Article

Two-dimensionally extended aromatic polyamines for optimization of charge-transporting properties by partial oxidation

  1. Tsuyoshi Michinobu1,2,
  2. Fumiaki Kato1,
  3. Jun Inui1,
  4. Hiroyuki Nishide1,*

Article first published online: 4 AUG 2009

DOI: 10.1002/pola.23510

Issue

Journal of Polymer Science Part A: Polymer Chemistry

Journal of Polymer Science Part A: Polymer Chemistry

Volume 47, Issue 18, pages 4577–4586, 15 September 2009

Additional Information

How to Cite

Michinobu, T., Kato, F., Inui, J. and Nishide, H. (2009), Two-dimensionally extended aromatic polyamines for optimization of charge-transporting properties by partial oxidation. Journal of Polymer Science Part A: Polymer Chemistry, 47: 4577–4586. doi: 10.1002/pola.23510

Author Information

  1. 1

    Department of Applied Chemistry, Waseda University, Tokyo 169-8555, Japan

  2. 2

    Global Edge Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan

*Department of Applied Chemistry, Waseda University, Tokyo 169-8555, Japan

Publication History

  1. Issue published online: 4 AUG 2009
  2. Article first published online: 4 AUG 2009
  3. Manuscript Accepted: 7 MAY 2009
  4. Manuscript Received: 26 JAN 2009

Funded by

  • Grants-in Aids for Scientific Research, Global COE Program
  • MEXT, Japan
  • Iketani Science and Technology Foundation

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Keywords:

  • charge transport;
  • conjugated polymers;
  • electrochemistry;
  • polyamines;
  • polycondensation

Graphical Abstract

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Hole-transporting properties of the two-dimensionally extended and cross-conjugated aromatic polyamines, prepared by the palladium-catalyzed polycondensation between the tri-sec-amine monomer and p-phenylenediamine-based dibromides, were significantly changed by partial oxidation. It was revealed that the oxidation lowers the injection barrier, but it also generates the hole-trapping sites. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Abstract

This article describes the synthesis of the two-dimensionally extended aromatic polyamines by polycondensation between the tri-sec-amine monomer and p-phenylenediamine-based dibromide, the polyradical generation by chemical and electrochemical oxidations, and the hole-transporting properties. The molecular weights (Mn) of the polyamines, 3a and 3b, were 7700 and 5000, respectively, and both polymers were very soluble in the typical organic solvents, ensuring a good film formation capability by a spin-coating technique. The thermal stability of the aromatic polyamines, elucidated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), was quite high. More important, the cross-conjugated structure is essential for the controlled radical generation and the maintenance of the radical stability. Cyclic voltammograms of the neutral polyamines in the presence of 1 vol % of trifluoroacetic acid and the intervalence bands of the partially oxidized polyamines with NOPF6 revealed that the generated radicals delocalize over the p-phenylenediamine moieties. The half-life of the polyradicals was about 12 h even under ambient conditions, which allowed us to fabricate and measure the hole-only devices. The charge-transporting properties of the polyamines were dramatically changed by the partial oxidation (20 mol %/aminium unit) with NOPF6. The neutral polyamines showed the conventional injection-limit behaviors, whereas the hole-transporting behaviors of the polyradicals are bulk-limit and highly dependent on the chemical structure. The efficient hole-transport of the all-conjugated poly(aminium cationic radical)s was for the first time realized for the polyradical of 3b. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4577–4586, 2009

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