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  • 301.
    Åsberg, Peter
    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, 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.
    Surface energy modified chips for detection of conformational states and enzymatic activity in biomolecules2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, no 5, p. 2205-2211Article in journal (Refereed)
    Abstract [en]

    A novel patterning method for anchoring biomolecules and noncovalent assembled conjugated polyelectrolyte (CPE)/biomolecule complexes to a chip surface is presented. The surface energy of a hydrophilic substrate is modified using an elastomeric poly(dimethylsiloxane) (PDMS) stamp, containing a relief pattern. Modification takes place on the parts where the PDMS stamp is in conformal contact with the substrate and leaves low molecular weight PDMS residues on the surface resulting in a hydrophobic modification, and then biomolecules and CPE/biomolecule complexes are then adsorbed in a specific pattern. The method constitutes a discrimination system for different conformations in biomolecules using CPEs as reporters and the PDMS modified substrates as the discriminator. Detection of different conformations in two biomacromolecules, a synthetic peptide (JR2E) and a protein (calmodulin), reported by the CPE and resolved by fluorescence was demonstrated. Also, excellent enzyme activity in patterned CPE/horseradish peroxidase (HRP) enzyme was shown, demonstrating that this method can be used to pattern biomolecules with their activity retained. The method presented could be useful in various biochip applications, such as analyzing proteins and peptides in large-scale production, in making metabolic chips, and for making multi-microarrays.

  • 302.
    Zhang, Fengling
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Lacic, Sasa
    Linköpings universitet.
    Svensson, Mattias
    Chalmers Tekniska Högskola.
    Andersson, Mats R
    Chalmers Tekniska Högskola.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Theoretical models and experimental results on the temperature dependence of polyfluorene solar cells2006In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 90, p. 1607-1614Article in journal (Refereed)
  • 303.
    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.

  • 304.
    Admassie, Shimelis
    et al.
    IFM Linköpings universitet.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Manoj, A.G.
    IFM Linköpings universitet.
    Svensson, Mattias
    Chalmers university of Technology.
    Andersson, Mats 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 polymer photodiode using vapour-phase polymerized PEDOT as an anode2005In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 90, p. 133-141Article in journal (Refereed)
    Abstract [en]

      

  • 305.
    Inganäs, Olle
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Wang, Xiangjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Gadisa, Abay
    IPS/ÌFM Linköpings universitet.
    Persson, Nils-Krister
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Svensson, Mattias
    Chalmers Tekniska Högskola.
    Perzon, Erik
    Chalmers Tekniska Högskola.
    Mammo, W
    Chalmers Tekniska Högskola.
    Andersson, M.R.
    Chalmers Tekniska Högskola.
    Alternating fluorene copolymer/fullerene blend solar cells2005In: Organic Photovoltaics: Mechanisms, Materials and Devices / [ed] Sam-Shajing Sun, Niyazi Serdar Sariciftci, Boca Raton, FL, USA: CRC Press , 2005, 1, p. 387-402Chapter in book (Other academic)
    Abstract [en]

    Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices.

    Organic Photovoltaics: Mechanisms, Materials, and Devicesfills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world.  It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center.

    Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades.

  • 306.
    Lindgren, Lars
    et al.
    Chalmers University of Technology.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Admassie, Shimelis
    Addis Ababa University.
    Wang, Xiangjun
    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 .
    Andersson, M.R.
    Chalmers University of Technology.
    Blue Polymer Light-Emitting Diodes Based on Novel Polymers2005In: 14:th International Conference on Luminescence ICL05,2005, 2005Conference paper (Other academic)
  • 307.
    Nilsson, Peter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Olsson, Johan
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stabo-Eeg, Franz
    The Norwegian University of Scinece and Technology.
    Lindgren, Mikael
    The Norwegian University of Science and Technology.
    Konradsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Chiral Recognition of a Synthetic Peptide Using Enantiomeric Conjugated Polyelectrolytes and Optical Spectroscopy2005In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 38, p. 6813-6821Article in journal (Refereed)
  • 308.
    Zhang, Fengling
    et al.
    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.
    Conducting and Transparent Polymer Electrodes2005In: Organic Photovoltaics: Mechanism, Materials and Devices / [ed] Sam-Shajing Sun, Niyazi Serdar Sariciftci, Boca Raton, FL, USA: CRC Press , 2005, 1, p. 479-494Chapter in book (Other academic)
    Abstract [en]

    Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices.

    Organic Photovoltaics: Mechanisms, Materials, and Devicesfills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world.  It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center.

    Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades

  • 309.
    Nilsson, Peter
    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.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. 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.
    Conjugated polyelectrolytes: conformation-sensitive optical probes for detection of amyloid fibril formation2005In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 44, no 10, p. 3718-3724Article in journal (Refereed)
    Abstract [en]

    The in vivo deposition of amyloid fibrils is a hallmark of many devastating diseases known as the amyloidoses. Amyloid formation in vitro may also complicate production of proteins in the biotechnology industry. Simple, sensitive, and versatile tools that detect the fibrillar conformation of amyloidogenic proteins are thus of great importance. We have developed a negatively charged conjugated polyelectrolyte that displays different characteristic optical changes, detected visually or by absorption and emission, depending on whether the protein with which it forms a complex is in its native state or amyloid fibril conformation. This simple, rapid, and novel methodology was applied here to two amyloidogenic proteins, insulin and lysozyme, and its validity for detection of their fibrillar conformation was verified by currently used methods such as circular dichroism, transmission electron microscopy, and Congo red absorption.

