| 1. |
- de Jong, Michel P, 1970-, et al.
(författare)
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Orbital-specific dynamic charge transfer from Fe(II)-tetraphenylporphyrin molecules to molybdenum disulfide substrates
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:3, s. 35448-
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Tidskriftsartikel (refereegranskat)abstract
- Orbital-specific femtosecond charge transfer dynamics between Fe(II)-tetraphenylporphyrin molecules and semimetallic molybdenum disulfide substrates is investigated using core-level resonant photoemission spectroscopy. The electronic coupling to the substrate and the efficiency of charge transport across the interface is found to be different for the individual molecular electronic subsystems. In particular, electrons excited at the phenyl substituents are transferred within 3–6 fs, while hopping from the porphyrin ring is slower than 30 fs.
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| 2. |
- Tengstedt, Carl, 1974-
(författare)
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Materials study of organic electronics
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The electronic structure of materials for use in organic electronics is studied in this thesis. The first part includes applied research in the form of studies of polymers for use in polymer light emitting devices. The second part is more directed toward organic based spintronics and contains research regarding a room temperature organic ferrimagnetic material. Common for the studies, apart from that all regard organic material, are the use of electron spectroscopy techniques. The studies give new spectroscopic evidence of how the energy level alignment occurs between electrical conductors and spin coated semiconducting polymers, i.e. alignment at the anode side of polymer light emitting devices. The studies prove theoretical predictions regarding spontaneous charge injection forming positive polaronic species in the semiconducting polymer, pinned to the Fermi level of the substrate. The first part also includes studies of novel conducting polymers, based on PEDOT and polyaniline, with work functions spanning from 4.2 eV to 6.4 eV. In the case of organic magnets, our design and construction of the purpose built vacuum deposition system allowed for the first time oxygen free films of the extremely reactive organic ferrimagnet, vanadium tetracyanoethylene (V(TCNE)x), to be studied by means of several different electron spectroscopies, proving or disproving several previous results and assumptions.
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| 3. |
- Tengstedt, Carl, 1974-, et al.
(författare)
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Study and comparison of conducting polymer hole injection layers in light emitting devices
- 2005
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Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 6:1, s. 21-33
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Tidskriftsartikel (refereegranskat)abstract
- A set of polyaniline- and poly(3,4-ethylene dioxythiophene)-based materials were studied as hole injection layers in polymer light emitting devices. The choice of polymeric counterion/dopant poly(styrenesulfonic acid), and poly(acrylamido-2-methyl-1-propanesulfonic acid), and poly(acrylamide) blended with polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) was found to influence both work function and film morphology, which in turn affects device performance. The work functions of the polymer films spanned the range of over 1 eV and the surface region of the films were found to be low in conducting polymer content compared to the bulk. This was particularly the case of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) blended with poly(acrylamide) which showed device efficiency equal to that of the poly(3,4-ethylene dioxythiophene)–poly(styrenesulfonic acid) reference. The turn on voltage, however, was significantly larger, likely due to the insulating poly(acrylamide)-rich surface region of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid)/poly(acrylamide) film. The polymer blend of polyaniline/poly(styrenesulfonic acid) yielded the highest work function (5.5 ± 0.1 eV).
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