O2 and organic semiconductors: Electronic effects

Pabitra K. Nayak, Ron Rosenberg, Lee Barnea-Nehoshtan, David Cahen

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Contact potential difference (CPD) measurements of the relative work functions of a range of organic semiconductor thin films show that oxygen causes effective p-type doping (with work functions increasing 0.1-0.3 eV). This doping effect is found to be reversible by exposure to high vacuum or heating in inert atmosphere. The mechanism of doping is explained by a model, based on a reversible formation of an O-substrate charge transfer state. Conductivity measurements of p-phthalocyanine films at variable temperatures support this doping model. The oxygen doping effect is consistent with filling of tail states in the gap, as shown by the increase of activation energy of hole transport with decreased O-doping, and by the good fit between experimental data and simulations of the in-gap density of states. A model hybrid solar cell configuration also shows the effect of doping by O2 and corroborates the fact that O-doping fills the tail states in the system.

Original languageEnglish
Pages (from-to)966-972
Number of pages7
JournalOrganic Electronics
Volume14
Issue number3
DOIs
StatePublished - Mar 2013
Externally publishedYes

Keywords

  • Charge transfer complex
  • Doping
  • Gap states
  • Tail states

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