Polarons charged

In discussing low temperature-dependent mobility, we should mention charge transport by polarons, an intermolecular phonon-assisted hopping process 24>25>. Polarons (charge carriers trapped in their polarization field) arise from a strong electron-phonon interaction where there is a weak overlap of wave functions of... 

Bipolaron — Bipolarons are double-charged, spinless quasiparticles introduced in solid state physics [i]. A bipolaron is formed from two -> polarons (charged defects in the solid). For chemists the double-charged states mean dications or dianions, however, bipolarons are not localized sites, they alter and move together with their environment. By the help of the polaron-bipolaron model the high conductivity of -> conducting polymers can be explained. 

Polarons (charged soliton-neutral Radical ions... 

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. 

This combination of two resonance forms is known as a polaron. Charge can sustain itself on the unsatisfied bond indicated by the + sign in Fig. 2.10, and this charge can be moved on the molecule by an electric field. This phe-... 

Bianconi, A., and M. Missori, 1994, Xhe coupling of a Wigner polaronic charge density wave with a Fermi liquid - A possible pairing mechanism in HTc superconductors, in Phase Separation in Cuprate Superconductors, eds E. Sigmund and K.A. Muller (Springer, Berlin). 

In the case of traw -polyacetylene (a degenerate polymer), band-structure calculations [126] indicate that a polaron lattice has a metallic band whereas a charged soliton lattice has no metallic band. An alternating polaron-charged soliton lattice [128] has been proposed for explaining the metallic properties of heavily doped states. 

Figure 20.50. Interaction between carboxylic acid functionality and the V-atom leading to delocalization of the polaronic charge. (Reprinted by permission of ref 39)...

A percolative picture emerges from these results [8, 30, 32, 35, 55, 56]. As the density of polarons is increased, they start to become in contact. If the polarons are single-site polarons, charges will remain localized even if two polarons are in contact because of the high coulomb repulsion to place two carriers on the same site (Hubbard U). However, if the polarons are more extended over several sites, as is the case for (La/Sr)Mn03 shown above, charge carriers will become mobile within the connected network of the polarons. If the size of the network of the connected polarons reaches a macroscopic scale, metallic conduction commences. At the M-I transition the number of short Mn—O bonds is about 5, as shown in Fig. 10, indicating that the volume fraction of the undistorted, metaUic sites is 50%. This is consistent with the percolation in a two-dimensional square lattice [57]. 

Luntz AC, Viswanathan V, Voss J et al (2013) Tunneling and polaron charge transport through Li202 in Li-02 batteries. J Phys Chem Lett 4 3494—34997. doi 10.1021/jz401926f... 

Dygas JR, Kopec M, Krok F, Julien CM (2007) Relaxation of polaronic charge carriers in lithium manganese spinels. J Non-Cryst Solids 353 4384—4389... 

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