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  • 251.
    Berggren, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Nilsson, David
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Chen, Miaoxiang
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Andersson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Kugler, Thomas
    Acreo AB, Norrköping.
    Malmström, Anna
    Acreo AB, Norrköping.
    Häll, Jessica
    ITN Fysik och elektroteknik.
    Remonen, Tommie
    Acreo AB, Norrköping.
    Robinson, Nathaniel D
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Polymer-based electrochemical devices for logic functions and paper displays2003In: SPIE Annual Meeting,2003, Bellingham: SPIE Publication Service , 2003, p. 429-Conference paper (Refereed)
  • 252.
    Chen, Miaoxiang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. null.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. null.
    Printed low-pass organic filters2003In: Polytronic,2003, 2003Conference paper (Refereed)
  • 253.
    Andersson, Peter
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kugler, Thomas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Switchable Optical Polarizer Based on Electrochromism in Stretch-Aligned Polyaniline2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 83, no 7, p. 1307-1309Article in journal (Refereed)
    Abstract [en]

    We report on the polarizing electrochromic (EC) effect of a conjugated polymer. This has been achieved in a planar flexible electrochemical device cell comprised of a patterned stretch-aligned thin film of polyaniline and an electrolyte, all made on a polyethylene foil substrate. The resulting device exhibits polarized absorption characteristics, of a dichroic ratio of 4, that can be controlled by the voltage applied. Also, thin flexible EC polarizers have been realized by combining two stretch-aligned polyaniline films with orthogonal stretching direction. In the resulting EC polarizer the orientation of the polarized absorption can be switched between two orthogonal directions, depending on the voltage applied.

  • 254.
    Andersson, Peter
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nilsson, David
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Svensson, Per-Olof
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Chen, Miaoxiang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Malmström, Anna
    ACREO Institute, Norrköping, Sweden.
    Remonen, Tommi
    ACREO Institute, Norrköping, Sweden.
    Kugler, Thomas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Active Matrix Displays Based on All-Organic Electrochemical Smart Pixels Printed on Paper2002In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 14, no 20, p. 1460-1464Article in journal (Refereed)
    Abstract [en]

    An organic electronic paper display technology (see Figure and also inside front cover) is presented. The electrochromic display cell together with the addressing electrochemical transistor form simple smart pixels that are included in matrix displays, which are achieved on coated cellulose-based paper using printing techniques. The ion-electronic technology presented offers an opportunity to extend existing use of ordinary paper.

     

  • 255.
    Nilsson, David
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kugler, Thomas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Svensson, Per-Olof
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bergren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    An all-organic sensor-transistor based on a novel electrochemical transducer concept printed electrochemical sensors on paper2002In: Sensors and Actuators B: Chemical, ISSN 0925-4005, Vol. 86, no 2-3, p. 193-197Article in journal (Refereed)
    Abstract [en]

    A novel transducer concept based on an organic electrochemical transistor is described. Its function as an integral part of an air humidity sensor, in which the proton conductor Nafion acts as sensitivity layer has been realised. The resulting electrochemical sensor–transistor, based on the conducting polymer PEDOT:PSS, operates at low voltages, on the order of 1 V. The sensor response, measured as the drain–source current of the electrochemical transistor, versus air humidity, has a close to exponential behaviour. The sensor can be realised using exclusively printing and coating fabrication techniques. Here, we demonstrate devices realised on plastic foils and on ordinary coated fine paper substrates. This organic electrochemical transducer promise future applications such as all-integrated low-cost sensor tags for single-use chemical sensors.

  • 256.
    Nilsson, David
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Chen, Miaoxiang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kugler, Thomas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Remonen, Tommi
    ACREO Institute, Norrköping, Sweden.
    Armgarth, Mårten
    ACREO Institute, Norrköping, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bi-stable and dynamic current modulation in electrochemical organic transistors2002In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 14, no 1, p. 51-54Article in journal (Refereed)
    Abstract [en]

    Novel electrochemical transistors, based on the conductive polymer PEDOT, operating at driving voltages of only a few volts in bulk material, and with little demand on substrate planarity, are described by the authors. The underlying polymer ion pair PEDOT:PSS is conductive in both oxidized and reduced state. Two transistor architectures, a bi-stable and a dynamic transistor (the first electrochemical specimen of its kind) with an on/off ratio of 105 and 200 Hz modulation speed, were realized.

