Effect Of Cage-type Organic Amines On The Resistive Memory Of Perovskite

With the advent of the era of big data,internet of things and 5G,people put forward higher requirements for the capacity,density and storage speed of memory.Resistive random-access memory（RRAM）is the most promising candidate for the next-generation memory technology,due to its simple architecture,rapid operation speed,good endurance,high integration density and low power consumption.Among them,the organic-inorganic hybrid perovskites（OHP）,as one of the common resistive medium materials have attracted great attention owing to their unique hybrid structure and various physical characteristics,such as tunable band gap,high bipolar carrier mobility,long carrier diffusion length（>1μm）,weak exciton binding energy and strong light absorption.However,research shows that OHP may be sensitive to oxygen and moisture,which easily induce the perovskite to break down,resulting in the poor environmental stability and low switching window of the resistive memory.Therefore,in this thesis,based on interface engineering,two types of cage-type organic amine small molecules were introduced to prepare perovskite resistive switching memory devices with high switching ratio and long-term stability.1.The intergranular interfacial modification of OHP is an important issue to regulate the switching performance of RRAM,such as switching ratio and device stability.In this work,ADNH₃I with cage cavity structure was introduced into Pb I₂:MAI precursor solution as additive to modify the perovskite interface.The cage cavity structure of ADNH₃I was anchorted at the perovskite interface by using-NH₃⁺to occupy its A position,thus regulating the interface properties and grain size of perovskite.Under the air ambient conditions,compared with the unmodified device,the OHP RRAM devices modified by 4%ADNH₃I take on the improved resistive switching performance,such as the switching ratio（ON/OFF）about 10⁴,2000-cycle SET/RESET endurance,low-voltage operation（～0.6 V）and long-term data retention（>10⁴ s）.The switching ratio of ADNH₃I-modified device is two orders of magnitude higher than that of the unmodified device.In addition,the introduction of ADNH₃I not only can reduce the grain size of perovskite,but also can greatly improve the humidity stability of perovskite.2.On the basis of the first part,the influence of cavity structure on the resistance of perovskite was further discussed and verified.The influence of different contents of octaammonium-POSS（OA-POSS）on the performance of perovskite resistive memory was studied.The cavity structure of POSS could be better anchored at the perovskite grain boundary by using the multiple branch chains of OA-POSS containing eight-NH₃⁺groups.While the OA-POSS also acts as nucleation sites and crystallization templates.The results show that the switching ratio of the device reaches 10⁵ when the introduced proportional concentration of OA-POSS is 4%,which is three orders of magnitude higher than that of the unmodified perovskite device.Notably,the improvement of the switching ratio of the device is due to the introduction of cavity molecules.In the high resistance state,the introduction of the cavity structure could effectively hinder the transport of carriers among the perovskite grain boundaries.At the same time,the device still showed typical bipolar resistive switching（RS）performance after being placed in air ambient conditions for half a year,indicating that the environmental stability of the device had been also greatly improved.3.ADA-PAA was synthesized through the interaction between the polymer（PAA）and the cavity molecule（ADA）.Then,ADA-PAA was introduced into the perovskite system to improve its dispersion at the perovskite interface,and further improve the resistance and flexibility of the RRAM.Finally,the fiber flexible resistive memory with the device structure of Al@MAPb I₃:ADA-PAA/Al was prepared by using the flexibility of polymer and the cavity structure of 1-adamantylamine.When the ADA-PAA introduction ratio is 2 mg/m L,the switching ratio of the device reaches 10⁸.In addition,the switch ratio almost not change at the bending angles of 30°and 90°in the device’s bending performance tests.After the resistive memory device was weaved to form the cross matrix structure,it still showed good resistive behavior,and the switching ratio remained at 10⁵.