Photoelectrochemical studies of thin films of monomer, dimer and trimer stacked-ring silicon phthalocyanines

T. Mezza, N. R. Armstrong, M. Kenney

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19 Scopus citations


Thin films of silicon phthalocyanines (SiPc) on SnO2 and Au substrates have been studied as photoelectrodes. These SiPc molecules were the same monomer, dimer and trimer stacked-ring Pc's (m-SiPc, d-SiPc and t-SiPc) which had been previously characterized by voltammetry in CH2Cl2 solutions. As thin solid films, the m-SiPc proved to yield high photocurrent quantum efficiencies for oxidation of hydroquinone and ferrocyanide, up to 10% at surface coverages below 40 equivalent monolayers. Transmission spectra and photoaction spectra, using frontside and backside illumination, showed that the m-SiPc films consisted of at least two distinguishable phases on the SnO2 surface where as d-SiPc and t-SiPc films appeared to consist of only one phase at all coverages, d-SiPc and t-SiPc films on SnO2 substrates photoenhanced the reduction of benzoquinone over the oxidation of hydroquinone, while on m-SiPc on SnO2, the hydroquinone oxidation was preferentially photoenhanced. The two phases of m-SiPc on SnO2 appear to be first deposited as a porous, ordered photoactive phase of less than 100 equivalent monolayer thickness, and second as a randomly oriented phase, with lower photoactivity. This last phase filters light incident first on the m-SiPc/electrolyte interface, producing a photocurrent strongly dependent upon illumination direction.

Original languageEnglish (US)
Pages (from-to)259-273
Number of pages15
JournalJournal of Electroanalytical Chemistry
Issue number1-2
StatePublished - Sep 25 1984

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry


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