Analysis of pressure dependence of electrical conductivity in polypyrrole

Pressure dependence of the electrical conductivity of a range of polypyrrole samples doped to various levels is interpreted in terms of variable-range hopping theory. All samples are well described by a model that treats the density of localized states around the Fermi level as the pressure-dependent commodity. The presumption of invariance of wave-function inverse localization length is vindicated by samples with a range of mean hopping lengths all being described by a single state-compressibility term. This term is defined by the elastic constants of polypyrrole and measurements of macroscopic elasticity confirm the value deduced from the pressure dependence of conductivity versus temperature curves.