The effect of spatial disorder on the mobility of charge carriers hopping through energetically disordered dipolar lattices

Abstract The mobilities of charge carriers hopping through cubic lattices occupied by a site fraction, C, of randomly oriented dipoles have been evaluated using Monte Carlo simulations. Spatial disorder is introduced in the simulations through random assignment of the occupied lattice sites. Computed mobilities (μ) are found to depend upon the applied electric field (F), where the type of field dependence determined by the magnitude of F relative to a critical field (Fc). When F>F c μ∝F −1 , due to saturation of the carrier velocities, whereas for F c ,μ∝ exp ( F ) , in agreement with reported dependence for doped organic materials. The magnitude of Fc is affected by the amounts of energetic and spatial disorder employed in the simulations. As C is reduced, Fc decreases and hopping increasingly involves sites which are less correlated.