Kion Norrman

Technical University of Denmark, Lyngby, Capital Region, Denmark

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Publications (80)325.98 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Degradation phenomena of La0.58Sr0.4Co0.2Fe0.8O3/Ce0.9Gd0.1O2 (LSCF/CGO) cathodes were investigated via post-mortem analyses of an experimental solid oxide fuel cell (SOFC) stack tested at 700 °C for 2000 h using advanced electron microscopy (SEM-EDS, HR-TEM-EDS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Similar studies were carried out on non-tested reference cells for comparison. The analysis focused on the LSCF/CGO cathode and the CGO barrier layer, as the cathode degradation can be a major contributor to the overall degradation in this type of SOFC. SEM-EDS and TOF-SIMS were used to investigate inter-diffusion across the barrier layer—electrolyte interface and the barrier layer—cathode interface. In addition, TOF-SIMS data were employed to investigate impurity distribution before and after testing. HR-TEM-EDS was used to investigate possible phase segregation in the LSCF and to look for reaction between the phases. The results show that phase separation and inter-diffusion across the cathode–barrier layer interface and the barrier layer–electrolyte interface happened mainly during sintering and cathode firing, and to a very little degree during the test period.
    Journal of Power Sources 06/2015; 283. DOI:10.1016/j.jpowsour.2015.02.064 · 6.22 Impact Factor
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    ABSTRACT: TOF-SIMS analyses of state-of-the-art high temperature solid oxide electrolysis cells before and after testing under different operating conditions were performed. The investigated cells consist of an yttria stabilized zirconia (YSZ) electrolyte, a La1-xSrxMnO3-δ composite anode and a Ni-YSZ cermet cathode. The surfaces and cross-sections of the cells were analyzed, and several elemental impurities like Si, Ca and Na were identified and spatially mapped and their enrichment and migration during operation is reported. With advancing operation time, the concentration of these elements, especially Na and Ca, increases. For Si, a concentration gradient is found from the gas inlet to the gas outlet. Additionally, a loss of Ni percolation in the active cathode is observed in the same area where the Si enrichment is found. Based on the obtained TOF-SIMS results, the influence of the operating conditions on degradation is discussed.
    Dalton Transactions 05/2014; 43(40). DOI:10.1039/c4dt01053a · 4.10 Impact Factor
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    ABSTRACT: Production of large-area polymer solar cells by industrial silk screen printing, lifetime considerations and lamination with polyethyleneterephthalate. Production of large-area polymer solar cells by industrial silk screen printing, lifetime considerations and lamination with polyethyleneterephthalate. Sol.
    Materials for Advanced Applications, MLA; 01/2014
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    ABSTRACT: The photo-oxidation mechanism of thin-film blends based on poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) upon irradiation with ultraviolet–visible light (UV-Vis) was studied. The use of deuterated P3HT, i.e., poly(3-hexyl-d13-thiophene) (P3HdT), permitted discrimination of carbon originating from the hexyl-d13 chain and carbon originating from PCBM and the nondeuterated thiophene unit. The photo-oxidation of both components of the blend was monitored using the combination of various analytical techniques to probe the bulk and the surface of the deposits. The results show that the stabilization of P3HT by PCBM is due to a morphological reorganization between P3HT and PCBM. This change occurs at a low temperature (ca. 42 °C) and increases the lifetime of the primary property, i.e., the ability of the active layer to absorb light. However, this is counterbalanced by the enhanced formation of oxidized PCBM molecules, which may act as electrons traps. It is shown that UV light is harmful for P3HT, PCBM, and P3HT:PCBM blend stabilities, even if PCBM provides a filter effect that is strongest at short wavelengths. It is proposed that the photochemical behavior of the chromophoric species involved in the chain radical oxidation of P3HT is a key characteristic in the underlying mechanism. The results obtained in this work advance the understanding of active layer stability and will help improve the design of long lifetime organic solar cells thanks to the use of cutoff filter in the substrate or encapsulation of the devices.