  • 310.
    Perzon, Erik
    et al.
    Chalmers Tekniska Högskola.
    Wang, Xiangjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Mammo, Wendimagegn
    Chalmers Tekniska Högskola.
    Delgado, Juan Luis
    Universidad de Castilla-La Mancah, Spain.
    de la Cruz, Pilar
    Universidad de Castilla-La Mancha, Spain.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Langa, Fernando
    Universidad de Castilla-La Mancha, Spain.
    Andersson, Mats R
    Chalmers Tekniska Högskola.
    Design, Synthesis and Properties of Low Band Gap Polyfluorenes for Photovoltaic Devices2005In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 154, p. 53-56Article in journal (Refereed)
  • 311.
    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.

  • 312.
    Herland, Anna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Björk, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Nilsson, K. Peter R.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. 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.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry . Linköping University, The Institute of Technology.
    Electroactive luminescent self-assembled bio-organic nanowires: Integration of semiconducting oligoelectrolytes within amyloidogenic proteins2005In: Advanced Materials, ISSN 0935-9648, Vol. 17, no 12, p. 1466-1471Article in journal (Refereed)
  • 313.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Perzon, Erik
    Materials and Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
    Oswald, Frédéric
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Toledo, Spain.
    Langa, Fernando
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Toledo, Spain.
    Admassie, Shimelis
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Materials and Surface Chemistry, 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.
    Enhanced photocurrent spectral response in low-bandgap polyfluorene and C70-Derivative-Based Solar Cells2005In: Advanced Functional Materials, ISSN 1616-301X, Vol. 15, no 10, p. 1665-1670Article in journal (Refereed)
    Abstract [en]

    Plastic solar cells have been fabricated using a low-bandgap alternating copolymer of fluorene and a donor-acceptor-donor moiety (APFO-Green1), blended with 3-(3,5-bis-trifluoromethylphenyl)-1-(4-nitrophenyl)pyrazolino[70]fullerene (BTPF70) as electron acceptor. The polymer shows optical absorption in two wavelength ranges, < 500 nm and 600 <  < 1000 nm. The BTPF70 absorbs light at < 700 nm. A broad photocurrent spectral response in the wavelength range 300 <  < 1000 nm is obtained in solar cells. A photocurrent density of 3.4 mA cm-2, open-circuit voltage of 0.58 V, and power-conversion efficiency of 0.7 % are achieved under illumination of AM1.5 (1000 W m-2) from a solar simulator. Synthesis of BTPF70 is presented. Photoluminescence quenching and electrochemical studies are used to discuss photoinduced charge transfer.

  • 314.
    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.

  • 315.
    Åsberg, Peter
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Björk, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Höök, Fredrik
    Solid State Physics, Lund University, Lund, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Hydrogels from a water-soluble Zwitterionic polythiophene: dynamics under pH change and biomolecular interactions observed using quartz crystal microbalance with dissipation monitoring2005In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 16, p. 7292-7298Article in journal (Refereed)
    Abstract [en]

    The water-soluble zwitterionic polythiophene, poly(3-((S)-5-amino-5- carboxyl-3-oxapentyl)-2,5-thiophene) hydrochloride (POWT), is a conjugated polyelectrolyte (CPE) with properties well suited for biochip applications. CPEs readily form hydrogels when exposed to water-based buffer solutions or biomolecule solutions. In this work, we used in situ quartz crystal microbalance with dissipation (QCM-D) monitoring to collect information on the interaction between POWT films exposed to buffers with different pH and POWT/DNA chains. Our data show that POWT swells significantly when exposed to low-pH buffers, such as pH 4 acetate, this is seen as an increase in thickness and decrease in viscosity obtained via a Voight-based modeling of combined f and D QCM-D measurements. The magnitude of thickness and viscosity change upon changing from a pH 10 carbonate buffer to pH 4 acetate is 100% increase in thickness and 50% decrease in viscosity. The response of the hydrogel under pH change is well correlated with fluorescence data from POWT films on glass. The state of the hydrogel is important during interaction with biomolecules; illustrated by the observation that a swollen CPE hydrogel adsorbs a higher amount of DNA than a compacted one. In agreement with previous results, the QCM-D data confirmed that the POWT/DNA hydrogel sense complementary DNA specifically and with negligible binding of noncomplementary DNA. These results are important for efficient constructions of biochips in water environments using this class of materials.

  • 316.
    Karlsson, Fredrik
    et al.
    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.
    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.
    Interactions between a zwitterionic polythiophene derivative and oligonucleotides as resolved by fluorescence resonance energy transfer2005In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 17, no 16, p. 4204-4211Article in journal (Refereed)
    Abstract [en]

    The interactions between a zwitterionic polythiophene derivative, POWT, and DNA oligonucleotides in solution have been studied by FRET (fluorescence resonance energy transfer). When POWT and ssDNA are bound alone in a complex, the distance between them is at its smallest. The distance increases when adding complementary DNA, but POWT is still mainly bound to the first DNA strand. We find that two POWT chains bind to one DNA strand, and the two POWT chains seem held together in pairs, unable to separate, as they can only bind to and quench half their own amount of labeled DNA. This POWT−POWT complex appears to dissociate at lower concentrations. ssDNA attached to POWT in a complex can also be substituted by other ssDNA in solution; this occurs to 50% when the free DNA is present in 10-fold concentration compared to the ssDNA bound to POWT. Titration studies at different concentrations show positive cooperativity in the binding of POWT and ssDNA into a complex. The hybridization of complementary DNA to the same complex involves no cooperativity. These observations indicate interesting possibilities for the use of POWT as a DNA sensor.

