Organic electrochemical transistors are extensively studied for applications ranging from bioelectronics to analog and neuromorphic computing. Despite significant advances, the fundamental interactions between the polymer semiconductor channel and the electrolyte, which critically determine the device performance, remain underexplored. Here, we examine the coupling between the benchmark semiconductor PEDOT:PSS and an ionic liquid to explain the bistable and non-volatile behavior observed in OECTs. Using X-ray scattering and spectroscopy techniques, we demonstrate how the electrolyte modifies the channel composition, enhances molecular order, and reshapes the energetic landscape. Notably, the observed bistability arises from asymmetric and path-dependent energetics during doping and dedoping, resulting in two distinct paths, driven by a direct interaction between the electronic and ionic charge carriers. These findings highlight the electrolyte's role in tuning charge carrier dynamics, positioning it as a powerful yet underutilized lever for enabling novel device functionalities.
@article{arxiv.2412.07921,
title = {Electron-Ion Coupling Breaks Energy Symmetry in Bistable Organic Electrochemical Transistors},
author = {Lukas M. Bongartz and Garrett LeCroy and Tyler J. Quill and Nicholas Siemons and Gerwin Dijk and Adam Marks and Christina Cheng and Hans Kleemann and Karl Leo and Alberto Salleo},
journal= {arXiv preprint arXiv:2412.07921},
year = {2025}
}