Optoelectronic Synaptic Devices Based On MAPbI₃/oxide Hybrid Structures

Inspired by the human brain,neuromorphic computing has been considered the best way to overcome the von Neumann Bottleneck,owing to extremely fast operation speed,high parallelism,and ultra-low energy consumption.The first step to implementation of neuromorphic computing is to fabricate a device that can mimic biological synaptic functions,which is also called the synaptic device.At present,two terminal optoelectronic synaptic devices have been widely studied due to their unique advantages of high bandwidth,low energy consumption and high integration intensity.Among perovskites,MAPb I₃ has high optical absorption coefficients and long carrier diffusion lengths,which has been widely applied in varieties of optoelectrical devices.In this paper,two photoelectric synaptic devices based on MAPb I₃/oxide hybrid structure are fabricated.Owing to photovoltaic effect,the excellent optical absorption property of the perovskite and capture effect of the oxide,these synaptic devices mimic various synaptic functions.On this basis,the synaptic devices are applied in reservoir computing（RC）and successfully finish the prediction tasks.The main content of the paper include:（1）The optoelectronic synaptic device based on ITO/SnO₂/MAPb I₃/Spiro-OMe TAD/Au is prepared.Among them,oxygen vacancies in SnO₂ can trap the photoelectrons in MAPb I₃,leading to the increase of the response current decay.On this basis,the device successfully mimics EPSC,PPF,SNDP,SRDP via using optical stimulation.In terms of device performance,the synaptic device shows a higher rectification characteristic（3×10²）and a large dynamic range（14.3）,which is of great significance to build a high-performance artificial neural network（ANN）.（2）A hole-conductor-free synaptic device based on FTO/TiO₂/MAPb I₃/Carbon is fabricated.Under the stimulation of 532 nm optical pulses,the device successfully mimics various synaptic functions such as EPSC,PPF,SNDP,SRDP.The mimicking of synaptic functions is attributed to the capture effect of oxygen vacancies in TiO₂.In addition,the synapse device shows good endurance and low device-to-device variation,which is conducive to implement high-performance neuromorphic hardware systems.（3）RC and its applications are introduced.The RC system has nonlinear and short-term memory properties.The prepared synaptic devices have nonlinear and short-term memory characteristics,which provides theoretical support for realization of RC.Herein,the synaptic device based on MAPb I₃/TiO₂ is applied in RC and finish Mackey-Glass（M-G）prediction and Lorenz prediction.On this basis,predictive accuracy,which is affected by the nonlinear response of the device,is investigated.