  • 257.
    Chen, Miaoxiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nilsson, David
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kugler, Thomas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Remonen, Tommie
    Acreo AB, Norrköping, Sweden.
    Electric current rectification by an all-organic electrochemical device2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, p. 2011-2013Article in journal (Refereed)
    Abstract [en]

    An all-organic printed electrochemical rectifier is reported. The device is based on a patterned layer of poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) that interfaces a patterned electrolyte top layer. Overlap between the electrolyte layer and the conducting polymer pattern results in the formation of two electrochemically active areas within the conducting polymer pattern. When bias voltage is applied across the conducting polymer pattern, the PEDOT in the negatively biased areas is reduced electrochemically, while the PEDOT in the positively biased area is further oxidized. Reducing PEDOT from its p-doped, pristine state to the neutral state results in a marked loss of electrical conductivity. Due to the unsymmetrical device geometry, the current through the device may be shut off for one polarity of applied bias voltage with an electrical current rectification ratio of 100 compared to the opposite polarity. The output characteristics of a corresponding half wave rectifier as well as those from a full wave bridge rectifier show stable performance at frequencies below 15 Hz.

  • 258.
    Tehrani, Payman
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Remonen, Tommie
    Acreo AB, Norrköping.
    Hennerdal, Lars-Olov
    Acreo AB, Norrköping.
    Malmström, Anna
    Acreo AB, Norrköping.
    Häll, Jessica
    ITN Fysik och elektroteknik.
    Nilsson, David
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Leenders, Luc
    Agfa-Gevaert NV, Mortsel, Belgium.
    Kugler, Thomas
    Acreo AB, Norrköping.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Electrochemical Patterning of Conducting Polymer Layers: A Novel Technology for "Printing" Polymer Electronic Devices2002In: Material Research Society Spring Meeting,2002, 2002Conference paper (Refereed)
  • 259.
    Chen, Miaoxiang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Printed electrochemical diodes based on conducting polymers2002In: E-MRS,2003, 2002Conference paper (Refereed)
  • 260.
    Berggren, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Kugler, Thomas
    Acreo AB, Norrköping.
    Electronics turns over a new leaf2001In: Physics world, ISSN 0953-8585, Vol. 14, p. 21-22Article in journal (Refereed)
  • 261.
    Nilsson, David
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Chen, Miaoxiang
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Andersson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Svensson, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Kugler, Thomas
    Acreo AB, Norrköping.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Organic Electrochemical Transistors, Based on Electrolytes-Conducting Polymer Bilayers2001In: Material Reseach Socity Fall Meeting,2001, 2001Conference paper (Refereed)
  • 262.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fagerström, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical 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.
    Weman, Helge
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Granström, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Wennerström, O
    Chalmers Tekniska Högskola.
    Hjertberg, T
    Chalmers Tekniska Högskola.
    Controlling inter-chain and intra-chain excitations of a poly(thiophene) derivative in thin films1999In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 304, no 1-2, p. 84-90Article in journal (Refereed)
    Abstract [en]

    The decay of photoexcitations in polythiophene chains has been studied in solid solutions of the polymer from room temperature to 4 K. A strong blue shift of the emission spectrum is observed in the polymer blend, as compared to the homopolymer. Dispersion of the polythiophene suppresses the non-radiative processes, which are suggested to be correlated to close contacts of polymer chains. Quantum chemistry modeling of the excited state distributed on two chains corroborate this conclusion.

  • 263.
    Granlund, Thomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Theander, Mathias
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mats
    Chalmers Tekniska Högskola.
    Ruzeckas, A
    Lunds universitet.
    Sundström, V
    Lunds universitet.
    Björk, G
    KTH.
    Granström, Magnus
    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.
    Lasing in substituted polythiophene between dielectric mirrors1999In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 102, no 1-3, p. 1038-1041Article in journal (Refereed)
    Abstract [en]

    We report photopumped lasing in a microcavity device with a polythiophene layer as emitter. The microcavity is made of a polymer film between two dielectric Bragg reflecting mirrors (DBR). The:microcavity devices is built by joining two polymer coated DBR mirrors at elevated temperature. When photopumping the film,a lasing threshold is observed at 120 nJ/cm(2). Comparative studies with fast pump-probe spectroscopy of thin polythiophene films, and the same polymer in photopumped lasing studies, indicate that the gain coefficient is 80 +/- 20 cm(2) and that the exciton concentration is 2X10(17) cm(2) at the lasing transition, well below the exciton-exciton recombination level.

  • 264. Roman, L.S.
    et al.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Polymer diodes with high rectification1999In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 75, p. 3557-3557Article in journal (Refereed)
  • 265.
    Granlund, Thomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Theander, Mathias
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, M
    Chalmers Tekniska Högskola.
    Ruzeckas, A
    Lunds universitet.
    Sundström, V
    Lunds universitet.
    Björk, G
    KTH.
    Granström, Magnus
    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.
    A polythiophene microcavity laser1998In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 288, no 5-6, p. 879-884Article in journal (Refereed)
    Abstract [en]

