| 11. |
- Ding, L., et al.
(författare)
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Photovoltaic cells with a conjugated polyelectrolyte
- 2000
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Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 110:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- We describe photovoltaic cells made from a novel conjugated polyelectrolyte, the lithium salt of poly(thiophene-3-acetic acid) (PTAA-Li). The aqueous solubility of this polyelectrolyte allows formation of blend electrodes with a dispersion of the metallic polymer Poly(Ethylene DiOxyThiophene) (PEDOT). The incident monochromatic photon to current conversion efficiency (IPCE) of the cells were improved up to 19% by blending PTAA-Li with PEDOT to modify the ITO electrode, in combination with the low bandgap polymer poly(3-(4-octylphenyl)thiophene) (POPT), and C60 as electron acceptor. We attribute the increase of efficiency to the improved contact area between the conjugated polyelectrolyte and PEDOT.
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| 12. |
- Duineveld, P.C., et al.
(författare)
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Diffusion of solvent in PDMS elastomer for micromolding in capillaries
- 2002
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 18:24, s. 9554-9559
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Tidskriftsartikel (refereegranskat)abstract
- Micromolding in capillaries is a soft lithography method for patterning materials. We have studied the diffusion of solvent from the excavated microsized channels in the stamp into the PDMS material, both theoretically and experimentally. It was demonstrated that a model of 1-D diffusion of solvent through a PDMS stamp, coupled with a mass conservation of the solvent in the channels, leads to a quantitatively accurate model for the velocity of the boundary between liquid-filled and vapor-filled microchannels in the stamp. With the model the diffusion coefficient of the solvent into PDMS was successfully determined.
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| 13. |
- Filippini, Daniel, et al.
(författare)
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Computer screen photo-assisted spectral fingerprinting of luminescent polythiophene pH reporter
- 2004
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Ingår i: IEEE Sensors. Proceedings. - : IEEE. - 1930-0395 .- 2168-9229. ; 3, s. 1377-1380
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Tidskriftsartikel (refereegranskat)abstract
- The capability of the computer screen photo-assisted technique (CSPT)for the spectral fingerprinting of a photoactive polythiophene derivative (POWT) used as pH reporter is demonstrated. POWT is part of a family of industrial scalable materials, well established for organic electronics and biomedical applications, which is used here to demonstrate the capability of CSPT for tracing key spectral features. The ability of CSPTfor substance classification, corroborated by principal component analysis (PCA), successfully compares to standard spectroscopy, especially considering the involved equipments: CSPT is only a computer set and a web camera.
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| 14. |
- Gadisa, Abay, et al.
(författare)
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Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 84:9, s. 1609-1611
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Tidskriftsartikel (refereegranskat)abstract
- The photovoltaic parameters of donor/acceptor blend organic solar cells are highly influenced by several parameters, such as the strength of the acceptor species, the morphology of the film due to the solvent, and the mobility of the free charge carriers. In this work, the open-circuit voltage (Voc) of solar cells based on series of conjugated polythiophene polymers were measured and compared. In every cell, the donor polymer was blended with an electron acceptor fullerene molecule. The devices were constructed in a sandwich structure with indium tin oxide (ITO)/metallic polymer (PEDOT:PSS) acting as an anode and Al or LiF/Al acting as a cathode. Comparing the Voc of all the cells shows that this important photovoltaic parameter is systematically varying with the polymer. The variation of photovoltage is attributed to the variation of the oxidation potential of the donor conjugated polymers after due consideration of the different injection conditions in the varying polymers.
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| 15. |
- Ghosh, S., et al.
(författare)
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Electrochemical characterization of poly(3,4-ethylene dioxythiophene) based conducting hydrogel networks
- 2000
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 147:5, s. 1872-1877
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Tidskriftsartikel (refereegranskat)abstract
- Poly(3,4-ethylene dioxythiophene), a conjugated polymer, doped with excess of polystyrenesulfonate (PSS), has been assembled into a mesoscopic conducting network in the form of a hydrogel. When used as an electrode, the material shows fast electrochemical kinetics as evident from cyclic voltammetry, chronopotentiometry, and impedance measurements. Due to high ionic mobility in the material, the electrochemical process is not limited by ion diffusion in the electrode, as normally is the case for conducting polymers, but by the resistance in the electronically conducting network. This resistance is decreased by growing another conducting polymer, polypyrrole (PPy), inside the hydrogel. Homogeneous deposition of PPy is confirmed by atomic force microscopy. The composite hydrogel also shows larger capacitance, only slightly affecting the kinetics of the electrode. Since the material can be charged and discharged in a very short time, application of such electrodes in high power density supercapacitors has been envisaged.
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| 16. |
- Ghosh, S., et al.
(författare)
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Nano-structured conducting polymer network based on PEDOT-PSS
- 2001
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Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 121:1-3, s. 1321-1322
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Tidskriftsartikel (refereegranskat)abstract
- Poly(3,4-ethylenedioxythiophene)-polystyrenesulphonate (PEDOT-PSS) has been crosslinked into network morphology. The morphologies of different crosslinked PEDOT-PSS firms have been characterised by atomic force microscopy (AFM). The crosslinked polymer shows highly efficient and fast redox activity, both in aqueous and non-aqueous media.
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| 17. |
- Ghosh, S., et al.
(författare)
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Networks of electron-conducting polymer in matrices of ion-conducting polymers. Applications to fast electrodes
- 2000
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Ingår i: Electrochemical and solid-state letters. - : The Electrochemical Society. - 1099-0062 .- 1944-8775. ; 3:5, s. 213-215
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Tidskriftsartikel (refereegranskat)abstract
- Poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT-PSS), an electronically conductive electroactive polymer, has been blended with an ion conducting polymer, polyethylene oxide (PEO), to increase the ionic mobility in the material. A substantial increase in the current density is observed in the cyclic voltammogram of the PEDOT-PSS, when the latter is blended with PEO. As supercapacitor electrodes, the blends give much higher energy densities at high power densities compared to the pure PEDOT-PSS. This enhancement of electrochemical properties has been ascribed to both intrinsic ionic conductivity of the PEO, and the swelling of the latter in liquid electrolyte solution, creating space for ion movement.
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| 18. |
- Gillissen, S, et al.
(författare)
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Synthesis and characterization of poly(pyridine vinylene) via the sulfinyl precursor route
- 2001
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 34:21, s. 7294-7299
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and characterization of poly(pyridine vinylene) (PPyV) via the nonionic sulfinyl precursor route is presented. Starting from an unsymmetrical monomer, precursor polymers were prepared in various solvents, which led to polymers with variable molecular weights. The thermal conversion to the conjugated structure, as well as its stability, was studied with different techniques such as FT-IR, UV-vis, TGA, and direct insertion probe mass spectroscopy (DIP-MS). From these results we were able to derive the most suitable conditions to perform the conversion. The fully conjugated PPyV was further characterized with photoluminescence (PL) and cyclic voltammetry (CV) measurements. The PL efficiency was found to be as high as 14%. The CV measurements showed that the polymer can be reduced (n-doped).
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| 19. |
- Godovsky, D, et al.
(författare)
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The use of combinatorial materials development for polymer solar cells
- 2000
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Ingår i: Advanced Materials for Optics and Electronics. - 1057-9257 .- 1099-0712. ; 10:2, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- Vile use a combinatorial approach to develop molecular plastic solar cells based on soluble fullerene derivatives blended with conjugated polymers. A combinatorial way of sample preparation is well suited to deal with the multitude of possible combinations of the components of such blends. We use high mobility poly(thiophene) and poly(phenylenevinylene) derivatives to be combined with accepters, Gradients of methanofullerene/polymer concentration were formed by diusion of the low molecular weight component in the spin-cast polymer matrix, Likewise the gradients of zinc phthalocyanine/C-60 were prepared by co-evaporation of the two materials from two sources to make a linear array of photodiode devices, Photo- and electrophysical properties, such as absorption, luminescence, short circuit photocurrent and open circuit photovoltage, were measured using a specially designed installation with a resolution of 70-100 mu. Clear evidence was obtained that the photoconversion efficiency increased with the amount of methanofullerene up to very high levels, in the case of methanofullerene/polymer blends, verifying the important role of the acceptor in the photoconversion. By choosing the optimal ratio between C-60 and ZnPc in the evaporated layer it Is possible to obtain high photocurrent in the 600-700 nm range, due to the added contribution from photoinduced electron transfer between the two molecules, Copyright (C) 2000 John Wiley & Sons, Ltd.
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| 20. |
- Grage, M.M.-L., et al.
(författare)
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Conformational disorder of a substituted polythiophene in solution revealed by excitation transfer
- 2001
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Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 339:1-2, s. 96-102
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Tidskriftsartikel (refereegranskat)abstract
- Anisotropy and isotropic transient absorption decays of a polythiophene derivative in dilute solution have been measured and compared to calculated decays on Monte Carlo simulated polymer chains to obtain knowledge about the geometrical conformation of the polymer. The polymer chain conformations are generated by a partially correlated self-avoiding random walk. Excitation migration along the isolated chain is modeled assuming a hopping mechanism. This approach can be used to determine conformational disorder and possible realizations of the polymer chains in solution as well as the trapping time and migration length of the excitation. © 2001 Elsevier Science B.V.
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