Spectroscopic and photoelectrochemical studies of trivalent phthalocyanine thin films. The role of gaseous dopants (O2 and H2) in determining photoelectrochemical response

T. J. Klofta, T. D. Sims, J. W. Pankow, J. Danziger, K. W. Nebesny, Neal R Armstrong

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Abstract

Thin films of vacuum-deposited chlorogallium phthalocyanine (GaPc-Cl) and other trivalent-metal Pc's show widely variable photoelectrochemical properties depending upon vacuum deposition conditions and postdeposition doping with either O2 or H2. Combination of scanning electron microscopy (SEM), infrared spectroscopy (ATR-FTIR), visible absorbance spectroscopies, and X-ray diffraction indicates that typical GaPc-Cl films consist of a mixture of at least two different phases, with different proportions of each depending upon growth conditions. High-temperature O2 doping of GaPc-Cl can turn a film that behaves like a lightly doped semiconductor into a p-type material; H2 doping can reverse the effect. ESR experiments indicate the presence of high concentrations of radical species (ca. 1017 cm-3) whose populations can be increased or decreased with O2 or H2 doping, respectively. Photocurrent yield spectra of lightly doped or p-type GaPc-Cl films confirm that photocurrents are limited by hole transport in the first instance and electron transport in the second instant.

Original languageEnglish (US)
Pages (from-to)5651-5659
Number of pages9
JournalJournal of Physical Chemistry
Volume91
Issue number22
Publication statusPublished - 1987

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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