    Chemistry of Materials 11/2013; 25(22):4522–4528. DOI:10.1021/cm402193y · 8.54 Impact Factor
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    ABSTRACT: Lanthanum strontium manganate (LSM) micro-electrodes with the nominal composition of (La0.75Sr0.25)(0.95)MnO3 were deposited on yttria stabilized zirconia (YSZ). The diameter varied from 20 100 mu m and the thickness was kept constant at ca. 0.5 mu m. Electrochemical characterization was carried out in situ at temperatures from 660 to 860 degrees C using a controlled atmosphere high temperature scanning probe microscope (CAHT-SPM) set-up for measurements of impedance spectroscopy and potential sweep. The oxygen partial pressure, pO(2), was varied. Further, ex situ surface analysis by time of flight secondary ion mass spectrometry (TOF-SIMS) and structure examination by scanning electron microscopy (SEM) were performed. Segregation of Sr and La oxides to LSM surfaces and Mn rich oxide to the three phase boundary (TPB) was observed. YSZ and LSM attract different oxides/impurities. The oxygen electrode kinetics are discussed in light of the surface compositions and compared with the literature on microelectrode and composite LSM-YSZ electrode kinetics.
    ECS Transactions 10/2013; 57(1):1673-1682. DOI:10.1149/05701.1673ecst
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    ABSTRACT: Inverted all polymer solar cells based on a blend of a perylene diimide based polymer acceptor and a dithienosilole based polymer donor were fabricated from small area devices to roll-to-roll (R2R) coated and printed large area modules. The device performance was successfully optimized by using solvent additive to tune the phase separation. By adding 2% chloronaphthalene as solvent additive for small area (0.25 cm2) devices, a power conversion efficiency (PCE) up to 0.63% was achieved for inverted geometry, higher than that (0.39%) of conventional geometry. This polymer blend showed excellent solution processibility and R2R coated and printed large area (4.2 cm2) solar cells exhibited a PCE of 0.20%.
    Solar Energy Materials and Solar Cells 05/2013; 112:157–162. DOI:10.1016/j.solmat.2013.01.025 · 5.03 Impact Factor
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    ABSTRACT: Glass-fiber-reinforced polyester (GFRP) plates are treated using a 50 Hz dielectric barrier discharge at a peak-to-peak voltage of 30 kV in helium at atmospheric pressure with and without ultrasonic irradiation to study adhesion improvement. The ultrasonic waves at the fundamental frequency of around 30 kHz with the sound pressure level of approximately 155 dB were introduced vertically to the GFRP surface through a cylindrical waveguide. The polar component of the surface energy was almost unchanged after the plasma treatment without ultrasonic irradiation, but drastically increased approximately from 20 up to 80 mJ m−2 with ultrasonic irradiation. The plasma treatment with ultrasonic irradiation also introduced oxygen- and nitrogen-containing functional groups at the GFRP surface. These changes would improve the adhesion properties of the GFRP plates.
    Journal of Adhesion Science and Technology 04/2013; 27(7):825-833. DOI:10.1080/01694243.2012.727156 · 1.09 Impact Factor
  • Advanced Energy Materials 04/2013; 3(4). DOI:10.1002/aenm.201200663 · 16.15 Impact Factor
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    ABSTRACT: Efficient and stable polymer bulk-heterojunction solar cells based on regioregular poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) blend active layer have been fabricated with a MoO3–Au co-evaporation composite film as the anode interfacial layer (AIL). The optical and electrical properties of the composite MoO3–Au film can be tuned by altering the concentration of Au. A composite film with 30% (weight ratio) Au was used as the AIL and showed a better performance than both pure MoO3 and PEDOT:PSS as AIL. The surface morphology of the MoO3–Au composite film was investigated by atomic force microscopy (AFM) and showed that the originally rough ITO substrate became smooth after depositing the composite film, with the root mean square roughness (RMS) decreased from 4.08 nm to 1.81 nm. The smooth surface reduced the bias-dependent carrier recombination, resulting in a large shunt resistance and thus improving the fill factor and efficiency of the devices. Additionally, the air stability of devices with different AILs (MoO3–Au composite, MoO3 and PEDOT:PSS) were studied and it was found that the MoO3–Au composite layer remarkably improved the stability of the solar cells with shelf life-time enhanced by more than 3 and 40 times compared with pure MoO3 layer and PEDOT:PSS layer, respectively. We argue that the stability improvement might be related with the defect states in MoO3 component.
