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- 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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| 2. |
- Johansson, Tomas, et al.
(författare)
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Moving Redox Fronts in Conjugated Polymers Studies from Lateral Electrochemistry in Polythiophenes
- 2004
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 151:4
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Tidskriftsartikel (refereegranskat)abstract
- The propagation speed of the front of electrochemical conversion, from semiconductor to highly doped polymer, in films of regioregular poly(3-hexylthiophene) spin cast on insulating substrates was analyzed. Propagation of the p-doped zone in polymer electrochromic devices was imaged simultaneously with recording of electrochemical data. The current is proportional to the propagation speed and has a Tafel-like behavior when taking the resistive drop in the film into account. The resistivity in the film, which gradually lowers the propagation speed, was used for determination of the conductivity of the p-doped polymer. By combining these values with the doping charge injected into the film during front migration we estimated the hole carrier mobility for different doping levels. © 2004 The Electrochemical Society.
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| 3. |
- Persson, Nils-Krister, et al.
(författare)
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Optical modelling of a layered photovoltaic device with a polyfluorene derivative/fullerene as the active layer
- 2004
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 83:2-3, s. 169-186
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Tidskriftsartikel (refereegranskat)abstract
- Here we report on optical modelling of organic photovoltaic devices having a layered geometry, with polyfluorene-copolymer as the active material and C60 as the acceptor. Thin film theory in a matrix formalism enables analysis of the impact of reflection and interference on the optical electric field. The model allows us to predict an optimal C60 thickness where concern has been taken for light being both polychromatic and distributed according to solar irradiation. Fundamental for light–matter interaction is the dielectric function. We have extracted it for two variants of a new polyfluorene copolymer, PFDTBT, from UV via visible to the nearest infrared, using spectroscopic ellipsometry (SE). n is found to be relatively high with a max-value above 2.1. The process of spin coating induces anisotropy in the polymer film.
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