  • 317. Lacic, Sasa
    et al.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Modeling electrical transport in blend heterojunction organic solar cells2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, p. 12490-1-142490-7Article in journal (Refereed)
  • 318.
    Persson, Nils-Krister
    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.
    Optical optimization of polyfluorene-fullerene blend photodiodes2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 3, p. 034503-1-034503-8Article in journal (Refereed)
    Abstract [en]

    Blends of polyfluorene-fullerenes are promising materials for polymer-based photovoltaic devices (PPVD). Using spectroscopic ellipsometry we deduce the dielectric function for the blend of the fullerene derivative [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM) and the alternating polyfluorene copolymer, poly [2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1', 3'-benzothiadiazole)] DiO-PFDTBT (4:1 by weight), for the wavelength interval 250-1300 nm. n reaches above 2 and saturates to 1.9 for high wavelengths. Absorption starts at 720 nm (1.72 eV) and reaches a crest around 550 nm (2.25 eV). The spin coating introduces anisotropy in the blend, manifested in birefringence as well as in dichroism. The dielectric function for the blend versus its constituents is not additive. There are indications that the constituents lost their dielectric identity, as screening cannot explain the experimental data. Simulations of optical absorption inside a PPVD are performed for both monochromatic and polychromatic light, using an air mass 1.5 distributed solar irradiation. The model allows calculation of absorbed energies in absolute values in all layers within the device. An optimization is carried out with respect to the layer thicknesses. From a purely optical perspective there is no gain of optical absorbance in including an additional layer of acceptor. Spatially resolved energy dissipation within the device is presented for polychromatic light. Estimates for quantum efficiencies are derived. Experimental and theoretical results for reflectance are compared.

  • 319.
    Persson, Nils-Krister
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Sun, Mengtao
    Chemical Physics, Lund University, Lund, Sweden .
    Kjellberg, Pär
    Chemical Physics, Lund University, Lund, Sweden .
    Pullerits, Tänu
    Chemical Physics, Lund University, Lund, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Optical properties of low band gap alternating copolyfluorenes for photovoltaic devices2005In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 123, no 20, p. 204718-Article in journal (Refereed)
    Abstract [en]

    In a joint experimental and theoretical work the optical response and excited-state character of two novel conjugated polymers for photovoltaic applications are studied. The polymers, alternating polyfluorene (APFO) Green 1 and APFO Green 2, are both copolymers of fluorene, thiophene, and electron accepting groups. The band gaps are extended into the red and near infrared with onsets of 780 and 1000 nm, respectively, due to alternating donor and acceptor moieties along the polymer chain. Spectroscopic ellipsometry and subsequent modeling made it possible to extract the dielectric function in the range of 260-1200 nm. Semiempirical quantum chemical calculations (ZINDO) revealed the character of the main electronic transitions in the studied spectral region. The spectral band just above 400 nm was assigned to a delocalized π - π* transition for both polymers. The red band lying at 622 and 767 nm in the two polymers corresponds to an electronic state mainly occupying the acceptor units and having a strong charge-transfer character. We show that the ZINDO transition energies are valuable input to the application of Lorentz oscillators in modeling of the dielectric function of the polymer material.

  • 320.
    Zhang, Fengling
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Perzon, Erik
    Chalmers Tekniska Högskola.
    Wang, Xiangjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Mammo, Wendimagegn
    Chalmers Tekniska Högskola.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Polymer Solar Cells Based on a Low-Bandgap Fluorence Copolymer and a Fullerene Derivative with Photocurrent Extended to 850 nm2005In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 15, no 5, p. 745-750Article in journal (Refereed)
  • 321.
    Persson, Nils-Krister
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. 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.
    Simulations of optical processes in organic photovoltaic devices2005In: Organic Photovoltaics: Mechanisms, Materials and Devices / [ed] Sam-Shajing Sun, Niyazi Serdar Sariciftci, Boca Raton, FL, USA: CRC Press , 2005, 1, p. 107-138Chapter in book (Other academic)
    Abstract [en]

    Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices.

    Organic Photovoltaics: Mechanisms, Materials, and Devicesfills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world.  It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center.

    Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades.

  • 322.
    Wang, Xiangjun
    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.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Single and bilayer submicron arrays of fluorescent polymer on conducting polymer surface with surface energy controlled dewetting2005In: Nanotechnology, ISSN 0957-4484, Vol. 16, p. 437-443Article in journal (Refereed)
    Abstract [en]

    Construction of luminescent single- and bilayer polymer arrays in micron and submicron scales through dewetting on a heterogeneous conducting polymer surface is demonstrated. We study the influence of the pattern geometry and film thickness of polymer dewetting upon annealing, and the morphology of created polymer arrays on the heterogeneous surface. The materials used for patterning are an insulating poly(methyl methacrylate) (PMMA) or a conjugated fluorescent polymer, poly(dioctylphenylthiophene) (PDOPT). The substrate used is the conducting polymer poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT–PSS), with modified heterogeneous surface energy obtained by application of a bare polydimethylsiloxane (PDMS) stamp.

  • 323.
    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.

