THE INFLUENCE OF DOPANT SPECIES ON TRANSPORT-PROPERTIES IN AS-GROWN POLYPYRROLE FILMS PREPARED BY ELECTROCHEMICAL METHOD

A transport study was made on electrochemically micallp prepared polyp yrrole (PPy) films to elucidate the influence of dopant species on the electrical transport properties. We present the experimental results on as-grown PPy films prepared with several anion species such as ClO4 ., PF6., BF6., TsO(.) and HSO4.. The conductivities of these films at room temperature were between 50-200 S/cm. The temperature dependence exhibited a semiconductor-like behaviour over the whole range between 1.6-300K, with the only exception of PF6. doped PPy, which changed to a metal-like dependence at 8K. At 300K, the absolute thermoelectric po wer S(T) takes very small values (3-7 mu V/K) like ordinary metals. Ch aracteristic behaviour was observed in their temperature dependence. S (T) is linearly dependent on temperature below about 230K but becomes nearly constant above 230K. The Voltage-Shorted-Compaction (VSC) resis tivity (rho(VSC)) showed a metallic temperature dependence with its sl ope definitely changed at 230K, corresponding well to the result of S( T), which implies a transition between metallic states of different na ture.