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  • 51.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Gustafsson, Göran
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mats
    Chalmers Tekniska Högskola.
    Wennerström, Olof
    Chalmers Tekniska Högskola.
    Hjertberg, Thomas
    Chalmers Tekniska Högskola.
    Thermal control of near‐infrared and visible electroluminescence in alkyl‐phenyl substituted polythiophenes1994In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 65, no 12, p. 1489-1491Article in journal (Refereed)
    Abstract [en]

    We report electroluminescence from a regioregular alkyl-phenyl substituted polythiophene. The polymer film exists in two forms, giving widely different optical absorption, as well as photoluminescence and electroluminescence spectra. In the low-bandgap form, we observe high emission intensity centered at 1.55 eV (800 nm), well into the infrared, while the high-bandgap form gives a maximum at 1.85 eV (670 nm). The conversion from the high-bandgap form to the low-bandgap form can be done by thermal treatment of the polymer light emitting diodes.

  • 52.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Granlund, Thomas
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. null.
    Guo, S,
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. null.
    Gustafsson, Göran
    IMC, Linköping.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Polymer light-emitting diodes placed in microcavities1996In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 76, no 1-3, p. 121-123Article in journal (Refereed)
    Abstract [en]

    The use of resonant optical microcavities to influence the emission properties of conjugated polymer light-emitting diodes (LEDs) is reported. The microcavities, which are built using metallic mirrors and polymeric spacers, incorporate polymer LEDs in between the mirrors. We report experimental results of polymer LEDs based on substituted polythiophenes. The effects include substantial narrowing of the spectral width of the emitted light, enhancement of the emission at the microcavity resonance, and coupling of two emission processes to different resonance modes in the same cavity.

  • 53.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Gustafsson, Göran
    Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Hjertberg, Thomas
    Chalmers Tekniska Högskola.
    Wennerström, Olof
    Chalmers Tekniska Högskola.
    Controlling colour by voltage in polymer light emitting diodes1995In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 71, no 1-3, p. 2185-2186Article in journal (Refereed)
    Abstract [en]

    We report electroluminescence using different substituted polythiophenes as the emitting mterial. Different substituents cause different sterical interacion which force the thiophene rings out of planarity. This results in different bandgaps. Colours from blue to near infrared have been demonstrated in electroluminescent devices. We also demonstrate voltage controlled electroluminescence using mixtures of these polymers.

  • 54.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Gustafsson, Göran
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Rasmusson, J.
    Chalmers Tekniska Högskola.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Light-emitting diodes with variable colours from polymer blends1994In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 372, no 6505, p. 444-446Article in journal (Refereed)
    Abstract [en]

    THE range of materials now available for polymer-based light-emitting diodes (LEDs) is such that electroluminescence can be obtained throughout the visible spectrum(1-12). Here we show that, by blending polymers with different emission and charge-transport characteristics, LEDs can be fabricated in which the emission colour varies as a function of the operating voltage. This phenomenon arises from the self-organizing properties of the blends, in which entropy drives phase separation of the constituent polymers and gives rise to submicrometre-sized domains having a range of compositions and emission characteristics. Emission from domains of different composition is controlled by the ease with which charge is injected, which in turn depends on the applied voltage.

  • 55.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Determination of optical constants and phase transition temperatures in polymer fullerene thin films for polymer solar cells2012Conference paper (Other academic)
    Abstract [en]

    Plastic photovoltaics combining semiconducting polymers with fullerene derivatives have the potentialto become the first cost efficient solar cells able to compete with fossil fuels. The maximum powerconversion efficiency is already 8.3%[1] , and new polymers arrive frequently in the search for efficienciesof 10%. As a first step in the screening of candidate materials, the optical constants of the purepolymer as well as the polymer blend with fullerenes are determined from Variable Angle SpectroscopicEllipsometry (VASE), using Tauc-Lorentz oscillator models, throughout the solar spectrum. Thesemodels are then used to predict the upper limits to photocurrent generation in devices, in transfermatrix simulations of the multilayer thin film photovoltaic devices. This forms an essential step in thechoice of materials for optimization in devices.Materials optics measurements are also used to deduce the phase diagram of polymer and polymerblend films. The glass transition temperature is very important for plastic solar cells and mustbe higher than the 80C a device can reach to avoid degradation during operation. Temperaturedependent ellipsometric measurements has proven to be a feasible way to determine phase transitionsin polymer thin films[2] . These transitions are displayed as a sudden change of the volumetricexpansion coefficient, and are manifested by an abrupt increase of thickness at the phase transitiontemperature. For thickness determination a Cauchy model is applied to the transparent infrared partof the spectra.References1. Z. He, C. Zhong, X. Huang, W-Y. Wong, H. Wu, L. Chen, S. Su, Y Cao, Advanced Materials 23, 4636(2011)2. M. Campoy-Quiles, P.G. Etchegoin, D.D.C. Bradley, Synthetic Metals 155, 279(2005)

  • 56.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    In situ reflectance imaging of organic thin film formation from solution2012Conference paper (Other academic)
  • 57.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Uniaxial anisotropy in PEDOT:PSS electrodes enhances the photo current at oblique incidence in organic solar cells2015Manuscript (preprint) (Other academic)
    Abstract [en]

    In this work an uniaxial anisotropic treatment of the transparent conductor PEDOT:PSS is included in the transfer matrix method (TMM), used to calculate the optical power dissipation in organic solar cells. PEDOT:PSS is known to be anisotropic and exhibit a weaker absorption and lower refractive index in the out of plane direction. For p-polarized light at large oblique incidence the inclusion of anisotropy show a gain of over 10% for the maximum photocurrent as compared to an isotropic treatment. Due to the interference in devices with reflecting bottom electrodes, the active layer absorption gain is not always occurring for the wavelengths with highest dichroism. This work show that using PEDOT:PSS as top electrode further strengthens the argument that thin film solar cells perform better than their silicon counterparts under oblique incidence. We also confirm previous studies showing that the optical interference maxima is shifted to slightly thicker films for oblique incidence for solar cells with reflective bottom electrodes.

  • 58.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Lindqvist, Camilla
    Chalmers, Sweden .
    Backe, Olof
    Chalmers, Sweden .
    Ma, Zaifei
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tress, Wolfgang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Gustafsson, Stefan
    Chalmers, Sweden .
    Wang, Ergang
    Chalmers, Sweden .
    Olsson, Eva
    Chalmers, Sweden .
    Andersson, Mats R.
    Chalmers, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Müller, Christian
    Chalmers, Sweden .
    Sub-glass transition annealing enhances polymer solar cell performance2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 17, p. 6146-6152Article in journal (Refereed)
    Abstract [en]

    Thermal annealing of non-crystalline polymer: fullerene blends typically results in a drastic decrease in solar cell performance. In particular aggressive annealing above the glass transition temperature results in a detrimental coarsening of the blend nanostructure. We demonstrate that mild annealing below the glass transition temperature is a viable avenue to control the nanostructure of a non-crystalline thiophene-quinoxaline copolymer: fullerene blend. Direct imaging methods indicate that coarsening of the blend nanostructure can be avoided. However, a combination of absorption and luminescence spectroscopy reveals that local changes in the polymer conformation as well as limited fullerene aggregation are permitted to occur. As a result, we are able to optimise the solar cell performance evenly across different positions of the coated area, which is a necessary criterion for large-scale, high throughput production.

