Research On Resistive Properties Of Non Perovskite CsPbI₃ Thin Film Heterojunction

As a typical non-volatile storage device,resistance switch random access memory(RRAM)has simple structure,scalability,fast switching speed,low power consumption and high integration.It provides a promising application for information storage and processing in the next generation computing system.Recently,the perovskite phase CsPbI3 has been widely concerned in the application of RRAM due to its excellent electrical properties.However,CsPbI3 is very easy to change from cubic phase to non perovskite phase at room temperature.Its stable phase at room temperature is yellow phase CsPbI3(?-CsPbI3).Because ?-CsPbI3 has poor film-forming properties on fluorine-doped tin oxide conductive glass(FTO)substrates by spin-coating deposition,it is difficult to detect the resistive characteristics of pure ?-CsPbI3 on FTO substrates.Previous studies have shown the device(Ag/PMMA@CsPbI3/FTO)which is made by PMMA@CsPbI3 composite film prepared by adding polymethyl methacrylate(PMMA)has the memristive characteristics can be detected and utilized,but the resistance switch is only about 100.Compared with the current switching ratios of other advanced materials,there is still a big gap.This is a problem that hinders the practical application of ?-CsPbI3 memristors.In order to improve the application value of ?-CsPbI3 in RS memory,this article introduces the use of vapor-deposited Ag substrate,which is naturally oxidized in the air to form amorphous AgOx,and then ?-CsPbI3 is prepared on it,finally the device is prepared which is Ag/CsPbI3/AgOx/Ag.Under the read voltage of 0.01 V,the device has a resistive switch ratio of up 107,endurance is over 120 cycles,and the retention time is more than 10000s.Through the analysis of the conduction mechanism of the device,it is revealed that the conduction mechanism of the device in accordance with Schottky emission,ohmic conduction,traps control space charge limited conduction(TCSCL),shallow trap space charge limited(STSCL)conduction.At the same time,in this device,both the interface type conduction mechanism and the conductive filaments play a very important role.In another work to improve the device structure of a memristor based on ?-CsPbI3,the heterojunction memristor of Ag/PMMA@CsPbI3/TiO2/FTO structure was prepared by constructing an anatase phase TiO2 interface layer and applying low-temperature solution method to make PMMA@CsPbI3 film.The memristor has a resistive switching ratio of above 5×104 in more than 120 repeated tests,which is 1000 times higher than that of a single-layer ?-CsPbI3 memristive device(Ag/PMMA@CsPbI3/FTO).The retention time can be maintained above 5000 s holding the on-off ratio(105).The experiment and the resistance change mechanism analysis shows that PMMA@CsPbI3/TiO2 heterojunction,PMMA and electrodes have a significant impact on the performance of the device.The conduction mechanism analysis indicates that conduction mechanism of the device in accordance with ohmic conduction and STSCL conduction.The conductive filament and the interface type conduction mechanism both play a very important role in the memristive device.