| 1. |
- Andersson, Mats R., et al.
(författare)
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Electroluminescence from Substituted Poly(thiophenes) : From Blue to Near-Infrared
- 1995
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Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 28:22, s. 7525-7529
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Tidskriftsartikel (refereegranskat)abstract
- 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%.
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| 2. |
- Andersson, Mats R., et al.
(författare)
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Improved photoluminescence efficiency of films from conjugated polymers
- 1997
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 85:1-3, s. 1383-1384
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Andersson, Mats R., et al.
(författare)
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Synthesis of poly(alkylthiophenes) for light-emitting diodes
- 1995
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2183-2184
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Berggren, Magnus, et al.
(författare)
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Controlling inter-chain and intra-chain excitations of a poly(thiophene) derivative in thin films
- 1999
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Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 304:1-2, s. 84-90
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Berggren, Magnus, et al.
(författare)
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Light-emitting diodes with variable colours from polymer blends
- 1994
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 372:6505, s. 444-446
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Berggren, Magnus, et al.
(författare)
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White light from an electroluminescent diode made from poly[3(4‐octylphenyl)‐2,2′‐bithiophene] and an oxadiazole derivative
- 1994
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 76:11, s. 7530-7534
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 7. |
- Bergling, Per, 1967-, et al.
(författare)
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Rule of law in public administration : problems and ways ahead in post-conflict peace-building
- 2010
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Ingår i: Hague Journal on the Rule of Law. - Cambridge UK : T.M.C.Asser/Cambridge University press. - 1876-4045. ; 2:2, s. 171-202
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This article demonstrates that in many peace-building environments, public administration reform and justice sector reform are promoted as separate projects and underpinned by different paradigms, namely making the administration more effective and efficient while introducing and strengthening rule of law and human rights principles in the justice sector. The reasons for this division include lack of knowledge among international and national policy-makers concerning the relevance of the rule of law for public administration reform, vague and conflicting peace-building mandates and objectives, and differences in topical orientation and ‘culture’ among the international actors concerned. The resulting rule of law deficit in public administration reform has adverse effects on both states and individuals, not least for the protection of fundamental human rights. This deficit is also symptomatic of an even deeper dilemma: the distinction between ends and means in post-conflict efforts. In order to more closely integrate rule of law dimensions in public administration reform, the article suggests an inventory of possible approaches, and relates these to current and future challenges and needs. The inventory comprises developing concepts of rule of law in public administration, promoting transformation of international rule of law principles to national law, facilitating institutional reforms to ensure the presence of institutions willing and able to adhere to the rule of law; the development of manuals, handbooks and other ‘aids’ for law-makers and administrators; developing tools for monitoring the ‘qualitative’ dimensions of public administration; transparency enhancement to enable individuals to enforce their rights; and improving inter-agency/sector co-operation in order to promote coordination and integrated approaches.
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| 8. |
- Granström, Magnus, et al.
(författare)
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Phase separation of conjugated polymers - Tools for new functions in polymer LEDs
- 1997
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 85:1-3, s. 1193-1194
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Granström, Magnus, et al.
(författare)
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Self organizing polymer films - a route to novel electronic devices based on conjugated polymers
- 1997
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Ingår i: Supramolecular science. - : ELSEVIER SCI LTD. - 0968-5677 .- 1873-4146. ; 4:1-2, s. 27-34
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Högberg, Hans-Erik, et al.
(författare)
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Synthesis of Some Bicyclophanes.
- 1982
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Ingår i: Acta Chemica Scandinavica, B-Organic chemistry and biochemistry. - 0302-4369. ; 36:10, s. 661-667
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Tidskriftsartikel (refereegranskat)
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