Saroj
    Chalmers University of Technology, Sweden.
    Yakimova, Rositsa
    Linköping University, Sweden.
    Zeng, Lunjie
    Chalmers University of Technology, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Sweden.
    Lara-Avila, Samuel
    Chalmers University of Technology, Sweden; NPL National Physical Laboratory, UK.
    Scalable Fabrication of Edge Contacts to 2D Materials: Implications for Quantum Resistance Metrology and 2D Electronics2023In: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 6, no 7, p. 6292-Article in journal (Refereed)
    Abstract [en]

    We report a reliable and scalable fabrication method for producing electrical contacts to two-dimensional (2D) materials based on the tri-layer resist system. We demonstrate the applicability of this method in devices fabricated on epitaxial graphene on silicon carbide (epigraphene) used as a scalable 2D material platform. For epigraphene, data on nearly 70 contacts result in median values of the one-dimensional (1D) specific contact resistances ρc ∼ 67 Ω·μm and follow the Landauer quantum limit ρc ∼ n-1/2, consistently reaching values ρc < 50 Ω·μm at high carrier densityn. As a proof of concept, we apply the same fabrication method to the transition metal dichalcogenide (TMDC) molybdenum disulfide (MoS2). Our edge contacts enable MoS2 field-effect transistor (FET) behavior with an ON/OFF ratio of >106 at room temperature (>109 at cryogenic temperatures). The fabrication route demonstrated here allows for contact metallization using thermal evaporation and also by sputtering, giving an additional flexibility when designing electrical interfaces, which is key in practical devices and when exploring the electrical properties of emerging materials. © 2023 The Authors. 

  • 22.
    Simatos, Dimitrios
    et al.
    University of Cambridge, UK.
    Dobryden, Illia
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Sirringhaus, Henning
    University of Cambridge, UK.
    Effects of Processing-Induced Contamination on Organic Electronic Devices2023In: Small Methods, E-ISSN 2366-9608Article in journal (Refereed)
    Abstract [en]

    Organic semiconductors are a family of pi-conjugated compounds used in many applications, such as displays, bioelectronics, and thermoelectrics. However, their susceptibility to processing-induced contamination is not well understood. Here, it is shown that many organic electronic devices reported so far may have been unintentionally contaminated, thus affecting their performance, water uptake, and thin film properties. Nuclear magnetic resonance spectroscopy is used to detect and quantify contaminants originating from the glovebox atmosphere and common laboratory consumables used during device fabrication. Importantly, this in-depth understanding of the sources of contamination allows the establishment of clean fabrication protocols, and the fabrication of organic field effect transistors (OFETs) with improved performance and stability. This study highlights the role of unintentional contaminants in organic electronic devices, and demonstrates that certain stringent processing conditions need to be met to avoid scientific misinterpretation, ensure device reproducibility, and facilitate performance stability. The experimental procedures and conditions used herein are typical of those used by many groups in the field of solution-processed organic semiconductors. Therefore, the insights gained into the effects of contamination are likely to be broadly applicable to studies, not just of OFETs, but also of other devices based on these materials. © 2023 The Authors. 

  • 23.
    Skedung, Lisa
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, Sweden.
    Buraczewska-Norin, Izabela
    Omega Pharma Nordic, Sweden.
    Dawood, Nagum
    Omega Pharma Nordic, Sweden; Uppsala University, Sweden.
    Rutland, Mark W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, Sweden.
    Ringstad, Lovisa
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Tactile friction of topical formulations2016In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 22, no 1, p. 46-54Article in journal (Refereed)
    Abstract [en]

    Background: The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Methods: Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. Results: The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. Conclusion: The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations.

