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Lögdlund, Michael
Publications (9 of 9) Show all publications
Xing, K. Z., Fahlman, M., Berggren, M., Inganäs, O., Andersson, M. R., Boman, M., . . . Salaneck, W. R. (1996). The electronic and geometric structures of neutral and potassium-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy. Synthetic metals, 76(1-3), 263-267
Open this publication in new window or tab >>The electronic and geometric structures of neutral and potassium-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy
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1996 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 76, no 1-3, p. 263-267Article in journal (Refereed) Published
Abstract [en]

The electronic and geometric structures of poly [3-(4-octylphenyl)thiophene] have been studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively). Thermochromic effects, and new charge induced states generated by potassium doping, have been observed by direct UPS measurements. The experimental results are in very good agreement with the results of theoretical quantum chemical calculations performed with the Austin Model 1 semi-empirical model and the valence-effective Hamiltonian pseudo-potential model.

Place, publisher, year, edition, pages
Elsevier, 1996
Keywords
structure; doping; poly[3-(4-octylphenyl)thiophene]; spectroscopy
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-74927 (URN)10.1016/0379-6779(95)03467-X (DOI)A1996UD99400061 ()
Available from: 2012-02-10 Created: 2012-02-10 Last updated: 2017-12-07
Xing, K. Z., Fahlman, M., Lögdlund, M., Berggren, M., Inganäs, O., Andersson, M. R., . . . Salaneck, W. R. (1996). The electronic structure of neutral and alkali metal-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy. Synthetic metals, 80(1), 59-66
Open this publication in new window or tab >>The electronic structure of neutral and alkali metal-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy
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1996 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 80, no 1, p. 59-66Article in journal (Refereed) Published
Abstract [en]

The electronic structure of poly [3-(4-octylphenyl)thiophene] (POPT) has been studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS), as well as by quantum chemical calculations. Both temperature-dependent effects on the electronic structure of the neutral system, as well as the generation of new electronic states induced by doping with alkaline metals, have been observed. The experimental results are in good agreement with the results of the quantum chemical calculations.

Place, publisher, year, edition, pages
Elsevier, 1996
Keywords
poly[3-(4-octylphenyl)thiophene]; electronic structure; doping; spectroscopy
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-74924 (URN)10.1016/0379-6779(96)80203-7 (DOI)A1996VD48700008 ()
Available from: 2012-02-10 Created: 2012-02-10 Last updated: 2017-12-07
Lögdlund, M., Dannetun, P., Fredriksson, C., Salaneck, W. R. & Brédas, J. L. (1996). Theoretical and experimental studies of the interaction between sodium and oligothiophenes. Physical Review B. Condensed Matter and Materials Physics, 53(24), 16327-16333
Open this publication in new window or tab >>Theoretical and experimental studies of the interaction between sodium and oligothiophenes
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1996 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 53, no 24, p. 16327-16333Article in journal (Refereed) Published
Abstract [en]

Quantum-chemical calculations and ultraviolet photoelectron spectroscopy (UPS) measurements have been performed in order to study the interaction between sodium and oligothiophenes, with a focus on the origin of experimentally observed relaxation energy effects in alkali-metal-doped conjugated molecules. Upon doping of a -sexithienylene (α-6T) with sodium atoms, (1) a broad feature appears in the valence band, in an energy region corresponding to the band gap in pristine α-6T, and (2) certain structural features in the valence band shift towards lower binding energies in the doped material. In particular, upon doping, a structural peak related to electronic levels mainly localized to the sulfur and b-carbon atoms destabilizes to an energy corresponding to that of the valence-band edge in pristine α-6T. The results of ab initio Hartree-Fock and local-spin-density calculations on α-trithienylene and bithiophene are consistent with the experimental data, and allow for an assignment of these destabilization effects in terms of initial-state relaxations. We stress that similar destabi-lization effects, reported for other alkali-metal-doped conjugated systems, had previously been proposed to be associated with final-state electronic screening, i.e., a dynamic artifact within the UPS measurements; this is in contradiction to the results of our ab initio theoretical studies. Our present results show that all structural features in the UPS data are contained in the results of sufficiently complete quantum chemical calculations.

