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

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

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

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
Volume176
Issue number1-2
DOIs
StatePublished - Sep 25 1984

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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