| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Meskers, Stefan C. J.
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (29/29 displayed)
- 2023Origin and Energy of Intra-Gap States in Sensitive Near-Infrared Organic Photodiodescitations
- 2023Origin and Energy of Intra-Gap States in Sensitive Near-Infrared Organic Photodiodescitations
- 2021Photo-controlled alignment and helical organization in main-chain liquid crystalline alternating polymerscitations
- 2021Consequences of Chirality in Directing the Pathway of Cholesteric Helix Inversion of π-Conjugated Polymers by Lightcitations
- 2021Consequences of Chirality in Directing the Pathway of Cholesteric Helix Inversion of π-Conjugated Polymers by Lightcitations
- 2021Ultralow dark current in near-infrared perovskite photodiodes by reducing charge injection and interfacial charge generationcitations
- 2020Long-lived charge-transfer state from B−N frustrated Lewis pairs enchained in supramolecular copolymerscitations
- 2020Long-lived charge-transfer state from B−N frustrated Lewis pairs enchained in supramolecular copolymerscitations
- 2020Circularly Polarized Photoluminescence from Chiral Perovskite Thin Films at Room Temperaturecitations
- 2020On the origin of dark current in organic photodiodescitations
- 2019Impact of polymorphism on the optoelectronic properties of a low-bandgap semiconducting polymercitations
- 2018The effect of oxygen on the efficiency of planar p-i-n metal halide perovskite solar cells with a PEDOT:PSS hole transport layercitations
- 2018Bis(arylimidazole) iridium picolinate emitters and preferential dipole orientation in filmscitations
- 2017Thiophene rings improve the device performance of conjugated polymers in polymer solar cells with thick active layerscitations
- 2017Ultrafast charge and triplet state formation in Diketopyrrolopyrrole Low Band Gap Polymer/Fullerene blendscitations
- 2014Photoluminescence quenching in films of conjugated polymers by electrochemical dopingcitations
- 2014Effect of the fibrillar microstructure on the efficiency of high molecular weight diketopyrrolopyrrole-based polymer solar cellscitations
- 2014Relation between the electroforming voltage in alkali halide-polymer diodes and the bandgap of the alkali halidecitations
- 2012Electroforming process in metal-oxide-polymer resistive switching memories
- 2012Role of hole injection in electroforming of LiF-polymer memory diodescitations
- 2010Trapping of electrons in metal oxide-polymer memory diodes in the initial stage of electroformingcitations
- 2008Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blendscitations
- 2006Synthesis and characterization of long perylenediimide polymer fibers : from bulk to the single-molecule levelcitations
- 2006Electronic memory effects in a sexithiophene - poly(ethylene oxide) block copolymer doped with NaCl. combined diode and resistive switching behaviorcitations
- 2006Triplet formation from the charge-separated state in blends of MDMO-PPV with cyano-containing acceptor polymerscitations
- 2005Exciplex dynamics in a conjugated polymer blend of MDMO-PPV and PCNEPV
- 2003Thermally induced transient absorption of light by poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonic acid) (PEDOT:PSS) films: A way to probe charge-carrier thermalization processescitations
- 2002Simulation of electrical conductivity in a pi-conjugated polymeric conductor with infrared lightcitations
- 2000Relaxation of photo-excitations in films of oligo- and poly-(para-phenylene vinylene) derivativescitations
Places of action
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article
Relaxation of photo-excitations in films of oligo- and poly-(para-phenylene vinylene) derivatives
Abstract
The photo-luminescence from solid films of poly(para-phenylene vinylene) polymers and an oligomeric model system, consisting of seven repeat units, are investigated at low temperature (8 K) using time-resolved spectroscopic techniques. Results are compared to those for the materials in solution. In the case of the oligomer, the shape of the visible absorption band observed for the film is quite different from the band shape for the polymer in frozen solution and is characteristic of H-type aggregates. Theoretical models are presented describing the dependence of the band shape of absorption and emission spectra on intermolecular excited state interactions, electron-vibration coupling and disorder represented by distributions of the molecular excitation and intermolecular interaction energies. Using these models, it is concluded that intermolecular interactions in the film of the oligomer are strong (1400 cm-1), and the disorder low, implying delocalization of the excitation over several molecules. In accordance with these models the fluorescence lifetime for the film (2 ns) is considerably longer than for isolated molecules in solution (0.45 ns). The emission spectra of the film, taken early after excitation, are consistent with delocalization of the excitation over several molecules. A time-dependent red shift of the fluorescence band is observed and interpreted in terms of migration of localized excitations between disorder induced trap sites, which exist in the low energy tail of the density of excited states. For the polymers, differences between the shape of the absorption bands of solid film and frozen solution are smaller than for the oligomer indicating that interchain interactions that are, on average, weaker than for the oligomer. For the polymer films, a time-dependent red shift of the emission is observed and fluorescence depolarization measurements provide direct evidence for migration of the photo-excitations between trap sites. For one polymer, a time dependent change in the band shape of the fluorescence after pulsed excitation is observed with the band shape of the long-lived emission being compatible with that expected for an excitation delocalized over at least two, nearly parallel aligned, chains. For a second polymer, the emission band shape and its time evolution indicate that the major part of the fluorescence originates from disorder induced luminescent sites. These results indicate that the spectroscopic properties of films of p-conjugated polymer critically depend on parameters such as density of defects and excited state interchain interaction energy.