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Controlling energy level positions in hole conducting molecular films by additives

Lindblad, Rebecka LU ; Oscarsson, Johan; Fredin, Kristofer; Eriksson, Susanna K.; Siegbahn, Hans; Johansson, Erik M.J. and Rensmo, Håkan (2018) In Journal of Electron Spectroscopy and Related Phenomena 224. p.100-106
Abstract

Hard X-ray photoelectron spectroscopy (HAXPES) has been used to study the bulk electronic structure of thin molecular films of the organic compounds 2,2′,7,7′-tetrakis (N,N’-di-p-methoxyphenyl-amine)-9,9’-spiro-bifluorene (spiro-OMeTAD), 4-(diethylamino)-benzaldehyde-1,1)-diphenyl-hydrazone (DEH) and poly(3-hexylthiophene) (P3HT). Molecular layers of these compounds are hole conducting, a property that for example has been used in different solar cell configurations. The function of such a device benefits from the inclusion of additives such as Li-TFSI, or dopants such as Co-complexes, into the molecular layer. Here we report on effects of adding Li-TFSI to DEH and P3HT as observed by photoelectron spectroscopy and we compare with... (More)

Hard X-ray photoelectron spectroscopy (HAXPES) has been used to study the bulk electronic structure of thin molecular films of the organic compounds 2,2′,7,7′-tetrakis (N,N’-di-p-methoxyphenyl-amine)-9,9’-spiro-bifluorene (spiro-OMeTAD), 4-(diethylamino)-benzaldehyde-1,1)-diphenyl-hydrazone (DEH) and poly(3-hexylthiophene) (P3HT). Molecular layers of these compounds are hole conducting, a property that for example has been used in different solar cell configurations. The function of such a device benefits from the inclusion of additives such as Li-TFSI, or dopants such as Co-complexes, into the molecular layer. Here we report on effects of adding Li-TFSI to DEH and P3HT as observed by photoelectron spectroscopy and we compare with results on the spiro-OMeTAD hole conductor. It can be concluded that the Li-salt causes a shift of the Fermi level in DEH and P3HT towards the HOMO resulting in a p-doping of the molecular material. Similar shifts of the Fermi level could also be observed when adding different Co(+III) complexes to the Spiro-OMeTAD hole conductor, indicating means for more controlled doping.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
HAXPES, Mesoscopic solar cells, P3HT, Spiro-OMeTAD
in
Journal of Electron Spectroscopy and Related Phenomena
volume
224
pages
7 pages
publisher
Elsevier
external identifiers
  • scopus:85018401977
ISSN
0368-2048
DOI
10.1016/j.elspec.2017.03.009
language
English
LU publication?
yes
id
77854bdd-1a42-434e-983c-4a4ad3c95f1f
date added to LUP
2018-03-28 08:16:03
date last changed
2019-02-20 11:12:14
@article{77854bdd-1a42-434e-983c-4a4ad3c95f1f,
  abstract     = {<p>Hard X-ray photoelectron spectroscopy (HAXPES) has been used to study the bulk electronic structure of thin molecular films of the organic compounds 2,2′,7,7′-tetrakis (N,N’-di-p-methoxyphenyl-amine)-9,9’-spiro-bifluorene (spiro-OMeTAD), 4-(diethylamino)-benzaldehyde-1,1)-diphenyl-hydrazone (DEH) and poly(3-hexylthiophene) (P3HT). Molecular layers of these compounds are hole conducting, a property that for example has been used in different solar cell configurations. The function of such a device benefits from the inclusion of additives such as Li-TFSI, or dopants such as Co-complexes, into the molecular layer. Here we report on effects of adding Li-TFSI to DEH and P3HT as observed by photoelectron spectroscopy and we compare with results on the spiro-OMeTAD hole conductor. It can be concluded that the Li-salt causes a shift of the Fermi level in DEH and P3HT towards the HOMO resulting in a p-doping of the molecular material. Similar shifts of the Fermi level could also be observed when adding different Co(+III) complexes to the Spiro-OMeTAD hole conductor, indicating means for more controlled doping.</p>},
  author       = {Lindblad, Rebecka and Oscarsson, Johan and Fredin, Kristofer and Eriksson, Susanna K. and Siegbahn, Hans and Johansson, Erik M.J. and Rensmo, Håkan},
  issn         = {0368-2048},
  keyword      = {HAXPES,Mesoscopic solar cells,P3HT,Spiro-OMeTAD},
  language     = {eng},
  month        = {04},
  pages        = {100--106},
  publisher    = {Elsevier},
  series       = {Journal of Electron Spectroscopy and Related Phenomena},
  title        = {Controlling energy level positions in hole conducting molecular films by additives},
  url          = {http://dx.doi.org/10.1016/j.elspec.2017.03.009},
  volume       = {224},
  year         = {2018},
}