    We report photopumped lasing in a microcavity device with a polythiophene layer as the emitter. These microcavity devices are built by joining two polymer coated dielectric mirrors at elevated temperature. When photopumping the film, a lasing threshold is observed at 120 nJ/cm(2). Comparative studies with fast pump-probe spectroscopy of thin polythiophene films and the same polymer in photopumped lasing studies, indicate that the gain coefficient is 80 +/- 20 cm(-1), and that the exciton concentration is 2 X 10(17) cm(-3) at the lasing transition, well below the exciton-exciton recombination level. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 266.
    Inganäs, Olle
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Granlund, T
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Theander, M
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, MR
    Chalmers Tekniska Högskola.
    Ruseckas, A
    Lunds universitet.
    Sundström, V
    Lunds universitet.
    Optical emission from confined poly(thiophene) chains1998In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 9, no 1-4, p. 104-108Article in journal (Refereed)
    Abstract [en]

    We discuss the stages of the luminescence processes in substituted and soluble poly(thiophenes), using results from determinations of absolute quantum yields of photoluminescence, fast pump-probe experiments and microcavity devices. Enhancement of the quantum yield of photoluminescence, with poly(thiophenes) in the solid state, call be obtained by dispersing the conjugated chain in a molecularly dispersed polymer blend, or by adding side chains designed for forcing the conjugated main chains apart. At the wavelength of stimulated emission, we observe a narrow bandwidth emission in the high-Q one-dimensional microcavity devices prepared by sandwiching two dielectric mirrors around a thin polymer film, A strong enhancement of the power efficiency is observed at a pump power of 1 mu W/cm(2), but does not conclusively show lasing characteristics. (C) 1998 Elsevier Science B.V.

  • 267.
    Berggren, Magnus
    et al.
    Bell Laboratories, Murray Hill, NJ, USA.
    Dodabalapur, A.
    Bell Laboratories, Murray Hill, NJ, USA.
    Slusher, R.E.
    Bell Laboratories, Murray Hill, NJ, USA.
    Bao, Z.
    Bell Laboratories, Murray Hill, NJ, USA.
    Timko, A.
    Bell Laboratories, Murray Hill, NJ, USA.
    Nalamasu, O.
    Bell Laboratories, Murray Hill, NJ, USA.
    Organic laser based on lithographically defined photonic-bandgap resonators1998In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 34, no 1, p. 90-91Article in journal (Refereed)
    Abstract [en]

    The authors report the fabrication and characteristics of organic solid-state waveguide lasers with feedback from a photolithographically defined rhomboid photonic bandgap lattice. The lattice is formed by etching holes of depth 10-40 nm in SiO2 and filling them with the organic gain medium. The gain medium is part of a planar waveguide formed by air/organic layer/SiO2.

  • 268.
    Berggren, Magnus
    et al.
    Bell Laboratories, Murray Hill, USA.
    Dodabalapur, A
    Bell Laboratories, Murray Hill, USA.
    Slusher, RE
    Bell Laboratories, Murray Hill, USA.
    Timko, A
    Bell Laboratories, Murray Hill, USA.
    Nalamasu, O
    Bell Laboratories, Murray Hill, USA.
    Organic solid-state lasers with imprinted gratings on plastic substrates1998In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 72, no 4, p. 410-411Article in journal (Refereed)
    Abstract [en]

    Optically pumped laser emission has been observed from thin films of 8-hydroxyquinolinato aluminum (Alq) doped with a DCM dye deposited on a diffraction,orating formed by imprinting a film of BCB with a mold. The BCB film, which is 4 mu m thick, is deposited on a silicon or a flexible plastic substrate. Laser emission occurs at a wavelength war 655 nm which corresponds to the third order of the grating, which has a periodicity of similar to 0.6 mu m. (C) 1998 American Institute of Physics.

  • 269.
    Dodabalapur, A
    et al.
    Bell Laboratories, Murray Hill, USA.
    Berggren, Magnus
    Bell Laboratories, Murray Hill, USA.
    Slusher, RE
    ATandT Bell Labs, Lucent Technology, Murray Hill, NJ 07974 USA; .
    Bao, Z
    Bell Laboratories, Murray Hill, USA.
    Timko, A
    Bell Laboratories, Murray Hill, USA.
    Schiortino, P
    Bell Laboratories, Murray Hill, USA.
    Laskowski, E
    Bell Laboratories, Murray Hill, USA.
    Katz, HE
    Bell Laboratories, Murray Hill, USA.
    Nalamasu, O
    Bell Laboratories, Murray Hill, USA.
    Resonators and materials for organic lasers based on energy transfer1998In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 4, no 1, p. 67-74Article in journal (Refereed)
    Abstract [en]

    Optically pumped lasers have been fabricated with organic/polymeric materials capable of charge transport. The active materials employed are doped films with small molecule hosts and dye, oligomer, and conjugated polymer emitters, In these materials, the excited states created in the host are transferred nonradiatively to the guest molecules which are the emitters, This energy transfer results in very low absorption losses at the emission wavelength and relatively low-threshold powers for the onset of stimulated emission. Such gain media have been successfully included in many types of resonators including whispering-gallery mode, photonic bandgap, and distributed Bragg reflector (DBR) based resonators. A number of novel patterning and fabrication procedures have been developed for organic-based lasers.

