Optoelectronic synapses for two-dimensional neuromorphic photonics

The von Neumann architecture, with its separation between the processing unit and memory, is struggling with limited performances and huge energy consumption burdens. To address the limitation, neuromorphic computing is emerging due to the combination of data storage and processing abilities. Exhibiting a light-driven persistence of electrical memory, optoelectronic synapses are crucial components to performing neuromorphic computing tasks. Herein, the typical behaviors of optoelectronic synapses such as short/long-term memory, paired-pulse facilitation, and learning experience are introduced. The development of various types of planar optoelectronic synapses, including perovskite-based synapses and two-dimensional oxide semiconductor-based synapses, is reviewed, and their applications in neuromorphic computing, including classical conditioning and image recognition, are described. Finally, the challenges in the field and the possible outlooks are discussed. Further explorations in this research area could focus on the investigation of optoelectronic conversion mechanisms and the nanofabrication techniques toward the development of all-photonic neuromorphic hardware.