  • 59.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Mauger, Scott
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    In situ reflectance imaging of organic thin film formation from solution deposition2013In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 114, p. 89-98Article in journal (Refereed)
    Abstract [en]

    In this work we present reflectance imaging as a suitable method for in situ monitoring of the drying process of film formation for organic photovoltaics (OPV) over large areas, as well as for lab-scale spin-coating. The drying wet film is illuminated with a narrow bandwidth LED with the specularly reflected light recorded by a video camera as the film dries and forms the active layer of the OPV cell. The interference fringes generated by the thinning wet film can be used to measure the rate of solvent evaporation and the drying time. Subsequent mapping elucidates variations in drying conditions over the substrate, which lead to variations in morphology formation. The technique is suitable for tracking thickness variations of the dry film, with a sensitivity of 10 nm, by comparing the intensity of the reflected light from the dry film to simulated interference conditions calculated for each thickness. The drying process is furthermore accurately simulated by an optical model considering the changes in refractive index as the amount of solvent decreases with respect to the solid content. This non-invasive in situ method represents an important monitoring tool for future large scale OPV manufacturing where high performing morphologies with uniform thickness have to be formed over very large areas.

  • 60.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lindqvist, Camilla
    INTERACT, Department of Engineering and Physics, Karlstad University, Karlstad, Sweden.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Time-resolved morphology formation of solution cast polymer: fullerene blends revealed by in-situ photoluminescence spectroscopy2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The nanoscale morphology of the photo-active layer in organic solar cells is critical for device efficiency. The photoactive layer is cast from solution and during drying both the polymer and the fullerene self-assemble to form a blend. Here, we introduce in-situ spectroscopic photoluminescence (PL) combined with laser reflectometry to monitor the drying process of an amorphous polymer:fullerene blend. When casting only the pristine components (polymer or PCBM only), the strength of PL emission is proportional to the solid content of the drying solution, and both kinetics reveal a rapid aggregation onset at the final stage of film drying. On the contrary, when casting polymer:fullerene blends, the strength of PL emission is proportional to the wet film thickness and reveals polymer/fullerene charge transfer (CT) already at the earliest stages of film drying, i.e. in dilute solutions. The proposed method allows to detect polymer/fullerene phase separation during film casting – from a reduction in the PL quenching rate as the film dries. Poor solvents lead to phase separation already at early stages of film drying (low solid content), resulting in a coarse final morphology as confirmed by atomic force microscopy (AFM). We therefore anticipate that the proposed method will be an important tool in the future development of processing inks, not only for solution-cast polymer:fullerene solar cells but also for organic heterojunctions in general.

  • 61.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tholén, Erik A.
    al Institute of Technology (EPFL), Station 6, Lausanne, Switzerland.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    LED array scanner for inline characterization of thin film photovoltaic modules2016In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 157, no 17, p. 1057-1064Article in journal (Refereed)
    Abstract [en]

    Thin film solar cells, and in particular printed organic solar cells, offer a potential route to a low cost power generation from sunlight. However, manufacturing these solar cells rapidly generates large areas that have to be characterized, preferably in-line for a direct feed back in the production process. Here we introduce the LEDimage, a LED array illumination induced photocurrent method suitable for high speed inline characterization and defect detection of organic solar cell modules. The LEDimage enables simultaneous illumination of all connected subcells without additional bias light. Each LED in the array is amplitude modulated at an individual frequency and the photocurrent response is Fourier transformed to generate a photocurrent map. Furthermore, the LEDimage can be used as a hand scanner for fast device characterization. We expect that LEDimage can be an effective research and industry tool for characterization of large area thin film solar cells.

  • 62.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tress, Wolfgang
    Laboratory of Photonics and Interfaces, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
    Forchheimer, Daniel
    Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Haviland, David
    Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    New method for lateral mapping of bimolecular recombination in thin film organic solar cells2016In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 8, p. 1096-1108Article in journal (Refereed)
    Abstract [en]

    The best organic solar cells are limited by bimolecular recombination. Tools to study these losses are available; however, they are only developed for small area (laboratory-scale) devices and are not yet available for large area (production-scale) devices. Here we introduce the Intermodulation Light Beam-Induced Current (IMLBIC) technique, which allows simultaneous spatial mapping of both the amount of extracted photocurrent and the bimolecular recombination over the active area of a solar cell. We utilize the second-order non-linear dependence on the illumination intensity as a signature for bimolecular recombination. Using two lasers modulated with different frequencies, we record the photocurrent response at each modulation frequency and the bimolecular recombination in the second-order intermodulation response at the sum and difference of the two frequencies. Drift-diffusion simulations predict a unique response for different recombination mechanisms. We successfully verify our approach by studying solar cells known to have mainly bimolecular recombination and thus propose this method as a viable tool for lateral detection and characterization of the dominant recombination mechanisms in organic solar cells. We expect that IMLBIC will be an important future tool for characterization and detection of recombination losses in large area organic solar cells.

  • 63.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    In situ reflectance imaging of organic thin film formation from solution2012Conference paper (Other academic)
    Abstract [en]

    The rapid progress of organic photovoltaic devices during the last decade, with power conversion efficiencies now exceeding 8%, has brought the technology close to an industrial breakthrough. For polymer solar cells, roll to roll printing is desired to gain the production advantage. The formation of the photoactive material from solutions needs to be controlled and optimized. Therefore a suitable method to monitor the deposition process is needed as deviations of drying times1 and drying rates2 during the coating process have proven to generate morphology variations causing variations in photocurrent generation.

    Here we demonstrate how reflectance imaging can be used to monitor the drying process, both for spin coating and blade coating deposition. A blue LED is used as light source to generate specular reflections imaged by a CMOS camera. The thinning of the wet film can then be observed by thin film interference, and can be recorded for each pixel. This enables an estimation of the evaporation rate for each pixel mapped over the substrate. For spin coating the evaporation rate is shown to increase with the distance from the rotation center, whereas the air flow is the determining parameter during blade coating. By mapping the times when interference ceases, lateral variations in drying time are visualized. Furthermore the quenching of polymer photoluminescence during the drying process can be visualized, thus creating a possibility to estimate morphological variations. Moreover lateral thickness variations of the dry film can be visualized by scanning ellipsometry. After depositing a top electrode photocurrent images can be generated by a laser scanning method. This allows for a direct comparison of drying conditions and photocurrent generation.  The possibility to monitor the thin film formation as well as lateral variations in thickness in-situ by a non-invasive method, is an important step for future large scale applications where stable high performing generating morphologies have to be formed over large areas.