  • 270.
    Dodabalapur, A.
    et al.
    Bell Laboratories, Murray Hill, NJ, USA.
    Chandross, E. A.
    Bell Laboratories, Murray Hill, NJ, USA.
    Berggren, Magnus
    Bell Laboratories, Murray Hill, NJ, USA.
    Slusher, R. E.
    Bell Laboratories, Murray Hill, NJ, USA.
    Applied physics - Organic solid-state lasers: Past and future1997In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 277, no 5333, p. 1787-1788Article in journal (Other academic)
    Abstract [en]

    Researchers around the world are seeking organic materials that can be made into practical and efficient lasers. In their Perspective, Dodabalapur et al. review the past history and future prospects of this important class of laser materials.                                            

  • 271.
    Ostrick, J. R.
    et al.
    Bell Laboratories, Murray Hill, New Jersey .
    Dodabalapur, A.
    Bell Laboratories, Murray Hill, New Jersey .
    Torsi, L.
    Bell Laboratories, Murray Hill, New Jersey .
    Lovinger, A, J.
    Bell Laboratories, Murray Hill, New Jersey .
    Kwock, E. W.
    Bell Laboratories, Murray Hill, New Jersey .
    Miller, T. M.
    Bell Laboratories, Murray Hill, New Jersey .
    Galvin, M.
    Bell Laboratories, Murray Hill, New Jersey .
    Berggren, Magnus
    Bell Laboratories, Murray Hill, New Jersey .
    Katz, H. E.
    Bell Laboratories, Murray Hill, New Jersey .
    Conductivity-type anisotropy in molecular solids1997In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 81, no 10, p. 6804-6808Article in journal (Refereed)
    Abstract [en]

    Thin polycrystalline films of perylenetetracarboxylic dianyhydride (PTCDA), an organic molecular solid, exhibits substantial anisotropies in its electronic transport properties. Only electrons transport in the directions along molecular planes, while mainly holes transport in the direction normal to molecular planes. A series of measurements on both field effect transistors with PTCDA active layers and light emitting diodes with PTCDA transport layers documents the anisotropy seen in the electronic transport in thin films of PTCDA. (C) 1997 American Institute of Physics.

  • 272.
    Andersson, Mats R.
    et al.
    Chalmers Tekniska Högskola.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Olinga, T.
    Chalmers Tekniska Högskola.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Improved photoluminescence efficiency of films from conjugated polymers1997In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 85, no 1-3, p. 1383-1384Article in journal (Refereed)
    Abstract [en]

    We have demonstrated two general ways to increase the photoluminescence efficiency of films from conjugated polymers. One is to disperse the conjugated polymer on a molecular level by using attractive forces between the conjugated polymer and the matrix. The other method is to substitute the conjugated polymer with side chains which separates the conjugated backbones. Using this idea a new poly(thiophene) with a photoluminescence efficiency of 16% in films has been prepared. LEDs from this polymer exhibit an external efficiency of 0.1% for single layer and 0.7% for double layer diodes.

  • 273.
    Berggren, Magnus
    et al.
    Bell Laboratories, Murray Hill, New Jersey, USA.
    Dodabalapur, A.
    Bell Laboratories, Murray Hill, New Jersey, USA.
    Slusher, R. E.
    Bell Laboratories, Murray Hill, New Jersey, USA.
    Bao, Z.
    Bell Laboratories, Murray Hill, New Jersey, USA.
    Light amplification in organic thin films using cascade energy transfer1997In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 389, p. 466-469Article in journal (Refereed)
    Abstract [en]

    There is currently renewed interest in the development of lasers using solid-state organic and polymeric materials as the gain media. These materials have a number of properties that make them good candidates for such applications — for example, emission bands that are displaced (via a Stokes shift) from absorption bands, and the ease with which the emitting species can be embedded in a suitable host material1, 2, 3, 4, 5. But despite these advantages, the threshold power densities required for light amplification that have been reported so far have been high6, 7, 8. Here we describe an approach, based on energy transfer between molecular species, that can lower the threshold for stimulated emission and laser action while improving markedly the waveguiding properties of the active material. In our materials, an initial molecular excited state is generated in the host compound by absorption of light; this state is then resonantly and non-radiatively transferred down in energy (through one or more steps) between suitably matched dye molecules dispersed in the host, so ensuring that the absorption losses at the final emission wavelengths are very small. Such composite gain media provide provide broad tunability of the emission wavelength, and also decouple the optical emission properties from the transport properties, so providing greater flexibility for the design of future electrically driven device structures.

