Analog Synaptic Plasticity in 2D Layered Material Iontronic Memtransistors for Brain-Inspired Computing

A simple iontronic memtransistor capable of emulating synaptic plasticity and cognitive functions showcases high performance and low energy consumption, fostering admiration for its efficiency. Here, we report the versatile, high-performance memtransistor behavior of a solid polymer electrolyte-gated few-layer thick two-dimensional molybdenum disulfide (2D MoS₂) channel. Transfer characteristics exhibit pinched hysteresis, confirming n-channel enhancement-mode operation, supported by the low-voltage drain characteristics under the influence of the electrical double layer (EDL) formed by iontronic gating. The memtransistor shows a reproducible non-volatile memory window in its transfer characteristics with conductance retention exceeding 10³ s and endurance beyond 10³ switching cycles. Mechanistic studies reveal coupled slow ion migration and dipolar relaxation processes coexisting with purely electronic transport in the 2D material channel, highlighting mixed ionic-electronic carrier dynamics. Using tailored input-output pulse schemes, the device demonstrates key synaptic and cognitive learning functionalities with lower energy consumption per event and faster response speed down to the microsecond regime. Furthermore, higher-order behaviors such as Atkinson-Shiffrin-type memory behavior, Pavlovian associative learning, and logic gate operations are achieved. These achievements confirm the potential of our 2D iontronic memtransistor (IMT) as a reliable, reproducible building block for next-generation brain-inspired computing systems.