  • 24.
    Staaf, Henrik
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Sawatdee, Anurak
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Rusu, Cristina
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Nilsson, David
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Schäffner, Philipp
    Joanneum Research Forschungsgesellschaft mbH, Austria.
    Johansson, Christer
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    High magnetoelectric coupling of Metglas and P(VDF-TrFE) laminates2022In: Scientific Reports, Vol. 12, no 1, article id 5233Article in journal (Refereed)
    Abstract [en]

    Magnetoelectric (magnetic/piezoelectric) heterostructures bring new functionalities to develop novel transducer devices such as (wireless) sensors or energy harvesters and thus have been attracting research interest in the last years. We have studied the magnetoelectric coupling between Metglas films (2826 MB) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) in a laminate structure. The metallic Metglas film itself served as bottom electrode and as top electrode we used an electrically conductive polymer, poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Besides a direct electrical wiring via a graphite ink, a novel contactless readout method is presented using a capacitive coupling between the PEDOT:PSS layer and an electrode not in contact with the PEDOT:PSS layer. From the experimental result we determined a magnetoelectric coupling of 1445 V/(cm·Oe) at the magnetoelastic resonance of the structure, which is among the highest reported values for laminate structures of a magnetostrictive and a piezoelectric polymer layer. With the noncontact readout method, a magnetoelectric coupling of about 950 V/(cm·Oe) could be achieved, which surpasses previously reported values for the case of direct sample contacting. 2D laser Doppler vibrometer measurements in combination with FE simulations were applied to reveal the complex vibration pattern resulting in the strong resonant response.

  • 25.
    Ul Hassan Alvi, Naveed
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Digital Cellulose Center, Sweden.
    Mulla, Yusuf
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Digital Cellulose Center, Sweden.
    Abitbol, Tiffany
    RISE Research Institutes of Sweden. Digital Cellulose Center, Sweden.
    Fall, Andreas
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. Digital Cellulose Center, Sweden.
    Beni, Valerio
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. Digital Cellulose Center, Sweden.
    The Fast and One-Step Growth of ZnO Nanorods on Cellulose Nanofibers for Highly Sensitive Photosensors2023In: Nanomaterials, E-ISSN 2079-4991, Vol. 13, no 18, article id 2611Article in journal (Refereed)
    Abstract [en]

    Cellulose is the most abundant organic material on our planet which has a key role in our daily life (e.g., paper, packaging). In recent years, the need for replacing fossil-based materials has expanded the application of cellulose and cellulose derivatives including into electronics and sensing. The combination of nanostructures with cellulose nanofibers (CNFs) is expected to create new opportunities for the development of innovative electronic devices. In this paper, we report on a single-step process for the low temperature (<100 °C), environmentally friendly, and fully scalable CNF-templated highly dense growth of zinc oxide (ZnO) nanorods (NRs). More specifically, the effect of the degree of substitution of the CNF (enzymatic CNFs and carboxymethylated CNFs with two different substitution levels) on the ZnO growth and the application of the developed ZnO NRs/CNF nanocomposites in the development of UV sensors is reported herein. The results of this investigation show that the growth and nature of ZnO NRs are strongly dependent on the charge of the CNFs; high charge promotes nanorod growth whereas with low charge, ZnO isotropic microstructures are created that are not attached to the CNFs. Devices manufactured via screen printing/drop-casting of the ZnO NRs/CNF nanocomposites demonstrate a good photo-sensing response with a very stable UV-induced photocurrent of 25.84 µA. This also exhibits excellent long-term stability with fast ON/OFF switching performance under the irradiance of a UV lamp (15 W). 

  • 26.
    Zubkins, Martins
    et al.
    University of Latvia, Latvia.
    Timoshenko, Janis
    University of Latvia, Latvia.
    Gabrusenoks, Jevgenijs
    University of Latvia, Latvia.
    Pudzs, Kaspars
    University of Latvia, Latvia.
    Azens, Andris
    University of Latvia, Latvia.
    Wang, Qin
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Purans, Juris
    University of Latvia, Latvia.
    Amorphous p-Type Conducting Zn–xIr Oxide (x > 0.13) Thin Films Deposited by Reactive Magnetron Cosputtering2022In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 259, no 2, article id 2100374Article in journal (Refereed)
    Abstract [en]

    Zinc–iridium oxide (Zn–Ir–O) thin films have been demonstrated as a p-type conducting material. However, the stability of p-type conductivity with respect to chemical composition or temperature is still unclear. In this study we discuss the local atomic structure and the electrical properties of Zn–Ir–O films in the large Ir concentration range. The films are deposited by reactive DC magnetron co-sputtering at two different substrate temperatures—without intentional heating and at 300 °C. Extended X-ray absorption fine structure (EXAFS) analysis reveals that strongly disordered ZnO4 tetrahedra are the main Zn complexes in Zn–Ir–O films with up to 67.4 at% Ir. As the Ir concentration increases, an effective increase of Ir oxidation state is observed. Reverse Monte Carlo analysis of EXAFS at Zn K-edge shows that the average Zn–O interatomic distance and disorder factor increase with the Ir concentration. We observed that the nano-crystalline w-ZnO structure is preserved in a wider Ir concentration range if the substrate is heated during deposition. At low Ir concentration, the transition from n- to p-type conductivity is observed regardless of the temperature of the substrates. Electrical resistivity decreases exponentially with the Ir concentration in the Zn–Ir–O films. 

