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de Jong, Michel P
Alternative names
Publications (10 of 31) Show all publications
de Jong, M. P., Osikowicz, W., Sorensen, S., Sergeyev, S., Geerts, Y. & Salaneck, W. R. (2008). Femtosecond charge transfer in assemblies of discotic liquid crystals. The Journal of Physical Chemistry C, 112(40), 15784-15790
Open this publication in new window or tab >>Femtosecond charge transfer in assemblies of discotic liquid crystals
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2008 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, no 40, p. 15784-15790Article in journal (Refereed) Published
Abstract [en]

The electronic coupling strength within columns of discotic liquid crystals is investigated using core-level resonant photoemission spectroscopy. Coexisting well-ordered and disordered regions are identified in thin films of tetra-alkoxy-substituted phthalocyanines with the aid of near edge X-ray absorption fine structure and photoelectron spectroscopies. These different regions are used to derive a lower limit for the intermolecular charge transfer bandwidth within the framework of the core-hole clock principle. We find average charge transfer times on the order of a few femtoseconds, that is, significantly faster than the C(ls) core-hole lifetime, which indicates a surprisingly strong electronic coupling between the phthalocyanine units as compared to what is expected from the charge transport characteristics of this material. © 2008 American Chemical Society.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49943 (URN)10.1021/jp8037494 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
Carlegrim, E., Gao, B., Kanciurzewska, A., de Jong, M. P., Wu, Z., Luo, Y. & Fahlman, M. (2008). Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films: A model system for the V(TCNE)x room-temperature molecular magnet. Physical Review B. Condensed Matter and Materials Physics, 77, 054420
Open this publication in new window or tab >>Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films: A model system for the V(TCNE)x room-temperature molecular magnet
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2008 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 77, p. 054420-Article in journal (Refereed) Published
Abstract [en]

V(TCNE)x, with TCNE=tetracyanoethylene and x~2, is an organic-based molecular magnet with potential to be used in spintronic devices. With the aim of shedding light on the unoccupied frontier electronic structure of V(TCNE)x we have studied pristine TCNE and sodium-intercalated TCNE by near edge x-ray absorption fine structure (NEXAFS) spectroscopy as well as with theoretical calculations. Sodium-intercalated TCNE was used as a model system of the more complex V(TCNE)x and both experimental and theoretical results of the model compound have been used to interpret the NEXAFS spectra of V(TCNE)x. By comparing the experimental and theoretical C K-edge of pristine TCNE, the contributions from the various carbon species (cyano and vinyl) could be disentangled. Upon fully sodium intercalation, TCNE is n doped with one electron per molecule and the features in the C and N K-edge spectra of pristine TCNE undergo strong modification caused by partially filling the TCNE lowest unoccupied molecular orbital (LUMO). When comparing the C and N K-edge NEXAFS spectra of fully sodium-doped TCNE with V(TCNE)x, the spectra are similar except for broadening of the features which originates from structural disorder of the V(TCNE)x films. The combined results from the model system and V(TCNE)x suggest that the lowest unoccupied molecular orbital with density on the nitrogen atoms in V(TCNE)x has no significant hybridization with vanadium and is similar to the so-called singly occupied molecular orbital of the TCNE anion. This suggests that the LUMO of V(TCNE)x is TCNE or vanadiumlike, in contrast to the frontier occupied electronic structure where the highest occupied molecular orbital is a hybridization between V(3d) and cyano carbons. The completely different nature of the unoccupied and occupied frontier electronic structure of the material will most likely affect both charge injection and transport properties of a spintronic device featuring V(TCNE)x.

Place, publisher, year, edition, pages
Institutionen för teknik och naturvetenskap, 2008
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-11753 (URN)10.1103/PhysRevB.77.054420 (DOI)
Note
Original publication: E. Carlegrim, B. Gao, A. Kanciurzewska, M. P. de Jong, Z. Wu, Y. Luo and M. Fahlman, Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films: A model system for the V(TCNE)x room-temperature molecular magnet, 2008, Physical Review B, (77), 054420. http://dx.doi.org/10.1103/PhysRevB.77.054420. Copyright: The America Physical Society, http://prb.aps.org/Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2017-12-13
Carlegrim, E., Kanciurzewska, A., de Jong, M. P. & Fahlman, M. (2008). The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2. Chemical Physics Letters, 452(1-3), 173-177
Open this publication in new window or tab >>The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2
2008 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 452, no 1-3, p. 173-177Article in journal (Refereed) Published
Abstract [en]

The unoccupied electronic structure of the organic-based magnet V(TCNE)x (TCNE = tetracyanoethylene, x~2) has been studied with near edge x-ray absorption fine structure (NEXAFS) and with photoelectron spectroscopy (PES). By studying V(TCNE)x upon sodium-doping, the electron-accepting state, i.e. the lowest unoccupied molecular orbital (LUMO) of V(TCNE)x was shown mainly to be localized on (TCNE)--units in contrast to the hole-accepting state, i.e. the highest occupied molecular orbital (HOMO), which previously was assigned primarily to be V(3d)-derived. This study also showed that there are trap states for electron transport located below the (TCNE)2- level, likely leading to decreased electron mobility.

