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Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110).

Johansson, E M J; Odelius, M; Karlsson, P G; Siegbahn, H; Sandell, Anders LU and Rensmo, H (2008) In Journal of Chemical Physics 128(18).
Abstract
The molecular and electronic surface structure of a triarylamine based hole-conductor (HC) molecule evaporated onto rutile TiO2(110) single crystal is investigated by means of synchrotron light based photoelectron spectroscopy and x-ray absorption spectroscopy in combination with calculations based on density functional theory. Different amounts of the HC molecule was evaporated spanning the monolayer to multilayer region. The molecular surface structure is investigated and the results indicate that no specific covalent chemical bonding is formed and that the plane formed by the different nitrogens in the HC molecules has a rather small angle versus the TiO2 substrate surface plane. Some molecular ordering also persists in the multilayer... (More)
The molecular and electronic surface structure of a triarylamine based hole-conductor (HC) molecule evaporated onto rutile TiO2(110) single crystal is investigated by means of synchrotron light based photoelectron spectroscopy and x-ray absorption spectroscopy in combination with calculations based on density functional theory. Different amounts of the HC molecule was evaporated spanning the monolayer to multilayer region. The molecular surface structure is investigated and the results indicate that no specific covalent chemical bonding is formed and that the plane formed by the different nitrogens in the HC molecules has a rather small angle versus the TiO2 substrate surface plane. Some molecular ordering also persists in the multilayer region. The experimental core level spectra, valence level spectra, and the N 1s x-ray absorption spectroscopy spectra are well modeled by calculations on an individual molecule. Interestingly, the formation of the TiO2HC interface results in significant binding energy shifts in core levels and valence levels shifting all peaks of a the HC material to the same extent. Smaller shifts were also observed in the substrate core level peaks. The shift is discussed in terms of nanoscale energy level bending and final state hole screening. With respect to electronic applications, specifically in a solid state dye-sensitized solar cell, it is argued that the observed energy level alignment at the TiO2HC interface can act as a hole trap. (Less)
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author
organization
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Contribution to journal
publication status
published
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in
Journal of Chemical Physics
volume
128
issue
18
publisher
American Institute of Physics
external identifiers
  • wos:000255983500053
  • pmid:18532838
  • scopus:43949095816
ISSN
0021-9606
DOI
10.1063/1.2913245
language
English
LU publication?
yes
id
877ad958-d15f-4651-863f-c794d909a604 (old id 1169108)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/18532838?dopt=Abstract
date added to LUP
2008-07-03 09:48:07
date last changed
2017-04-30 15:20:53
@article{877ad958-d15f-4651-863f-c794d909a604,
  abstract     = {The molecular and electronic surface structure of a triarylamine based hole-conductor (HC) molecule evaporated onto rutile TiO2(110) single crystal is investigated by means of synchrotron light based photoelectron spectroscopy and x-ray absorption spectroscopy in combination with calculations based on density functional theory. Different amounts of the HC molecule was evaporated spanning the monolayer to multilayer region. The molecular surface structure is investigated and the results indicate that no specific covalent chemical bonding is formed and that the plane formed by the different nitrogens in the HC molecules has a rather small angle versus the TiO2 substrate surface plane. Some molecular ordering also persists in the multilayer region. The experimental core level spectra, valence level spectra, and the N 1s x-ray absorption spectroscopy spectra are well modeled by calculations on an individual molecule. Interestingly, the formation of the TiO2HC interface results in significant binding energy shifts in core levels and valence levels shifting all peaks of a the HC material to the same extent. Smaller shifts were also observed in the substrate core level peaks. The shift is discussed in terms of nanoscale energy level bending and final state hole screening. With respect to electronic applications, specifically in a solid state dye-sensitized solar cell, it is argued that the observed energy level alignment at the TiO2HC interface can act as a hole trap.},
  articleno    = {184709},
  author       = {Johansson, E M J and Odelius, M and Karlsson, P G and Siegbahn, H and Sandell, Anders and Rensmo, H},
  issn         = {0021-9606},
  language     = {eng},
  number       = {18},
  publisher    = {American Institute of Physics},
  series       = {Journal of Chemical Physics},
  title        = {Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110).},
  url          = {http://dx.doi.org/10.1063/1.2913245},
  volume       = {128},
  year         = {2008},
}