| At present,the traditional storage technology based on CMOS technology approaching its physical limits,computer storage wall problems have become more and more serious.These are serious obstacles to the further development of the computer.Memristor is the fourth kind of circuit components except for resistance,capacitance and inductance,which can be used for information storage and logic operations at the same time.It was a strong candidate for the new type of nonvolatile storage technology,and was a kind of very promising technology to ease or even solve the problem of computer storage wall.Organic polymer-based memristor materials have many advantages,such as multicategory,designable ability of polymer molecules and flexibility.Organic polymer matrix composites could take advantage of the simple and abundant modulation relationship between matrix material and object material to control the storage characteristics.Organic polymer matrix composite film has many advantages,such as simple preparation proccess,and convenient for through changing mixing ratio to achieve adjustment of electrical characteristics.But some of the key scientific problems need to clarify and solve,especially the resistive switching mechanism was still out,and still need further researches and studies.Furthermore,the current memristor performance is unable to meet the needs of development and application technology,still need to optimize in all aspects,especially the key memristor characteristics,such as homogeneity of the parameters,consistency of operating current and voltage,the reliability of the component and multilevel resistive switching storage capacity are all await to further optimize.In this paper,nanometer thin film of organic polymer composites was prepared by spin coating method,memristor with the ITO/organic polymer matrix composite film/Al of sandwich structure has been prepared.The memristor property has been studied.The improvement of stability and repeatability for Flash storage based on poly(N-vinylcarbazole)have been studied.By controlling the different spin speed and time,different thickness of the composite films were prepared,and influence of film thickness on memristor characteristics were studied.Based on the experimental results of composite film absorption spectra,combined with I-V curve slope analysis in double logarithmic coordinate system,the resistive switching mechanism of ITO/poly(Nvinylcarbazole)donor and oxadiazoles acceptor composite film/Al memristor was analyzed.The relationships between film thickness and OFF state current verify the model of carriers transport.The electric field-induced charge transfer effect between carbazole donor and oxadiazoles acceptor effectively improve the stability and repeatability of the memristor.The improvement of ON/OFF ratio for Flash storage based on polyurethane has been studied.Small molecule oxadiazoles were mixed with polyurethane to form the continuous conductive network of composite material.Because of the polyurethane suitable for solution processing,the polyurethane blend with oxadiazoles small molecules can effectively avoid the small molecules crystallization precipitation in the process of spin coating.Containing oxadiazoles and not containing oxadiazoles of two kinds of components have been prepared by spin coating method.The resistive switching properties of two kinds of equipment are analyzed and compared.The experiment results show that the addition of oxadiazoles in the polyurethane can effectively reduce the OFF state current,and can effectively increase the current ratio.Using solution absorption spectra and cyclic voltammograms data of polyurethane film and oxadiazoles,the HOMO and LUMO of polyurethane and oxadiazoles were calculated.Resistive switching mechanism is analyzed using polyurethane,oxadiazoles and top and bottom electrode materials combined with I-V curve analysis in double logarithmic coordinate system.The transformation for nonvolatile storage features based on poly(4-vinylphenol)have been studied.Poly(4-vinylphenol)and oxadiazole composite films with the same thickness with different contents of oxadiazoles were prepared through the spin coating method.Resistive switching characteristics based on the composite film have been studied.When oxadiazoles content changing,memristor based on the composite film shows the different storage types,including rewriteable Flash,WORM and insulation characteristic.And the influence of the oxadiazoles in composite material content on the OFF state current,current ratio and the open voltage was studied.Resistive switching mechanism is analyzed using the relationship of ON and OFF state resistance and temperature,composite solution absorption spectra combined with I-V curve slope analysis in double logarithmic coordinate system.The realization of WORM and the ON/OFF ratio modulation based on PEDOT:PSS have been studied.The microstructure of carbon nanotubes was characterized by using transmission electron microscopy,and composite thin films have been characterized by transmission electron microscopy and scanning electron microscopy.Thermogravimetric analysis had been used to characterize the thermal characteristics of the composite material,and the initial conductivity of composite films was characterized.The composite films with different contents of carbon nanotubes were prepared by spin coating.The influence of the carbon nanotubes in composite material content on Resistive switching characteristics was studied.The WORM storage features of erase once read many times was found in the composite material.Resistive switching mechanism in ITO/PEDOT:PSS and carbon nanotube composite film/Al is analyzed using I-V curve slopefitting in double logarithmic coordinate system.The multilevel Flash storage based on epoxy methacrylate resin has been studied.A novel multilevel resistive switching was observed in epoxy methacrylate resinand carbon nanotubes composite films fabricated by spin coating method.The fabricated devices demonstrated the rewritable Flash nonvolatile memory characteristics.More significantly,the memory device based on epoxy methacrylate resin and carbon nanotube composite film exhibits multilevel stable conductivity states with stable intermediate resistance states in response to the applied voltage.By setting different compliance current and content of carbon nanotubes in composite film,the multilevel ON-states and even the multilevel OFF-states can be observed.As fabricated devices exhibit multilevel resistive switching with stable resistance ratio between different resistance states. |
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