The Sensitivity of Hopping Transport in Dipolar Glasses and Molecularly Doped Polymers to Localised Dipole Ordering

Abstract

The influence of ordered dipole regions upon hopping transport through dipolar glasses and molecularly doped polymers has been evaluated via Monte Carlo simulation. Ordered dipole regions were introduced as a set of randomly distributed cubes throughout disordered dipolar lattices where the number and size of the cubes could be independently varied. Within each cube neighbouring dipoles were anti-aligned to minimise the local energetic disorder but the specific dipole orientation for each inserted cube was randomly selected. Whilst the underlying density of states appears to become energetically narrower as the overall proportion of disordered dipole sites is diluted by inserted ordered cubes this is not generally reflected in the associated transport properties. It is demonstrated that the lattice potential that is associated with background non-aligned dipoles in dipolar glasses have a controlling influence upon the observed macroscopic mobility. Confirmation of the importance of such non-aligned dipoles is provided by complimentary simulations using molecularly doped polymers where the dopant dipoles are agglomerated and ordered into cubic regions. The implication of the simulation results for the interpretation of experimental transport data in dipolar glasses and molecularly doped polymers is evaluated.