Bridging length scales in organic mixed ionic-electronic conductors through internal strain and mesoscale dynamics

Understanding structural and dynamic properties of inherently disordered
systems at the mesoscale is crucial. This is particularly important in
organic mixed ionic-electronic conductors (OMIECs), which undergo
significant and complex structural changes when operated in electrolyte.
In this study, we investigate the mesoscale strain, reversibility, and
dynamics of a model OMIEC material under external electrochemical
potential using operando X-ray photon correlation spectroscopy. Our
results reveal mesoscale strain and structural hysteresis that depend on
the sample's cycling history, establishing a comprehensive kinetic
sequence bridging the macroscopic and microscopic behaviors of OMIECs.
Furthermore, we uncover equilibrium and non-equilibrium dynamics of charge
carriers and material doping states, highlighting the unexpected coupling
between charge carrier dynamics and mesoscale order. These findings
advance our understanding of the structure-dynamics-function relationships
in OMIECs, opening pathways for designing and engineering materials with
improved performance and functionality in non-equilibrium states during
device operation.