Anomalous migration of polarons in disordered organic semiconductors and its manifestation in magnetic-field effects

摘要

The specific features of the anomalous (dispersive) migration of polarons P (electrons and holes) in disordered organic semiconductors and manifestations of these features in the magnetic field effects on the conductivity of semiconductors are theoretically examined. According to the results, the most important reason for the influence of weak magnetic fields on the photoconductivity is their impact on PP-recombination (recombination of electrons and holes), a spin-selective process. Within the framework of an approach based on the continuous time random walk (CTRW) model, it is shown that anomalous (dispersive) migration, which is described in the CTRW model by a heavy-tailed hop waiting time distribution psi(t)similar to t (-(1+alpha)), clearly manifests itself in the magnetic field dependence of the PP-recombination yield and, hence, the conductivity. The specific features of this influence are illustrated by the example of the dependence of the recombination yield on the magnetic induction, which is predicted by the Delta g-mechanism of magnetic sensitivity.