Effects of pressure on the electrical properties of organic semiconductors : pyrolyzed polyacrylonitrile and α, α-diphenyl-β-picrylhydrazyl

Abstract

The electrical resistivity of PAN obtained at various pyrolysis temperatures and applied pressures and of DPPH obtained by the crystallization from various solvents were measured under high pressures up to 70 kbar by using a compact cubic anvil apparatus. Its temperature dependence which follows the usual exponential law was also measured to obtain the activation energy for conduction. From these values the carrier mobility under high pressure was estimated. The conduction mechanism was also investigated. The contribution of lone-pair electrons must be taken into account for these substances under consideration in addition to the mobile free π electrons.