| 1. |
- Aasmundtveit, K.E., et al.
(författare)
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Structural ordering in phenyl-substituted polythiophenes
- 2000
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 33:15, s. 5481-5489
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Tidskriftsartikel (refereegranskat)abstract
- Various substituted poly(phenylthiophene)s have been studied by X-ray diffraction. They are semicrystalline, with very different degrees of crystallinity. Those with para-substituted phenyl groups have a low degree of crystallinity, whereas those with ortho-substituted phenyl groups are more crystalline. The most crystalline materials in this study have two equally long substituents on the phenyl ring, one at the ortho position and the other at the ortho or meta position on the opposite side of the phenyl ring. Poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) was most thoroughly studied, and a structural model is proposed. The structure of PDOPT is quite different from previously studied substituted polythiophenes in that the octyl side chains are directed normal to the thiophene planes. In this way, the conjugated polymer chains are kept separated from each other. Solution-cast and spin-cast PDOPT films are anisotropic, with the octyl side chains oriented normal to the film surface in both cases. This is contrary to the situation for poly(3-alkylthiophene)s, where solution-cast and spin-cast films orient in different ways.
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| 2. |
- Inganäs, Olle, 1951-, et al.
(författare)
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Alternating fluorene copolymer/fullerene blend solar cells
- 2005. - 1
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Ingår i: Organic Photovoltaics. - Boca Raton, FL, USA : CRC Press. - 082475963X - 9780824759636 ; , s. 387-402
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices.Organic Photovoltaics: Mechanisms, Materials, and Devicesfills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world. It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center.Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades.
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| 3. |
- Inganäs, Olle, et al.
(författare)
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Low bandgap alternating polyfluorene copolymers in plastic photodiodes and solar cells
- 2004
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 79:1, s. 31-35
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Tidskriftsartikel (refereegranskat)abstract
- We report a comparative study of plastic photodiodes using four different copolymers of fluorene, with a variation of alkyl side chain length and chemical structure. Photodiode materials are formed by blending the polymers with a fullerene derivative and spincoating the blend solution. A photovoltage of 1 V is obtained in devices, where the anode is a doped polymer and the cathode is LiF/Al. Monochromatic quantum efficiencies are better than 40% over most of the absorption range, and under solar light AM 1.5 simulation, we reach energy efficiencies beyond 2%. The high fill factors obtained in some of the devices indicate that these are of interest for more elaborate optimisation. Reasons for the benign electrical transport are discussed. © Springer-Verlag 2004.
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| 4. |
- Johansson, Tomas, et al.
(författare)
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Electrochemical bandgaps of substituted polythiophenes
- 2003
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 13:6, s. 1316-1323
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Tidskriftsartikel (refereegranskat)abstract
- The electrochemical bandgaps for different soluble substituted polythiophenes have been measured by cyclic voltammetry. The effect of substituents on the oxidation/reduction potentials is discussed. Bandgaps obtained by cyclic voltammetry have been found to be in general higher than optical bandgaps. Among regioregular polymers substituted with a phenyl group at position 3 of the thiophene ring, examples are found that give very symmetric voltammograms. Rationalization for this behaviour is discussed from a conformational point of view.
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| 5. |
- Jonforsen, M., et al.
(författare)
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Photodiodes made from poly(pyridopyrazine vinylene) : polythiophene blends
- 2001
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Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 119:1-3, s. 185-186
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Tidskriftsartikel (refereegranskat)abstract
- A PPV-type polymer with the pyridopyrazine heterocycle (EHH-PPyPzV) has been synthesised and found to have high electron affinity according to electrochemical measurements. When used as the electron accepting material in single-layer-photodiodes, with a thiophene copolymer (PEOPT-co-PAAPT) as the electron donating material, IPCE (incident photon to current conversion efficiency) up to 1% was measured. Atomic force microscopy was used to analyse the blend morphology in the devices.
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| 6. |
- Ruseckas, A., et al.
(författare)
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Luminescence from inter-chain aggregates in polythiophene films
- 2001
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Ingår i: Synthetic Metals. - 0379-6779 .- 1879-3290. ; 119:1-3, s. 603-604
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Svensson, M., et al.
(författare)
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High-performance polymer solar cells of an alternating polyfluorene copolymer and a fullerene derivative
- 2003
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 15:12, s. 988-991
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Tidskriftsartikel (refereegranskat)abstract
- High-performance polymer solar cells of an alternating polyfluorene copolymer, PFDTBT, and a fullerene derivative were studied. It was shown that PFDTBT is a promising candidate for obtaining high energy conversion efficiency when combined with a suitable electron acceptor. Results showed that high-performance solar cells with extended spectral coverage and increased open-circuit voltage could be prepared from composites prepared from electron acceptor.
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| 8. |
- Svensson, M., et al.
(författare)
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Synthesis and properties of alternating polyfluorene copolymers with redshifted absorption for use in solar cells
- 2003
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 135-136, s. 137-138
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Tidskriftsartikel (refereegranskat)abstract
- Three fluorene based alternating copolymers with redshifted absorption were synthesized and used as the active layer in photodiodes. The polymers are soluble in common solvents. The photodiodes cover a large part of the solar spectrum with high external quantum efficiency and we reach 2.4% power conversion efficiency for the best device in this study.
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| 9. |
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| 10. |
- Theander, M., et al.
(författare)
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High luminescence from a substituted polythiophene in a solvent with low solubility
- 2001
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Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 337:4-6, s. 277-283
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Tidskriftsartikel (refereegranskat)abstract
- Steady-state and rime-resolved photoluminescence (PL) is used to probe different states of order in highly regular poly(3-(2'-methoxy-5'-octylphenyl)thiophene) (POMeOPT). In a good solvent (chloroform) the polymer has a PL yield of 0.33 and in a solvent with low solubility (mixture of chloroform and toluene) a new phase appears with higher PL yield (0.50). The new phase is attributed to micro-crystals formed by the regular part of the polymer which have low solubility in toluene. The crystallites have highly structured and redshifted electronic transitions compared with chains which are dissolved. (C) 2001 Published by Elsevier Science B.V.
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