Place, publisher, year, edition, pages
American Physical Society, 1996
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-124179 (URN)10.1103/PhysRevB.53.16327 (DOI)A1996WR76200035 ()
Available from: 2016-01-20 Created: 2016-01-20 Last updated: 2017-11-30Bibliographically approved
Lazzaroni, R., Lögdlund, M., Calderone, A., Brédas, J. L., Dannetun, P., Fauquet, C., . . . Salaneck, W. R. (1995). Chemical and electronic aspects of metal/conjugated polymer interfaces: Implications for electronic devices. Paper presented at Proceedings of the International Conference on Science and Technology of Synthetic Metals (ICSM ’94), Seoul, Korea, 24–29 July 1994, Vols. 69/71. Synthetic metals, 71(1-3), 2159-2162
Open this publication in new window or tab >>Chemical and electronic aspects of metal/conjugated polymer interfaces: Implications for electronic devices
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1995 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 71, no 1-3, p. 2159-2162Article in journal (Refereed) Published
Abstract [en]

The chemical nature and the electronic structure of metal/conjugated polymer interfaces are investigated in the context of polymer-based light-emitting diodes. We consider the interaction of low-workfunction metals (Al, Ca) with the surface of conjugated polymers or model oligomer molecules with a combined experimental and theoretical approach. The early stages of the interface formation are followed with X-ray and ultraviolet photoelectron spectroscopies and the experimental data are compared to the results of quantum chemical calculations. The reactions of Al and Ca with the organic surface are found to be fundamentally different: while the former forms new covalent bonds onto the polymer backbone, the latter tends to dope the conjugated system. Both types of reaction are expected to modify drastically the electronic properties of the polymer semiconductor.

Place, publisher, year, edition, pages
Elsevier, 1995
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-124177 (URN)10.1016/0379-6779(94)03203-I (DOI)A1995QT32600261 ()
Conference
Proceedings of the International Conference on Science and Technology of Synthetic Metals (ICSM ’94), Seoul, Korea, 24–29 July 1994, Vols. 69/71
Available from: 2016-01-20 Created: 2016-01-20 Last updated: 2017-11-30Bibliographically approved
Dannetun, P., Lögdlund, M., Fredriksson, C., Lazzaroni, R., Fauquet, C., Stafström, S., . . . Salaneck, W. R. (1994). Reactions of low work function metals Na, Al, and Ca on α,ω-€diphenyltetradecaheptaene. Implications for metal/polymer interfaces. Journal of Chemical Physics, 100(9), 6765-6771
Open this publication in new window or tab >>Reactions of low work function metals Na, Al, and Ca on α,ω-€diphenyltetradecaheptaene. Implications for metal/polymer interfaces
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1994 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 100, no 9, p. 6765-6771Article in journal (Refereed) Published
Abstract [en]

The interactions between different low work function metals aluminium,calcium and sodium, and α,ω‐diphenyltetradecaheptaene, a model molecule for certain conjugated polymers, have been investigated using both x‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The spectra are interpreted with the help of the results of quantum chemical calculations performed within the local spin density (LSD) approximation methodology. The metals are found to interact with the conjugated system in very different ways. Aluminium forms a covalent bond, which strongly modifies the π‐electronic structure of the conjugated molecule, while both the sodium and the calcium atoms act as doping agents, inducing new states in the otherwise forbidden bandgap. These new gap states can be viewed as a soliton–antisoliton pair for the Na/DP7 and a bipolaronic‐like defect for Ca/DP7.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 1994
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-124172 (URN)10.1063/1.467035 (DOI)A1994NH84600072 ()
Available from: 2016-01-20 Created: 2016-01-20 Last updated: 2017-11-30Bibliographically approved
Dannetun, P., Lögdlund, M., Fahlman, M., Fauquet, C., Beljonne, D., Brédas, J. L., . . . Salaneck, W. R. (1994). The evolution of charge-induced gap states in degenerate and non-degenerate conjugated molecules and polymers as studied by photoelectron spectroscopy. Paper presented at Symposium D on Organic Materials for Electronics - Polymer Interfaces with Metals and Semiconductors, at the 1994 E-MRS Spring Conference, Strasbourg, France, May 24-27, 1994. Synthetic metals, 67(1), 81-86
Open this publication in new window or tab >>The evolution of charge-induced gap states in degenerate and non-degenerate conjugated molecules and polymers as studied by photoelectron spectroscopy
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1994 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 67, no 1, p. 81-86Article in journal (Refereed) Published
Abstract [en]

We report the results of ultraviolet photoelectron spectroscopy (UPS) studies of the interaction between sodium and conjugated systems for a series of diphenylpolyees and diffrent oligomers of poly(p-phenylenevinylene) (PPV). The diphenylpolyenes include molecules containing two (i.e., stilbene) to 14 carbon atoms in the polyene part; stilbene itself can also be considered as a phenyl-capped monomer of PPV. Furthermore, a PPV oligomer with three phenylene units, as well as PPV itself, has been studied. The experimental results are interpreted with the help of quantum-chemical calculations using the Hartree-Fock semi-empirical Austin Model 1 (AM1) and valence-effective Hamiltonian (VEH) methods. An important result is that all the systems react strongly with sodium; at high doping levels two new doping-induced states are detected above the valence band edge of the pristine material. In the case of saturation-doped diphenylpolyenes (i.e., two sodiums per molecule), the new states can be discussed in terms of soliton-antisoliton pairs confined within the polyene part of the molecules; in contrast, the self-localized states induced in PPV and its oligomers have to be referred to as bipolarons.

