Flexible Electrolyte-Gated Synaptic Transistors with Biphasic Current under Photoelectric Synergistic Modulation

Brain-inspired neuromorphic computing has been proven to be an effective solution to overcome the traditional von Neumann bottleneck. To construct a neuromorphic system, an artificial synapse is deemed as one of the most essential elements. Among various artificial synapse candidates, electrolyte-gated synaptic transistors based on oxide semiconductors have been enabled to emulate synaptic plasticity owing to their proton-related electric double-layer and persistent photoconductivity effects. However, the corresponding synaptic behavior is restricted to either excitatory or inhibitory responses even under costimulation of light and electric pulses, a so-called monophasic synaptic behavior. Herein, a flexible indium–gallium–zinc-oxide-based synaptic transistor with an eco-friendly konjac glucomannan electrolyte is successfully demonstrated with biphasic current behavior when costimulated by light and electric pulses. The coexistence of paired pulse facilitation/depression is realized, which can be synergistically modulated by light and electric pulses. In addition, with the photoelectric synergistic modulation, the learning and memory processes of the human brain can be mimicked, and enhanced memory and accelerated forgetting can be further achieved. These findings contribute to a more comprehensive understanding of synaptic plasticity, thereby providing a foundation for the development of wearable neuromorphic devices capable of performing more sophisticated operations.