Effects of Pressure on the Electrical Conductivity of Some Organic Charge-Transfer Complexes

Abstract

The effects of pressure and temperature on the electrical conductivity of some highly conductive charge-transfer complexes such as dibenzo[c, d]phenothiazine—dichlorodicyano-p-benzoquinone (2:1), dibenzo-[c, d]phenothiazine—dibromodicyano-p-benzoquinone (3:2), tetrathiotetracene—o-chloranil (3:1), tetrathiotetracene—o-bromanil (3:1) complexes are reported. The resistivity of these complexes under pressure follows the usual exponential law; 1/σ=ρ=ρ0 exp (E/kT). The measurements are carried out at a temperature range of 27°—120°C. The highest pressure applied is 40 kbar. The resistivity decreases with increasing pressure. However, this change is only of the order of 10 (from 1 to 30 000 bar). The activation energies also decrease with increasing applied pressure and the values in the tetrathiotetracene complexes become almost zero at about 35 kbar. The ρ0 obtained for these complexes increases with increasing pressure. The effect of pressure on the electrical properties of the organic solids is discussed.