    Organic Electronics 03/2013; 14(3):797–803. DOI:10.1016/j.orgel.2012.12.020 · 3.68 Impact Factor
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    ABSTRACT: The performance of SOFC (solid oxide fuel cell) anodes is influenced negatively by impurities. In the present study segregation of impurities is minimized by using high purity materials at relatively low temperatures to prevent fast segregation. Ni point electrodes on polished single crystals of stabilized zirconia (SZ) with 10, 13 and 18 mol% yttria and one with 6 mol% scandia plus 4 mol% yttria were studied at open circuit voltage at 400–500 °C in mixtures of H2/H2O over 46 days. The polarization resistances (Rp) for all samples increased significantly during the first 10–20 days at 500 °C. No effect of the electrolyte composition on Rp was found. Surface sensitive techniques were used to analyze the composition of the nickel and the electrolytes before and after the electrochemical experiment. Impurities were found to segregate to the surfaces/interfaces, and they are believed to impede the electrode processes and hence to cause the increase in polarization resistance.
    Solid State Ionics 03/2013; 234:11–18. DOI:10.1016/j.ssi.2012.12.015 · 2.11 Impact Factor
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    ABSTRACT: A dielectric barrier discharge in a gas mixture of tetrafluoromethane (CF4) and O2 was used for tailoring the surface properties of nanofibrillated cellulose (NFC) films. The surface chemical composition of plasma-modified NFC was characterized by means of X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry, while surface morphology was illustrated by atomic force microscopy. Wettability was characterized through the static sessile drop method. The adhesion between NFC and polylactide (PLA) laminated films was tested by the double cantilever beam technique. As a result of atmospheric pressure plasma treatment, the water contact angle of NFC films increased and the values were comparable with those of PLA films. On the other hand, surface chemical characterization revealed inhomogeneity of the plasma treatment and limited improvement in adhesion between NFC and PLA films. Further research in this direction is required in order to enhance the uniformity of the plasma treatment results.
    Journal of Adhesion Science and Technology 02/2013; 27(3):294-308. DOI:10.1080/01694243.2012.705522 · 1.09 Impact Factor
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    ABSTRACT: Silicon nano-particles grafted with two different organic oligomers were prepared; the oligomers used were a phenylene-vinylene (PV) oligomer and a 3,3'''-didodecylquaterthiophene. The graftings were performed by the use of two different functional groups, the PV oligomer was grafted by a hydroxyl-group in the form of a phenol and a lithium derivative was used to graft the 3,3'''-didodecylquaterthiophene. The morphology and size of the grafted particles were analyzed by atomic force microscopy (AFM) and the extent of the grafting was analyzed by NMR. Organic photovoltaics with normal geometry (ITO/PEDOT:PSS/active layer/Al) were prepared using these materials as a donor and phenyl-C61-butyric acid methyl ester ([60]PCBM) as the acceptor and yielded a power conversion efficiency (PCE) of 0.27%, an open circuit voltage (V-OC) of 0.93 V, a short circuit current density (J(SC)) of 0.89 mA/cm(2), and a fill factor (FF) of 32.5% for a lead device with an active area of 0.25 cm(2).
    Polymers 12/2012; 4(2-2):1242-1258. DOI:10.3390/polym4021242 · 2.51 Impact Factor
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    ABSTRACT: We are here presenting a comparative study between four different types of functionalities for cross-linking. With relatively simple means bromine, azide, vinyl and oxetane could be incorporated into the side chains of the low band-gap polymer TQ1. Cross-linking of the polymers was achieved by UV-light illumination to give solvent resistant films and reduced phase separation and growth of PCBM crystallites in polymer:PCBM films. The stability of solar cells based on the cross-linked polymers was tested under various conditions. This study showed that cross-linking can improve morphological stability but that it has little influence on the photochemical stability which is also decisive for stable device operation under constant illumination conditions.
