We present Monte Carlo simulation results for time-independent drift and spatial spreading of a packet of charge carriers executing a random walk within a manifold of hopping sites under a bias field. The shape of the density-of-states profile is assumed to be Gaussian (width a). The ratio eD/μkT, equal to unity for ordinary diffusion, is found to increase dramatically with increasing disorder and bias field. For σ/kT= 3.5 and fields of order 106Vcm-1, eD/μkT reaches values of order 103. The effect accounts for the anomalous spreading of time-of-flight profiles often seen in photocarrier transit time studies on various polymeric systems. The role of disorder in charge-carrier transport is emphasized.
|Original language||English (US)|
|Number of pages||15|
|Journal||Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties|
|State||Published - Mar 1991|
ASJC Scopus subject areas
- Chemical Engineering(all)
- Physics and Astronomy(all)