INTRINSIC TRANSPORT-PROPERTIES IN ELECTROCHEMICALLY PREPARED POLYTHIOPHENE DOPED WITH PF6-

We have studied the transport properties in polythiophene doped with P F6-. The intrinsic transport properties inherent in the crystallized r egions were abstracted from the precise experiments of the d.c. resist ivity rho(dc)(T), voltage-shorted-compaction (VSC) resistance ratio r( VSC)(T) and absolute thermoelectric power S(T) as a function of temper ature at 1.6-300 K. At high temperatures between 35 and 80 K, r(VSC)(T ) clearly exhibits a metallic behavior following the temperature depen dence approximately expressed by T-2.7, characteristic of the low-dime nsional electronic structure. Unlike the behavior above 35 K, r(VSC)(T ) increases steeply with decreasing temperature below 35 K. Correspond ing to r(VSC)(T),S(T) also shows a metallic behavior at high temperatu res, while at low temperatures an anomalous behavior is observed as re ported in tetracyanoquinodimethane (TCNQ) salt. The results are interp reted in terms of a metal-insulator transition within the crystallized region that is believed to originate the fundamental transport charac ter of conducting polymer as a novel low-dimensional metal.