SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WAKA:ref ;pers:(Inganäs Olle);srt2:(2005-2009);conttype:(refereed)"

Sökning: WAKA:ref > Inganäs Olle > (2005-2009) > Refereegranskat

  • Resultat 51-60 av 112
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
51.
  • Inganäs, Olle, et al. (författare)
  • Alternating Polyfluorenes Collect Solar Light in Polymer Photovoltaics
  • 2009
  • Ingår i: ACCOUNTS OF CHEMICAL RESEARCH. - : American Chemical Society (ACS). - 0001-4842 .- 1520-4898. ; 42:11, s. 1731-1739
  • Tidskriftsartikel (refereegranskat)abstract
    • The effort to improve the energy conversion efficiency of polymer solar cells has led to the design of novel donor polymers. To improve open circuit photovoltages (OCVs) and the spectral coverage of the solar spectrum, researchers have looked for materials with high HOMO values, an easily modified electronic structure, and sufficient electronic transport within the polymers. One advance in design from our laboratories has been the development of a class of alternating polyfluorene copolymers (APFOs), which can be combined with fullerenes to make bulk heterojunction materials for photovoltaic conversion. This Account describes copolymers of fluorene that we designed to expand the range the optical absorption of solar cells to include wavelengths out to 1000 nm. In most cases, we combine these polymers with acceptors from the fullerene family, typically the phenyl C-61 butyric acid methyl ester (PCBM) molecule, to generate solar cell materials. The synthesis of alternating copolymers of fluorene with various donor-acceptor-don or elements provides the opportunity to shift both HOMO and LUMO, which we have followed by electrochemical spectroscopy. Moving the LUMO of the APFOs farther from the vacuum level eventually leads to a situation where the driving force for photo-induced charge transfer from polymer donor to fullerene acceptor goes to zero, resulting in inefficient charge generation. Moving the HOMO level closer to the vacuum level reduces the OCV of devices made from bulk heterojunction blends. As we move the bandgap toward lower energies and increase the overlap of optical absorption with the solar spectrum, both these events eventually occur. In devices based on these APFO/fullerene blends, the performance depends on the OCV, the photocurrent under solar illumination, and the fill factor. The fill factor is influenced by electrical transport and charge generation. Optimizing these parameters requires new solutions to the perennial conflict between optically thin devices, where electrical extraction of charge is not a limitation, and the optically thick devices, where extraction of charge is hampered by trapping and recombination. As a result, we have developed methods to trap light in optically thin devices. When the thin film flexible solar cells are folded, multiple reflection between adjacent solar cells leads to a longer path length for the photon through the devices and considerable improvement of the optical dissipation in the active material. These optical tricks also enable an alternative route to tandem devices, where two different bandgap materials are located on adjacent folds. Thus light not absorbed in one cell is reflected onto the next cell to produce an effective optical series arrangement. Using experiments and simulations of the light trapping effects, we demonstrate power conversion efficiency enhancements of up to a factor of 1.8.
  •  
52.
  •  
53.
  • Jespersen, Kim, et al. (författare)
  • Charge formation and transport in bulk-heterojunction solar cells based on alternating polyfluorene copolymers blended with fullerenes
  • 2006
  • Ingår i: Organic Electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 7:4, s. 235-242
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate charge formation in bulk-heterojunction solar cells based on conjugated polymers in the form of alternating polyfluorene copolymers and the methanofullerene PCBM. Using transient absorption spectroscopy we show that optimal charge formation is obtained with 20-50 wt% PCBM. This is in contrast to the maximum short circuit current density obtained at similar to 80 wt% PCBM as determined by steady state current density-voltage characterization. Hence, we show explicitly that the solar cell performance of these interpenetrating polymer networks containing PCBM is limited by charge transport rather than by formation of charges. (c) 2006 Elsevier B.V. All rights reserved.
  •  
54.
  • Karlsson, Fredrik, et al. (författare)
  • Interactions between a zwitterionic polythiophene derivative and oligonucleotides as resolved by fluorescence resonance energy transfer
  • 2005
  • Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 17:16, s. 4204-4211
  • Tidskriftsartikel (refereegranskat)abstract
    • The interactions between a zwitterionic polythiophene derivative, POWT, and DNA oligonucleotides in solution have been studied by FRET (fluorescence resonance energy transfer). When POWT and ssDNA are bound alone in a complex, the distance between them is at its smallest. The distance increases when adding complementary DNA, but POWT is still mainly bound to the first DNA strand. We find that two POWT chains bind to one DNA strand, and the two POWT chains seem held together in pairs, unable to separate, as they can only bind to and quench half their own amount of labeled DNA. This POWT−POWT complex appears to dissociate at lower concentrations. ssDNA attached to POWT in a complex can also be substituted by other ssDNA in solution; this occurs to 50% when the free DNA is present in 10-fold concentration compared to the ssDNA bound to POWT. Titration studies at different concentrations show positive cooperativity in the binding of POWT and ssDNA into a complex. The hybridization of complementary DNA to the same complex involves no cooperativity. These observations indicate interesting possibilities for the use of POWT as a DNA sensor.
  •  
55.
  •  
56.
