Herein, we propose a strategy to enhance the synaptic behavior of neuromorphic devices based on organic electrochemical transistors (OECT) by introducing (3-aminopropyl)triethoxysilane (APT) into the conjugated polymer film channel. Various film analyses utilizing optical and atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that the addition of APT to the poly(3-hexylthiophene) (P3HT) film facilitated the formation of highly crystalline P3HT aggregation, thereby suppressing film degradation induced by repetitive ion injection and ejection under gate bias. Furthermore, electrical characterization of the OECT devices incorporating P3HT channels demonstrated an expanded hysteresis region and improved memory characteristics upon APT addition, which contains functional groups with high electron density, favorably influencing synaptic plasticity features such as short-term plasticity (STP), long-term plasticity (LTP), short-term memory (STM), and long-term memory (LTM). Consequently, it led to the fortification and resilience of synaptic behavior in OECTs, positioning them as a promising candidate for neuromorphic devices.