Controlling energy level positions in hole conducting molecular films by additives

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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.


  • Rebecka Lindblad
  • Johan Oscarsson
  • Kristofer Fredin
  • Susanna K. Eriksson
  • Hans Siegbahn
  • Erik M.J. Johansson
  • Håkan Rensmo
Enheter & grupper
Externa organisationer
  • Uppsala universitet, Historiska institutionen

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Oorganisk kemi
  • Den kondenserade materiens fysik


Sidor (från-till)100-106
Antal sidor7
TidskriftJournal of Electron Spectroscopy and Related Phenomena
StatusPublished - 2018 apr 1
Peer review utfördJa