Near‐Infrared Optical Synapses Based on Multilayer MoSe₂ Moiré Superlattice for Artificial Retina

Abstract

Near‐infrared (NIR) synaptic devices have attracted great attention in the field of NIR vision sensors due to their highly parallel sensing and memory functions, which emulate the basic biomimetic behaviors of the human visual system. However, it is a great challenge for the 2D material to achieve NIR light response and integration, which obstructs the progress of NIR synaptic devices. Hence, a two‐terminal NIR synaptic device based on a multilayer MoSe2 moiré superlattice is reported. The moiré structure dominated by interlayer excitons significantly enhances the interlayer coupling of multilayer MoSe2, resulting in a narrower band gap nearly to that of bulk to achieve NIR light response and broadband absorption from 240 nm to 1700 nm. The existence of Se vacancies in MoSe2 moiré superlattice makes the device show the fundamental synaptic performance. Furthermore, a 10×10 integrated retinal morphologic device array is constructed. Under the 100 s light pulse stimulation of 1060 nm, the pattern obtained after attenuation of 50 s still has a memory level of 14.84%, reflecting the excellent storage function under NIR illumination. This research opens up a new avenue for the realization of NIR artificial retina and bionic eye based on 2D materials.

Self-Powered Optoelectronic Synaptic Devices for Neuromorphic Computing with the Lowest Energy Consumption Density

“…29 The EPSC in response to a single 405 nm optical pulse increases from ∼7 nA to ∼30 nA versus the increase in optical density from 4 μW/cm 2 to 16 μW/cm 2 (Figure 2h), which is a characteristic manifestation of the spike power-dependent plasticity (SPDP). 30 This behavior was also observed for 532 and 780 nm pulses in the devices. It is worth mentioning that our devices are volatile and erase operations for the synaptic weight changes are not needed for returning back to their initial states.…”

“…The synaptic current regulation through pulse frequency represents the successful mimicking of spike rate-dependent plasticity (SRDP) . The EPSC in response to a single 405 nm optical pulse increases from ∼7 nA to ∼30 nA versus the increase in optical density from 4 μW/cm 2 to 16 μW/cm 2 (Figure h), which is a characteristic manifestation of the spike power-dependent plasticity (SPDP) . This behavior was also observed for 532 and 780 nm pulses in the devices.…”

Dual‐Mode Conversion of Photodetector and Neuromorphic Vision Sensor via Bias Voltage Regulation on a Single Device

“…Inspired by the human visual system, a neuromorphic vision sensor (NVS) is another optoelectronic device that can process light information in a way similar to that of the human eye, enabling perception, memory, and processing of light signals (Figure 1a). [17][18][19][20][21][22][23][24] In contrast to the conventional digital vision system that converts the light intensity received by each pixel into a digital value, NVS can imitate how neurons operate in the human brain. [25][26][27] Accordingly, it enables not only noise reduction and contrast enhancement of images but also can undertake more adaptable image analysis and recognition.…”

High-performance artificial synapses based on two-dimensional MoSe2 powder with Se vacancies

“…18 Duan et al prepared 2D MoSe 2 by a salt-assisted chemical vapor deposition (CVD) method and fabricated horizontal memristors, which implements the synaptic function simulation with a large switching voltage of 5 V. 19 Yang et al developed an optical synaptic device based on multilayer MoSe 2 by CVD, which exhibited fundamental behavior of biological synapses with different illumination conditions. 20 Nevertheless, there has been few studies on MoSe 2 -based artificial synapses with low switching voltages, and the process of preparing MoSe 2 thin films based on CVD and mechanical exfoliation is complex and uncontrollable. 21 Therefore, it is necessary to develop a simple method to prepare the MoSe 2 -based RS layer for artificial synaptic devices.…”