Organic synaptic devices for neuromorphic systems

The development of synaptic devices with biologically-inspired information processing functions and low power consumption is critically important for the hardware implementation of highly anticipated brain-like computing systems. Organic materials arc regarded as the most promising candidates for synaptic devices and bio-electronics due to several advantages such as low cost, easy processability, mechanical flexibility and ductility. In this review, a description of the current advances in organic synaptic devices, including two-terminal memristors and three-terminal transistors, is provided. Organic two-terminal memristors with the characteristics of non-volatility and reasonable on/off switching ratio are reported to be popular synaptic devices. On the other hand, organic memristive and electrochemical electric-double-layer transistors can accurately select working devices by applying a gate spike to the corresponding gate electrode. Therefore, these three-terminal organic devices provide an alternative approach to the development of neuromorphic systems. Lastly, the novel applications of organic synaptic devices are discussed, and some current challenges are presented.