Artificial Synaptic Devices Based on P-type and N-type Organic Materials for Advanced Neuromorphic Computing

Neuromorphic computing offers a promising alternative by mimicking the human brain, where memory and computation are co-located. Artificial synaptic devices play a central role in this paradigm by emulating key brain-like functions such as plasticity, learning, and signal modulation. While both inorganic and organic materials have been explored for such devices, organic semiconductors are particularly attractive due to their low cost, mechanical flexibility, CMOS compatibility, and biocompatibility. Among device structures, three-terminal configurations such as organic electrochemical transistors (OECTs) and organic field-effect transistors (OFETs) allow for precise modulation of synaptic weights. Organic semiconductors are generally categorized as p-type and n-type, each offering distinct charge transport characteristics and processing advantages. Representative p-type materials include conjugated polymers such as poly(3-hexylthiophene) (P3HT) and diketopyrrolopyrrole (DPP)-based polymers, whereas n-type semiconductors based on perylene or naphthalene diimide derivatives have recently attracted attention despite their limited air stability. This review discusses both p-type and n-type organic materials, their fabrication strategies, and their applications in artificial synaptic devices mimicking brain, visual, tactile, and auditory functions, aiming to provide guidance for future advances in organic neuromorphic technologies.