    1Schmidt-Hansberg, B.; Sanyal, M.; Klein, M.F.G.; Pfaff, M.; Schnabel, N.; Jaiser, S.; Vorobiev, A.; Müller, E.; Colsmann, A.; Scharfer, P.; Gerthsen, D.; Lemmer, U.; Barrena, E.; and Schabel, W., ACS Nano 5 , 2011, 8579-8590

    2 Hou, L.; Wang, E.; Bergqvist, J.; Andersson, V.B.; Wang, Z.; Müller, C.; Campoy-Quiles, M.; Andersson, M.R.; Zhang, F.; Inganäs, O.,Adv. Func. Mat. 21 , 2011, 3169–3175

  • 64.
    Bjorstrom, Cecilia M.
    et al.
    Karlstad University.
    Nilsson, Svante
    Karlstad University.
    Magnusson, Kjell O.
    Karlstad University.
    Moons, Ellen
    Karlstad University.
    Bernasik, Andrzej
    AGH-Univ. of Science and Technology .
    Rysz, Jakub
    Jagiellonian Univ.
    Budkowski, Andrzej
    Jagiellonian Univ.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers.
    Influence of solvents and substrates on the morphology and the performance of low-bandgap polyfluorene: PCBM photovoltaic devices - art. no. 61921X2006In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6192, p. X1921-X1921Article in journal (Refereed)
    Abstract [en]

    Spin-coated thin films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (APFO-3) blended with [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) are used as the active material in polymer photovoltaic cells. Such blends are known for their tendency to phase separate during film formation. Tuning the morphology of the blend in a controlled way is one possible road towards higher efficiency. We studied the effect of adding chlorobenzene to chloroform-based blend solutions before spin-coating on the conversion efficiency of APFO-3:PCBM photodiodes, and related that to the lateral and vertical morphology of thin films of the blend. The lateral morphology is imaged by atomic force microscopy (AFM) and the vertical compositional profile is obtained by dynamic secondary ion mass spectrometry (SIMS). The profiles reveal compositional variations consisting of multilayers of alternating polymer-rich and PCBM-rich domains in the blend film spin-coated from chloroform. The vertical compositional variations are caused by surface-directed spinodal waves and are frozen in during the rapid evaporation of a highly volatile solvent. With addition of the low-vapour pressure solvent chlorobenzene, a more homogeneous vertical composition is found. The conversion efficiency for solar cells of this blend was found to be optimal for chloroform: chlorobenzene mixtures with a volume-ratio of 80:1. We have also investigated the role of the substrate on the morphology. We found that blend films spin-coated from chloroform solutions on PEDOT:PSS-coated ITO show a similar compositional structure as the films on silicon, and that changing the substrate from silicon to gold only affects the vertical phase separation in a region close to the substrate interface.

  • 65.
    Bjorstrom Svanstrom, Cecilia M
    et al.
    Karlstad University, Department Phys and Elect Engn, S-65188 Karlstad, Sweden .
    Rysz, Jakub
    Jagiellonian University, Institute Phys, PL-30059 Krakow, Poland .
    Bernasik, Andrzej
    AGH University Science and Technology, Fac Phys and Appl Comp Science, PL-30059 Krakow, Poland .
    Budkowski, Andrzej
    Jagiellonian University, Institute Phys, PL-30059 Krakow, Poland .
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Andersson, Mats R
    Chalmers, Department Polymer Technology, S-41296 Gothenburg, Sweden .
    O Magnusson, Kjell
    Karlstad University, Department Phys and Elect Engn, S-65188 Karlstad, Sweden .
    J Benson-Smith, Jessica
    University London Imperial Coll Science Technology and Med, Department Phys, London SW7 2BW, England .
    Nelson, Jenny
    University London Imperial Coll Science Technology and Med, Department Phys, London SW7 2BW, England .
    Moons, Ellen
    Karlstad University, Department Phys and Elect Engn, S-65188 Karlstad, Sweden .
    Device Performance of APFO-3/PCBM Solar Cells with Controlled Morphology2009In: ADVANCED MATERIALS, ISSN 0935-9648, Vol. 21, no 43, p. 4398-+Article in journal (Refereed)
    Abstract [en]

    Polymer/fullerene solar cells with three different device structures: A) diffuse bilayer, B) spontaneously formed multilayer and C) vertically homogeneous thin films, are fabricated. The photocurrent/voltage performance is compared and it is found that the self-stratified structure (B) yields the highest energy conversion efficiency.

  • 66.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Herland, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Hamedi, Mahiar
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Biomolecular nanowires decorated by organic electronic polymers2010In: JOURNAL OF MATERIALS CHEMISTRY, ISSN 0959-9428, Vol. 20, no 12, p. 2269-2276Article in journal (Refereed)
    Abstract [en]

    We demonstrate the shaping and forming of organic electronic polymers into designer nanostructures using biomacromolecules. In order to create nanowires, nanohelixes and assemblies of these, we coordinate semiconducting or metallic polymers to biomolecular polymers in the form of DNA and misfolded proteins. Optoelectronic and electrochemical devices utilizing these shaped materials are discussed.

  • 67.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Herland, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Scheblykin, Ivan
    Department of Chemical.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA2005In: Nano Letters, ISSN 1530-6984, Vol. 5, no 10, p. 1948-1953Article in journal (Refereed)
    Abstract [en]

    DNA is the prototype template for building nanoelectronic devices by self-assembly. The electronic functions are made possible by coordinating electronic polymer chains to DNA. This paper demonstrates two methods for fabrication of aligned and ordered DNA nanowires complexed with conjugated polyelectrolytes (CPEs). The complex can be formed either in solution prior to stretching or after stretching of the bare DNA on a surface. Molecular combing was used to stretch the complexes on surface energy patterned surfaces, and PMMA for the bare DNA. Single molecular spectroscopy, in fluorescence, and microscopy, in atomic force microscopy, give evidence for coordination of the short CPE chains to the aligned DNA.

  • 68.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Holmström, Sven
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Soft lithographic printing of patterns of stretched DNA and DNA/electronic polymer wires by surface-energy modification and transfer2006In: Small, ISSN 1613-6810, Vol. 2, no 8-9, p. 1068-1074Article in journal (Refereed)
    Abstract [en]

    Aligned and stretched λ DNA is directed to specific locations on solid substrates. Surface-energy modification of glass substrates by using patterned polydimethylsiloxane (PDMS) stamps is used to direct DNA onto the surface-energy-modified micrometer-scale pattern through molecular combing. As an alternative, patterned and nonpatterned PDMS stamps modified with polymethylmethacrylate (PMMA) are utilized to direct the stretched DNA to the desired location and the results are compared. The DNA is elongated through molecular combing on the stamp and transfer printed onto the surfaces. PMMA-modified stamps show a more defined length of the stretched DNA, as compared to bare PDMS stamps. A combination of these two methods is also demonstrated. As an application example, transfer printing of DNA decorated with a semiconducting conjugated polyelectrolyte is shown. The resulting patterned localization of stretched DNA can be utilized for functional nanodevice structures, as well as for biological applications.

