Molecularly doped polymer mobility

Dunlap DH, Parris PE, Kenkre VM (1996) Charge-dipole model for the universal field dependence of mobilities in molecularly doped polymers. Phys Rev Lett 77 542... 

Time-of-flight experiments have been used for over three decades to characterize carrier mobilities in crystal, and polycrystalline and disordered organic solids including molecularly doped polymers and molecular glasses [28,424,430,431]. Relatively high values (up to several hundreds cm2/V s) and hot carrier effects have been observed in... 

Figure 109 Poole-Frenkel-type plots of the field dependent mobility in a molecular-doped polymer (TAPC PC) at different temperatures. A change from the negative to positive value of [see Eq. (265)] is well pronounced at T > 240 K. After Ref. 479. Copyright 1991 American Institute of Physics.

Table 8.2 Mobilities in semiconducting and molecularly doped polymers...

As in all aliphatic polysilylenes, the overall temperature dependence of p is unusually small. Unlike molecularly doped polymers or even aromatic side group containing polysilylenes, the variation of mobilities over the experimental temperature range from 210 tO 324K barely extends over one order of magnitude. 

In photoconductive polymers the intersite hopping distance is not variable it is determined by the structure and morphology of the polymer. In molecularly doped polymers the average hopping distance can be varied at will, simply by changing the concentration of the transport-active species in the host polymer. In the PVK/TNF bipolar system there is evidence that holes move via uncomplexed carbazole groups, while electrons move via both complexed and uncomplexed TNF molecules [14]. The hole mobility decreases and the electron mobility increases as the TNF concentration increases [14] (Fig. 8.10). 

Charge-carrier mobilities in amorphous disordered organic photo-conductive polymers that include molecularly doped polymers are typically near or below 10" m V s at E 10 Vm and T 295K. a-Conjugated silicon backbone polymers under similar conditions display hole mobilities around 1 m V s [40, 41]. 

The relaxation-localization model recently has been applied to derive explicit expressions for electron (hole) transfer probabilities between two molecular sites in pendant-group and molecularly-doped polymers. These probabilities are the input data used in multiple-hopping models of measured transport properties, e.g., drift mobilities and photoconductivity. ... 

Hole transport in polymers occurs by charge transfer between adjacent donor functionalities. The functionalities can be associated with a dopant molecule, pendant groups of a polymer, or the polymer main chain. Most literature references are of doped polymers. The more common donor molecules include various arylalkane, arylamine, enamine, hydrazone, oxadiazole, oxazole, and pyrazoline derivatives. Commonly used polymers are polycarbonates, polyesters, and poly(styrene)s. Transport processes in these materials are unipolar. The mobilities are very low, strongly field and temperature dependent, as well as dependent on the dopant molecule, dopant concentration, and the polymer host This chapter reviews hole transport in polymers and doped polymers of potential relevance to xerography. The organization is by chemical classification. The discussion mainly includes molecularly doped, pendant, and... 

Mobilities of disordered molecular solids are very low and strongly field and temperature dependent. For doped polymers, the mobilities are also dependent on the dopant molecule, dopant concentration, and the polymer host. 

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