Ultra-low power MoS2 optoelectronic synapse with wavelength sensitivity for color target recognition

Bo Wei, Yabo Chen, Xiaotong Han, Yan Kang, Bujia Liang, Cheng Li, Xiaokuo Yang, Liang Fang, Yuanxi Peng

Abstract: Optoelectronic synapses that integrate visual perception and pre-processing hold significant potential for neuromorphic vision systems (NVSs). However, due to a lack of wavelength sensitivity, existing NVS mainly focuses on gray-scale image processing, making it challenging to recognize color images. Additionally, the high power consumption of optoelectronic synapses, compared to the 10 fJ energy consumption of biological synapses, limits their broader application. To address these challenges, an energy-efficient NVS capable of color target recognition in a noisy environment was developed, utilizing a MoS2 optoelectronic synapse with wavelength sensitivity. Benefiting from the distinct photon capture capabilities of 450, 535, and 650 nm light, the optoelectronic synapse exhibits wavelength-dependent synaptic plasticity, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and long-term plasticity (LTP). These properties can effectively mimic the visual memory and color discrimination functions of the human vision system. Results demonstrate that the NVS, based on MoS2 optoelectronic synapses, can eliminate the color noise at the sensor level, increasing color image recognition accuracy from 50% to 90%. Importantly, the optoelectronic synapse operates at a low voltage spike of 0.0005 V, consuming only 0.075 fJ per spike, surpassing the energy efficiency of both existing optoelectronic and biological synapses. This ultra-low power, color-sensitive device eliminates the need for color filters and offers great promise for future deployment in filter-free NVS.