The performance of organic mixed ionic–electronic conductors (OMIECs) for applications spanning bioelectronics, energy storage, and neuromorphic computing relies on careful optimization of both polymer and electrolyte properties. While most prior studies have focused on tuning polymer chemical structure, electrolyte chemistry remains an important yet underexplored factor governing electrochemical doping of OMIECs, influencing doping kinetics, stability, and electronic mobility. To investigate the relationships between anion identity and OMIEC performance, we performed spectroelectrochemistry measurements with 94 sulfonate anions using a custom-built robotic high-throughput spectroelectrochemistry (HT-SEC) platform. Leveraging this robust experimental data set, we built regression models that correlate OMIEC performance metrics with key molecular descriptors. We find that the extent of electrochemical doping correlates with several molecular features, including the anion’s highest occupied molecular orbital (HOMO), as well as its dipole moment, size, and propensity for intramolecular hydrogen bonding. Guided by these insights, our model identifies three sulfonate anions that enable OMIEC doping at substantially lower voltages than Cl–, yielding significantly enhanced volumetric capacitance (C*) in organic electrochemical transistors (OECTs). Together, this work establishes electrolyte design as a powerful and general lever for controlling electrochemical doping in OMIECs, transforming ion chemistry from a passive component into an active design parameter for next-generation OMIEC-based devices.
Collins et al. (2026) studied this question.