Place, publisher, year, edition, pages
Elsevier, 1994
Keywords
Spectroscopy, Conjugated molecules and polymers, Gap states
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-124173 (URN)10.1016/0379-6779(94)90015-9 (DOI)A1994PW12000013 ()
Conference
Symposium D on Organic Materials for Electronics - Polymer Interfaces with Metals and Semiconductors, at the 1994 E-MRS Spring Conference, Strasbourg, France, May 24-27, 1994
Available from: 2016-01-20 Created: 2016-01-20 Last updated: 2017-11-30Bibliographically approved
Lögdlund, M., Dannetun, P., Fredriksson, C., Salaneck, W. R. & Brédas, J. L. (1994). Theoretical study of the interaction between sodium and oligomers of poly(p-phenylenevinylene) and poly(p-phenylene). Synthetic metals, 67(1-3), 141-145
Open this publication in new window or tab >>Theoretical study of the interaction between sodium and oligomers of poly(p-phenylenevinylene) and poly(p-phenylene)
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1994 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 67, no 1-3, p. 141-145Article in journal (Refereed) Published
Abstract [en]

The semi-empirical Austin Model 1 and the non-empirical pseudo-potential valence effective Hamiltonian (VEH) methods as well as the local spin density (LSD) approximation technique have been applied to the investigation of the doping-induced electronic and geometrical changes in some conjugated molecules related to poly(p-phenylene) and poly(p-phenylenevinylene) (PPV): biphenyl, stilbene and a phenyl-capped dimer of PPV. The theoretical results are compared with experimental valence band spectra, as recorded by ultraviolet photoelectron spectroscopy (UPS). The experimental UPS studies show that two ingap states are detected upon doping with alkali metals. The energy splitting between the two in-gap states increases as the molecule size decreases. The results of the LSD calculations agree very well with the experimental results, while the VEH method overestimates the energy splitting for the small molecules. The LSD modelling also indicates a destabilization of several high binding energy valence levels, due to the presence of counter-ions, in agreement with experiment.

Place, publisher, year, edition, pages
Elsevier, 1994
Keywords
Sodium, Oligomers, Poly(p-phenylenevinylene), Poly(p-phenylene)
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-124176 (URN)10.1016/0379-6779(94)90028-0 (DOI)A1994PW12000026 ()
Available from: 2016-01-20 Created: 2016-01-20 Last updated: 2017-11-30Bibliographically approved
Dannetun, P., Lögdlund, M., Salaneck, W. R., Fredriksson, C., Stafström, S., Holmes, A. B., . . . Lhost, O. (1993). New Results on Metal-Polymer Interfaces. Molecular Crystals and Liquid Crystals, 228(1), 43-48
Open this publication in new window or tab >>New Results on Metal-Polymer Interfaces
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1993 (English)In: Molecular Crystals and Liquid Crystals, ISSN 1542-1406, E-ISSN 1563-5287, Vol. 228, no 1, p. 43-48Article in journal (Refereed) Published
Abstract [en]

New results on studies of the early stages of formation of the aluminum-poly(p-phenylenevinylene) interface are presented.

Place, publisher, year, edition, pages
Taylor & Francis, 1993
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-124070 (URN)10.1080/10587259308032141 (DOI)A1993LF82900004 ()
Available from: 2016-01-19 Created: 2016-01-19 Last updated: 2017-11-30Bibliographically approved
Salaneck, W. R., Dannetun, P. & Lögdlund, M. (1992). Photoelectron Spectroscopy: A Basic Tool for the Study of Molecular Materials. In: W. Gopel and Ch Ziegler (Ed.), Nanostructures Based on Molecular Materials: (pp. 329-348). Weinhem: Vch Pub
Open this publication in new window or tab >>Photoelectron Spectroscopy: A Basic Tool for the Study of Molecular Materials
1992 (English)In: Nanostructures Based on Molecular Materials / [ed] W. Gopel and Ch Ziegler, Weinhem: Vch Pub , 1992, p. 329-348Chapter in book (Refereed)
Place, publisher, year, edition, pages
Weinhem: Vch Pub, 1992
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-124069 (URN)1560812109 (ISBN)
Available from: 2016-01-19 Created: 2016-01-19 Last updated: 2016-02-01Bibliographically approved
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