Brief Summary of Transport in 3-D CP Materials

In contrast to single crystalline materials, the heterogeneity in CP structures introduces remarkable complexity in the electronic transport on different material levels and different 

Based on the doping concentration, in their early studies of PAc and PPY materials, Heeger and colleagues observed the transition from insulator to metallic as the dopant, (e.g. AsFs , PFe , I3, etc.) concentration increases. The conductivity of these materials can be characterized under three distinct categories, i.e. insulating, critical, and metallic [107-109]. These three cases can be summarized as follows. 

at low dopant concentrations, both PPY and PAc act as insulators. At a relatively high temperature, electronic transport can be described by Mott variable-range-hopping (VRH) model. Resistivity is a function of temperature that follows  

Second, as the dopant concentration increases, the conductivity is in the critical regime when the metal-insulator transition occurs. For a 3-D system, the temperature dependence of the resistivity follows a power law [110]  

at high a dopant concentrations the materials become metallic. The total resistivity is a combination of the resistance from the doped metallic islands and resistance rising from the fluctuation-induced-tunneling (FIT) between metallic islands. The latter part has a temperature dependence that follows [111]  

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