Hopping conduction evolution

Although the thermopower, 5(7), of doped conducting polymers has been studied for many years, the evolution of 5(7) as a function of the extent of disorder is not yet fully understood. Usually, thermopower is not as sensitive to disorder as electrical conductivity, since the latter is strongly dependent on the scattering and hopping processes involved in charge transport in the disorder-induced localized regime. Kaiser [19] analyzed the... 

For heavy doping, and to take into account both the finite value of cr when temperature tends to 0 K and the increase of a with T at low temperatures, Kaiser and Graham [65] proposed to modify the representation of the previous interfibril domain (index 2). They replace it (Fig. 21.22b) by two parallel domains one, whose conductivity is equal to 0-3, continues to represent the interfibril hoppings the other, an amorphous metal type, introduces into the conductivity formula a new component (T4 such that (T4(T) = (T40 + aT, where 0-40 and a are constant. For high doping levels, the metallic evolution of thermoelectric power with temperature displays a distortion at low temperatures (at around 50 K) Kaiser and Graham [63-66] take this into account by... 

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