| Due to their different resistance behaviors,memristors can be divided into digital memristors and analog memristors,which are respectively used in resistive random access memory and neurosynaptic device bionics.Among them,resistive random access memory(RRAM),due to its simple structure,fast speed,low power consumption and other advantages,is considered to replace flash memory as the next generation of new non-volatile memory.At the same time,the analog memristor is regarded as one of the most potential devices for simulating nerve synapses because of its continuously adjustable resistance,which is highly similar to the transmission characteristics of nerve synapses.As a natural polysaccharide,sodium alginate(SA)can be used as an ideal material for constructing flexible electronic devices due to its solubility,stability,and non-toxicity.Based on the preparation of memristive devices with sodium alginate material,we doped two-dimensional black phosphorous quantum dots(BPQDs)into SA.By adjusting the proportion of black phosphorous quantum dots in the material,the effect of digital memristive devices is improved.The resistance change parameters were adjusted and the device was transformed from a digital memristor to an analog memristor.In addition,using the good response characteristics of BPQDs to ultraviolet light,the performance of RRAM and neurosynaptic bionics can be adjusted by ultraviolet light radiation to realize the simulation of photoelectric synapse function.The specific work is as follows:1.Research on the digital resistive characteristics of sodium alginate-based memristors:Firstly,the Ag/SA-BPQDs/ITO devices are constructed in this paper.Through the relevant electrical tests and the research on the resistive mechanism,the following results are obtained:Adjusting the proportion of black phosphorous quantum dots in the device can realize the regulation of the RRAM function of the device.It is confirmed that when the mass fraction of the quantum dots doped in sodium alginate is below 10%,the device can achieve good storage functions.And when the mass fraction of doped quantum dots is 8%,the turn-on voltage of the device is the lowest,and the device has the best volatility.And by adjusting the size of the limiting current,the multi-level resistance state transition behavior is realized in the device.In addition,using the good fluorescence characteristics of BPQDs,by adjusting the time of ultraviolet light irradiating the device,the transition voltage and resistance state of the device are further controlled,and the resistive behavior of the device is extended to the field of optoelectronic functions.2.Research on the analog resistive characteristics of sodium alginate-based memristors:First,we built Ag/SA-BPQDs/ITO with 15% and 20% quantum dots by increasing the proportion of quantum dots in sodium alginate.Thus,the memristive device is changed from high and low resistance switching to continuously adjustable resistance.Secondly,based on the construction of Ag/SA-BPQDs/ITO analog devices,the simulation of biological synaptic plasticity such as spike-timing-dependent plasticity(STDP)has been successfully realized.In addition,ultraviolet light is used to control the memristive behavior of the device: the device is more sensitive to the current response when the synaptic function is simulated after the light is illuminated.Finally,we constructed a bendable Ag/SA-BPQDs/ITO analog device based on a flexible substrate,and related tests confirmed that the device still has good memristive performance after many times and large-angle bending. |
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