  • 274.
    Berggren, Magnus
    et al.
    Bell Laboratories, Murray Hill, USA.
    Dodabalapur, A
    Bell Laboratories, Murray Hill, USA.
    Slusher, RE
    Bell Laboratories, Murray Hill, USA.
    Bao, Z
    Bell Laboratories, Murray Hill, USA.
    Organic lasers based on Forster transfer1997In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 91, no 1-3, p. 65-68Article in journal (Refereed)
    Abstract [en]

    The light amplification characteristics of organic guest-host systems with Forster transfer from absorbing small molecule hosts to dye/ polymer dopants are described. Such material systems are shown to be very promising for use in low-threshold organic lasers. A number of laser resonators have been experimentally realized with Forster gain media including microdisk, ring, spheroid, and distributed Bragg reflector lasers. (C) 1997 Elsevier Science S.A.

  • 275.
    Granström, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    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 R.
    Chalmers Tekniska Högskola.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Phase separation of conjugated polymers - Tools for new functions in polymer LEDs1997In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 85, no 1-3, p. 1193-1194Article in journal (Refereed)
    Abstract [en]

    Within the single family of substituted poly(thiophenes) it is possible to realize such diverse device designs as voltage controlled colours from polymer LEDs, sub-micron size LEDs, and white light emitters. Many of these features become possible by the use of polymer blends in which one or more poly(thiophenes) are mixed with a matrix polymer (PMMA). The phase structure in these blends can be controlled by stoichiometry and mode of formation. That phase structure can be used to prevent exciton transfer, and to define new colours in polymer LEDs. It also allows us to make anisotropic conductors suitable for contacting optical devices.

  • 276.
    Granström, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Pede, Danilo
    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 R.
    Chalmers Tekniska Högskola.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Self organizing polymer films - a route to novel electronic devices based on conjugated polymers1997In: Supramolecular science, ISSN 0968-5677, E-ISSN 1873-4146, Vol. 4, no 1-2, p. 27-34Article in journal (Refereed)
    Abstract [en]

    Polymer blends are often used in polymer light emitting diodes as a tool to increase the efficiency of the devices. In this report, we show the necessity to take the phase separation properties of such blends into account, as the miscibility of the involved polymers drastically affects the resulting film structure. By using phase separated polymer blends involving conjugated poly(thiophenes) and different nonconjugated polymers as matrices, different types of applications, such as light emitting diodes with improved voltage control of emitted colour, sub-micron size LEDs and anisotropic conductors are demonstrated. (C) 1997 Elsevier Science Ltd. All rights reserved.

  • 277.
    Berggren, Magnus
    et al.
    Bell Laboratories, Murray Hill, USA.
    Dodabalapur, A
    Bell Laboratories, Murray Hill, USA.
    Bao, ZN
    Bell Laboratories, Murray Hill, USA.
    Slusher, RE
    Bell Laboratories, Murray Hill, USA.
    Solid-state droplet laser made from an organic blend with a conjugated polymer emitter1997In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 9, no 12, p. 968-Article in journal (Refereed)
    Abstract [en]

    Lasers based on organic materials have been produced with a wide range of resonator design and in a variety of geometries. A new strategy is presented for fabricating permanently near-spherical whispering gallery mode (WGM) lasers from a blend of PPV7 and PBD (see Figure) by a melting and resolidification process. The thresholds and quality factors of these resonators are estimated and discussed.

  • 278.
    Berggren, Magnus
    et al.
    Bell Laboratories, Murray Hill, USA.
    Dodabalapur, A
    Bell Laboratories, Murray Hill, USA .
    Slusher, RE
    Bell Laboratories, Murray Hill, USA.
    Stimulated emission and lasing in dye-doped organic thin films with Forster transfer1997In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 71, no 16, p. 2230-2232Article in journal (Refereed)
    Abstract [en]

    Optically pumped stimulated emission and lasing in thin films of an absorbing host 8-hydroxyquinolinato aluminum(Alq) doped with small amounts of the laser dye DCM II is observed. Forster transfer of the excitation from the Alq molecules to the DCM II molecules results in a high absorption coefficient at pump wavelength (337 nm) as well as low absorption loss at the emission wavelengths (610-650 nm). (C) 1997 American Institute of Physics.

  • 279.
    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.

  • 280.
    Granström, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    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.
    Polymeric light-emitting diodes of submicron size - Structures and developments1996In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 76, no 1-3, p. 141-143Article in journal (Refereed)
    Abstract [en]

    Micron- and submicron-sized light-emitting diodes (LEDs) made using conjugated polymers as electroluminescent layers and contact materials are presented. Two different routes to make arrays of such small light sources have been developed. The benefits and drawbacks of the use of the conjugated polymer poly(2,3-ethylene-dioxythiophene) (PEDOT) as hole injector in polymer LEDs are also discussed.

