Electrophoretic deposition of phthalocyanine in organic solutions containing trifluoroacetic acid

Nabeen K. Shrestha, Hideki Kohn, Mitsuharu Imamura, Kazunobu Irie, Hitoshi Ogihara, Tetsuo Saji

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The absorption spectra of copper phthalocyanine (CuPc) 1,2-dichloroethane (DCE) solutions containing trifluoroacetic acid (TFAA) shows that the number of protons coordinating to the CuPc molecule was 1 and 2 for the first and second proton adducts, respectively, which indicates the formations of CuPcH + and CuPcH22+. This CuPc molecule may act as a catalyst to dissociate TFAA into trifluoroacetate anion (A-) and H+ and form the proton adducts. The electrical conductivity dependence of the solution on CuPc concentration also supports this mechanism. A dense film of CuPc was deposited on an indium tin oxide cathode plate by electrophoresis of the solution. Similar dense films of a wide variety of phthalocyanines (MPc; M = Cu, H2, Fe, Ni, Zn, Pb, VO) were also deposited using this method. Similar films of CuPc were also formed using dichloromethane (DCM) and 1,1,1-trichloroethane (TCE) in place of DCE. Depositions are ascribed to the migration of positively charged monomers (i.e., protonated MPc). Scanning electron microscopy revealed that these films are composed of fibrous crystallites, size of which was found to increase with the electrophoresis time, the strength of the applied electrical field and the concentration of CuPc in the bath. The influence of the dielectric constant of the organic solvent on the film growth is discussed.

Original languageEnglish
Pages (from-to)17024-17027
Number of pages4
JournalLangmuir
Volume26
Issue number22
DOIs
StatePublished - 16 Nov 2010

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