Near-infrared photonic artificial synapses based on organic heterojunction phototransistors

Photonic synapses provide fast response, high bandwidth, and less crosstalk in neuromorphic computation as well as simulation of visual perception systems. Herein, phototransistor-based photonic synapses that can be triggered by near-infrared light are reported. The artificial synapse is based on organic heterojunction phototransistors comprising the organic polymer semiconductor PDPPBTT and inorganic SnO2. The organic semiconducting polymer PDPPBTT serves as the near-infrared light absorbing materials and transistor channel, whereas SnO2 serves as the charge trapping materials. By adopting the heterojunction architecture, generation, separation, and transport of charge carriers are optimized under near-infrared illumination and electrical gating to yield photonic synaptic properties that can be readily modulated, including the excitatory postsynaptic current and paired-pulse facilitation. The results reveal a simple and effective concept for photonic synapses in the near-infrared region and provide insights into the development of advanced visual processing, neuromorphic computation, and biological nervous systems.