  • 324.
    Lindgren, L.J.
    et al.
    Chalmers Tekniska Högskola.
    Wang, Xiangjun
    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 .
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Synthesis and properties of polyfluorenes with phenyl substituents2005In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 154, p. 97-100Article in journal (Refereed)
  • 325.
    Herland, Anna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Nilsson, K. Peter R.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Olsson, Johan D. M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. 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.
    Synthesis of a regioregular zwitterionic conjugated oligoelectrolyte, usable as an optical probe for detection of amyloid fibril formation at acidic pH2005In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 7, p. 2317-2323Article in journal (Refereed)
    Abstract [en]

    Changes of the optical properties of conjugated polyelectrolytes have been utilized to monitor noncovalent interactions between biomolecules and the conjugated polyelectrolytes in sensor applications. A regioregular, zwitterionic conjugated oligoelectrolyte was synthesized in order to create a probe with a defined set of optical properties and hereby facilitate interpretation of biomolecule−oligoelectrolyte interactions. The synthesized oligoelectrolyte was used at acidic pH as a novel optical probe to detect amyloid fibril formation of bovine insulin and chicken lysozyme. Interaction of the probe with formed amyloid fibrils results in changes of the geometry and the electronic structure of the oligoelectrolyte chains, which were monitored with absorption and emission spectroscopy.

  • 326.
    Schubert, Mattias
    et al.
    Fakultät für Physik und Geowissenschaften Institut für Experimentelle Physik II, Leipzig.
    Bundesmann, C.
    Fakultät für Physik und Geowissenschaften Institut für Experimentelle Physik II, Leipzig.
    v. Wenckstern, H.
    Fakultät für Physik und Geowissenschaften Istitut für Experimentelle Physik II, Leipzig.
    Jakopic, G.
    Institut für Nanostrukturierte Materialien und Photonik JOHANNEUM Research Forschungsgesellschaft mbH.
    Haase, A.
    Institut für Nanostrukturierte Materialien und Photonik JOANNEUM Research Forschungsgesellschaft mbH.
    Persson, Nils-Krister
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Carrier redistribution in organic/inorganic (poly(3,4-ethylenedioxy thiophene/poly(styrenesulfonate)polymer)-Si) heterojunction determined from infrared ellipsometry2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, p. 1311-1313Article in journal (Refereed)
  • 327.
    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.

  • 328.
    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.

  • 329.
    Admassie, S.
    et al.
    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.
    Electrochromism in diffractive conducting polymer gratings2004In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, no 6Article in journal (Refereed)
    Abstract [en]

    The electrochromic polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT-PSS) spin-coated on ITO/glass was patterned with a soft lithographic method in order to diffract the incident light and thereby modify absorption of light by the film to improve the electrochromic efficiency of the polymer. The absorbance peak at around 610 nm was found to be much higher in the patterned PEDOT-PSS film than the one observed in the unpatterned film. Values of coloration efficiencies varying from 107 to 174 cm2/C were obtained for three different unpatterned PEDOT-PSS films, whereas for three different patterned PEDOT-PSS films higher values ranging from 211 to 371 cm2/C were found. These increased values of the electrochromic efficiencies are attributed to diffraction. © 2004 The Electrochemical Society. All rights reserved.

  • 330.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Thomson, Mark E.
    Department of Chemistry, University of Southern California, Los Angeles, USA.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Electrophosphorescence from substituted poly(thiophene) doped with iridium or platinum complex2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 468, no 1-2, p. 226-233Article in journal (Refereed)
    Abstract [en]

    Electrophosphorescence has been observed in doped polythiophene light-emitting diodes (LEDs) with poly(3-methyl-4-octylthiophene) [PMOT] as host and the phosphorescent compounds bis(2-phenylbenzothiazole) iridium acetylacetonate (BTIr) or platinum(II) 2,8,12,17-tetraethyl-3,7,13,18-tramethyl porphyrin (PtOX) as guest. The photoluminescence (PL) and electroluminescence (EL) of host–phosphorescent guest blends PMOT:BTIr (or PMOT:PtOX) showed the existence of energy transfer from host to guest, which were guest concentration-dependent. At a certain guest concentration, emission from host PMOT was completely quenched in both blends based LEDs, and this gave rise to electrophosphorescence. The PL from host PMOT in the PMOT:BTIr blend film could not be quenched completely but was totally quenched in PMOT:PtOX. This implies a more efficient energy transfer from PMOT to PtOX than that from PMOT to BTIr under optical excitation. Comparison of PL and EL showed that the mechanism of exciton formation at the guest site under electrical excitation was not identical for these two systems. Energy transfer was a dominating route for exciton formation in PMOT:PtOX-based LEDs; charge trapping effect additionally contributed to the formation of exciton at BTIr in PMOT:BTIr-based LEDs. This study demonstrates a new direction in which polythiophene can be a candidate as a host to realize electrophosphorescence in polymer light-emitting diodes (PLEDs). Authors further indicate that to optimize the performance of the polythiophe/phosphorescent complexes, LEDs proper polythiophenes with large bang gap are needed.

