A series of trivalent and tetravalent metal phthalocyanines (Pc) has been examined in thin film form on metal substrates by electron microscopy, UV-visible spectrophotometry, and electrochemical and photoelectrochemical techniques. These Pc's are compared with other divalent metal and demetallated phthalocyanines. The tri-and tetravalent phthalocyanines show enhanced photoresponses vs. the divalent metal and demetallated systems. This enhanced activity correlates with their broadened and red-shifted visible spectra and their tendency to grow as block-like or platelet-like microcrystals in the thin film. The divalent and demetallated Pc's grow as smaller, needle-like deposits with poor photoresponses. The trivalent and tetravalent Pc's have been grown in this study as thin films that act as highly doped p-type photoelectrodes or as nearly intrinsic photoconductors, exhibiting both positive and negative photopotentials, depending upon the E°' of the redox couple.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry