Molecular Backbone Regulation for Enhanced Ion Retention in Nonvolatile Organic Electrochemical Synaptic Transistors.

Organic electrochemical synaptic transistors (OESTs) provide a promising platform for high-performance neuromorphic devices by enabling ion-driven synaptic weight modulation. Most studies have primarily adopted interface-dominant organic strategies to maintain ion doping, while relatively overlooking the intrinsic molecular-level effects on ion implantation. From a molecular structure control perspective, the role of the polymer backbone remains poorly understood, resulting in an unclear correlation between ion dynamics and thin-film microstructure. In this study, we present a molecular design strategy that enhances ion doping stability through polymer backbone regulation. This strategy induces a favorable thin-film microstructure that promotes dense packing and enhanced crystallinity, enabling efficient ion implantation and transport. These structural characteristics have effectively emulated enhanced nonvolatile memory properties and biological synaptic operations, including long-term potentiation and depression. Furthermore, high accuracy was achieved in artificial neural network (ANN) simulations using the MNIST dataset. These results suggest that molecular-level control of thin-film microstructure governs the synaptic performance of OESTs, providing valuable molecular design guidelines for high-performance neuromorphic devices.