Exciton-polaron complexes in pulsed electrically-detected magnetic resonance

TL;DR

This paper develops a time domain theory for exciton-polaron complexes in organic semiconductors, enabling better understanding of magnetic effects through pulsed electrically-detected magnetic resonance and providing tools to analyze multi-pulse experiments.

Contribution

It introduces a general formalism for analyzing spin-dependent reactions of exciton-charge complexes using pulsed magnetic resonance, including a Hamiltonian treatment and methods to estimate coupling and rates.

Findings

Transition frequencies and resonance positions can estimate inter-species coupling.

The formalism allows extraction of relaxation and transport rates.

Provides a framework for analyzing multi-pulse experiments.

Abstract

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.