  • 331.
    Nilsson, Peter
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Olsson, Johan
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Enantiomeric substituents determine the chirality of luminescent conjugated polythiophenes2004In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 17, p. 6316-6321Article in journal (Refereed)
    Abstract [en]

    Chiral isomers of 3-substituted polythiophenes with amino acid functiontionalized side chains are compared. The polymers show pH-dependent absorption, emission, and circular dichroism spectra in buffered aqueous solution. At pH equal to pI of the amino acid, the backbones adopt nonplanar helical conformations, and the polymer chains are separated from each other. Increasing pH leads to more planar conformations of the backbones and an aggregation of the polymer chains occurs. A lower pH will also lead to more planar conformation of the backbones, but aggregation of the polymer chains appears to be absent. The nonplanar to planar transition of the polymer backbone and the separation/aggregation of different polymer chains is not affected by stereochemistry of the zwitterionic side chain. The two isomers have almost identical pH-dependent absorption and emission spectra. However, the chirality of the zwitterionic side chain is reflected in the conformation of the polymer backbone, giving rise to a right-handed and left-handed helical form of polythiophene chains since the induced circular dichroism patterns of the two polymers are mirror images.

  • 332.
    Åsberg, Peter
    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, 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.
    Fluorescence quenching and excitation transfer between semiconducting and metallic organic layers2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 6, p. 3140-3147Article in journal (Refereed)
    Abstract [en]

    Here we present a simple approach to study the interaction of singlet excitons with polarons in conjugated polymers in organic electronic devices. Interlayer quenching constants KIL of 1.5 M−1 between a fluorescent molecule and a doped polymer in a layered sample demonstrates the importance of understanding the quenching of excited states in polymeric devices. A combination of Förster resonance energy transfer and quenching of photoluminescence between a fluorescent molecule and a conjugated polymer in its semiconducting and metallic states were studied. The polymer is a chiral 3-substituted polythiophene (POWT) and the fluorescent molecule is fluorescein bound to dextran (D-FITC). Bilayer samples with fluorescein on top of the POWT were fabricated and studied with absorption spectroscopy, fluorescence microscopy, and electrochemical doping methods. When POWT is electrochemically dedoped it is possible to enhance the photoluminescence in the polymer layer by excitation transfer from the fluorescein layer. Our results demonstrate that PL from the polythiophene disappears rapidly as soon as the layer is doped. As the doping of polymer layer increases the fluorescence from the fluorescein on top of the polymer decreases, due to excitation quenching. Models for excitation transfer and excitation quenching in POWT/FITC bilayer devices have been developed. This model predicts a linear relationship between the PL from the two molecules, in agreement with our experimental findings. These results are relevant for the development of electroluminescent devices or solar cells based on conjugated polymers.

  • 333.
    Zhang, Fengling
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Gadisa, Abay
    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 .
    Svensson, M.
    Mat./Surf. Chem./Polymer Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Andersson, M.R.
    Mat./Surf. Chem./Polymer Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Influence of buffer layers on the performance of polymer solar cells2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 19, p. 3906-3908Article in journal (Refereed)
    Abstract [en]

    The study of the influence of different anode buffer layers on the performance of solar cells based on blends of polyfluorene copolymers, acting as electron donor, and [6,6]-phenyl-C61-butyric acid methylester (PCBM), acting as electron acceptor was presented. The construction of buffer later was done from different forms of poly(3, 4-ethylenedioxythiophene) poly-(styrenesulfonate) (PEDOT-PSS). Variations in open-circuit voltage, short-circuit current and fill factor were also observed. The anode buffer layer influences the photovoltage of polymer solar cells by controlling the conditions for charge injection at the anode.

  • 334.
    Schubert, Mattias
    et al.
    Inst for Experimental Physics II University of Leipzig.
    Bundesmann, C.
    Inst for Experimental Physics University of Leipzig.
    Jacopic, G.
    JOANNEUM Research Forschungsgesellschaft mbH, Austria.
    Maresch, H.
    JOANNEUM Research Forschungsgesellschaft Mbh, Austria.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Persson, Nils-Krister
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    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 .
    Infrared ellipsometry characterization of conducting thin organic films2004In: Elsevier Science, ISSN 1626-3200, Vol. 455-456, p. 295-300Article in journal (Refereed)
  • 335.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Perzon, Erik
    Materials and Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
    Delgado, Juan Luis
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla—La Mancha, Toledo, Spain.
    de la Cruz, Pilar
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla—La Mancha, Toledo, Spain.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Langa, Fernando
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla—La Mancha, Toledo, Spain.
    Andersson, Mats
    Materials and Surface Chemistry, 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.
    Infrared photocurrent spectral response from plastic solar cell with low-bandgap polyfluorene and fullerene derivative2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 21, p. 5081-5083Article in journal (Refereed)
    Abstract [en]

    Plastic solar cells were fabricated using a low-band-gap alternating copolymer of fluorene and a donor–acceptor–donor moiety (APFO-Green1), blended with [6,6]-phenyl-C61-butyric acid methylester or 3-(3,5-Bis-trifluoromethylphenyl)-1-(4-nitrophenyl)pyrazolino[60]fullerene as electron acceptors. The polymer shows optical absorption in two wavelength ranges from 300<<500  nm and 650<<1000  nm. Devices based on APFO-Green1 blended with the later fullerene exhibit an outstanding photovoltaic behavior at the infrared range, where the external quantum efficiency is as high as 8.4% at 840  nm and 7% at 900  nm, while the onset of photogeneration is found at 1  µm. A photocurrent density of 1.76  mA/cm2, open-circuit voltage of 0.54  V, and power conversion efficiency of 0.3% are achieved under the illumination of AM1.5 (1000  W/m2) from a solar simulator.

