Doping efficiency and energy-level scheme in C60F 48-doped zinc-tetraphenylporphyrin films

Yaou Smets, Christian B. Stark, Felix Schmitt, Mark T. Edmonds, Stefan Lach, Christopher A. Wright, Daniel P. Langley, Kevin J. Rietwyk, Alex Schenk, Anton Tadich, Martina Wanke, Christiane Ziegler, Lothar Ley, Christopher I. Pakes

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


High resolution synchrotron-based core level spectroscopy was used to examine the energy level alignment at the interface of zinc-tetraphenylporphyrin films doped by the surface acceptor C60F48. Two distinct fluorofullerene charge states were identified, corresponding to ionized and neutral molecules, and their relative concentration as a function of coverage was used to evaluate the probability of occupation of the acceptor lowest unoccupied molecular orbital (LUMO). From an initial acceptor energy of -0.25 eV, the C60F48 LUMO shifts upwards with coverage due to a doping-induced interfacial dipole potential, and stabilization of the LUMO at an energy 0.45 eV above the Fermi energy was obtained. While the energy difference upon saturation is consistent with the results obtained for other donor-acceptor systems that have been interpreted as Fermi level pinning, the present work shows that the energy offset is a direct consequence of the interplay between Fermi-Dirac statistics in combination with the interfacial dipole potential.

Original languageEnglish
Pages (from-to)169-174
Number of pages6
JournalOrganic Electronics
Issue number1
StatePublished - Jan 2013
Externally publishedYes

Bibliographical note

Funding Information:
We acknowledge financial support of the Australian Research Council under DP0879827. Y. S. would like to thank the University of Kaiserslautern for their generous hospitality.


  • Doping efficiency
  • Energy level alignment
  • Surface transfer doping


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