  • 281.
    Xing, K. Z.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    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.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Boman, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Iucci, G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bröms, P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The electronic and geometric structures of neutral and potassium-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy1996In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 76, no 1-3, p. 263-267Article in journal (Refereed)
    Abstract [en]

    The electronic and geometric structures of poly [3-(4-octylphenyl)thiophene] have been studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively). Thermochromic effects, and new charge induced states generated by potassium doping, have been observed by direct UPS measurements. The experimental results are in very good agreement with the results of theoretical quantum chemical calculations performed with the Austin Model 1 semi-empirical model and the valence-effective Hamiltonian pseudo-potential model.

  • 282.
    Xing, K. Z.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    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.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Boman, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Iucci, G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bröms, P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The electronic structure of neutral and alkali metal-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy1996In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 80, no 1, p. 59-66Article in journal (Refereed)
    Abstract [en]

    The electronic structure of poly [3-(4-octylphenyl)thiophene] (POPT) has been studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS), as well as by quantum chemical calculations. Both temperature-dependent effects on the electronic structure of the neutral system, as well as the generation of new electronic states induced by doping with alkaline metals, have been observed. The experimental results are in good agreement with the results of the quantum chemical calculations.

  • 283.
    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.

  • 284.
    Andersson, Mats R.
    et al.
    Chalmers Tekniska Högskola.
    Berggren, Magnus
    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, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Gustafsson-Carlberg, J. C.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Selse, D.
    Chalmers Tekniska Högskola.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Electroluminescence from Substituted Poly(thiophenes): From Blue to Near-Infrared1995In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 28, no 22, p. 7525-7529Article in journal (Refereed)
    Abstract [en]

    We report a systematic approach to the control of the conjugation length along the poly(thiophene) backbone. The planarity of the main chain can be permanently modified by altering the pattern of substitution and character of the substituents on the poly(thiophene) chain, and the conjugation length is thus modified. We obtain blue, green, orange, red, and near-infrared electroluminescence from four chemically distinct poly(thiophenes). The external quantum efficiencies are in the range of 0.01-0.6%.

  • 285.
    Granström, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    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.
    Micrometer- and Nanometer-Sized Polymeric Light-Emitting Diodes1995In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 267, no 5203, p. 1479-1481Article in journal (Refereed)
    Abstract [en]

    A method for the fabrication of micrometer- and submicrometer-sized polymeric light-emitting diodes is presented. Such diodes have a variety of applications. Light sources of dimensions around 100 nanometers are required for subwavelength, near-field optical microscopy. Another possible application is patterning on the micrometer and nanometer scale. The diodes have been made in the form of a sandwich structure, with the conductive polymer poly(3,4-ethylene-dioxythiophene) polymerized in the pores of commercially available microfiltration membranes defining the hole-injecting contacts, poly[3-(4-octylphenyl)-2,2-bithiophene] as the light-omitting layer, and a thin film of calcium-aluminum as the electron injector.

  • 286.
    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.

  • 287.
    Andersson, Mats R.
    et al.
    Chalmers Tekniska Högskola.
    Berggren, Magnus
    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.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Synthesis of poly(alkylthiophenes) for light-emitting diodes1995In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 71, no 1-3, p. 2183-2184Article in journal (Refereed)
    Abstract [en]

    We have demonstrated a general way to tune the emission of poly(alkylthiophenes) by using steric interaction between the repeating units. Light-emitting diodes prepared of the polymers have blue to near-infrared emission.

  • 288.
    Inganäs, Olle
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Gustafsson, Göran
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    Dyreklev, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Granström, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Thiophene polymers in light emitting diodes: Making multicolour devices1995In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 71, no 1-3, p. 2121-2124Article in journal (Refereed)
    Abstract [en]

    We can control the bandgap of thiophene polymers over 2 eV by choosing the nature, position and regularity of side chain substitutions. Electroluminescence from these polymers cover the full visible spectrum, from the blue into the near infra-red. Blends of these polymer materials allow us to construct voltage controlled variable colour light sources. A newly developed transfer technique allow us to mount thin oriented films of the polymers in polymer LEDs to obtain polarised light sources giving polarisation anisotropys of up to 3. Sub-lambda light sources have been constructed from these polymer materials using nanometer polymer electrodes.

  • 289.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Granström, Magnus
    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.
    Ultraviolet electroluminescence from an organic light emitting diode1995In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 7, no 11, p. 900-903Article in journal (Refereed)
    Abstract [en]

    The extension of the emission region for organic LEDs into the ultraviolet region is reported. Emission at 394 nm is achieved by modifying the geometry of a device based on poly(octylphenyl)bithiophene (PTOPT) and poly(octylphenyl)oxadiazole (PBD) which had previously been shown to emit white light. Through changing the geometry the red and green emission peaks have been suppressed and the UV band (from the PBD) enhanced.

