Nondispersive-to-dispersive charge-transport transition in disordered molecular solids

The transition from nondispersive to dispersive charge transport at low temperatures is studied on p-diethylaminobenzaldehyde diphenyl hydrazone and by computer simulation. It is shown that the concept of hopping in a Gaussian density-of-states distribution provides a consistent framework for data analysis. Variation of time-of-flight current transients with sample thickness and temperature can quantitatively be accounted for in terms of the energetic disorder parameters inferred from nondispersive transport data. It is shown that deviations from scaling behavior is a signature of dispersive hopping in a Gaussian density-of-states distribution.