Lead‐Free Perovskites‐Based Photonic Synaptic Devices with Logic Functions

Abstract

Lead halide perovskites have shown great potential in photonic synaptic devices owing to their notable optical properties. However, the inherent toxicity of lead and complex configuration of the device hinder the further development of perovskites‐based photonic synaptic devices. Here, lead‐free double perovskite Cs2AgSbBr6 is first used to fabricate photonic synaptic devices. The photonic synaptic device with a simple structure exhibits decent reproducibility and stability. By tuning external light signals, photonic synaptic devices based on Cs2AgSbBr6 can mimic primary synaptic behaviors, such as excitatory postsynaptic current, paired pulse facilitation, short‐term memory (STM), long‐term memory (LTM), the transfer between STM and LTM, and the “learning‐forgetting‐relearning” process. Furthermore, the temperature effect on the learning and memory process is investigated. Importantly, logic functions of “OR” and “AND” operations are realized. This work suggests the great potential of Cs2AgSbBr6 in future neuromorphic computation.

Low Switching Power Neuromorphic Perovskite Devices with Quick Relearning Functionality

“…The PTP index was calculated using the following formula: PTP index = A10/A1, where A1 and A10 represent the post-synaptic current (PSC) responses of the first and last pulse. Transition process from Short-Term Potentiation (STP) to Long-Term Potentiation (LTP): To determine the transition process, a group of sequential train stimuli (20,40,60,80, and 100 pulses) was applied to the presynaptic electrode. The pulse width was fixed at 100 ms and the pulse amplitude at 200 mV.…”

“…It simplifies the process of regaining previously thought knowledge, even if the information has been forgotten. [38][39][40][41][42] Figure 3g represents the five cycles of consecutive training pulses applied to the presynaptic electrode for the synaptic device. In the emulation of the learning and relearning process in our synaptic device, an increment in conductance occurs with an applied pulse stimulus.…”

Recent Developments of Optoelectronic Synaptic Devices Based on Metal Halide Perovskites

“…Our group reported logic functions utilizing double perovskites Cs 2 AgSbBr 6 OSDs by regulating the wavelength and intensity of illuminated light on the device (Figure 12a). [72] In the measurement, the output current is higher (lower) than 0.075 nA is defined as "1" ("0"). "OR" logic operation was achieved when light spikes (365 and 400 nm) with an intensity of 0.15 mW cm −2 triggered the device.…”

“…[76] Inspired by human visual system, the neuromorphic visual system with the functions of sensing, processing and memorizing optical Reproduced with permission. [72] Copyright 2021, Wiley-VCH. d) Schematic diagram of flexible synaptic device and logic operations by regulating light and electric signals synergistically.…”

“…b) "OR" logic function simulated by 365 and 400 nm light spikes with an intensity of 0.3 mW cm −2 . c) "AND" logic function mimicked by 365 and 400 nm light spikes with an intensity of 0.15 mW cm −2 .Reproduced with permission [72]. Copyright 2021, Wiley-VCH.…”