  • 69.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Lenner, Liselotte
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Kågedal, Bertil
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Persson, Birgitta
    Linköping University, Department of Biomedicine and Surgery. Linköping University, Faculty of Health Sciences.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Jonasson, Jon
    Linköping University, Department of Clinical and Experimental Medicine, Molecular and Immunological Pathology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pathology and Clinical Genetics.
    Conjugated polythiophene probes target lysosome-related acidic vacuoles in cultured primary cells2007In: Molecular and Cellular Probes, ISSN 0890-8508, Vol. 21, no 5-6, p. 329-337Article in journal (Refereed)
    Abstract [en]

    Conformation-sensitive optical probes for studying biological processes and structures are of great interest. The present work shows for the first time that conjugated polyelectrolyte (CPE) probes can be used for specific targeting of chromatin, nuclear and cytoplasmatic vesicles, and cytoskeletal components in a complex system of cultured cells. One of the probes could also be used for vital staining of live cells. When bound to different entities, the polythiophene derivative probes emitted light with different colors due to the unique spectral properties of these conformation sensitive probes. The physical pre-requisites for binding could also be exploited for characterization of the target. Unexpectedly, lysosome-related acidic vacuoles were targeted in cultured primary cells by both anionic, cationic, and zwitter-ionic polythiophene derivatives. Pre-treatment with Bafilomycin A1, a specific inhibitor of vacuolar-type H+-ATPase, caused redistribution of the staining. The targeting of lysosome-related acidic vesicles could not be demonstrated in transformed cells (melanoma, neuroblastoma, and prostate cancer cell lines), indicating a difference in the localization, structure, accessibility, or quantity of the target in cultured normal cells as compared with the malignant cell lines. The chemical nature of the conjugated polyelectrolyte complex in the cytoplasmatic vacuoles remains elusive.

  • 70.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Persson, Nils-Krister
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Åsberg, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Dynamics of complex formation between biological and luminescent conjugated polyelectrolytes - a surface plasmon resonance study2005In: Biosensors and Bioelectronics, ISSN 0956-5663, Vol. 20, no 9, p. 1764-1771Article in journal (Refereed)
    Abstract [en]

    A water-soluble polythiophene, POWT, with zwitterionic peptide like side chains possess good characteristics for biosensor applications. The zwitterionic side chains of the polymer can couple to biomolecules via electrostatic and hydrogen bonding. This creates possibilities to imprint biomolecules to spin-coated polymer films with maintained functionality, and use the resulting matrix as a biosensor. Polymer-biomolecular interaction studies done with surface plasmon resonance (SPR) reveal a well performing sensor matrix with high affinity for DNA hybridizations as well as for protein detection. The responses are distinct and very specific. A directional dependence of antibodies binding to POWT layer has also been observed. The polymer films have also been characterized by optical methods. Emission and absorption measurements in different buffer systems confirm that the polymer matrix can undergo structural and conformational changes on surfaces. The dielectric function in the interval 300–800 nm of POWT is reported, based on variable angle spectroscopic ellipsometry. This modeling reveals that a considerable amount of water is included in the material. The polymer layer possesses the characteristics needed for biochip applications and micro array techniques.

  • 71.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Thomsson, Daniel
    Lund University.
    Mirzov, Oleg
    Lund University.
    Andersson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Scheblykin , Ivan G
    Lund University.
    Oligothiophene Assemblies Defined by DNA Interaction: From Single Chains to Disordered Clusters2009In: SMALL, ISSN 1613-6810 , Vol. 5, no 1, p. 96-103Article in journal (Refereed)
    Abstract [en]

    The organization of conjugated polyelectrolytes (CPEs) interacting with biomolecules sets conditions for the biodetection of biological processes and identity, through the use of optical emission from the CPE. Herein, a well-defined CPE and its binding to DNA is studied. By using dynamic light scattering and circular dichroism spectroscopy, it is shown that the CPE forms a multimolecule ensemble in aqueous solution that is more than doubled it? size when interacting with a small DNA chain, while single chains are evident in ethanol. The related changes in the fluorescence spectra upon polymer aggregation are assigned to oscillator strength redistribution between vibronic transitions in weakly coupled H-aggregates. An enhanced single-molecule spectroscopy technique that allows full control of excitation and emission light polarization is applied to combed and decorated;,DNA chains. It is found that the organization of combed CPE-lambda DNA complexes (when dry on the surface) allows considerable variation of CPE distances and direction relative to the DNA chain. By analysis of the polarization data. energy transfer between the polymer chains in individual complexes is confirmed and their sizes estimated.

  • 72.
    Bolognesi, A.
    et al.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Giacometti, Schieroni A.
    Giacometti Schieroni, A., Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Botta, C.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Marinelli, M.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Mendichi, R.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Rolandi, R.
    Ist. Naz. per la Fis. della Materiae, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
    Relini, A.
    Ist. Naz. per la Fis. della Materiae, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Theandher, M.
    High photoluminescence efficiency in substituted polythiophene aggregates2003In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 139, no 2, p. 303-310Article in journal (Refereed)
    Abstract [en]

    In this paper we discuss the optical (absorption and photoluminescence) and solvatochromic properties of a newly synthesized alternating copolymer based on poly(3-alkylthiophene) structure. In this copolymer an unsubstituted thiophene ring is linked to a 3-alkyl-substituted thiophene, the two repeating units being alternated in the copolymer chains. Moreover, a bulky group, THP, with high steric hindrance has been introduced in the side chain. This copolymer, designed to preserve the backbone planarity of polythiophenes and to prevent a close packing arrangement through the non-regioregular insertion of the bulky substituted monomer, shows high PL quantum yield in the solid state and in solution aggregates. The electroluminescence of this copolymer is reported for a simple single layer device. © 2003 Elsevier Science B.V. All rights reserved.

  • 73.
    Borgani, Riccardo
    et al.
    Royal Institute Technology, Sweden.
    Forchheimer, Daniel
    Royal Institute Technology, Sweden.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Thoren, Per-Anders
    Royal Institute Technology, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Haviland, David B.
    Royal Institute Technology, Sweden.
    Intermodulation electrostatic force microscopy for imaging surface photo-voltage2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 14, p. 143113-Article in journal (Refereed)
    Abstract [en]

    We demonstrate an alternative to Kelvin Probe Force Microscopy for imaging surface potential. The open-loop, single-pass technique applies a low-frequency AC voltage to the atomic force microscopy tip while driving the cantilever near its resonance frequency. Frequency mixing due to the nonlinear capacitance gives intermodulation products of the two drive frequencies near the cantilever resonance, where they are measured with high signal to noise ratio. Analysis of this intermodulation response allows for quantitative reconstruction of the contact potential difference. We derive the theory of the method, validate it with numerical simulation and a control experiment, and we demonstrate its utility for fast imaging of the surface photo-voltage on an organic photovoltaic material.

  • 74.
    Bäcklund, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Elfwing, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ajjan, Fatimá Nadia
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Babenko, Viktoria
    Department of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Poland.
    Dzwolak, Wojciech
    Department of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Poland.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    PEDOT-S coated protein fibril microhelicesManuscript (preprint) (Other academic)
    Abstract [en]

    We show here the preparation and characterization of micrometer sized conductive helices. We utilize protein fibrils as structural templates to create chiral helices with either right or left handed helicity. The helices are coated with the conductive polymer alkoxysulfonate poly(ethylenedioxythiophene) (PEDOT-S) to create micrometer sized conductive helices. The coating acts as a stabilizer for the template structure, facilitates the preparation of solid state films and shows significant conductivity. The helices have been investigated using Circular Dichroism (CD) and scanning electron microscopy (SEM) and the conductivity have been measured for solid state films.