  • 290.
    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.
    Green Electroluminescence in Poly-(3-cyclohexylthiophene) light-emitting diodes1994In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 6, no 6, p. 488-490Article in journal (Refereed)
    Abstract [en]

    Electoluminescent devices based on polythiophene-system this films have been demonstrated that together span the entire visible range, steric hindrance being used to vary the bandgap between compunds. Poly-(3-cyclohexylthiophene), see Figures, exhibits green electoluminescence. Possible interpretations of this observation are proposed.

  • 291.
    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.

  • 292.
    Andersson, Mats R.
    et al.
    Chalmers Tekniska Högskola.
    Selse, D.
    Chalmers Tekniska Högskola.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Järvinen, H.
    Neste Chemicals, Poruoo, Finland.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Wennerström, Olof
    Chalmers Tekniska Högskola.
    Österholm, J.-E.
    Neste Chemicals, Poruoo, Finland.
    Regioselective polymerization of 3-(4-octylphenyl)thiophene with FeCl31994In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 27, no 22, p. 6503-6506Article in journal (Refereed)
    Abstract [en]

    We have shown that it is possible to regioselectively polymerize 3-(4-octylphenyl) thiophene with FeCl3. Adding FeCl3 slowly to the monomer leads to a soft and therefore regioselective polymerization. The head-to-tail content was determined by H-1 NMR to be 94 +/- 2%. Thin films of the polymer treated with chloroform vapor have an absorption maximum at 602 nm (2.06 eV) with clear vibronic fine structure. Free standing films have a conductivity of 4 S/cm, which is 100 times higher than for earlier prepared poly(3-(4-octylphenyl)thiophene). A mechanism for the regioregular polymerization is also proposed.

  • 293.
    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.

  • 294.
    Berggren, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Gustafsson, Göran
    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.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Hjertberg, T.
    Chalmers Tekniska Högskola.
    Wennerström, O.
    Chalmers Tekniska Högskola.
    White light from an electroluminescent diode made from poly[3(4‐octylphenyl)‐2,2′‐bithiophene] and an oxadiazole derivative1994In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 76, no 11, p. 7530-7534Article in journal (Refereed)
    Abstract [en]

    We report on an electroluminescent diode emitting red, green, and blue light simultaneously. The device is based on a thin polymer layer, poly[3‐(4‐octylphenyl)‐2,2′‐bithiophene] and a thick molecular layer, 2‐(4‐biphenylyl)‐5‐(4‐tertbutyl‐phenyl)1,3,5‐oxadiazole. The quantum efficiency for light conversion is 0.3% and the turn‐on voltage for light emission is 7 V. In this article we present electric and spectroscopic characterizations. A mechanism for the light emission, based on electron and hole recombination between the two organic layers, is proposed

  • 295.
    Bubnova, Olga
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ullah Khan, Zia
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Wang, Hui
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Dagnelund, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Arlin, Jean-Baptiste
    Free University of Brussels Laboratoire de Chimie des Polymères, Bruxelles, Belgium.
    Geerts, Yves
    Free University of Brussels Laboratoire de Chimie des Polymères, Bruxelles, Belgium.
    Desbief, Simon
    University of Mons Laboratoire de chimie des materiaux nouveaux, Mons, Belgium.
    Breiby, Dag W.
    Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Andreasen, Jens W.
    Imaging and Structural Analysis Programme, Department of Energy Conversion and Storage, Technical University of Denmark, Roskilde, Denmark.
    Lazzaroni, Roberto
    University of Mons Laboratoire de chimie des materiaux nouveaux, Mons, Belgium.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Advantageous thermoelectric properties of a semimetallic polymerManuscript (preprint) (Other academic)
    Abstract [en]

    Thermoelectric generation potentially holds a solution for waste heat recovery issues provided that the availability of inexpensive, biodegradable and highly efficient thermoelectric materials is insured in the near future. Plastic thermoelectrics could successfully comply with the said requirements if the thermoelectric efficiency (ZT) of conducting polymers was higher. However, given the novelty of the subject, at present there are no clear guidelines for ZT optimization in this class of materials. The most important piece of information that is currently missing is the description of a specific electronic makeup that conducting polymers must possess in order to enable good thermoelectric performance. In the present study the thermoelectric properties of poly(3,4-ethylenedioxythiophene) derivatives with two types of counterions, i.e. poly(styrenesulfonate) (PSS) and tosylate (Tos) are evaluated. A striking variation in their thermoelectric performance is attributed to structural and morphological differences between two polymers that manifest itself in dissimilar charge transport mechanism. The superior properties of PEDOT-Tos presumably originate from a high degree of crystallinity and structural order that predetermines the tendency for bipolaron band formation. Unlike polaronic PEDOT-PSS with slowly varying density of localized states (DOS) near the Fermi level (EF), the DOS in PEDOT-Tos is characterized by higher asymmetry and higher charge carrier density at EF (similar to semimetals), which allows for higher thermopower and electrical conductivity. Therefore, we conclude that the polymers with semimetallic electronic makeup are expected to exhibit promising thermoelectric properties with bigger variation in thermopower upon doping.

