Electrically conducting glasses: incorporation of polypyrrole in a porous SiO2 matrix

Electrically conducting glasses have been synthesized by incorporating polypyrrole in an SiO2 sol-gel derived glass matrix. Adsorption of pyrrole in the porous network of Cu2+-containing silica gels, in both bulk and thin film form, results in an oxidative polymerization to polypyrrole as demonstrated by electronic, infrared and Raman spectroscopies. Upon doping with iodine vapors, the polypyrrole-glass hybrids become electrically conducting with an average room temperature dc conductivity of 2 × 10−3 S/cm in the bulk and 3 × 10−4 S/cm in thin film form. DC conduction is described by a variable-range hopping model. The dielectric response of the hybrids is characteristics of conductor-insulator composites.