Optically Stimulated Artificial Synapse Based on Layered Black Phosphorus

Abstract

The translation of biological synapses onto a hardware platform is an important step toward the realization of brain‐inspired electronics. However, to mimic biological synapses, devices till‑date continue to rely on the need for simultaneously altering the polarity of an applied electric field or the output of these devices is photonic instead of an electrical synapse. As the next big step toward practical realization of optogenetics inspired circuits that exhibit fidelity and flexibility of biological synapses, optically‑stimulated synaptic devices without a need to apply polarity‑altering electric field are needed. Utilizing a unique photoresponse in black phosphorus (BP), here reported is an all‑optical pathway to emulate excitatory and inhibitory action potentials by exploiting oxidation‑related defects. These optical synapses are capable of imitating key neural functions such as psychological learning and forgetting, spatiotemporally correlated dynamic logic and Hebbian spike‑time dependent plasticity. These functionalities are also demonstrated on a flexible platform suitable for wearable electronics. Such low‐power consuming devices are highly attractive for deployment in neuromorphic architectures. The manifestation of cognition and spatiotemporal processing solely through optical stimuli provides an incredibly simple and powerful platform to emulate sophisticated neural functionalities such as associative sensory data processing and decision making.

Multifunctional Optoelectronics via Harnessing Defects in Layered Black Phosphorus

“…Based on the retention time of sensory information, psychological memory behavior can be classified into short‐term memory (STM) and long‐term memory (LTM), where through consecutive rehearsal processes, the level of the memory can be changed. Our few‐layer BP synaptic devices show a slower recovery of photocurrent after exposure to 280 nm illumination (as compared to 365 nm), which can be attributed to the persistent photocurrent in BP (Section S6, Supporting Information) . This indicates that the BP synaptic devices exhibit LTM behavior under 280 nm and STM under 365 nm stimulation spikes.…”

Synergistic Improvement of Long‐Term Plasticity in Photonic Synapses Using Ferroelectric Polarization in Hafnia‐Based Oxide‐Semiconductor Transistors

“…Particularly, photonic synapse devices have received attention because they have several advantages compared to the electronic synapse devices, such as wide bandwidth, low crosstalk, and low power consumption characteristics 18–28. Therefore, researchers have attempted to mimic synaptic behaviors by utilizing optical stimulation and photonic synapse devices have been realized with various materials such as carbon nanotubes,29,30 oxide semiconductors,18,19,25,31,32 perovskite quantum dots,21,33 2D materials,23,24,27,28,34,35 and hybrid perovskites 20,26,36. These devices have demonstrated synaptic functions, such as short‐term plasticity (STP), paired‐pulse facilitation (PPF), long‐term plasticity (LTP), STP‐to‐LTP transition, and spike‐timing‐dependent plasticity by optical stimulation.…”

Flexible Neuromorphic Electronics for Computing, Soft Robotics, and Neuroprosthetics

“…The combination of synaptic and sensing capabilities in a single device has the advantage of high compactness without the need for additional sensing elements. [195] Artificial synapses developed so far can detect light, [134,135,158,[196][197][198] pH, [142] and chemicals ( Table 3). [199,200] Light-sensitive artificial synapses have mostly used flexible 2-T devices.…”