  • 296.
    Gabrielsson, Erik O.
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Armgarth, Astrid
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Nilsson, K. Peter N.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Controlled Microscopic Formation of Amyloid-Like Aβ Aggregates Using an Organic Electronic DeviceManuscript (preprint) (Other academic)
    Abstract [en]

    Alzheimer’s disease (AD), primarily associated with formation of fibrillar amyloid-beta peptide (Aβ) aggregates in the brain, is one of the most common old-age diseases. It is therefore crucial with an elevated scientific interest in Aβ, and its fundamental properties in a wide sense, to develop efficient methods for early detection and to combat AD. For the development of new techniques, both for AD detection and prevention, researchers are dependent on either tissue samples from deceased patients, animal models or in vitro systems. In vitro systems, such as producing protein aggregates of the Aβ-peptide in a test tube by incubation under denaturing conditions, offers us a simple but rather blunt tool for evaluating aggregation inhibition caused by compounds or to investigate new detection methods. We recently introduced the organic electronic ion pump (OEIP) as a method for creating amyloid-like aggregates at high spatiotemporal control as compared to the resulting aggregates manufactured using regular test tube-conditions. Combined with a fluorescent probe that is specific for the fibrillar aggregated form of misfolded peptides commonly seen in AD, this allowed us to control and to monitor the aggregation of a model peptide system in a highly confined space.

    To further elaborate the functionality of the OEIP together with amyloid-specific probes, we here present experiments demonstrating electronically controlled micron sized formation of Aβ-aggregates with morphologies ranging from fine fibers, to bundles of fibers, and thick mesh-like fiber structures. We foresee that the methodology can be implemented in multi array systems that can be utilized for studies of protein aggregation in confined spaces or together with cultured cells, as well as for the development of screening platforms for assessment of molecules influencing the Aβ-aggregation process.

  • 297.
    Jönsson, Stina
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Södergren, H.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Perzon, E.
    Department of Material and Surface Chemistry, Chalmers University of Technology, Gothenburg, Sweden.
    Chen, Miaoxiang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson, M. R.
    Department of Material and Surface Chemistry, Chalmers University of Technology, Gothenburg, Sweden.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    de Jong, M. P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Tengstedt, Carl
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Electronic structure of novel low band gap conjugated polymersManuscript (preprint) (Other academic)
    Abstract [en]

    The electronic structures of two novel low band gap conjugated polymers have been studied. Both materials are conjugated alternating copolymers based on fluorene units and low band gap donor-acceptor-donor units. The emphasis in this study has been to study the valence and the conduction bands. In particular the degree of localization or delocalization along the polymers and the symmetry of these states have been studied, since these features can be related to their transport properties. The main experimental part of this work is photoelectron spectroscopy, near-edge X-ray photon absorption and resonant photoemission. These techniques have been used to probe the frontier electronic structure of these systems. The experimental results are interpreted with the help of density functional theory calculations. The valence bands are dispersed originating from orbitals delocalized along the polymer chain shile the conduction bands are more flat, as they are derived from orbitals localized on the acceptor units. This band structure would predict good hole transporting properties but poor electron transport.

  • 298.
    Jakobsson, Fredrik L. E.
    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.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Filamentary switching of Rose Bengal devicesManuscript (preprint) (Other academic)
    Abstract [en]

    Switch devices with a structure of metal / orgamc layer / metal were fabricated, with the organic layer being Rose Bengal sodium salt, Rose Bengal bis(tricthylammonium) salt, Rose Bengal lactone and Fluorescein. All devices showed reversible switch behavior, ruling out electro reduction or conformational switching. Furthermore, only devices with ITO as substrate and Al or Ag as top electrode showed reversible switch behavior. Electrical characterization of the ITO substrate indicated that the switching is due to the reversible formation of conducting filaments, initiated from the ITO.

  • 299.
    Wang, Xiaodong
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Improving the stability of water-gated organic transistors for sensing applicationsManuscript (preprint) (Other academic)
    Abstract [en]

    The instability of water-gated organic transistors is a major obstacle for their sensing applications in aqueous media. In the present work, we demonstrate that adding a fluorinated ion exchange membrane, Nafion, on a water-gated organic transistor can increase significantly the stability of the device to air exposure. In addition, choosing a suitable operating voltage range, e.g. Vg=0 ↔ -0.7 V, is shown to be crucial for achieving stable (repeatable) measurements in aqueous media. It is also feasible to exploit this kind of transistor as a chemical sensor to discriminate different chemicals which are dissolved in water.

  • 300.
    Bubnova, Olga
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ph effect on thermoelectric properties of poly-(3,4-ethylenedioxythiophene):tosylateManuscript (preprint) (Other academic)
    Abstract [en]

    Abstract not available.

34567 251 - 300 of 307
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