Self-Powered Bidirectional Photoresponse in High-Detectivity WSe₂ Phototransistor with Asymmetrical van der Waals Stacking for Retinal Neurons Emulation

Abstract

An artificial retina system shows a promising potential to achieve fast response, low power consumption, and high integration density for vision sensing systems. Optoelectronic sensors, which can emulate the neurobiological functionalities of retinal neurons, are crucial in the artificial retina systems. Here, we propose a WSe 2 phototransistor with asymmetrical van der Waals (vdWs) stacking that can be used as an optoelectronic sensor in artificial retina systems. Through the utilization of the gate-tunable self-powered bidirectional photoresponse of this phototransistor, the neurobiological functionalities of both bipolar cells and cone cells, as well as the hierarchical connectivity between these two types of retinal neurons, are successfully mimicked by a single device. This self-powered bidirectional photoresponse is attributed to the asymmetrical vdWs stacking structure, which enables the transition from an n−p to p + −p homojunction in the WSe 2 channel under different polarities of gate bias. Moreover, the detectivity and ON/OFF ratio of this phototransistor reach as high as 1.8 × 10 13 Jones and 5.3 × 10 4 , respectively, and a rise/ fall time <80 μs is achieved, as well, which reveals good photodetection performance. The proof of this device provides a pathway for the future development of neuromorphic vision devices and systems.

All‐In‐One Hardware Devices with Event‐Based Vision Sensor Arrays for Image Sensing, Computing, and Learning

“…In general, the human retina contains various kinds of neurons, including photoreceptors, bipolar cells, and ganglion cells. [ 24 ] The vision information is received by photoreceptors and transmitted to the bipolar cells to generate positive or negative electrical signals and eventually to the brain, significantly improving process speed in the brain. [ 1 ] Bipolar cells can be classified into ON‐bipolar and OFF‐bipolar cells, which respond to light stimuli with a bidirectional photoresponse.…”

Vertical Graphene/Pentacene Single Crystal/Graphene Transistors for Self‐Powered Weak Light Detection and High‐Speed Imaging

“…)) is about 74 kHz, which is a more competitive performance parameter for the organic photodetectors. Table 1 summarizes several significant parameters of the high-performance photodetectors in recent literature, [14,16,21,29,31,32,43,[45][46][47][48][49][50][51][52][53][54][55][56][57] in which the overall performance of our device is very competitive. The device stability is a significant factor of the organic optoelectrical devices for future practical applications.…”

Recent developments in the state-of-the-art optoelectronic synaptic devices based on 2D materials: a review

“…12g). 216 The hybrid heterostructure of MoS 2 /perylene-3,4,9,10-tetracarboxylic dianhydride (PTDCA) was reported as a multi-functional synaptic transistor by S. Wang et al (Fig. 12h), wherein the electrical and optical pulses modulate the device output.…”

“…Copyright 2019 Wiley-VCH). (g) The device structure of a WSe 2 /SiO 2 artificial synaptic phototransistor ((g) is reproduced with permission 216. Copyright 2022 American Chemical Society).…”