  • 75.
    Bäcklund, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wigenius, Jens
    Chalmers, Sweden.
    Westerlund, Fredrik
    Chalmers, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Amyloid fibrils as dispersing agents for oligothiophenes: control of photophysical properties through nanoscale templating and flow induced fibril alignment2014In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 2, no 37, p. 7811-7822Article in journal (Refereed)
    Abstract [en]

    Herein we report that protein fibrils formed from aggregated proteins, so called amyloid fibrils, serve as an excellent dispersing agent for hydrophobic oligothiophenes such as alpha-sexithiophene (6T). Furthermore, the protein fibrils are capable of orienting 6T along the fibril long axis, as demonstrated by flow-aligned linear dichroism spectroscopy and polarized fluorescence microscopy. The materials are prepared by solid state mixing of 6T with a protein capable of self-assembly. This results in a water soluble composite material that upon heating in aqueous acid undergoes self-assembly into protein fibrils non-covalently functionalized with 6T, with a typical diameter of 5-10 nm and lengths in the micrometre range. The resulting aqueous fibril dispersions are a readily available source of oligothiophenes that can be processed from aqueous solvent, and we demonstrate the fabrication of macroscopic structures consisting of aligned 6T functionalized protein fibrils. Due to the fibril induced ordering of 6T these structures exhibit polarized light emission.

  • 76.
    Cai, Tianqi
    et al.
    Chalmers.
    Zhou, Yi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Chalmers.
    Hellstrom, Stefan
    Chalmers.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Xu, Shiai
    East China University of Science and Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, Mats R
    Chalmers.
    Low bandgap polymers synthesized by FeCol(3) oxidative polymerization2010In: SOLAR ENERGY MATERIALS AND SOLAR CELLS, ISSN 0927-0248, Vol. 94, no 7, p. 1275-1281Article in journal (Refereed)
    Abstract [en]

    Four low bandgap polymers, combining an alkyl thiophene donor with benzo[c][1,2,5]thiadiazole, 2,3-diphenylquinoxaline, 2,3-diphenylthieno[3,4-b]pyrazine and 6,7-diphenyl-[1,2,5]thiadiazolo[3,4-g] quinoxaline acceptors in a donor-acceptor-donor architecture, were synthesized via FeCl3 oxidative polymerization. The molecular weights of the polymers were improved by introducing o-dichlor-obenzene (ODCB) as the reaction solvent instead of the commonly used solvent, chloroform. The photophysical, electrochemical and photovoltaic properties of the resulting polymers were investigated and compared. The optical bandgaps of the polymers vary between 1.0 and 1.9 eV, which is promising for solar cells. The devices spin-coated from an ODCB solution of P1DB:[70]PCBM showed a power conversion efficiency of 1.08% with an open-circuit voltage of 0.91 V and a short-circuit current density of 3.36 mA cm(-2) under irradiation from an AM1.5G solar simulator (100 mW cm(-2)).

  • 77.
    Camacho, Rafael
    et al.
    Lund University, Sweden.
    Meyer, Matthias
    Lund University, Sweden.
    Vandewal, Koen
    Technical University of Dresden, Germany.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Scheblykin, Ivan G.
    Lund University, Sweden.
    Polarization Imaging of Emissive Charge Transfer States in Polymer/Fullerene Blends2014In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 26, no 23, p. 6695-6704Article in journal (Refereed)
    Abstract [en]

    Photoexcitation of conjugated polymerfullerene blends results in population of a local charge transfer (CT) state at the interface between the two materials. The competition between recombination and dissociation of this interfacial state limits the generation of fully separated free charges. Therefore, a detailed understanding of the CT states is critical for building a comprehensive picture of the organic solar cells operation. We applied a new fluorescence microscopy method called two-dimensional polarization imaging to gain insight into the orientation of the transition dipole moments of the CT states, and the associated excitation energy transfer processes in TQ1:PCBM blend films. The polymer phase was oriented mechanically to relate the polymer dipole moment orientation to that of the CT states. CT state formation was observed to be much faster than energy transfer in the polymer phase. However, after being formed an emissive CT state does not exchange excitation energy with other CT states, suggesting that they are spatially and/or energetically isolated. We found that the quantum yield of the CT emission is smaller for CT states spatially located in the highly oriented polymer domains, which is interpreted as the result of enhanced CT state dissociation in highly ordered structures.

  • 78.
    Campoy-Quiles, M.
    et al.
    ICMAB CSIC, Spain.
    Müller, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology. ICMAB CSIC, Spain.
    Garriga, M.
    ICMAB CSIC, Spain.
    Wang, E.
    Chalmers, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Alonso, M. I.
    ICMAB CSIC, Spain.
    On the complex refractive index of polymer:fullerene photovoltaic blends2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, p. 371-376Article in journal (Refereed)
    Abstract [en]

    We present a detailed investigation of the refractive index of polymer:fullerene blends for photovoltaic applications. The donor polymers poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (APFO3), poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), and poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(5,10-di-2-thienyl-2,3,7,8-tetraphenyl-pyrazino[2,3-g] quinoxaline)] (APFO-Green9) were blended with either [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) or [6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM). We measured variable angle spectroscopic ellipsometry for three systems, namely APFO3:PCBM, TQ1:PC71BM and APFO-Green9:PC71BM, as a function of composition and analyze the data employing a number of models. We found that Bruggeman effective medium approximations (EMA) are not precise for the description of the optical properties of these blends. This is due to a number of reasons. First, we find that there are energy shifts associated to changes in conjugation length that cannot be accounted for using EMA. Second, blending results in a strong reduction of anisotropy. Finally, our data suggest that there is some degree of vertical segregation between components. Therefore, our results support the idea that the optical properties of polymer:fullerene mixtures should be treated as alloys rather than non-interacting blends.

