| 1. |
- Chekalin, S, et al.
(author)
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Femtosecond pump–probe investigation of primary photoinduced processes in C60–Sn nanostructures
- 2003
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In: Synthetic Metals. - 0379-6779. ; 139:3, s. 799-802
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Journal article (peer-reviewed)abstract
- Investigation of photoinduced processes in different C60–Sn nanostructures excited by 150 fs laser pulses at 400 nm (109 W/cm2) was performed with femtosecond supercontinuum probing of difference absorption and reflection in the spectral range of 400–1600 nm. The dynamics of relaxation are quite different for various nanostructures depending on the deposition mode and the ratio of tin and fullerene content. Non-monotonic relaxation, observed in the samples with Sn nanocrystallites, is explained by electron exchange between C60 and the metal.
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| 2. |
- Friedlein, Rainer, et al.
(author)
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Electronic structure of conjugated polymers and interfaces in polymer-based electronics
- 2003
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In: Synthetic Metals (Proceedings of the International Conference on Science and Technology of Synthetic Metals). - 0379-6779. ; 135:1-3, s. 275-277
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Conference paper (peer-reviewed)abstract
- The electronic structure of conjugated polymers and interfaces in polymer-based electronics were analyzed. Fine structure were observed in the region of the first resonance with pi-final state symmetry, between 284.1 eV and 285.8 eV. The electronic transitions from the non-dispersed C(1s) level to specific parts of the unoccupied band structure were generated. It was found that for a dispersing valence band, in the presence of a core-hole, a given photon energy corresponded to an excitation into a state with a distinct wave vectors.
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| 3. |
- Ruseckas, A., et al.
(author)
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Luminescence from inter-chain aggregates in polythiophene films
- 2001
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In: Synthetic Metals. - 0379-6779 .- 1879-3290. ; 119:1-3, s. 603-604
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Journal article (peer-reviewed)abstract
- We report time-resolved photoluminescence of two polythiophene derivatives with different chain packing. Emission of inter-chain aggregates is distinguished from that of intra-chain singlet excitons. The aggregate luminescence is shifted towards lower energies relative to that of intra-chain exciton by 0.17 eV, and the Huang-Rhys factor of the coupling to the intra-chain C double bondC vibration is S = 1.5. The excitonic coupling in aggregates is of intermediate strength.
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| 4. |
- Theander, M., et al.
(author)
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Interchain photoluminescence in substituted polyfluorenes
- 2001
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In: Synthetic metals. - 0379-6779 .- 1879-3290. ; 119:1-3, s. 615-616
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Journal article (peer-reviewed)abstract
- We have characterised the interchain emitting states of two substituted polyfluorenes with steady-state and time-resolved photoluminescence (PL). Site selective excitation of the interchain state shows that physical dimers are formed in the film. These dimers have low concentration in the films but exciton diffusion to the dimers is reducing the intrachain exciton lifetime. With asymmetrical substituents, the PL quantum yield is higher and the PL lifetime is longer due to lower concentration of dimers. Slow cooling from the melt, gives a new red shifted emission band and less intrachain emission. A discrepancy in the calculated radiative lifetimes suggest a fast formation of this new band.
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| 5. |
- Jager, Edwin, 1973-, et al.
(author)
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Polypyrrole micro actuators
- 1999
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In: Synthetic metals. - 0379-6779 .- 1879-3290. ; 102:1-3, s. 1309-1310
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Journal article (peer-reviewed)abstract
- The doping and undoping of conjugated polymers is accompanied by a volume change. This volume change can be used to make micro-actuators. We have built polypyrrole (PPy) gold bilayer structures. The volume change of PPy induces a bending of the bilayer. We have made micro-actuators based on this principle, which have been examined with video-microscopy. Some applications for these microactuators are proposed, including opening and closing boxes for cell biology and nanoliter chemistry and micro-robotics.
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| 6. |
- Aasmundtveit, K.E., et al.
(author)
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Structural aspects of electrochemical doping and dedoping of poly(3,4-ethylenedioxythiophene)
- 2000
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In: Synthetic metals. - 0379-6779 .- 1879-3290. ; 113:1, s. 93-97
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Journal article (peer-reviewed)abstract
- Electrochemical dedoping and redoping of p-toluene sulfonate doped poly(3,4-ethylenedioxythiophene) (PEDOT) has been studied with in situ grazing incidence diffraction with water used as an electrolyte. The diffraction peak positions and integrated intensities do not change significantly during doping and dedoping, while the peak widths increase upon dedoping and decrease upon doping. This implies that the lattice parameters and the relative positions of the polymer chains and the p-toluene sulfonate ions remain unchanged, the redox processes being carried out by the motion of smaller ions between the polymer and the electrolyte, and that the structural order decreases upon dedoping and increases upon doping in a reversible manner.
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| 7. |
- Andersson, Mats R., et al.
(author)
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Improved photoluminescence efficiency of films from conjugated polymers
- 1997
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In: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 85:1-3, s. 1383-1384
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Journal article (peer-reviewed)abstract
- 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.
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| 8. |
- Andersson, Mats R., et al.
(author)
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Synthesis of poly(alkylthiophenes) for light-emitting diodes
- 1995
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In: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2183-2184
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Journal article (peer-reviewed)abstract
- 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.
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| 9. |
- Andersson, M.R., et al.
(author)
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The effect of the polymerisation temperature on molecular weight and photoluminescence quantum yield for a phenylsubstituted PPV
- 2001
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In: Synthetic metals. - 0379-6779 .- 1879-3290. ; 119:1-3, s. 63-64
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Journal article (peer-reviewed)abstract
- We present the synthesis and characterisation of poly(2-(2',5'-bis(2?-ethylhexyloxy)phenyl)-1, 4-phenylenevinylene) (BEHP-PPV) polymerised under different conditions. The photoluminescence efficiencies (?PL) in the solid state of BEHP-PPV obtained at 144°C and 0°C are 28% and 60%, respectively. Polymerisation temperatures below 0°C decreases the molecular weight without changing the photoluminescence efficiency to any large extent.
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| 10. |
- Bantikassegn, W., et al.
(author)
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Proceedings of the International Conference on Science and Technology of Synthetic Metals Electronic properties of polypyrrole (polystyrene-sulphonate)/metal junctions
- 1993
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In: Synthetic metals. - 0379-6779 .- 1879-3290. ; 55:1, s. 36-42
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Journal article (peer-reviewed)abstract
- The nature of polymer/metal interfaces is decisive for the operation of polymer based electronic devices. At such interfaces charge transport may be affected by barrier formation, or by formation of insulating interfaces of various types. We have prepared thin films of conducting polypyrrole doped with large polymeric anions of polystyrenesulphonate for studies in metal/polymer junctions. Aluminium and gold contacts are vacuum deposited to form metal/polymer/gold sandwich structures. The current-voltage characteristics show that the interface between polypyrrole and gold is ohmic with no current limitation. However, the aluminium/polypyrrole interface forms highly resistive and nonohmic contacts. Photoelectron spectroscopy using UV and X-ray photons reveals a decrease of the work function upon Al deposition, reactions between Al and the sulphonate anions, and immediate oxidation of the aluminium upon exposure to oxygen. These observations corroborate the interpretation that the current limitation found at Al/polypyrrole junctions is due to formation of insulating aluminium oxide, not excluding reactions between the metal and dopant. It is also pointed out that interfaces between reactive metals and polymers are prone to such oxide interface formation, considering the high diffusivity of oxygen in many polymers.
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