  • 336.
    Inganäs, Olle
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Svensson, M.
    Materials and Surface Chemistry, Chalmers University of Technology, 412 96 Göteborg, Sweden.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Gadisa, Abay
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Persson, Nils-Krister
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Wang, Xiangjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Andersson, M.R.
    Materials and Surface Chemistry, Chalmers University of Technology, 412 96 Göteborg, Sweden.
    Low bandgap alternating polyfluorene copolymers in plastic photodiodes and solar cells2004In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 79, no 1, p. 31-35Article in journal (Refereed)
    Abstract [en]

    We report a comparative study of plastic photodiodes using four different copolymers of fluorene, with a variation of alkyl side chain length and chemical structure. Photodiode materials are formed by blending the polymers with a fullerene derivative and spincoating the blend solution. A photovoltage of 1 V is obtained in devices, where the anode is a doped polymer and the cathode is LiF/Al. Monochromatic quantum efficiencies are better than 40% over most of the absorption range, and under solar light AM 1.5 simulation, we reach energy efficiencies beyond 2%. The high fill factors obtained in some of the devices indicate that these are of interest for more elaborate optimisation. Reasons for the benign electrical transport are discussed. © Springer-Verlag 2004.

  • 337.
    Koehler, M.
    et al.
    Depto. de Engenharia Elétrica, Univ. Federal do Paraná, 81531-990 Curitiba-PR, Brazil.
    Roman, L.S.
    Departamento de Física, Univ. Federal do Paraná, C.P. 19044, 81531-990 Curitiba-PR, Brazil.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Da, Luz M.G.E.
    Da Luz, M.G.E., Departamento de Física, Univ. Federal do Paraná, C.P. 19044, 81531-990 Curitiba-PR, Brazil.
    Modeling bilayer polymer/fullerene photovoltaic devices2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 1, p. 40-43Article in journal (Refereed)
    Abstract [en]

    The electrical transport and charge generation of polymer/fullerene photovoltaic devices were investigated. The polymer/fullerene photodiodes were formed by a heterojunction of fullerene and a semiconducting polymer poly (3,4-ethylenedioxythiophene). The current-voltage characteristic of the devices were measured with variable thickness of the C60 layer, under monochromatic light of different wavelengths. The results show that the values of the electrical photoconductivity are related to the optical absorption coefficient of the fullerene, and thus implying a large contribution of the C60 films to the diode photocurrent.

  • 338.
    Johansson, Tomas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Nils-Krister
    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 .
    Moving Redox Fronts in Conjugated Polymers Studies from Lateral Electrochemistry in Polythiophenes2004In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, no 4Article in journal (Refereed)
    Abstract [en]

    The propagation speed of the front of electrochemical conversion, from semiconductor to highly doped polymer, in films of regioregular poly(3-hexylthiophene) spin cast on insulating substrates was analyzed. Propagation of the p-doped zone in polymer electrochromic devices was imaged simultaneously with recording of electrochemical data. The current is proportional to the propagation speed and has a Tafel-like behavior when taking the resistive drop in the film into account. The resistivity in the film, which gradually lowers the propagation speed, was used for determination of the conductivity of the p-doped polymer. By combining these values with the doping charge injected into the film during front migration we estimated the hole carrier mobility for different doping levels. © 2004 The Electrochemical Society.

  • 339.
    Nilsson, Peter
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Optical emission of a conjugated polyelectrolyte: calcium-induced conformational changes in calmodulin and calmodulin-calcineurin interactions2004In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 24, p. 9109-9113Article in journal (Refereed)
    Abstract [en]

    Electronic polymers in aqueous media offer bioelectronic detection of biomolecular processes. Here we report fluorometric detection of calcium-induced conformational changes in calmodulin based on noncovalent assembly of calmodulin to a water-soluble zwitterionic polythiophene derivative. Assembly with calmodulin will induce a planar geometry and aggregation of the polymer chains, detected as a decrease of the intensity and a red shift of the fluorescence. Upon addition of Ca2+ the intensity of the emitted light is increased and blue-shifted. The geometrical alteration of the polymer chains can further be utilized for recording of the binding of calcineurin to the calcium-activated POWT−calmodulin complex. This novel methodology, using a conformation-sensitive probe, allows fluorometric detection of conformational changes in biomolecules and protein−protein interactions without any covalent modifications of the biomolecules. The rapid and selective method is based on noncovalent interactions between a zwitterionic polythiophene derivative and the biomolecule of interest. This offers a novel way to create microarrays without using covalent attachment of the receptor or labeling of the analyte.

  • 340.
    Persson, Nils-Krister
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Schubert, Mathias
    Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, AG Festkörperoptik und Akustik, Germany.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Optical modelling of a layered photovoltaic device with a polyfluorene derivative/fullerene as the active layer2004In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 83, no 2-3, p. 169-186Article in journal (Refereed)
    Abstract [en]

    Here we report on optical modelling of organic photovoltaic devices having a layered geometry, with polyfluorene-copolymer as the active material and C60 as the acceptor. Thin film theory in a matrix formalism enables analysis of the impact of reflection and interference on the optical electric field. The model allows us to predict an optimal C60 thickness where concern has been taken for light being both polychromatic and distributed according to solar irradiation. Fundamental for light–matter interaction is the dielectric function. We have extracted it for two variants of a new polyfluorene copolymer, PFDTBT, from UV via visible to the nearest infrared, using spectroscopic ellipsometry (SE). n is found to be relatively high with a max-value above 2.1. The process of spin coating induces anisotropy in the polymer film.

