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Organic mixed ionic–electronic conductors (OMIECs) are a unique class of soft, conjugated polymeric materials. The simultaneous electronic and ionic transport of OMIECs enables a new type of device, namely, organic electrochemical transistors, among other emerging technologies. However, the dynamic nature—where charge transport, doping kinetics, and morphological changes occur concurrently—poses significant challenges in the characterization and understanding of OMIECs. Recent advances in in situ optical techniques, including ultraviolet–visible–near-infrared spectroscopy, Raman spectroscopy, and microscopy imaging, have provided valuable insights into the charge transport mechanisms and ionic doping dynamics spanning from the microscopic to the device scale. In this perspective, based on several archetypal OMIECs, we survey how spectroscopic signatures were used to reveal key physical processes in these materials. Looking forward, we propose that ultrafast spectroscopy and microscopy techniques—such as transient absorption spectroscopy, terahertz time-domain spectroscopy, pump–probe microscopy, and photothermal microscopy—hold great potential for uncovering more fundamental mechanisms of OMIEC operation, including quasiparticle dynamics, intrinsic electrical conductivity, and carrier mobility, which remain under-explored. Integrating optical characterization with electrochemical measurements will enable in operando studies on state-of-the-art devices, with results further refined by parallel advancements in theoretical modeling. Altogether, we envision in operando optical characterization with spatial, spectral, and temporal resolution across multiple scales as a powerful pathway to advance the understanding of OMIEC mechanisms and their structure–property relationships.
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This content will become publicly available on May 1, 2026
Mechanics and Dynamics of Organic Mixed Ionic-Electronic Conductors
Abstract Organic mixed ionic-electronic conductors (OMIECs) are a class of materials that can transport ionic and electronic charge carriers simultaneously. They have shown broad applications in soft robotics, electrochemical transistors, and bio-electronics. The structural response of OMIECs to the mixed conduction populates from molecular conformation to devices, presenting challenges in understanding their mechanical behavior and constitutive descriptions. Furthermore, OMIECs feature strong multiphysics interactions among mechanics, electrostatics, charge conduction, mass transport, and microstructural evolution. In this review, we summarize recent progress in mechanistic understanding of OMIECs and highlight dynamics and heterogeneity underlying each element of mechanics. We introduce strain activation and breathing, mechanical properties, and degradation of OMIECs upon electrochemical doping and dedoping. Drawing on the state-of-the-art experimental and simulation insights, we highlight the critical role of multiscale dynamics in governing the functionality of OMIECs. We discuss the current understanding and limitation of constitutive relations and present computational frameworks that integrate multiphysics. We synthesize mechanics-driven strategies—spanning strain modulation, material stretchability, and interfacial stability—from molecular design to macroscopic structural engineering. We conclude with our perspective on the outstanding questions and key challenges for continued research. This review aims to organize the fundamental mechanical principles of OMIECs, offering a multidisciplinary framework for researchers to identify, analyze, and address mechanical challenges in mixed conducting polymers and their applications.
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- PAR ID:
- 10596091
- Publisher / Repository:
- ASME
- Date Published:
- Journal Name:
- Applied Mechanics Reviews
- Volume:
- 77
- Issue:
- 3
- ISSN:
- 0003-6900
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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