Study On Transparent Optoelectronic Neural Synaptic Devices Based On Copper(Ⅰ) Iodide

With the growth of science and technology,the speed of information transmission and processing urgently needs to be upgraded.However,the computational system based on Von Neumann architecture is hampered by the separation of data storage and processing modules,even the optimization algorithm cannot break through this bottleneck.For this reason,a large number of researchers have focused on the research of brain-like neural networks,trying to simulate the ability of human brain to process information in parallel,and realize the artificial intelligence neural network system integrating perception,storage,and computing.In the field of artificial intelligence,optoelectronic synaptic devices are considered as a cornerstone of neuromorphic intelligence system.They can not only directly process optical signals,but also have advantages such as high bandwidth and low crosstalk,therefore they are very suitable for building neural network systems that integrate perception,storage and computing.At the same time,transparent optoelectronic synaptic devices are receiving high attention because of their great potential in "invisible" electronic products.In transparent synaptic devices,finding suitable electrodes and functional layer materials are two problems that need to be solved at present.Copper(I)iodide(Cu I),as a p-type semiconductor material,not only has excellent conductivity and transparency,but also has low cost and high hole mobility,which is very suitable for transparent synaptic devices.In this paper,three categories of transparent optoelectronic synaptic devices on the basis of Cu I have been manufactured.The main research contents are as follows:1.The indium tin oxide(ITO)was used as the bottom electrode,greatly steady organic semiconductor copper(II)phthalocyanine(Cu Pc)was used as the active functional layer material,and Cu I was used as the top electrode,the transparent optoelectronic synaptic device with ITO/Cu Pc/Cu I sandwich structure was prepared.The synaptic device has a sensitive response to visible light at 660 nm.In view of this characteristic,a simulation experiment of synaptic plasticity has been carried out systematically.The effects of the number of light pulses,pulse width,pulse frequency,etc.on the device performance have been studied,the internal mechanism of synaptic plasticity has been explained,and the device has been applied to realize arithmetic operation and digital recognition.2.In order to simplify the process flow and further improve device transparency,the ITO/Cu I optoelectronic synaptic device with simple structure has been manufactured,Cu I was used as both electrode and functional layer material.In accordance with the ultraviolet(UV)absorption peak of Cu I film,a series of experiments on synaptic plasticity were carried out with a 405 nm laser.The short-term plasticity(STP)represented by paired-pulse facilitation(PPF)and the long-term plasticity(LTP)achieved by enhanced light pulse stimulation were analyzed.In addition,the function of letter recognition and memory was successfully simulated by using the positive correlation of excitatory postsynaptic current(EPSC)to light pulse intensity.3.The PET/ITO/Cu I optoelectronic synaptic device based on flexible substrate polyethylene terephthalate(PET)was prepared.The device not only has transparency and mechanical flexibility,but also has ultra-low power consumption.The minimum power consumption in operating mode is 1.33 p J.The effects of the number of light pulses,pulse frequency and other factors on synaptic plasticity were studied,at the same time,its mechanical flexibility was tested to verify the potential of Cu I for flexible synapses.In addition,using its sensitive response to 375 nm and 405 nm lasers,the logical operation of "AND" and "OR" is realized.