    Journal of Materials Chemistry 11/2012; 22(46):24417-24423. DOI:10.1039/C2JM34284G · 7.44 Impact Factor
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    ABSTRACT: Intrinsic polymer parameters such as regio-regularity, molecular weight, and crystallinity play an important role when studying polymer stability. 18 different batches of poly-3-hexyl-thiophene (P3HT) were degraded in a solar simulator (AM1.5G, 1000 W/m2) and the degradation kinetics were monitored. The results suggest that the radical reaction responsible for the photodegradation takes place at terminal thiophene rings exposed at points were the conjugation is broken. This proposed mechanism is supported by the fact that stability scales with regio-regularity following the ratio of head-to-tail connected thiophene units. Annealing was found to relax the P3HT films and increase conjugation length and, in turn, increase stability observed as a delayed spectral blueshift caused by photochemical degradation. Crystallinity was found to play a minor role in terms of stability. Oxygen diffusion and light shielding effects were shown to have a negligible effect on the photochemical degradation rate. The results obtained in this work advance the understanding of polymer stability and will help improve the design of materials used for polymer solar cells resulting in longer lifetimes, which will push the technology closer to large-scale applications.
    Polymer Degradation and Stability 11/2012; 97(11):2412–2417. DOI:10.1016/j.polymdegradstab.2012.07.021 · 2.63 Impact Factor
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    ABSTRACT: Here we show polymer solar cells manufactured using only printing and coating of abundant materials directly on flexible plastic substrates or barrier foil using only roll-to-roll methods. Central to the development is a particular roll-to-roll compatible post-processing step that converts the pristine and non-functional multilayer-coated stack into a functional solar cell through formation of a charge selective interface, in situ, following a short electrical pulse with a high current density. After the fast post-processing step the device stack becomes active and all devices are functional with a technical yield and consistency that is compelling.
    Energy & Environmental Science 10/2012; 5(11):9467-9471. DOI:10.1039/C2EE23244H · 15.49 Impact Factor
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    ABSTRACT: This work is part of the inter-laboratory collaboration to study the stability of seven distinct sets of state-of-the-art organic photovoltaic (OPVs) devices prepared by leading research laboratories. All devices have been shipped to and degraded at the Danish Technical University (DTU, formerly RISO-DTU) up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. In this work we present a summary of the degradation response observed for the NREL sample, an inverted OPV of the type ITO/ZnO/P3HT:PCBM/PEDOT:PSS/Ag/Al, under full sun stability test. The results reported from the combination of the different characterization techniques results in a proposed degradation mechanism. The final conclusion is that the failure of the photovoltaic response of the device is mainly due to the degradation of the electrodes and not to the active materials of the solar cell.
    Proceedings of SPIE - The International Society for Optical Engineering 10/2012; DOI:10.1117/12.929579 · 0.20 Impact Factor
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    ABSTRACT: Electrode materials are primarily chosen based on their work function to suit the energy levels of the absorber materials. In this paper, we focus on the modification of aluminum cathodes with a thin silver interlayer (2 nm) in copper indium sulfide/poly[(2,7-silafluorene)-alt-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (PSiF-DBT) nanocomposite solar cells, which improves the fill factor compared to pure aluminum electrodes. A comprehensive structural investigation was performed by means of transmission electron microscopy and time-of-flight secondary ion mass spectrometry revealing the presence of silver nanoparticles in an aluminum oxide matrix between the absorber layer and the aluminum cathode. In combination with complementary optical investigations, the origin of the improvement is ascribed to a facilitated charge extraction.
