HOPPING CONDUCTION IN POLYMERS

The concept of hopping within a Gaussian density of localized states i ntroduced earlier to rationalize charge transport in random organic ph otoconductors is developed further to account for temporal features of time of flight (TOF) signals. At moderate degree of energetic disorde r (sigma/kT approximately 3.5...4.5) there is a transport regime inter mediate between dispersive and quasi-Gaussian type whose signatures ar e (i) universal TOF signals that can appear weakly dispersive despite yielding a well defined carrier mobility and (ii) an asymmetric propag ator of the carrier packet yielding a time dependent diffusivity.