  • 79.
    Campoy-Quiles, M.
    et al.
    Experimental Solid State Physics Group, Blackett Laboratory, Imperial College London, UK.
    Nelson, J.
    Experimental Solid State Physics Group, Blackett Laboratory, Imperial College London, UK.
    Etchegoin, P.G.
    Experimental Solid State Physics Group, Blackett Laboratory, Imperial College London, UK.
    Bradley, D.D.C.
    Experimental Solid State Physics Group, Blackett Laboratory, Imperial College, UK.
    Zhokhavets, V
    Inst of Physics, Ilmenau Technical University, Germany.
    Gobsch, G.
    Inst of Physics, Ilmenau Technical University, Germany.
    Vaughan, H.
    Dept of Physics University of Durham, UK.
    Monkman, A,
    Dept of Physics, University of Durham, UK.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Persson, Nils-Krister
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Garriga, M.
    Inst de Ciència de Materials de Barcelona - CSIS, Campus de la UAB, Spain.
    Alonso, M.I.
    Inst de Ciència de Materials de Barcelona - CSIS, Campus de la UAB, Spain.
    Herrmann, G.
    Max Planck Institute for Polymer Research, Germany.
    Becker, M.
    Max Planck Institute for Polymer Research, Germany.
    Scholdei, W.
    Max Planck Institute for Polymer Research, Germany.
    Jahja, M.
    Max Planck Institute for Polymer Research, Germany.
    Bubeck, C.
    Max Planck Institute for Polymer Research, Germany.
    On the determination of anistropy in polymer thin films: A comparative study of optical techniques2008In: Physica Status Solidi. C: Current Topics in Solid State Physics, ISSN 1862-6351, Vol. 5, no 5, p. 1270-1273Article in journal (Refereed)
    Abstract [en]

    We have used seven different techniques to measure the anisotropic refractive index of poly(vinylcarbazole) films. These techniques are: two types of variable angle spectroscopic ellipsometry (VASE) with multiple sample analysis, Interference enhanced VASE, Transmittance combined with VASE, Polarised Reflectance, beta-scan VASE, and prism coupling. We have found the average ordinary and extraordinary indices at 633 nm to be no = nTE = 1.675 ± 0.008, and ne = nTM = 1.722 ± 0.018, respectively, consistent amongst methods and conclusive on the magnitude of Δn in polymer films.

  • 80. Chen, LC
    et al.
    Godovsky, D
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Groningen, Stratingh Inst, NL-9747 AG Groningen, Netherlands Eindhoven Univ Technol, Lab Macromol & Organ Chem, NL-5600 MB Eindhoven, Netherlands Chalmers Univ Technol, Dept Organ Chem, S-41296 Gothenburg, Sweden Chalmers Univ Technol, Dept Polymer Technol, S-41296 Gothenburg, Sweden.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Hummelen, JC
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Groningen, Stratingh Inst, NL-9747 AG Groningen, Netherlands Eindhoven Univ Technol, Lab Macromol & Organ Chem, NL-5600 MB Eindhoven, Netherlands Chalmers Univ Technol, Dept Organ Chem, S-41296 Gothenburg, Sweden Chalmers Univ Technol, Dept Polymer Technol, S-41296 Gothenburg, Sweden.
    Janssens, RAJ
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Groningen, Stratingh Inst, NL-9747 AG Groningen, Netherlands Eindhoven Univ Technol, Lab Macromol & Organ Chem, NL-5600 MB Eindhoven, Netherlands Chalmers Univ Technol, Dept Organ Chem, S-41296 Gothenburg, Sweden Chalmers Univ Technol, Dept Polymer Technol, S-41296 Gothenburg, Sweden.
    Svensson, M
    Andersson, MR
    Polymer photovoltaic devices from stratified multilayers of donor-acceptor blends2000In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 12, no 18, p. 1367-1370Article in journal (Refereed)
  • 81. Chen, LC
    et al.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Roman, LS
    Linkoping Univ, Dept Phys, Appl Phys Lab, S-58183 Linkoping, Sweden Chalmers Univ Technol, Dept Organ Chem & Polymer Technol, S-41296 Gothenburg, Sweden.
    Johansson, M
    Andersson, M
    Self organised polymer photodiodes for extended spectral coverage2000In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 363, no 1-2, p. 286-289Article in journal (Refereed)
    Abstract [en]

    We report the use of self organised blends of conjugated polymers for improving the spectral coverage of the solar spectrum, and in this way to enhance solar energy conversion efficiency in photodiodes and solar cells. (C) 2000 Elsevier Science S.A. All rights reserved.

  • 82. Chen, LC
    et al.
    Roman, LS
    Linkoping Univ, Appl Phys Lab, IFM, S-58183 Linkoping, Sweden Chalmers Univ Technol, Dept Organ Chem & Polymer Technol, SE-41296 Gothenburg, Sweden Eindhoven Univ Technol, Lab Macromol & Organ Chem, NL-5600 MB Eindhoven, Netherlands.
    Johansson, DM
    Svensson, M
    Andersson, MR
    Janssen, RAJ
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Excitation transfer in polymer photodiodes for enhanced quantum efficiency2000In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 12, no 15, p. 1110-+Article in journal (Refereed)
    Abstract [en]

    The realization of polymer solar cells is the driving force behind this research. In an idea inspired by photosynthesis, the authors have constructed efficient bilayer photodiodes by a well-chosen combination of conjugated polymers (see Figure) in the donor layer. Forster energy transfer within the donor layer allows the absorbed light to be channeled to the C-60 acceptor layer, improving the total photoconversion of the blend device.

  • 83.
    Chen, Miaoxiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Perzon, Erik
    Department of Materials and Surface Chemistry, Polymer Technology, Chalmers University of Technology, Göteborg, Sweden .
    Andersson, Mats R
    Department of Materials and Surface Chemistry, Polymer Technology, Chalmers University of Technology, Göteborg, Sweden .
    Pullerits, Tönu
    Department of Chemical Physics, Lund University, Lund, Sweden .
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    High carrier mobility in low band gap polymer-based field-effect transistors2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 25, p. 252105-1-252105-3Article in journal (Refereed)
    Abstract [en]

    A conjugated polymer with a low band gap of 1.21 eV, i.e., absorbing infrared light, is demonstrated as active material in field-effect transistors (FETs). The material consists of alternating fluorene units and low band gap segments with electron donor-acceptor-donor units composed of two electron-donating thiophene rings attached on both sides of a thiadiazolo-quinoxaline electron-acceptor group. The polymer is solution-processable and air-stable; the resulting FETs exhibit typical p-channel characteristics and field-effect mobility of 0.03 cm2 V−1 s−1.

  • 84.
    Dal Zilio, Simone
    et al.
    National Laboratory of Advanced Technology & NanoScience.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Tormen, Massimo
    National Laboratory of Advanced Technology & NanoScience.
    Fabrication of a light trapping system for organic solar cells2009In: MICROELECTRONIC ENGINEERING, ISSN 0167-9317, Vol. 86, no 4-6, p. 1150-1154Article in journal (Refereed)
    Abstract [en]

    Organic photovoltaic cells (OPV) are among the most promising systems for energy extraction and conversion from renewable energy sources. However, major problem to be solved before industrial production could become economically viable is represented by their still low conversion efficiency. The organic solar cell architectures are presently the result of a compromise between achieving complete light absorption using active layers that are thicker than the optical absorption length and achieving efficient charge collection at the electrodes which is favoured in thinner layers. We present a concept and its experimental demonstration that would solve efficiently the above trade-off problem by making use of a new type of light trapping elements. The simple fabrication scheme, based on a self-aligned UV exposure process, suggests its potential up-scalability to large systems, at low production cost.