  • Karlsson, Roger, et al. (författare)
  • Iron-Catalyzed Polymerization of Alkoxysulfonate-Functionalized 3,4-Ethylenedioxythiophene Gives Water-Soluble Poly(3,4-ethylenedioxythiophene) of High Conductivity
  • 2009
  • Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 21:9, s. 1815-1821
  • Tidskriftsartikel (refereegranskat)abstract
    • Chemical polymerization of a 3,4-ethylenedioxythiophene derivative bearing a sulfonate group (EDOTS) is reported. The polymer, PEDOT-S, is fully water-soluble and has been produced by polymerizing EDOT-S in water, using Na2S2O8 and a catalytic amount of FeCl 3. Elemental analysis and XPS measurements indicate that PEDOT-S is a material with a substantial degree of self-doping, but also contains free sulfate ions as charge-balancing counterions of the oxidized polymer. Apart from selfdoping PEDOT-S, the side chains enable full water solubility of the material; DLS studies show an average cluster size of only 2 nm. Importantly, the solvation properties of the PEDOT-S are reflected in spin-coated films, which show a surface roughness of 1.2 nm and good conductivity (12 S/cm) in ambient conditions. The electro-optical properties of this material are shown with cyclic voltammetry and spectroelectrochemical experiment reveals an electrochromic contrast (̃48% at λmax ) 606 nm).
  •  
57.
  • Krebs, Frederik C, et al. (författare)
  • A round robin study of flexible large-area roll-to-roll processed polymer solar cell modules
  • 2009
  • Ingår i: SOLAR ENERGY MATERIALS AND SOLAR CELLS. - : Elsevier BV. - 0927-0248. ; 93:11, s. 1968-1977
  • Tidskriftsartikel (refereegranskat)abstract
    • A round robin for the performance of roll-to-roll coated flexible large-area polymer solar-cell modules involving 18 different laboratories in Northern America, Europe and Middle East is presented. The study involved the performance measurement of the devices at one location (Riso DTU) followed by transportation to a participating laboratory for performance measurement and return to the starting location (Riso DTU) for re-measurement of the performance. It was found possible to package polymer solar-cell modules using a flexible plastic barrier material in such a manner that degradation of the devices played a relatively small role in the experiment that has taken place over 4 months. The method of transportation followed both air-mail and surface-mail paths.
  •  
58.
  •  
59.
  • Lindgren, L.J, et al. (författare)
  • Blue light-emitting diodes based on novel polyfluorene copolymers
  • 2007
  • Ingår i: Journal of Luminescence. - : Elsevier BV. - 0022-2313 .- 1872-7883. ; 122-123:1-2, s. 610-613
  • Tidskriftsartikel (refereegranskat)abstract
    • This study presents the synthesis and characterisation of a series of fluorene-based conjugated copolymers, together with the preparation and characterisation of the corresponding light-emitting devices. The polymers consist of alkoxyphenyl-substituted fluorene units together with different amounts of a hole-transporting triphenylamine-substituted fluorene unit: 0%, 10%, 25% and 50%. All polymers (P0, P1, P2, and P3) show high photoluminescence efficiency (ηPL) and light emission (both PL and EL) in the blue spectral region. Electrochemical studies show improved hole injection as the ratio of the triphenylamine-substituted segment is increased. The electroluminescence quantum efficiencies (EQEs) of the devices increase six times going from P0 to P1. Compared with P1, polymers P2 and P3 show lower efficiencies in devices. These findings indicate the presence of an optimal polymer composition, where balance between the charge-carrier mobilities has been reached. © 2006 Elsevier B.V. All rights reserved.
  •  
60.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 51-60 av 112
Typ av publikation
tidskriftsartikel (103)
konferensbidrag (8)
bokkapitel (1)
Typ av innehåll
Författare/redaktör
Inganäs, Olle, 1951- (36)
Zhang, Fengling (24)
Andersson, Mats, 196 ... (17)
Zhang, Fengling, 196 ... (15)
Andersson, Mats R (13)
visa fler...
Herland, Anna (13)
Tvingstedt, Kristofe ... (11)
Nilsson, Peter (8)
Admassie, Shimelis (8)
Perzon, Erik Per, 19 ... (8)
Björk, Per (8)
Hamedi, Mahiar (8)
Sundström, Villy (7)
Perzon, Erik (7)
Mammo, Wendimagegn, ... (6)
Hammarström, Per (6)
Andersson, Mattias (6)
Persson, Nils-Kriste ... (6)
Tvingstedt, Kristofe ... (6)
Andersson, Viktor (6)
Konradsson, Peter (6)
Yartsev, Arkady (5)
Lindgren, Mikael (5)
Nilsson, Peter, 1970 ... (5)
Wang, Xiangjun (5)
von Holst, Hans (4)
Mammo, Wendimagegn (4)
Herland, Anna, 1979- (4)
Andersson, Lars Matt ... (4)
Lindgren, Lars Johan ... (4)
Åslund, Andreas (4)
Barrau, Sophie (4)
Scheblykin, Ivan (4)
Wigenius, Jens (4)
Andersson, Mattias, ... (4)
Andersson, M.R. (3)
Svensson, Mattias (3)
Admassie, S. (3)
Forchheimer, Robert (3)
Hammarström, Per, 19 ... (3)
Åsberg, Peter, 1973- (3)
Němec, Hynek (3)
Nilsson, K. Peter R. (3)
Hellström, Stefan, 1 ... (3)
Persson, Nils-Kriste ... (3)
Tormen, Massimo (3)
Jespersen, Kim (3)
Oswald, Fréderic (3)
Zhou, Yinhua (3)
visa färre...
Lärosäte
Linköpings universitet (104)
Chalmers tekniska högskola (19)
Lunds universitet (12)
Kungliga Tekniska Högskolan (10)
Karolinska Institutet (4)
Uppsala universitet (1)
visa fler...
Högskolan i Borås (1)
RISE (1)
Karlstads universitet (1)
visa färre...
Språk
Engelska (112)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (36)
Teknik (10)
Lantbruksvetenskap (1)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy