Document Server@UHasselt
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Repository of the University of Hasselt containing publications in the fields of statistics, computer science, information strategies and material from the Institute for behavioural sciences.
Mostrando recursos 1 - 13 de 13
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Low band gap polymers via a new and versatile route: The dithiocarbamate precursor route - COLLADET, Kristof; LUTSEN, Laurence; CLEIJ, Thomas; GELAN, Jan; VANDERZANDE, Dirk
Much interest exists in conjugated polymers for use as the active layer in photovoltaic cells. However, such plastic solar cells often suffer from a mismatch between their absorption and the terrestrial solar spectrum. The solar emission has a maximum photon flux around 1.8 eV, whereas many conjugated polymers do not absorb sufficient light at this energy level. Hence, low band gap conjugated polymers (Eg<2.0 eV) are desirable, since their application would ultimately give rise to better efficiencies. We have developed an efficient synthetic method to obtain such polymers: the dithiocarbamate precursor route. The successful application of this new route is...
2.
Soluble low band gap polymers for solar cell applications via oxidative polymerization - COLLADET, Kristof; Mulhbacher, D.; LUTSEN, Laurence; Schraber, M.; Brabec, C.; CLEIJ, Thomas; GELAN, Jan; VANDERZANDE, Dirk
Mixtures of conjugated polymers and fullerenes command considerable attention for application in organic solar cells. To increase their efficiency, the design of new materials that absorb at longer wavelengths is of substantial interest. We have prepared such low band gap polymers using the donor-acceptor route, which is based on the concept that the interaction between alternating donors and acceptors results in a compressed band gap. Furthermore, for application in photovoltaic devices, sufficient polymer solubility is required. We have prepared two low band gap conjugated polymers, with a bis-(1-cyano-2-(3,4-ethylenedioxythienyl)-vinylene)phenylene base structure and achieved an excellent solubility by the introduction of long...
3.
Plasma deposition of thiophene derivatives under atmospheric pressure - DAMS, Roel; Vangeneugden, D.; VANDERZANDE, Dirk
Plasma deposition of conjugated polymer films under atmospheric pressure is described. Three thiophene derivatives (thiophene, 3-methylthiophene, and 3,4-ethylenedioxythiophene) are used as monomers. The plasma depositions with the various precursors are compared using analytical techniques such as X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, and resistance measurements. Good results are obtained with pulsed plasma depositions of poly(3,4-ethylenedioxythiophene). Conductivities of up to 1 x 10(-2) S cm(-1) are measured.
4.
Light-emitting organic field-effect transistor using an organic heterostructure within the transistor channel - De Vusser, S.; Schols, S.; Steudel, S.; Verlaak, S.; Genoe, J.; OOSTERBAAN, Wibren; LUTSEN, Laurence; VANDERZANDE, Dirk; Heremans, P.
The authors have realized a light-emitting organic field-effect transistor. Excitons are generated at the interface between a n-type and a p-type organic semiconductor heterostructure inside the transistor channel. The dimensions and the position of the p-n heterostructure are defined by photolithography. The p-n heterostructure is at a distance of several microns from the metal electrodes. Therefore, the exciton and photon quenching in this device is reduced. Numerical simulations fit well with the experimental data and show that the light-emitting zone can move within the transistor channel. (c) 2006 American Institute of Physics.
5.
Plasma deposition of thiophene derivatives under atmospheric pressure - DAMS, Roel; VANGENEUGDEN, Dirk; VANDERZANDE, Dirk
Plasma deposition of conjugated polymer films under atmospheric pressure is described. Three thiophene derivatives (thiophene, 3-methylthiophene, and 3,4-ethylenedioxythiophene) are used as monomers. The plasma depositions with the various precursors are compared using analytical techniques such as X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, and resistance measurements. Good results are obtained with pulsed plasma depositions of poly(3,4-ethylenedioxythiophene). Conductivities of up to 1 x 10(-2) S cm(-1) are measured.
6.
Light-emitting organic field-effect transistor using an organic heterostructure within the transistor channel - De Vusser, S.; Schols, S.; Steudel, S.; VERLAAK, Stijn; Genoe, J.; OOSTERBAAN, Wibren; LUTSEN, Laurence; VANDERZANDE, Dirk; Heremans, P.
The authors have realized a light-emitting organic field-effect transistor. Excitons are generated at the interface between a n-type and a p-type organic semiconductor heterostructure inside the transistor channel. The dimensions and the position of the p-n heterostructure are defined by photolithography. The p-n heterostructure is at a distance of several microns from the metal electrodes. Therefore, the exciton and photon quenching in this device is reduced. Numerical simulations fit well with the experimental data and show that the light-emitting zone can move within the transistor channel. (c) 2006 American Institute of Physics.
7.
The relation between open-circuit voltage and the onset of photocurrent generation by charge-transfer absorption in polymer: Fullerene bulk heterojunction solar cells - VANDEWAL, Koen; GADISA DINKU, Abay; OOSTERBAAN, Wibren; BERTHO, Sabine; BANISHOEIB, Fateme; VAN SEVEREN, Ineke; LUTSEN, Laurence; CLEIJ, Thomas; VANDERZANDE, Dirk; MANCA, Jean
Photocurrent generation by charge-transfer (CT) absorption is detected in a range of conjugated polymer-[6,61-phenyl C61 butyric acid methyl ester (PCBM) based solar cells. The low intensity CT absorption bands are observed using a highly sensitive measurement of the external quantum efficiency (EQE) spectrum by means of Fourier-transform photocurrent spectroscopy (FrPS). The presence of these CT bands implies the formation of weak ground-state charge-transfer complexes in the studied polymer-fullerene blends. The effective band gap (Eg) of the material blends used in these photovoltaic devices is determined from the energetic onset of the photocurrent generated by CT absorption. It is shown that...
9.
How stable are polymer: PCBM bulk heterojunction solar cells? - BERTHO, Sabine; HAELDERMANS, Ilse; SWINNEN, Ann; D'HAEN, Jan; LUTSEN, Laurence; MANCA, Jean; VANDERZANDE, Dirk
This paper investigates the thermal stability of organic bulk heterojunction solar cells, with a special focus on the thermal ageing of both photovoltaic parameters and morphology of the active layer. The photovoltaic parameters of a set of bulk heterojunction solar cells were determined by IV-characterization and their bulk morphology was investigated with transmission electron microscopy (TEM). A link could be made between the degradation of the short circuit current under a thermal treatment and the corresponding change in bulk morphology. A possible improvement of the thermal stability of bulk heterojunction solar cells is presented through the use of a polymer...
10.
Influence of thermal ageing on the stability of polymer bulk heterojunction solar cells - BERTHO, Sabine; HAELDERMANS, Ilse; SWINNEN, Ann; MOONS, Wouter; MARTENS, Tom; LUTSEN, Laurence; VANDERZANDE, Dirk; MANCA, Jean; Senes, Alessia; Bonfiglio, Annalisa
A new approach is presented in order to improve the thermal stability of polymer: [6-6]-phenyl C-61 butyric acid methyl ester (PCBM) bulk heterojunction solar cells. The central idea in this approach is the use of a polymer with high glass transition temperature (T-g), well above the normal operating temperatures of the devices. In this paper, a PPV-derivative with a T-g of 150 degrees C was used as an electron donor and the thermal stability of the obtained solar cells was compared with solar cells based on the reference material poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) with a T-g of 45 degrees C. The...
11.
Effect of temperature on the morphological and photovoltaic stability of bulk heterojunction polymer: fullerene solar cells - BERTHO, Sabine; Janssen, Griet; CLEIJ, Thomas; CONINGS, Bert; MOONS, Wouter; GADISA DINKU, Abay; D'HAEN, Jan; Goovaerts, E.; LUTSEN, Laurence; MANCA, Jean; VANDERZANDE, Dirk
In high performance polymer: fullerene bulk heterojunction solar cells the nanoscale morphology of interpenetrating acceptor:donor materials is optimized through appropriate preparation conditions such as annealing and choice of solvent, but this initial state-of-the-art morphology will not remain stable during long-term operation. We report the effects of prolonged storage at elevated temperatures on both the morphology and the photovoltaic performance for the model systems MDMO-PPV:PCBM and P3HT:PCBM as compared to 'High T-g PPV':PCBM based solar cells, where the 'High Tg PPV' is characterized by its high glass transition temperature (138 degrees Q. In situ monitoring of the photocurrent-voltage characteristics at elevated...
12.
Efficient formation, isolation and characterization of poly(3-alkylthiophene) nanofibres: probing order as a function of side-chain length - OOSTERBAAN, Wibren; VRINDTS, Veerle; RUTTENS, Bart; Berson, Solenn; Guillerez, Stephane; Douheret, Olivier.; D'HAEN, Jan; ADRIAENSENS, Peter; MANCA, Jean; LUTSEN, Laurence; VANDERZANDE, Dirk
Efficient fibre formation for all regioregular poly(3-alkylthiophene)s (P3ATs) with alkyl chain lengths (A) between 3 and 9 carbon atoms has been accomplished in several solvents. It was observed that for the aliphatic and (chlorinated) aromatic hydrocarbon solvents used, the solvent refractive index offers some rationale to predict the feasibility of a solvent for fibre formation. The fibres were separated from remaining non-organised polymer by centrifugation. This enabled the characterisation of the isolated fibres in function of alkyl chain length (A) with TEM, AFM, XRD and UV-Vis spectroscopy. The fibres are 20 ± 5 nm wide and 0.5 to >4 µm...
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