    The Journal of Physical Chemistry C 09/2012; 116(36-36):19191-19196. DOI:10.1021/jp306242e · 4.84 Impact Factor
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    ABSTRACT: The present work is the fourth (and final) contribution to an inter-laboratory collaboration that was planned at the 3rd International Summit on Organic Photovoltaic Stability (ISOS-3). The collaboration involved six laboratories capable of producing seven distinct sets of OPV devices that were degraded under well-defined conditions in accordance with the ISOS-3 protocols. The degradation experiments lasted up to 1830 hours and involved more than 300 cells on more than 100 devices. The devices were analyzed and characterized at different points of their lifetimes by a large number of non-destructive and destructive techniques in order to identify specific degradation mechanisms responsible for the deterioration of the photovoltaic response. Work presented herein involves time-of-flight secondary ion mass spectrometry (TOF-SIMS) in order to study chemical degradation in-plane as well as in-depth in the organic solar cells. Various degradation mechanisms were investigated and correlated with cell performance. For example, photo-oxidation of the active material was quantitatively studied as a function of cell performance. The large variety of cell architectures used (some with and some without encapsulation) enabled valuable comparisons and important conclusions to be drawn on degradation behaviour. This comprehensive investigation of OPV stability has significantly advanced the understanding of degradation behaviour in OPV devices, which is an important step towards large scale application of organic solar cells.
    Physical Chemistry Chemical Physics 07/2012; 14(33):11780-99. DOI:10.1039/c2cp41787a · 4.20 Impact Factor
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    ABSTRACT: This work is part of the inter-laboratory collaboration to study the stability of seven distinct sets of state-of-the-art organic photovoltaic (OPV) devices prepared by leading research laboratories. All devices have been shipped to and degraded at RISØ-DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. In this work, we apply the Incident Photon-to-Electron Conversion Efficiency (IPCE) and the in situ IPCE techniques to determine the relation between solar cell performance and solar cell stability. Different ageing conditions were considered: accelerated full sun simulation, low level indoor fluorescent lighting and dark storage. The devices were also monitored under conditions of ambient and inert (N(2)) atmospheres, which allows for the identification of the solar cell materials more susceptible to degradation by ambient air (oxygen and moisture). The different OPVs configurations permitted the study of the intrinsic stability of the devices depending on: two different ITO-replacement alternatives, two different hole extraction layers (PEDOT:PSS and MoO(3)), and two different P3HT-based polymers. The response of un-encapsulated devices to ambient atmosphere offered insight into the importance of moisture in solar cell performance. Our results demonstrate that the IPCE and the in situ IPCE techniques are valuable analytical methods to understand device degradation and solar cell lifetime.
    Physical Chemistry Chemical Physics 07/2012; 14(33):11824-45. DOI:10.1039/c2cp40821j · 4.20 Impact Factor
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    ABSTRACT: Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasma and the material surface, and thus, many reactive species generated in the plasma can reach the surface before they are inactivated and can be efficiently utilised for surface modification. In the present work, glass fibre reinforced polyester plates were treated using a dielectric barrier discharge and a gliding arc at atmospheric pressure to study adhesion improvement. The effect of ultrasonic irradiation with the frequency diapason between 20 and 40 kHz at the SPL of ∼150 dB was investigated. After the plasma treatment without ultrasonic irradiation, the wettability was significantly improved. The ultrasonic irradiation during the plasma treatment consistently enhanced the treatment efficiency. The principal effect of ultrasonic irradiation can be attributed to enhancing surface oxidation during plasma treatment. In addition, ultrasonic irradiation can suppress arcing, and the uniformity of the treatment can be improved.
    Surface Engineering 07/2012; 28(6):453-457. DOI:10.1179/1743294411Y.0000000084 · 1.51 Impact Factor

Publication Stats

4k Citations
325.98 Total Impact Points

Institutions

  • 2008–2015
    • Technical University of Denmark
      • • Department of Energy Conversion and Storage
      • • National Laboratory for Sustainable Energy
      Lyngby, Capital Region, Denmark
  • 2007
    • Institut Marqués, Spain, Barcelona
      Barcino, Catalonia, Spain
  • 2005
    • IT University of Copenhagen
      København, Capital Region, Denmark
  • 2002
    • Danish Technological Institute
      Tåstrup, Capital Region, Denmark
  • 1996–1998
    • University of Waterloo
      • Department of Chemistry
      Waterloo, Ontario, Canada