Conjugated Backbone-Directed Side Chain-Electrolyte Coupling toward Nonvolatile Artificial Synapse

Achieving stable and nonvolatile synaptic plasticity remains a central challenge for organic neuromorphic devices. While previous efforts have independently focused on backbone or side chain modifications, the fundamental role of conjugated backbone design in directing side chain–electrolyte coupling has remained elusive. Here, we demonstrate that modulation of thiophene units in the backbone governs the spatial arrangement and ionic accessibility of glycol side chains, thereby enabling strong anion adsorption and long-term retention. Electrolyte-gated organic synaptic transistors (EGOSTs) with extended backbones exhibit pronounced structural reorganization, suppressed ion back-diffusion, and stable nonvolatile characteristics. Backbone-directed side chain–anion coupling was identified as the key mechanism driving enhanced charge transport and persistent doping. As artificial synapses, the device realizes robust neuromorphic functions including paired-pulse facilitation, long-term potentiation/depression, and achieves 94.5% accuracy in artificial neural network simulations. This work establishes conjugated backbone regulation as a facile strategy to control side chain–electrolyte interactions, offering new design principles for nonvolatile synaptic devices and advancing the development of reliable organic neuromorphic computing.