Retina‐Inspired Carbon Nitride‐Based Photonic Synapses for Selective Detection of UV Light

Abstract

Photonic synapses combine sensing and processing in a single device, so they are promising candidates to emulate visual perception of a biological retina. However, photonic synapses with wavelength selectivity, which is a key property for visual perception, have not been developed so far. Herein, organic photonic synapses that selectively detect UV rays and process various optical stimuli are presented. The photonic synapses use carbon nitride (C3N4) as an UV‐responsive floating‐gate layer in transistor geometry. C3N4 nanodots dominantly absorb UV light; this trait is the basis of UV selectivity in these photonic synapses. The presented devices consume only 18.06 fJ per synaptic event, which is comparable to the energy consumption of biological synapses. Furthermore, in situ modulation of exposure to UV light is demonstrated by integrating the devices with UV transmittance modulators. These smart systems can be further developed to combine detection and dose‐calculation to determine how and when to decrease UV transmittance for preventive health care.

Recent Progress in Transistor‐Based Optoelectronic Synapses: From Neuromorphic Computing to Artificial Sensory System

“…Generally, the low‐dimensional photoabsorbers are applied at the FG region to provide nonvolatile channel conductance switching and optoelectronic responses. [ 72–74 ] For example, the FG transistor‐based optoelectronic synapse using perovskite quantum dots (QDs) photoabsorber with visible‐light bandgap is reported, showing photoprogrammable/electric‐erasable operation and multilevel conductance states. [ 72 ] Here, inorganic perovskite QD (photoactive FG), thick SiO 2 (blocking dielectric layer), thin poly(methyl methacrylate) (PMMA, tunneling dielectric layer), and pentacene (semiconducting channel) are introduced to individual functional regions (Figure 5b).…”

Two‐Dimensional Metal‐Organic Framework Film for Realizing Optoelectronic Synaptic Plasticity

“…This delay is the root of synaptic signal. [4,32] Figure 4 e shows the temporal response curve of artificial synaptic device triggered by two continuous light spikes. The DPSC of artificial synaptic device triggered after the second light spike is higher than that of the first spike, because the second light pulse is imposed to…”

Retina-Inspired Organic Heterojunction-Based Optoelectronic Synapses for Artificial Visual Systems

“…Nearly 80% of the obtained information, among these external stimuli, is detected through human visual systems [ 2 , 3 ]. Hence, retinas are supposed to be one of the most significant sensory organs in human bodies, which have stimulated the emergence of artificial vision by bioinspired electronics [ 4 – 7 ]. Additionally, towards the future development of humanoid soft robots and artificial intelligence systems, there is a tremendous demand to design advanced photoelectric detection devices capable of being operated under various ambient conditions to strengthen and ultimately substitute for human visual systems in the field of industry, science, and military [ 8 – 11 ].…”

“…They have a more compact architecture than the traditional one that is composed of two devices, and offer capabilities beyond simple sensing devices. So far, although diverse kinds of optoelectronic synapses including memristors [ 2 , 6 , 16 – 19 ], and field-effect transistors [ 4 , 20 – 28 ], have been extensively demonstrated, most reported optoelectronic synapses have focused on the simulation of basic synaptic behaviors by specific wavelength. Human retinas are responsible for recognizing and detecting different wavelengths of visible light, so it is extraordinarily meaningful to realize the mimicry of color recognition and visual-aided learning in artificial visual systems.…”