Charge transport activation energies

Analysis of the activation energies of charge transport as a function of temperature and concentration shows that a type of corresponding state is attained at concentration 41 characterized by constant critical energies of activation for a given temperature. Electrolytes based on salts with small nonsolvated ions or small Stokes radii attain high 41 and /rmax values, whereas those based on large ions attain only small 41 and /fmax values. 

If fluctuations in the intermolecular distances and orientations give rise to a large variation in the site energy and transition probability amplitude compared to the other terms, the static disorder dominates the charge transport. A charge carrier moves by uncorrelated hops in a broad density of states. Thermal activation is required to overcome the energy differences between different sites. 

Hopping occurs between neighboring molecules and the activation energies are small, from 0.12 to 0.15 eV for the hydrocarbons. Fast anions have also been suggested for liquid SFg [180]. Thus several examples of this type of transport for the negative charge exist and the mobilities are comparable. More examples of fast ions are expected to be found in the future. 

Consequently, shallow states that control charge transport and define the activation energy (about 0.4 eV for As2Se3) of the mobility should not undergo photo-... 

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