Multifunctional Optoelectronic Synapses Based on Arrayed MoS₂ Monolayers Emulating Human Association Memory

Abstract

Optoelectronic synaptic devices integrating light-perception and signal-storage functions hold great potential in neuromorphic computing for visual information processing, as well as complex brain-like learning, memorizing, and reasoning. Herein, the successful growth of MoS 2 monolayer arrays assisted by gold nanorods guided precursor nucleation is demonstrated. Optical, spectral, and morphology characterizations of MoS 2 prove that arrayed flakes are homogeneous monolayers, and they are further fabricated as optoelectronic devices showing featured photocurrent loops and stable optical responses. Typical synaptic behaviors of photo-induced short-term potentiation, long-term potentiation, and paired pulse facilitation are recorded under different light stimulations of 450, 532, and 633 nm lasers at various excitation powers. A visual sensing system consisting of 5 × 6 pixels is constructed to simulate the light-sensing image mapped by forgetting curves in real time. Moreover, the system presents the ability of utilizing associated images to restore vague and incomplete memories, which successfully mimics human intelligent behaviors of association memory and logical reasoning. The work emulates the brain-like artificial intelligence using arrayed 2D semiconductors, which paves an avenue to achieve smart retina and complex brain-like system.

Multicolor vision perception of flexible optoelectronic synapse with high sensitivity for skin sunburn warning

“…3(a)). 51 As a result, the range of light sensitivity in human eyes is 380-780 nm, which leads to the inability of the human eye to perceive UV light. Here, based on the ability of the device for wide-spectrum light detection (200-650 nm), tetrachromatic vision perception was investigated.…”

Recent Progress of Polymeric Dielectrics in Molybdenum Disulfide-Based Devices

“…However, most MoS 2 -based phototransistors used inorganic materials as the gate dielectrics, such as SiO 2, 17,122,123 6a) that not only can realize the photoresponse of four different wavelengths (Figure 6b) but also has light decay time that is gatevoltage dependent (Figure 6c). 67 After 1000 bending cycle tests, the electrical properties of the device remain basically unchanged thanks to the softness of the polymeric dielectric material.…”

“…As we all know, a typical field-effect transistor (FET) is usually composed of gate electrodes, dielectrics, active layers, and drain and source electrodes . Thereinto, metal electrodes and inorganic dielectrics are commonly prepared using high-energy preparation techniques, such as vacuum thermal evaporation, ,,,, e-beam evaporation, ,,, atomic layer deposition, ,, and so on. In general, high-energy atoms or atomic clusters will repeatedly bomb the contact area, resulting in many interface damage, defects, and surface states at the interface between metal and semiconductor, which will further affect the injection and transport of charge carriers .…”

“…However, most MoS 2 -based phototransistors used inorganic materials as the gate dielectrics, such as SiO 2, ,, Al 2 O 3 and so on: only a few cases of MoS 2 /polymeric dielectrics-based phototransistors have been reported. Poly(4-vinyl phenol) (PVP) as the gate dielectrics, possesses high transparency and excellent dielectric constant and has been well studied in devices based on MoS 2 .…”

“…Thus, it is urgent to find a new class of materials to overcome these technical problems. With the nature of ultrathin thickness, dangling-free bonds and tunable band structure, transition metal dichalcogenides (TMDCs) have shown excellent electrical properties, unique optoelectronic properties, and mechanical flexibility that could be transferred to arbitrary substrates, which are becoming one of the most promising materials to replace traditional silicon-based materials. − Thereinto, molybdenum disulfide (MoS 2 ) with a typical layered structure is widely studied. − According to current progress, MoS 2 possesses the thickness-dependent energy band to widen its absorption spectrum and the large surface-to-volume ratio to assist charge trapping, which lay a good foundation for the development of optoelectronic devices for sensors, − displays, − recognition, − and other diversified applications. − Furthermore, air-stabilized MoS 2 could overcome the phonon scattering through the interface engineering to obtain ultrahigh electrical properties at room temperature and achieve the large-size growth by the regulation of preparation process, which provide advantages for the development of large-scale miniaturized integrated circuits. , Markedly, MoS 2 -based flexible integrated logic circuits as the optimization of the growth process have been successfully studied, which obtained good device yield and excellent electrical performance with the mobility of 55 cm 2 V –1 s –1 , high on/off ratios of 10 10 , and current densities of 35 μA μm –1 …”