Electric-field dependence of the mobility

Minari T, Nemoto T, Isoda S (2006) Temperature and electric-field dependence of the mobility of a single-grain pentacene field-effect transistor. J Appl Phys 99 034506... 

Numerous models have been proposed for hopping transport (see e.g. [Ml], [M2]). Conceptionally the simplest and physically most well-founded is the model of Bassler [47], which we will outline in the next section. In the sections thereafter, we will present typical experimental results for the temperature and electric-field dependencies of the mobility and for the temperature, field and thickness dependence of the dark current I(V) as a function of the applied voltage in disordered organic semiconductors. 

Fig. 2.10 Electric field dependence of the mobility, fi, of holes in poly-(methyl phenyl silylene) at various temperatures (1) 295 K, (2) 312 K,...

Where a is the intersite distance, e is the electronic charge and the rest of the symbols have their usual meanings. There is no electric field dependence of the mobility in this model and the polaron binding energy transfer integrals can be extracted easily from a plot of In versus using the field independent... 

Figure 12-30. The electric field dependence of the hole mobility in McLPPP ut different lem-peralures.

Fig. 28. Electric field dependence of the solvated electron drift mobility in liquid ethane at various temperatures (K). After Doldissen et al. [348].

The other source of an effective electric field dependence of the diffusion coefficient is due to hydrodynamic repulsion. As the ions approach (or recede from) one another, the intervening solvent has to be squeezed out of (or flow into) the intervening space. The faster the ions move, the more rapidly does the solvent have to move. A Coulomb interaction will markedly increase the rate of approach of ions of opposite charge and so the hydrodynamic repulsion is correspondingly larger. It is necessary to include such an effect in an analysis of escape probabilities. Again, the force is directed parallel to the electric field and so the hydro-dynamic repulsion is also directed parallel to the electric field. Perpendicular to the electric field, there is no hydrodynamic repulsion. Hence, like the complication of the electric field-dependent drift mobility, hydro-dynamic repulsion leads to a tensorial diffusion coefficient, D, which is similarly diagonal, with components... 

The electric field dependence of the hole mobility in a series of PVK TNF films of varying composition is shown in Fig. 5(b)17. The carrier drift mobilities are extremely low and strongly dependent on the electric field. Similar electric field dependence was observed for electron drift mobilities. The mobilities obey the empirical relation... 

Figure 7 (left) The electric field dependence of the time-ofiflight hole mobility for poly(9.9-dioctylfluorene) films. The open circles are data for a film prepared by spin coating. The filled circles are for a sample spin coated on a rubbed polyimide orientation layer, annealed in the nematic phase and then quenched to form a glassy film. 

Ions exhibit patterns of K versus E/N due to characteristic values of a, and Equation 10.27 can be simplified as an a function to describe the electric field dependence of the coefficient of mobility as per Equation 10.28 ... 

Blom, P.W.M., M.J.M. de Jong, and M.G. van Muster. 1997. Electric-field dependence of the hole mobility in poly(p-phenylene vinylene). Phys Rev B 55 R656. 

It was established that the elevated hole drift mobility of DCZB polymers is due to the reduced concentration of trapping sites which are in fact excimer-forming sites. This was confirmed by the temperature and electric field dependencies of the hole mobility. These observations support the idea that eharge transport and exciton transport have... 

An in-depth treatment of the problem of hot electrons in liquefied rare gases has been given by lakubov and his co-workers (Atrazhev and lakubov, 1981 Atrazhev and Dmitriev, 1985). The electric field dependence of the mean electron energy (cf, Fig. 6) has been verified experimentally by the measurement of the ratio of the diffusion coefficient to mobility in liquid argon and liquid xenon by Shibamura et al. (1979) and Kubota et al. (1982). 

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