  • 85. De, S.
    et al.
    Pascher, T.
    Maiti, M.
    Kesti, T.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Yartsev, A.
    Sundstrom, V.
    Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 27, p. 8466-8472Article in journal (Refereed)
    Abstract [en]

    By measuring excited state and charge dynamics in blends of an alternating polyfluorene copolymer and fullerene derivative over nine orders in time and two orders in light intensity, we have monitored the light-induced processes from ultrafast charge photogeneration to much slower decay of charges by recombination. We find that at low light intensities relevant to solar cell operation relatively fast (∼30 ns) geminate recombination is the dominating charge decay process, while nongeminate recombination has a negligible contribution. The conclusion of our work is that under solar illumination conditions geminate recombination of charges may be directly competing with efficient charge collection in polymer/fullerene solar cells. © 2007 American Chemical Society.

  • 86.
    De, Swati
    et al.
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Kesti, Tero
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Maiti, Manisankar
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Yartsev, Arkady
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Pascher, Torbjörn
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Sundström, Villy
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Exciton Dynamics in Alternating Polyfluorene/Fullerene Blends2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 350, no 1-3, p. 14-22Article in journal (Refereed)
    Abstract [en]

    Exciton dynamics in alternating copolymer/fullerene solar cell blends have been investigated using femtosecond transient absorption spectroscopy. The acceptor concentrations have been varied over a wide range. Experimental data, kinetic modeling and simulations, all indicate that the efficiency of exciton conversion to charges is 100% even at acceptor concentrations as low as 20 wt%. The reported dependence of solar cell efficiency on fullerene concentration may thus arise from other factors. However, there exists an acceptor concentration threshold (5 wt%) below which a substantial fraction of the excitations remain unquenched. The results, we believe are very relevant to optimization of performance efficiency by clever manipulation of morphology. We have also observed exciton–exciton energy transfer in these blends at low acceptor concentrations.

  • 87.
    Diaz de Zerio Mendaza, Amaia
    et al.
    Chalmers, Sweden.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Rossbauer, Stephan
    University of London Imperial Coll Science Technology and Med, England; University of London Imperial Coll Science Technology and Med, England.
    Backe, Olof
    Chalmers, Sweden.
    Nordstierna, Lars
    Chalmers, Sweden.
    Erhart, Paul
    Chalmers, Sweden.
    Olsson, Eva
    Chalmers, Sweden.
    Anthopoulos, Thomas D.
    University of London Imperial Coll Science Technology and Med, England; University of London Imperial Coll Science Technology and Med, England.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Muller, Christian
    Chalmers, Sweden.
    High-Entropy Mixtures of Pristine Fullerenes for Solution-Processed Transistors and Solar Cells2015In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 27, no 45, p. 7325-Article in journal (Refereed)
    Abstract [en]

    The solubility of pristine fullerenes can be enhanced by mixing C-60 and C-70 due to the associated increase in configurational entropy. This "entropic dissolution" allows the preparation of field-effect transistors with an electron mobility of 1 cm(2) V-1 s(-1) and polymer solar cells with a highly reproducible power-conversion efficiency of 6%, as well as a thermally stable active layer.

  • 88. Ding, L.
    et al.
    Jonforsen, M.
    Department of Polymer Technology, Chalmers Univ. of Technol., S-41296, Göteborg, Sweden.
    Roman, L.S.
    Andersson, M.R.
    Department of Polymer Technology, Chalmers Univ. of Technol., S-41296, Göteborg, Sweden.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Photovoltaic cells with a conjugated polyelectrolyte2000In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 110, no 2, p. 133-140Article in journal (Refereed)
    Abstract [en]

    We describe photovoltaic cells made from a novel conjugated polyelectrolyte, the lithium salt of poly(thiophene-3-acetic acid) (PTAA-Li). The aqueous solubility of this polyelectrolyte allows formation of blend electrodes with a dispersion of the metallic polymer Poly(Ethylene DiOxyThiophene) (PEDOT). The incident monochromatic photon to current conversion efficiency (IPCE) of the cells were improved up to 19% by blending PTAA-Li with PEDOT to modify the ITO electrode, in combination with the low bandgap polymer poly(3-(4-octylphenyl)thiophene) (POPT), and C60 as electron acceptor. We attribute the increase of efficiency to the improved contact area between the conjugated polyelectrolyte and PEDOT.

  • 89.
    Duineveld, P.C.
    et al.
    Philips Research, Prof. Holstlaan 4, 5656 AA Eindhoven, Netherlands.
    Lilja, M.
    Johansson, Tomas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Diffusion of solvent in PDMS elastomer for micromolding in capillaries2002In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 18, no 24, p. 9554-9559Article in journal (Refereed)
    Abstract [en]

    Micromolding in capillaries is a soft lithography method for patterning materials. We have studied the diffusion of solvent from the excavated microsized channels in the stamp into the PDMS material, both theoretically and experimentally. It was demonstrated that a model of 1-D diffusion of solvent through a PDMS stamp, coupled with a mass conservation of the solvent in the channels, leads to a quantitatively accurate model for the velocity of the boundary between liquid-filled and vapor-filled microchannels in the stamp. With the model the diffusion coefficient of the solvent into PDMS was successfully determined.

  • 90.
    Dyreklev, Peter
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Wennerström, Olof
    Chalmers Tekniska Högskola.
    Hjertberg, Thomas
    Chalmers Tekniska Högskola.
    Polarized electroluminescence from an oriented substituted polythiophene in a light emitting diode1995In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 7, no 1, p. 43-45Article in journal (Refereed)
    Abstract [en]

    Polarized light sources based on stretch-oriented conjugated polymers are reported. The devices, based on poly 3(4-octylphenyl)-2,2′-bithiophene, show an external quantum efficiency of 0.1% and are produced using a very simple method which may be easily extended to other polymers. The fabrication of the devices is described and factors such as the emission and spectral differences parallel and prependicular to the stretching direction discussed.

  • 91.
    Elfwing, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Bäcklund, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Protein nanowires with conductive properties2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 25, p. 6499-6504Article in journal (Refereed)
    Abstract [en]

    Herein we report on the investigation of self-assembled protein nanofibrils functionalized with metallic organic compounds. We have characterized the electronic behaviour of individual nanowires using conductive atomic force microscopy. In order to follow the self assembly process we have incorporated fluorescent molecules into the protein and used the energy transfer between the internalized dye and the metallic coating to probe the binding of the polyelectrolyte to the fibril.

  • 92.
    Filippini, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Åsberg, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Computer screen photo-assisted spectral fingerprinting of luminescent polythiophene pH reporter2004In: IEEE Sensors. Proceedings, ISSN 1930-0395, E-ISSN 2168-9229, Vol. 3, p. 1377-1380Article in journal (Refereed)
    Abstract [en]

    The capability of the computer screen photo-assisted technique (CSPT)for the spectral fingerprinting of a photoactive polythiophene derivative (POWT) used as pH reporter is demonstrated. POWT is part of a family of industrial scalable materials, well established for organic electronics and biomedical applications, which is used here to demonstrate the capability of CSPT for tracing key spectral features. The ability of CSPTfor substance classification, corroborated by principal component analysis (PCA), successfully compares to standard spectroscopy, especially considering the involved equipments: CSPT is only a computer set and a web camera.

