DISORDERED POLARON TRANSPORT - A THEORETICAL DESCRIPTION OF THE MOTION OF PHOTOINJECTED CHARGES IN MOLECULARLY DOPED POLYMERS

We present a model for the description of the temperature and concentration dependence of the mobility of photoinjected charge carriers in molecularly doped polymers on the basis of polaron transport in disordered media. We develop an existing variable range hopping technique to incorporate excluded volume effects which can be of importance in molecularly doped polymers, use the technique in conjunction with a Gaussian distribution of site energies in the polymeric solid, apply the formalism to calculate the mobility and address recent observations on here motion in TPD and TTA in polycarbonate matrices. We show that the competition between spatial and energetic disorder can provide a reasonable mechanism for the observed concentration dependence of the activation energy for charge transport. Our theory thus provides an alternative to a recently proposed explanation based on an adiabatic-diabatic polaron transition.