  Several microscopic pathways have been proposed to explain the large magnetic
effects observed in organic semiconductors, but identifying and characterising
which microscopic process actually influences the overall magnetic field
response is challenging. Pulsed electrically-detected magnetic resonance
provides an ideal platform for this task as it intrinsically monitors the
charge carriers of interest and provides dynamical information which is
inaccessible through conventional magnetoconductance measurements. Here we
develop a general time domain theory to describe the spin-dependent reaction of
exciton-charge complexes following the coherent manipulation of paramagnetic
centers through electron spin resonance. A general Hamiltonian is treated, and
it is shown that the transition frequencies and resonance positions of the
exciton-polaron complex can be used to estimate inter-species coupling. This
work also provides a general formalism for analysing multi-pulse experiments
which can be used to extract relaxation and transport rates.
