Orientational defects effective charge

It is thus clear that neither orientational defects nor ion states can by themselves account for static electrical conductivity. Instead equal currents, measured in terms of the number of defects transported, must be carried by each mechanism so as to maintain the polarization of the ice structure at its equilibrium value. When both an orientational defect and an ion state move through the crystal in this way, leaving it in its original state, the total charge transported is that of a single proton, e. Thus the effective charges + of orientational defects and + of ion states are related by... 

Granicher (1957), which considered only the majority carriers in each region. It is somewhat more difficult to picture the polarization processes in terms of molecular orientations. In the regions where orientational defects provide the relaxation mechanism, their motion in the applied field simply reorients molecules or, if the effective charge associated with the defects is included, then this contributes a polarization in the same direction. In regions where ion states provide the relaxation mechanism, however, motion of these states in the direction of the field tends to orient molecular dipoles antiparallel to the field. The polarizations pro-... 

The effect of this is that the charged defects are independent of one another and can form domain walls that separate two phases of opposite orientation and identical energy. These are called solitons and can sometimes be neutral. Solitons produced in polyacetylene are believed to be delocalised over about 12 CH units with the maximum charge density next to the dopant counterion. The bonds closer to the defect show less amount of bond alternation than the bonds away from the centre. 

However, in most experimental systems, the manifestations of the polaronic character of the charge carriers are masked by the effects of disorder. In any solution-deposited thin him, disorder is present and causes the energy of a polaronic charge carrier on a particular site to vary across the polymer network. Variations of the local conformation of the polymer backbone, presence of chemical impurities or structural defects of the polymer backbone, or dipolar disorder due to random orientation of polar groups of the polymer semiconductor or the gate dielectric result in a signihcant broadening of the electronic density of states. 

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