Tunneling conduction in Co-cluster/tetraoctylammonium bromide/poly(phenyl-p-phenylenevinylene) nanocomposites

A system of nanometer sized cobalt clusters surrounded by dielectric shells has been investigated by electrical dc conductivity measurements. The cobalt clusters have a diameter of 36 Å and are surrounded by an approximately 12-Å-thick layer of tetra-octyl-ammonium bromide surfactant molecules and poly(phenyl-p-phenylenevinylene). The conductivity σ shows a temperature dependence ln(σ)∝(T0/T)1/2 in the range 100