DIELECTRIC RESPONSE ANALYSIS OF A CONDUCTING POLYMER DOMINATED BY THEHOPPING CHARGE-TRANSPORT

The d.c. conductivity and the electric a.c, response from 100 Hz up to 40 MHz of poly(3n-decylpynole) were measured in the 80-330 K interval to characterize the charge transport behaviour of the system. The d.c . conductivity well fitted the variable range hopping model, and the l oss factor. after having deducted the d.c. contribution showed a relax ation peak when the conductivity versus frequency started to rise. The strength of this relaxation increased with temperature and became too large to be related to a dipolar relaxation; moreover, the temperatur e dependence of the loss peak frequency and d.c. conductivity coincide d. The observed relaxation was attributed to the hopping charge transp ort, as further confirmed by the temperature behaviour of the relaxati on strength and by the frequency dependence of the exponents of the po wer law which locally approximate the conductivity behaviour. As the a ctivation energy of the d.c. conductivity differed from the frequency of the loss peak, the theoretical prediction concerning the selfsimila rity of the a.c, conductivity was roughly verified.