  • 341.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Östblom, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Johansson, Tomas
    Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    PEDOT surface energy pattern controls fluorescent polymer deposition by dewetting2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 449, no 1-2, p. 125-132Article in journal (Refereed)
    Abstract [en]

    An elastomeric stamp of poly(dimethylsiloxane) (PDMS) can modify the surface energy of some surfaces when brought into conformal contact with these for some time. The substrates under investigation are a conducting polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) and a polyelectrolyte poly(sodium 4-styrenesulfonate) (NaPSS). The changes in surface wetting are characterized by contact angle measurement. Changes are due to the PDMS stamp, which leaves low molecular weight residues on the surface, as shown by infrared reflection absorption spectroscopy. This process may also be operating when other inks are transferred in microcontact printing. Patterning of fluorescent polymer film with feature size of 10–100 μm range is done by confining polymer solutions on the modified surface, by means of spin- or dip-coating. The profile of the patterned film and factors that influence the profile are discussed. This technique is a convenient way to build polymer microstructures for application in organic and biomolecular electronics and photonics.

  • 342.
    Yohannes, T.
    et al.
    Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Svensson, M.
    Department of Organic Chemistry, Chalmers University of Technology, Göteborg S-41296, Sweden.
    Hummelen, J.C.
    Stratingh Institute, University of Groningen, Nijenborgh 4, Groningen 9747 AG, Netherlands.
    Andersson, M.R.
    Department of Organic Chemistry, Chalmers University of Technology, Göteborg S-41296, Sweden.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Polyfluorene copolymer based bulk heterojunction solar cells2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 449, no 1-2, p. 152-157Article in journal (Refereed)
    Abstract [en]

    Bulk heterojunction solar cells based on blends of photoactive layers of polyfluorene copolymer Poly((2,7-(9-(2'-ethylhexyl)-9-hexyl-fluorene)-alt-5,5-(4', 7'-di-2-thienyl-2',1',3'-benzothiadiazole))-co-(2, 7-(9-(2'-ethylhexyl)-9-hexyl-fluorene)-alt-2,5-thiophene)) (LBPF3) acting as electron donor, and [6,6]-phenyl-C61-butyric acid methylester (PCBM), acting as electron acceptor, were constructed and studied. The power conversion efficiency for a 1:4 (by weight) blend of LBPF3:PCBM under simulated solar light illumination having light intensity of 100 mW/cm2 was 1.7%, and 9.2% under monochromatic (565 nm) light illumination with light intensity of 0.145 mW/cm2. The maximum external quantum efficiency (incident photons to converted electrons) for this device was found to be above 40% from 400 to 560 nm. The effects of blend composition and film thickness on the photovoltaic parameters were also studied. The incident light intensity dependence of the short circuit current showed a linear relationship. © 2003 Elsevier B.V. All rights reserved.

  • 343.
    Tvingstedt, Kristofer
    et al.
    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 .
    Submicron gratings for conjugated polymer photonics2004In: Optik i Sverige - Svenska Optiksällskapet,2004, 2004Conference paper (Other academic)
  • 344.
    Nilsson, Peter
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Rydberg, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Baltzer, Lars
    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.
    Twisting macromolecular chains: self-assembly of a chiral supermolecule from nonchiral polythiophene polyanions and random-coil synthetic peptides2004In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 101, no 31, p. 11197-11202Article in journal (Refereed)
    Abstract [en]

    The self-assembly of a negatively charged conjugated polythiophene derivative and a positively charged synthetic peptide will create a chiral, well ordered supermolecule. This supermolecule has the three-dimensional ordered structure of a biomolecule and the electronic properties of a conjugated polymer. The molecular complex being formed clearly affects the conformation of the polymer backbone. A main-chain chirality, such as a predominantly one-handed helical structure induced by the acid–base complexation between the conjugated polymer and the synthetic peptide, is seen. The alteration of the polymer backbone influences the optical properties of the polymer, seen as changes in the absorption, emission, and Raman spectra of the polymer. The complexation of the polythiophene and the synthetic peptide also induce a change from random-coil to helical structure of the synthetic peptide. The supermolecule described in this article may be used in a wide range of applications such as biomolecular devices, artificial enzymes, and biosensors.

  • 345.
    Zaushitsyn, Y.
    et al.
    Department of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
    Gulbinas, V.
    Institute of Physics, Savanoriu 231, LT-02300, Vilnius, Lithuania.
    Zigmantas, D.
    Department of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
    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.
    Sundstrom, V.
    Sundström, V., Department of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
    Yartsev, A.
    Department of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
    Ultrafast light-induced charge pair formation dynamics in poly[3-(2'-methoxy-5' octylphenyl)thiophene]2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 7Article in journal (Refereed)
    Abstract [en]

    Charge pair photogeneration was investigated by ultrafast absorption spectroscopy for different excitation photon energies in poly[3-(2'- methoxy-5' octylphenyl)thiophene] (POMeOPT) film with and without an external electric field. Electric field-assisted charge pair photogeneration in POMeOPT occurs from vibrationally relaxed singlet excitons during their entire lifetime and charge pair formation takes place in this manner even in the absence of an external electric field. From our data there are no indications of hot exciton dissociation to charge pairs even when a large amount of excess energy is supplied to the excitons. To explain these observations we present a model with energy transfer to low-barrier dissociation sites as a key feature.