Place, publisher, year, edition, pages
Institutionen för teknik och naturvetenskap, 2008
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-11143 (URN)10.1016/j.cplett.2007.12.049 (DOI)
Note
Original publication: Elin Carlegrim, Anna Kanciurzewska, Michel P. de Jong, Carl Tengstedt and Mats Fahlman, The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2, 2008, Chemical Physics Letters, (452), 1-3, 173-177. http://dx.doi.org/10.1016/j.cplett.2007.12.049. Copyright: Elsevier Ltd, http://www.elsevier.com/Available from: 2008-02-27 Created: 2008-02-27 Last updated: 2017-12-13
Zhan, Y., Bergenti, I., Hueso, L., Dediu, V., de Jong, M. P. & Li, Z. (2007). Alignment of energy levels at the Al q3/La0.7 Sr0.3 Mn O3 interface for organic spintronic devices. Physical Review B. Condensed Matter and Materials Physics, 76(4)
Open this publication in new window or tab >>Alignment of energy levels at the Al q3/La0.7 Sr0.3 Mn O3 interface for organic spintronic devices
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2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 4Article in journal (Refereed) Published
Abstract [en]

The electronic structure of the interface between tris(8-hydroxyquinolino)- aluminum (Al q3) and La0.7 Sr0.3 Mn O3 (LSMO) manganite was investigated by means of photoelectron spectroscopy. As demonstrated recently, this interface is characterized by efficient spin injection in organic spintronic devices. We detected a strong interface dipole of about 0.9 eV that shifts down the whole energy diagram of the Al q3 with respect to the vacuum level. This modifies the height of the barrier for the injection into highest occupied molecular orbital level to 1.7 eV, indicating more difficult hole injection at this interface than expected for the undistorted energy level diagram. We believe that the interface dipole is due to the intrinsic dipole moment of the Al q3 layer. The presented data lead to significant progress in understanding the electronic structure of LSMO/Al q3 interface and represent a step toward the description of spin transport in organic spin valves. © 2007 The American Physical Society.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-48199 (URN)10.1103/PhysRevB.76.045406 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
de Jong, M. P., Tengstedt, C., Kanciurzewska, A., Carlegrim, E., Salaneck, W. R. & Fahlman, M. (2007). Chemical bonding in V (TCNE)x (x~2) thin-film magnets grown in situ. Physical Review B. Condensed Matter and Materials Physics, 75(6)
Open this publication in new window or tab >>Chemical bonding in V (TCNE)x (x~2) thin-film magnets grown in situ
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2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 6Article in journal (Refereed) Published
Abstract [en]

The molecule-based magnet V (TCNE)x, with TCNE=tetracyanoethylene, x˜2, shows an exceptionally high magnetic ordering temperature of about 400 K. With the aim to shed light on the origins of the robust magnetic ordering interactions, we have characterized the chemical bonding in V (TCNE)x thin films, prepared by an in situ chemical vapor deposition method, using photoelectron spectroscopy, x-ray absorption spectroscopy (XAS), and x-ray magnetic circular dichroism (XMCD). The XAS and XMCD results were interpreted by ligand field multiplet and charge transfer multiplet calculations, which show that the V-NC bonds are characterized by a large crystal field parameter 10Dq=2.3 eV and strong ligand to metal charge transfer effects, resulting in a hybrid V (3d) -CN ground state given by 60% 3 d3 and 40% 3 d4 L, where L is a hole on the cyano ligands. © 2007 The American Physical Society.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49994 (URN)10.1103/PhysRevB.75.064407 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
Fahlman, M., Crispin, A., Crispin, X., Henze, S., de Jong, M. P., Osikowicz, W., . . . Salaneck, W. R. (2007). Electronic structure of hybrid interfaces for polymer-based electronics. Journal of Physics: Condensed Matter, 19(18)
Open this publication in new window or tab >>Electronic structure of hybrid interfaces for polymer-based electronics
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2007 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 19, no 18Article, review/survey (Refereed) Published
Abstract [en]