  • 93.
    Filippini, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Åsberg, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Nilsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Computer screen photo-asssited detection of complementary DNA strands using a luminescent zwitterionic polythiophene derivative2006In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 1132006, p. 410-418Article in journal (Refereed)
  • 94. Frantz, S.E.A.
    et al.
    Mikael, L.A.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Quantum efficiency and two-photon absorption cross-section of conjugated polyelectrolytes used for protein conformation measurements with applications on amyloid structures2007In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 336, no 2-3, p. 121-126Article in journal (Refereed)
    Abstract [en]

    Amyloid diseases such as Alzheimer's and spongiform encephalopathies evolve from aggregation of proteins due to misfolding of the protein structure. Early disease handling require sophisticated but yet simple techniques to follow the complex properties of the aggregation process. Conjugated polyelectrolytes (CPEs) have shown promising capabilities acting as optical biological sensors, since they can specifically bind to polypeptides both in solution and in solid phase. The structural changes in biomolecules can be monitored by changes of the optical spectra of the CPEs, both in absorption and emission modes. Notably, the studied CPEs possess multi-photon excitation capability, making them potential for in vivo imaging using laser scanning microscopy. Aggregation of proteins depends on concentration, temperature and pH. The optical effect on the molecular probe in various environments must also be investigated if applied in these environments. Here we present the results of quantum efficiency and two-photon absorption cross-section of three CPEs: POMT, POWT and PTAA in three different pH buffer systems. The extinction coefficient and quantum efficiency were measured. POMT was found to have the highest quantum efficiency being approximately 0.10 at pH 2.0. The two-photon absorption cross-section was measured for POMT and POWT and was found to be more than 18-25 times and 7-11 times that of Fluorescein, respectively. We also show how POMT fluorescence can be used to distinguish conformational differences between amyloid fibrils formed from reduced and non-reduced insulin in spectrally resolved images recorded with a laser scanning microscope using both one- and two-photon excitation. © 2007 Elsevier B.V. All rights reserved.

  • 95.
    Gabrielsson, Roger H
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Milczarewic, Grzegorz
    Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Poland.
    Nagarajuc, D. H
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Hydrogels of polypyrrole and self doped PEDOT for porous electrodes and supercapacitors2012Manuscript (preprint) (Other academic)
    Abstract [en]

    The aim of this work is to extend the knowledge of the mechanism of electropolymerization of pyrrole and PEDOT-S by means of in situ electrochemical quartz microbalance with dissipation studies (EQCM-D), which allow us to evaluate the chemical and physical processes during electrochemical deposition of these conductive polymer composites. Meanwhile, the relationship between the morphology of the films and the mechanism of the electropolymerization of pyrrole in presence of PEDOT-S will be discussed. The resulting material is electroactive, black and conducting. This material is a polymer composite where doped polypyrrole chains are found in an environment of doped PEDOT-S chains. They can be identified through the cyclic voltammetry studies of the composite, through element composition and through their optical signatures in electrochromism. The composite has properties suitable for a supercapacitor electrode, and capacitance of up to 650 F/g has been obtained.

  • 96.
    Gadisa, Abay
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Mammo, W.
    Addis Ababa University.
    Andersson, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Admassie, S.
    Addis Ababa University.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Andersson, M.R.
    Chalmers University of Technology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    A New Donor-Acceptor-Donor Polyfluorence Copolymer with Balanced Electron and Hole Mobility2007In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 0000, no 00Article in journal (Refereed)
  • 97.
    Gadisa, Abay
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Perzon, Erik
    Department of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, M. R.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Red and near infrared polarized light emission from polyfluorene copolymer based light emitting diodes2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 11, p. 113510-Article in journal (Refereed)
    Abstract [en]

    The authors report polarized red, electroluminescence peak at 705  nm and near infrared, electroluminescence peak at 950  nm, light emission from light emitting diodes based on two polyfluorene copolymers. The copolymers are synthesized from a fluorene monomer combined with donor-acceptor-donor comonomers and designed to have a low band gap and form birefringent liquid crystalline phases. Emission occurs from aligned thin films of polymer layers. The emissive layers are aligned by spin coating on a layer of rubbed conducting polymer poly(3,4-ethylene dioxythiophene)-poly(styrene sulphonate) and thermally converted into glassy nematic liquid crystalline state.

  • 98.
    Gadisa, Abay
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Svensson, Mattias
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative2004In: Applied Physics Letters, ISSN 0003-6951, Vol. 84, no 9, p. 1609-1611Article in journal (Refereed)
    Abstract [en]

    The photovoltaic parameters of donor/acceptor blend organic solar cells are highly influenced by several parameters, such as the strength of the acceptor species, the morphology of the film due to the solvent, and the mobility of the free charge carriers. In this work, the open-circuit voltage (Voc) of solar cells based on series of conjugated polythiophene polymers were measured and compared. In every cell, the donor polymer was blended with an electron acceptor fullerene molecule. The devices were constructed in a sandwich structure with indium tin oxide (ITO)/metallic polymer (PEDOT:PSS) acting as an anode and Al or LiF/Al acting as a cathode. Comparing the Voc of all the cells shows that this important photovoltaic parameter is systematically varying with the polymer. The variation of photovoltage is attributed to the variation of the oxidation potential of the donor conjugated polymers after due consideration of the different injection conditions in the varying polymers.

  • 99.
    Gadisa, Abay
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Admassie, Shimelis
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lindell, Linda
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Transparent polymer cathode for organic photovoltaic devices2006In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 156, no 16-17, p. 1102-1107Article in journal (Refereed)
    Abstract [en]

    We demonstrate a prototype solar cell with a transparent polymer cathode, and indium-tin-oxide (ITO)/poly (3, 4-ethylene dioxythiophene)-poly (styrene sulphonate) (PEDOT:PSS) anode. As an active layer, thin film of a bulk heterojunction of polyfluorene copolymer poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2thienyl-2′,1′3′-benzothiadiazole)] (APFO-3) and an electron acceptor molecule [6] and [6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:4 wt.) was sandwiched between the two transparent polymer electrodes. The cathode is another form of PEDOT formed by vapor phase polymerised PEDOT (VPP PEDOT) of conductivity 102–103 S/cm. The cathode is supported on an elastomeric substrate, and forms a conformal contact to the APFO-3/PCBM blend. Transparent solar cells are useful for building multilayer and tandem solar cells.

  • 100.
    Gadisa, Abay
    et al.
    Hasselt University.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Vandewal, Koen
    Hasselt University.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    V Manca, Jean
    Hasselt University.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Bipolar Charge Transport in Fullerene Molecules in a Bilayer and Blend of Polyfluorene Copolymer and Fullerene2010In: ADVANCED MATERIALS, ISSN 0935-9648, Vol. 22, no 9, p. 1008-Article in journal (Refereed)
    Abstract [en]

    Efficient polymer solar cells typically contain the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which promotes dissociation of excited states and enhances charge transport. The ability of PCBM to transport holes in solar cell bulk heterojunction films is monitored via the electroluminescence emission of a bulk heterojunction blend of PCBM and a polyfluorene copolymer. In polymer/fullerene bilayer diodes, fullerene emission is also observed.

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