Synaptic plasticity and memory mimicked in solution-processed K-doped CuI thin film transistors

Low-voltage electric double layer p-type thin film transistors (TFTs) were fabricated on glass substrates with copper iodide doped with potassium iodide (Cu0.95K0.05Ix) as the channel and chitosan as the dielectric. Cu0.95K0.05IxTFTs exhibited I-on/I-off ratio of 2.5x10(4),subthreshold swing of 30 mV/dec, threshold voltage of 1.34V, operating voltage of 2 V, and saturation field-effect mobility of 16.6 cm(2)V(-1)s(-1).The relaxation phenomenon induced by ion migration was effectively utilized, enabling Cu0.95K0.05IxTFTs to simulate various synaptic plasticity functions. When a pulse is applied, the drain current reaches a peak, but it takes more time for the current to return to its equilibrium position after the pulse is removed, demonstrating the short-term memory (STM) characteristics of Cu0.95K0.05IxTFT. It was observed an increasing trend in excitatory postsynaptic current (EPSC) with enhanced pulse width and amplitude, and when the pulse amplitude increased to -10V, the TFT transitioned from STM to long-term memory characteristics. Furthermore, the measurement of consecutive EPSC revealed the paired-pulse facilitation (PPF) characteristics, with a gradual decrease in the PPF coefficient as the time interval increased, and a selective stronger response to high-frequency signals. Based on the aforementioned research, by extending the device structure to a dual in-plane-gate structure configuration and applying different pulse voltage sequences on the dual gate, the NOR logic functionality was achieved. The study demonstrates the significant potential of p-type Cu0.95K0.05IxTFTs in the field of synaptic bionics, simulating human learning and memory, and neural chips