  • 346.
    Immerstrand, Charlotte
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Jager, Edwin W.H.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Magnusson, Karl-Eric
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Sundqvist, Tommy
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Lundström, Ingemar
    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, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Peterson, K.H.
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Altered impedance during pigment aggregation in Xenopus laevis melanophores2003In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, no 3, p. 357-364Article in journal (Refereed)
    Abstract [en]

    Melanophores are dark-brown pigment cells located in the skin of amphibia, fish and many invertebrates. The skin colour of these organisms is regulated by the translocation of pigment organelles, and the pigment distribution can be altered by external stimuli. The ability to change colour in response to stimuli makes these cells of interest for biosensing applications. It was investigated whether pigment aggregation in Xenopus laevis melanophores can be detected by impedance measurements performed in transparent microvials. The results show that cell attachment, cell spreading and pigment aggregation all resulted in impedance changes, seen particularly at the highest frequency tested (10 kHz). The mechanisms behind the impedance changes were investigated by the addition of latrunculin or melatonin, both of which cause pigment aggregation. The latrunculin-induced aggregation was associated with cell area decrease and filamentous actin (F-actin) breakdown, processes that can influence the impedance. Lack of F-actin breakdown and an increase in cell area during melatonin-induced aggregation suggest that some other intracellular process also contributes to the impedance decrease seen for melatonin. It was shown that impedance measurements reflect not only cell attachment and cell spreading, but also intracellular events.

  • 347.
    Nilsson, Peter
    et al.
    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.
    Chip and solution detection of DNA hybridization using a luminescent zwitterionic polythiophene derivative2003In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 2, no 6, p. 419-424Article in journal (Refereed)
    Abstract [en]

    Electronic polymers in aqueous media may offer bioelectronic detection of biospecific interactions. Here we report a fluorometric DNA hybridization detection method based on non-covalent coupling of DNA to a water-soluble zwitterionic polythiophene derivative. Introduction of a single-stranded oligonucleotide will induce a planar polymer and aggregation of the polymer chains, detected as a decrease of the intensity and a red-shift of the fluorescence. On addition of a complementary oligonucleotide, the intensity of the emitted light is increased and blue-shifted. The detection limit of this method is at present ~10−11 moles. The method is highly sequence specific, and a single-nucleotide mismatch can be detected within five minutes without using any denaturation steps. The interaction with DNA and the optical phenomena persists when the polymer is deposited and patterned on a surface. This offers a novel way to create DNA chips without using covalent attachment of the receptor or labelling of the analyte.

  • 348.
    Nilsson, K.Peter R.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, M.R.
    Department of Polymer Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Conformational transitions in a free amino acid functionalized polythiophene2003In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 135-136, p. 291-292Article in journal (Refereed)
    Abstract [en]

    A chiral, 3-substituted polythiophene with an amino acid function shows pH-dependent visible, emission and circular dichroism spectra in buffered aqueous solution. At pH equal to pi of the amino acid, the backbone adopts a non-planar right-handed helical conformation and the polymer chains are separated from each other. Increasing pH leads to a more planar conformation of the backbone and an aggregation of the polymer chains occurs. A lower pH will also lead to a more planar conformation of the backbone, but aggregation of the polymer chains appears to be absent. © 2003 Elsevier Science B.V. All rights reserved.

  • 349.
    Johansson, Tomas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Mammo, W.
    Depts. Organ. Chem./Polymer Technol., Chalmers University of Technology, 412 83 Göteborg, Sweden, Addis Ababa University, Department of Chemistry, P.O. Box 1176, Addis Ababa, Ethiopia.
    Svensson, M.
    Depts. Organ. Chem./Polymer Technol., Chalmers University of Technology, 412 83 Göteborg, Sweden.
    Andersson, M.R.
    Depts. Organ. Chem./Polymer Technol., Chalmers University of Technology, 412 83 Göteborg, Sweden.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Electrochemical bandgaps of substituted polythiophenes2003In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 13, no 6, p. 1316-1323Article in journal (Refereed)
    Abstract [en]

    The electrochemical bandgaps for different soluble substituted polythiophenes have been measured by cyclic voltammetry. The effect of substituents on the oxidation/reduction potentials is discussed. Bandgaps obtained by cyclic voltammetry have been found to be in general higher than optical bandgaps. Among regioregular polymers substituted with a phenyl group at position 3 of the thiophene ring, examples are found that give very symmetric voltammograms. Rationalization for this behaviour is discussed from a conformational point of view.

  • 350.
    Wang, Xiangjun
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Andersson, M.R.
    Department of Organic Chemistry, Chalmers University of Technology, SE-412 96 Göteberg, Sweden.
    Thompson, M.E.
    Department of Chemistry, University Southern California, Los Angeles, CA 90089, United States.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Electrophosphorescence from polythiophene blends light-emitting diodes2003Conference paper (Refereed)
    Abstract [en]

    Electrophosphorescence has been observed in phosphorescent blend polythiophene LEDs with poly(3-methyl-4-octyl-thiophene) (PMOT) as host, bis (2-phenylbenzothiazole) iridium acetylacetonate (BTIr) as the guest. Investigation of photoluminescence and quantum yields shows that energy transfer exists in the host-guest system and depends on guest concentration. Electroluminescence indicates that charge trapping effect also contributes to the formation of exciton at phosphorescent centers.

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