Polymeric pthalocyanines and other electrically conducting polymers for electronic and photonic applications: a review

Abstract

Polymers are generally insulators and to exhibit electrical conductivity they must have ordered conjugation with extended pi electrons d large carrier concentrations. This review summarises the various methods of making conjugated polymers by either addition or condensation reactions of monomers by chemical or electrochemic routes. These reactions can follow either a direct route or an intermediate precursor route; follow by elimination, addition or isomerization reactions. Conjugated polymers are made conductive generally by doping or by thermal treatment. The doped polymers have limitations like poor stability, poor processibility and corrosivity. This review lists the various methods adopted for overcoming these drawbacks. The review also gives an account of various types of phthalocyanine polymers that have been prepared in our laboratory, and their electrical an magnetic properties. The conductivity of these polymers increases by seven orders of magnitude by thermal treatment. These polymers have suitable structures that facilitate solitonic, polaronic and bip laronic conformations leading to Iarge, ultra-fast nonlinear optical processes. The peripheral functional groups can be used for structural modifications to improve processibility and allow fabrication of various device structures such as films, channel wave guides, planar wave guides, fibres, etc. The presence of macrocyclic structures in these polymers imparts mechanical, thermal and environmental stabilities. Conjugated polymers, including phthalocyanine polymers, also exhibit nonlioptical properties because of their response to high intensity radiations like laser. The requires of organic molecules and polymer to have <img src='/image/spc_char/lembda.gif' border=0>⁽²⁾ and <img src='/image/spc_char/lembda.gif' border=0>⁽³⁾ properties, and the various methods to study their behaviour as well as techniques employed to improve the nonlinear optical response are also discussed. The various methods that have been used to synthesize ladder polymers solubilising groups for processibility have also been discussed.