A molybdenum dithiolene complex as p-dopant for hole-transport materials: A multitechnique experimental and theoretical investigation

Yabing Qi, Tissa Sajoto, Michael Kröger, Alexander M. Kandabarow, Wunjun Park, Stephen Barlow, Eung Gun Kim, Leszek Wielunski, L. C. Feldman, Robert Bartynski, Jean Luc Brédas, Seth R. Marder, Antoine Kahn

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Abstract

Molybdenum tris-[l ,2-bis(trifluoromethyl)ethane-l,2-dithiolene] (Mo(tfd) 3) is investigated as a P-dopant for organic semiconductors. With an electron affinity of 5.6 eV, Mo(tfd) 3 is a strong oxidizing agent suitable for the oxidation of several hole transport materials (HTMs). Ultraviolet photoemission spectroscopy confirms -doping of the standard HTM N,N-di-[(l-naphthyl)-N,N-diphenyl]-l, l'biphenyl-4,4'-diamine (a-NPD). Strong enhancement of hole injection at a-NPD/Au interfaces is achieved via doping-induced formation of a narrow depletion region in the organic semiconductor. Variable-temperature current-voltage measurements on a-NPD: Mo(tfd) 3 (0-3.8 mol%) yield an activation energy for polaron transport that decreases with increasing doping concentration, which is consistent with the effect of the doping-induced filling of traps on hopping transport. Good stability of Mo(tfd)3 versus diffusion in the a-NPD host matrix is demonstrated by Rutherford backscattering for temperatures up to 110 °C. Density functional theory (DFT) calculations are performed to obtain geometries and electronic structures of isolated neutral and anionic Mo(tfd) 3 molecules.

Original languageEnglish (US)
Pages (from-to)524-531
Number of pages8
JournalChemistry of Materials
Volume22
Issue number2
DOIs
Publication statusPublished - Jan 26 2010

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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