Role of incoherent dynamics in determining the electrical response of exciton-polaron complexes in pulsed magnetic resonance

Abstract

Triplet-exciton polaron quenching can lead to large changes in sample conductivity in organic devices. The application of pulsed magnetic resonance leads to changes in the quenching process by coherently driving spin populations between different eigenstates. Here, we investigate the influence of the exciton-polaron dissociation, intersystem crossing, and recombination rates on the electrical response of a device following such resonant excitation. Although these incoherent processes often occur on time scales that are orders of magnitude slower than coherent mixing, we find that they have a major influence on the electrical response. For example, as the relative recombination and dissociation rates are varied, certain resonant transitions can become electrically invisible. We demonstrate that transitions between different regimes are determined by a dimensionless parameter $\ensuremath{\chi}=\frac{r}{d}$, the ratio of the recombination to the dissociation rate.