  • 27.
    Österlund, Lars
    et al.
    Uppsala University, Sweden.
    Kim, Seohan
    Uppsala University, Sweden.
    Montero, José
    Uppsala University, Sweden.
    Vennberg, Felix
    KTH Royal Institute of Technology, Sweden.
    Karlsson, Stefan
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Anand, Srinivasan
    KTH Royal Institute of Technology, Sweden.
    Transparent multifunctional cover glass coating for solar energy applications2023Conference paper (Other academic)
    Abstract [en]

    In photovoltaics, the cover glass module has hitherto not yet been fully optimized for its purpose. Instead quite conventional architectural glass is used. In a recent review of the state-of-the-art on UV down converting dopants [1], a way forward to improve cover glasses was presented. Some of these possibilities, and others are covered in the present paper. We present possibilities to add several functionalities, instead of using dopants in the glass composition, including omnidirectional antireflection, dynamic solar control, and self-cleaning. Omni-directional anti-reflective coatings, were made by colloidal lithography templating methods on iron free glass, realizing nanopillar structures with dimensions /2 exploiting Mie scattering for wide angle light collection (Fig. 1). Yttrium oxyhydride (YHO) coatings were deposited on the nanopillar structures using magnetron sputtering methods [2]. The YHO film blocks UV light and photo-darkens upon solar light absorption and reverts to its transparent state in dark in reproducible manner [2]. In addition, the YHO film also becomes hydrophobic upon photo-darkening, acting as a self-cleaning layer. The fabricated coatings were compared with bare glass substrates. The results reveal suppressed reflectance, with acceptable anti-reflective properties up to about 50 degrees. Solar light modulation of a thin 100 nm YHO coating is below 10% thus having high transmittance throughput while allowing for solar cell life-time saving by removal of excess irradiance. Finally, the surface energy of the YHO coated glass structures are presented, demonstrating synergetic chemical and structural (the Lotus effect), showing promising self-cleaning properties. In conclusion, we show possibilities to combine photonic and chromogenic principles with suitable surface chemistry to achieve high-performance cover glass for solar energy application.

    .

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  • 28.
    Čapek, J.
    et al.
    Paul Scherrer Institute, Switzerland.
    Polatidis, E.
    Paul Scherrer Institute, Switzerland.
    Casati, N.
    Paul Scherrer Institute, Switzerland.
    Pederson, R.
    University West, Sweden.
    Lyphout, Christophe
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Strobl, M.
    Paul Scherrer Institute, Switzerland.
    Influence of laser powder bed fusion scanning pattern on residual stress and microstructure of alloy 7182022In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 221, article id 110983Article in journal (Refereed)
    Abstract [en]

    A comprehensive investigation is undertaken on the effect of laser scanning pattern on the microstructure of cylindrical samples made of Alloy 718 processed by Laser Powder Bed Fusion. It is observed that the common alternate direction scanning of the laser results in a more homogeneous microstructure than the less common concentric line scans where significant microstructural heterogeneities are seen between the edges and the center of the sample. The investigation focuses on the precipitation, crystallographic texture, grain size, grain morphology and residual stresses utilizing synchrotron X-ray diffraction, neutron diffraction and electron microscopy. The heterogeneous microstructure of the sample processed with the concentric laser pattern influences the chemical composition of the matrix, which alters the reference “strain free” interplanar spacing used for evaluating the residual strain. The investigation underlines the significance of the processing parameters on the homogeneity of the microstructure and the effect of the chemical variations on the determination of residual stresses in materials such as Alloy 718, where strong local chemical variations occur because of different types and extent of precipitation. © 2022

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