Gas sensitivity of some metal phthalocyanines

Abstract

Previous studies of the gas sensitivity of CuPC (copper phthalocyanine) and ZnPC have been extended to include CoPC and NiPC, with particular reference to ammonia detection. Ammonia sensitivity is found to depend on the crystal structure of the films, ammonia concentration and temperature. The alpha - beta phase transition is found to give different film morphologies for ZnPC and NiPC. alpha -NiPC is the only PC studied that shows an increase in resistance on exposure to air. The other PCs show enhanced conductivity resulting from hole injection associated with oxygen adsorption. Surface conduction dominates bulk properties for all the PCs. Ammonia adsorption decreases conductivity due to the catalytic removal of surface oxygen but the response of the various PCs varies by two orders of magnitude. The low response of ZnPC is thought to be associated with the formation of a ZnPC-NH3 surface complex. CoPC and NiPC offer the highest response for low ammonia concentrations in air and the improved linearity of the response-concentration characteristics with SiO2 sublayers suggests that these may be viable materials for the fabrication of an integrated NH3 detector.

The Electronic and Non-linear Optical Properties of Oxo-titanium Phthalocyanines

“…Apart from these important material properties, this class of compound also exhibits a wide range of other qualities [1], for instance in the area of electrical conductivity [2,3] and liquid crystals [4,5]. Phthalocyanines have been used in Langmuir-Blodgett films [6,7], as gas sensors [8], for optical data storage [9] and in non-linear optics (as described herein). Generally, the main restricting factor for their processing and application is a rather low solubility in common organic solvents.…”

Preparation of Organic Zn-Phthalocyanine-Based Semiconducting Materials and Their Optical and Electrochemical Characterization

“…These properties arise from their electronic delocalization and make these compounds applicable in different fields of materials science; they are particularly promising as building blocks in nanotechnology. Some of the potential uses for phthalocyanines include nonlinear optical materials [1], liquid crystals [2], Langmuir-Blodgett (LB) films [3], optical data storage (computer recordable DVDs) [4], as electrochromic substances [5], low dimensional metals [6], and gas sensors [7], as photosensitizers [8], in photoelectrochemical cells [9] and electrophotographic applications [10]. Substitution has a strong influence on the -electron conjugation of the macromolecule, since it makes salvation easier [11].…”

Photoacoustic spectrum of samarium phthalocyanine powder

“…Moreover, superior to many other conducting and semiconducting organic compounds such as charge-transfer complexes, doped poly-acetylene, poly-pyrrole, poly-thiophene and poly-aniline, metal substituted phthalocyanines possess substantially strong chemical and thermal stability. Optical data storage, gas sensing and electrochromic displays are some among the numerous potential applications of this wonderful compound [4][5][6]. Phthalocyanines of rare-earth metals primarily occur in the form of diphthalocyanines with a sandwich type structure and the cation is eightfold coordinated to the two macrocycles [7].…”