Simulation of polymeric mixed ionic and electronic conductors with a combined classical and quantum mechanical model

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Physics

Background:

• Organic polymeric materials with mixed ionic and electronic conduction (OMIEC) exhibit complex charge dynamics.
• Existing models struggle to accurately describe the interplay between mobile excess charges and slower polymer/ion movements.

Purpose of the Study:

• To develop a computational methodology for simulating the correlated dynamics of excess charge and ions in OMIEC.
• To investigate the behavior and mobility of excess charges within polymer chains at a molecular level.

Main Methods:

• Combined molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations.
• Modeling of polymer, water, and ion dynamics alongside electrostatic potential-driven charge rearrangement.

Main Results:

• Excess charge distribution is highly variable across different polymer chains.
• Charge location fluctuates significantly on multiple timescales due to structural dynamics.
• Correlated motions of excess charge and polymer chains are substantial.

Conclusions:

• The developed QM/MM-MD approach provides a framework for studying OMIEC.
• Accurate modeling of OMIEC requires accounting for dynamic charge-polymer interactions.
• Further model enhancements are needed for simulating processes like electrochemical doping.