Lithium doping of semiconducting organic charge transport materials

G. Parthasarathy, C. Shen, A. Kahn, S. R. Forrest

Research output: Contribution to journalArticlepeer-review

328 Scopus citations

Abstract

We study the effects of lithium (Li) incorporation in the cathodes of organic light-emitting devices. A thermally evaporated surface layer of metallic Li is found to diffuse through, and subsequently dope, the electron transporting organic semiconducting thin films immediately below the cathode, forming an Ohmic contact. A diffusion length of ∼700 Å is inferred from analyses of the current-voltage and secondary ion mass spectrometry data. The conductivity of the Li-doped organic films is ∼3 × 10-5 S/cm. Photoemission spectroscopy suggests that Li lowers the barrier to injection at the organic/cathode interface, introduces gap states in the bulk of the organic semiconductor, and dopes the bulk to facilitate efficient charge transport.

Original languageEnglish (US)
Pages (from-to)4986-4992
Number of pages7
JournalJournal of Applied Physics
Volume89
Issue number9
DOIs
StatePublished - May 1 2001

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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