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297 results on '"Gulbinas, V."'

51. Excited State Relaxation in Vacuum Deposited and Solution Processed Films of Merocyanine/Fulerene Blends

Author

Peckus, D., Devizis, A., Hertel, D., and Gulbinas, V.

Subjects
Organic solar cells, Electron acceptor, Electron donor, Heterojunction, Merocyanine, Exciton dynamics
Abstract

Exciton dynamics in merocyanine/fulerene blend films made by vacuum deposition and solution processing techniques were investigated by means of steady-state and time resolved fluorescence and absorption spectroscopy. Intermolecular charge transfer states are formed during several ps in neat merocianine films, which determine their fluorescence properties. Fullerene additives cause formation of new heterogeneous charge transfer states. Even a small fullerene concentration significantly influences the exciton dynamics by quenching inherent merocianine fluorescent states and causing appearance of new fluorescence bands caused by the charge transfer states between merocyanine and fullerene molecules. All fluorescence bands are quenched in films with high fulerence concentration due to the charge carrier generation, and the quenching effect is stronger in vacuum deposited films. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35299

Published
2012

52. spectral dependence of energy transfer in wild type peripheral light harvesting complexes or photosynthetic bacteria

Author

Gall, A., Sogaila, E., Gulbinas, V., Iloaia, O., Robert, B., Valkunas, L., Système membranaires, photobiologie, stress et détoxication (SMPSD), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut de Biologie et de Technologies de Saclay (IBITECS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Lentz, Celine

Subjects
[SDV.BBM.BP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics, [SDV.BBM.BP] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics
Published
2010

54. Dispersion-dominated photocurrent in polymer : fullerene solar cells

Author

Melianas, A., Pranculis, V., Devizis, A., Gulbinas, V., Inganas, O., Kemerink, M., Melianas, A., Pranculis, V., Devizis, A., Gulbinas, V., Inganas, O., and Kemerink, M.

Abstract

Organic bulk heterojunction solar cells are often regarded as near-equilibrium devices, whose kinetics are set by well-defined charge carrier mobilities, and relaxation in the density of states is commonly ignored or included purely phenomenologically. Here, the motion of photocreated charges is studied experimentally with picosecond time resolution by a combination of time-resolved optical probing of electric field and photocurrent measurements, and the data are used to define parameters for kinetic Monte Carlo modelling. The results show that charge carrier motion in a prototypical polymer:fullerene solar cell under operational conditions is orders of magnitude faster than would be expected on the basis of corresponding near-equilibrium mobilities, and is extremely dispersive. There is no unique mobility. The distribution of extraction times of photocreated charges in operating organic solar cells can be experimentally determined from the charge collection transients measured under pulsed excitation. Finally, a remarkable distribution of the photocurrent over energy is found, in which the most relaxed charge carriers in fact counteract the net photocurrent.

Published
2014

58. Hierarchical charge carrier motion in conjugated polymers

Author

Devizis, A., Meerholz, K., Hertel, D., Gulbinas, V., Devizis, A., Meerholz, K., Hertel, D., and Gulbinas, V.

Abstract

Motion of photogenerated charge carriers in p-conjugated polymer films with different disorder and chain orientation and also in a blend of conducting and insulating polymers has been investigated by means of time-resolved electric field-induced second harmonic generation technique. Experimental results and Monte Carlo simulation enabled us to distinguish three time domains of charge transport. The charge carriers become separated by about 10 nm in a strong electric field within 1 ps. Subsequently, carriers drift another 10-15 nm on a picosecond time scale with a high mobility. The third and the slowest carrier motion phase is well described by the stochastic drift and determines the macroscopic equilibrium mobility. We attribute the two ultrafast drift phases to carrier motion inside a conjugated segment and along a single polymer chain, respectively, whilst the slow motion phase involves interchain jumps. (C) 2010 Elsevier B.V. All rights reserved.

Published
2010

59. Ultrafast charge carrier mobility dynamics in poly(spirobifluorene-co-benzothiadiazole): Influence of temperature on initial transport

Author

Devizis, A., Meerholz, K., Hertel, D., Gulbinas, V., Devizis, A., Meerholz, K., Hertel, D., and Gulbinas, V.

Abstract

In this work we examine the influence of temperature on the transport dynamics of photogenerated charge carriers in pi-conjugated poly(spirobifluorene-co-benzothiadiazol) films. Investigations were performed by picosecond time-resolved electric field induced second-harmonic technique. The mobility is independent of temperature during the initial 100 ps. During this time, the carriers drift about 6 nm under an applied field of 1.2 x 10(6) V/cm, and the mobility decreases from 3 x 10(-2) cm(2)/V s by one order of magnitude. We attribute this change in mobility to the intrachain charge transport during carrier relaxation down in the density of states. At a time delay of 1 ns the transport is temperature dependent with an activation energy of about 22 meV.

Published
2010

61. Visualizing charge separation in bulk heterojunction organic solar cells

Author

Vithanage, D. Amarasinghe, primary, Devižis, A., additional, Abramavičius, V., additional, Infahsaeng, Y., additional, Abramavičius, D., additional, MacKenzie, R. C. I., additional, Keivanidis, P. E., additional, Yartsev, A., additional, Hertel, D., additional, Nelson, J., additional, Sundström, V., additional, and Gulbinas, V., additional

Published
2013
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63. Ultrafast light-induced charge pair formation dynamics in poly[3-(2'-methoxy-5' octylphenyl)thiophene]

Author

Zaushitsyn, Y., Gulbinas, V., Zigmantas, D., Zhang, Fengling, Inganäs, Olle, Sundstrom, V., Yartsev, A., Zaushitsyn, Y., Gulbinas, V., Zigmantas, D., Zhang, Fengling, Inganäs, Olle, Sundstrom, V., and Yartsev, A.

Abstract

Charge pair photogeneration was investigated by ultrafast absorption spectroscopy for different excitation photon energies in poly[3-(2'- methoxy-5' octylphenyl)thiophene] (POMeOPT) film with and without an external electric field. Electric field-assisted charge pair photogeneration in POMeOPT occurs from vibrationally relaxed singlet excitons during their entire lifetime and charge pair formation takes place in this manner even in the absence of an external electric field. From our data there are no indications of hot exciton dissociation to charge pairs even when a large amount of excess energy is supplied to the excitons. To explain these observations we present a model with energy transfer to low-barrier dissociation sites as a key feature.

Published
2004
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94. Charge transfer induced excited state twisting of N,N'-dimethylaminobenzylidene-1,3-indandione in solution

Author

Gulbinas, V., Kodis, G., Jursenas, S., Valkunas, L., Gruodis, A., Mialocq, J.-C., Pommeret, S., and Gustavsson, T.

Subjects
Charge transfer -- Research, Excited state chemistry -- Research, Relaxation (Nuclear physics) -- Research, Molecular dynamics -- Research, Molecular spectra -- Research, Molecules -- Research, Chemicals, plastics and rubber industries
Abstract

The excited state twisting of N,N'-dimethylaminobenzylidene-1,3-indandione in solution induced by charge transfer has been investigated using picosecond transient absorption and femtosecond fluorescence spectroscopy. Experimental data were analyzed to distinguish between different reaction phases of the molecular twisting in excited and ground states as well as to probe the molecular dynamics along reactive and nonreactive coordinates. The twisting was found to involve a bond identified as the C=C double bond, which is considerably weakened in the excited state.

Published
1999

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