Role of metal phthalocyanine in redox complex conductivity of polyaniline and aniline black

F.P. Xavier, AR Inigo, G.J. Goldsmith

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Polyaniline (PA) and aniline black (AB) were prepared in powder form by the chemical method of oxidative polymerization, from which free-standing thin films were obtained by solvent evaporation using N-methyl pyrrolidinone (NMP). The thin films contained 2, 4, 6 or 8 wt% AB. Electrical measurements showed that the samples containing 4% AB exhibited the highest photoconductivity of the four concentrations. Thus there appears to be a critical ratio of PA to AB for maximum photoconductivity. Annealing up to 570 K has little effect on the conductivity. Upon adding a small quantity of copper phthalocyanine (CuPc) to the PA + AB, the electrical conductivity increased considerably and the optical absorption was extended from the UV to the near IR. The electrical conductivity mechanism is a consequence of a redox process, since AB is the oxidized state of PA and, upon illumination, there is an exchange of charge carriers. The extension of the range of optical absorption upon addition of CuPc is interpreted to suggest that CuPc photosensitizes the material and enhances the carrier transport process in the redox couple. The activation energy from the temperature-dependent conductivity and the band gap from the electrolyte electroreflectance method were determined. The activation energy for 0.4% CuPc is lowest (0.52 eV) and the corresponding band gap is determined to be 3.0 eV. This organic compound could be a good candidate for inexpensive, reliable and efficient solar energy converting devices. Copyright (C) 1999 John Wiley & Sons, Ltd.

Original languageEnglish
Pages (from-to)679-686
Number of pages8
JournalJournal of Porphyrins and Phthalocyanines
Volume3
Issue number6-7
Early online date10 Sep 1999
DOIs
Publication statusPublished - Oct 1999

Keywords

  • electronic-structure
  • semiconductors
  • thin-film
  • Chinese hamster cells
  • copper phthalocyanine
  • photoconductivity
  • electroreflectance
  • optical properties
  • single-crystals
  • thin films
  • oxidation
  • phthalocyanine
  • polymers
  • temperature

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