The fundamentals of the energy level alignment at anode and cathode electrodes in organic electronics are described. We focus on two different models that treat weakly interacting organic/metal (and organic/organic) interfaces: the induced density of interfacial states model and the so-called integer charge transfer model. The two models are compared and evaluated, mainly using photoelectron spectroscopy data of the energy level alignment of conjugated polymers and molecules at various organic/metal and organic/organic interfaces. We show that two different alignment regimes are generally observed: (i) vacuum level alignment, which corresponds to the lack of vacuum level offsets (Schottky-Mott limit) and hence the lack of charge transfer across the interface, and (ii) Fermi level pinning where the resulting work function of an organic/metal and organic/organic bilayer is independent of the substrate work function and an interface dipole is formed due to charge transfer across the interface. We argue that the experimental results are best described by the integer charge transfer model which predicts the vacuum level alignment when the substrate work function is above the positive charge transfer level and below the negative charge transfer level of the conjugated material. The model further predicts Fermi level pinning to the positive (negative) charge transfer level when the substrate work function is below (above) the positive (negative) charge transfer level. The nature of the integer charge transfer levels depend on the materials system: for conjugated large molecules and polymers, the integer charge transfer states are polarons or bipolarons, for small molecules' highest occupied and lowest unoccupied molecular orbitals and for crystalline systems, the relevant levels are the valence and conduction band edges. Finally, limits and further improvements to the integer charge transfer model are discussed as well as the impact on device design. © IOP Publishing Ltd.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49754 (URN)10.1088/0953-8984/19/18/183202 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
Braun, S., de Jong, M. P. & Salaneck, W. R. (2007). Energy level alignment of organic interfaces under reversal of deposition sequence: the role of Fermi level pinning.
Open this publication in new window or tab >>Energy level alignment of organic interfaces under reversal of deposition sequence: the role of Fermi level pinning
2007 (English)Article in journal (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-14584 (URN)
Available from: 2007-07-03 Created: 2007-07-03
Osikowicz, W., de Jong, M. P. & Salaneck, W. R. (2007). Formation of the interfacial dipole at organic-organic interfaces: C 60/polymer interfaces. Advanced Materials, 19(23), 4213-4217
Open this publication in new window or tab >>Formation of the interfacial dipole at organic-organic interfaces: C 60/polymer interfaces
2007 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 19, no 23, p. 4213-4217Article in journal (Refereed) Published
Abstract [en]

The energetics at organic-organic interfaces comprising a thin film of a p-conjugated polymer and an overlayer of fullerene C60 was investigated. Two different polymers, poly(3-hexylthiophene) or P3HT, a polymer with moderate electron donor character were investigated. P3HT films were spin-coated from 5 mg mL-1 and 20 mg mL solutions in dichlorobenzene on conductive substrates such as native oxide terminated silicon SiO x/Si and aluminum, cleaned in acetone and isopropyl alcohol prior to spin coating and UV ozone treated gold. The thickness of the resulting polymer films obtained from the solutions with high concentrations was about 20 nm and 150 nm, as determined from reflectance ellipsometry. The results suggested that integer charge transfer provides a comprehensive description of energy level alignment at interfaces of organic semiconductors.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47388 (URN)10.1002/adma.200700622 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Bergenti, I., Dediu, V., Arisi, E., Cavallini, M., Biscarini, F., Taliani, C., . . . Natali, M. (2007). Spin polarized La0.7Sr0.3MnO3 thin films on silicon. Journal of Magnetism and Magnetic Materials, 312(2), 453-457
Open this publication in new window or tab >>Spin polarized La0.7Sr0.3MnO3 thin films on silicon
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2007 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 312, no 2, p. 453-457Article in journal (Refereed) Published
Abstract [en]

La0.7Sr0.3MnO3 polycrystalline manganite thin films were grown on silicon (Si) substrates covered by SiOx amorphous native oxide. Curie temperatures of about 325 K were achieved for 70-nm-thick films. Strong room temperature XMCD signal was detected indicating high spin polarization at the surface. Cross-sectional TEM images show sharp interface between SiOx and manganite without signature of chemical reaction at the interface. Unusual sharp splitting of the manganite film was observed: on the top of a transition layer characterized by low crystalline order, a magnetically robust layer is formed. © 2007 Elsevier B.V. All rights reserved.

Keyword
Interface, Manganite, Spintronics
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47955 (URN)10.1016/j.jmmm.2006.11.221 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Osikowicz, W., de Jong, M. P., Braun, S., Tengstedt, C., Fahlman, M. & Salaneck, W. R. (2006). Energetics at Au top and bottom contacts on conjugated polymers. Applied Physics Letters, 88(19)
Open this publication in new window or tab >>Energetics at Au top and bottom contacts on conjugated polymers
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2006 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 19Article in journal (Refereed) Published
Abstract [en]

Photoelectron spectroscopy was employed to examine the energetics, and therefore charge injection barriers, at top and bottom contact configurations of gold and conjugated polymers, i.e., polymer spin coated on gold and vapor-deposited gold on polymer interfaces. Very similar results are obtained for both ex situ (contaminated) and in situ (clean) prepared interfaces: a 0.7-0.8 eV decrease in the vacuum energy levels is consistently observed as compared to bare polycrystalline gold. These observations are explained by changes of the metal work function upon contacting either polymers or contaminants, associated with the reduction of the electron density tail that extends outside the metal surface. © 2006 American Institute of Physics.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-36041 (URN)10.1063/1.2201627 (DOI)29551 (Local ID)29551 (Archive number)29551 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
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