Study On Hysteresis And Storage Performance Of An Individual Organic-inorganic Hybrid Perovskite Micro/nanowire

Organic-inorganic hybrid perovskites,such as methylammonium lead iodide?CH₃NH₃PbI₃?perovskite,have great potential in solar cells due to their high power conversion efficiency and inexpensive preparation.However,their current-voltage?I-V?curves typically exhibit anomalous hysteresis characteristics that not only strongly affect the accuracy of the measurements and severely impair device performance,meanwhile their actual origin remains the subject of debate.Hysteresis behavior with a resistive switch?RS?can be applied to a RS memory device.The instability of organic-inorganic hybrid perovskites is also the focus of researches.Extrinsic effects and hybridization can obviously change the performance of the hybrid perovskite-based devices.Meanwhile,there are rich surface states for the nanomaterials.This study focuses on the application of one-dimensional organic-inorganic hybrid perovskite micro/nanomaterials.By constructing two-terminal devices and field effect transistors?FET?,utilizing the synergic effect of the external field,and hybridizing the micro/nanowire structures with quantum dots?QDs?,one-dimensional organic-inorganic hybrid perovskite micro/nanomaterial-based devices are successfully constructed to apply as controllable resistance switches,memristors,non-volatile memories,and self-powered photodetectors.An individual CH₃NH₃PbI₃ micro/nanowire-based two-terminal encapsulated device was constructed.Not only can its hysteresis properties be accurately modulated,but also their origin can clearly be identified as variations in the surface barrier related to trap filling of surface space charge region.Under illumination of the entire device with VIS light,two anticlockwise hysteresis loops appear symmetrically in cyclic I-V curves.Interestingly,the cyclic I-V curves can be switchably changed into asymmetrical“8”-shaped hysteresis loops with bipolar RS features when only the vicinity of one electrode is illuminated.The traps located in the surface space charge region play a crucial role in the tunable hysteresis behaviour.Owing to the presence of abundant surface states,two back-to-back connected diodes related to the surface barrier can be formed in the two-terminal device.With the synergistic assistance of illumination and bias,moreover,the injection and extraction of holes in the surface space charge region can effectively modulate the surface barrier,which triggers the formation of a bipolar RS device.Accordingly,two switchable back-to-back connected bipolar RS devices were built.Regarding the tunable hysteresis with nonvolatile memory properties controlled by the synergistic action of bias and illumination,our results provide a valuable insight into the identification of its origin and,furthermore,also indicate that the organic-inorganic hybrid perovskite materials have significant potential in nonvolatile memory applications.Electrical properties of an individual CH₃NH₃PbI₃ micro/nanowire-based two-terminal devices with encapsulation in different areas were investigated in a condensed water environment.For an unencapsulated device,it exhibits two symmetrical hysteresis loops with negative differential resistance?NDR?effect.For the device encapsulated one-end,contrastly,a bipolar RS with asymmetrical hysteresis loops is obtained.The origin of RS characteristic is mainly from the decomposition-induced the presence of PbI₂ and structure defects in CH₃NH₃PbI₃ micro/nanowire under the treatment with condensed water.As a consequence,quanties of trap centers,which can capture and store holes,are formed.For this device with decomposition at both of two ends,large bias can trigger a reversible asymmetrical filling of holes,resulting in an appearance of two symmetrical hysteresis loops with NDR effect.For this device with decomposition at one end,the filling and emptying of holes only occur at the decomposed end,resulting in an appearance of typical bipolar RS.The filled and emptied traps can well be retained at room temperature and low operation bias voltage,showing a memory behavior.The results demonstrate that not only the action mechanism of water on organic-inorganic hybrid perovskite materials is identify well by the investigation of electric transport properties,but also the decomposed organic-inorganic hybrid perovskite materials can show a promising potential in memory application.An individual CH₃NH₃PbI₃ micro/nanowire-based FET was successfully constructed.Its conductance can be accurately modulated by gate voltage and visible light,showing a gate voltage and illumination controlled nonvolatile memory feature.The constructed FET can reversibly transit between high resistance states?HRS?and low resistance states?LRS?by controlling the gate voltage.The nonvolatile RS memory effect predominantly originates from the controllable modulation of surface barrier triggered by the injection of holes into/from the traps located in surface space charge region under the synergy of gate voltage and illumination.For an individual CH₃NH₃PbI₃ micro/nanowire-based FET,its tunable electrical properties with nonvolatile memory,controlled by gate voltage and illumination via the adjustment of its surface states,suggests that it has a great potential in the application of gate voltage and illuminationdual-drive high performance nonvolatile information memory.The hybridization of PbS QDs noticeably improves photoelectric response of CH₃NH₃PbI₃ micro/nanowire.The photocurrent peak is red-shifted from 475 to 500nm,accompanied by the spectral response range being broadened to the infrared region,and it also shows a strong photoelectric response to the 800⁹00 nm infrared lights.This is mainly originated from the strong coupling between PbS QDs and CH₃NH₃PbI₃micro/nanowire that largely improves the carrier mobility.The two-terminal devices constructed with an individual PbS QD@CH₃NH₃PbI₃ micro/nanowire exhibit different photovoltaic characteristics upon being illuminated on different regions,indicating their potential applications in self-powered photodetectors.The individual PbS QD@CH₃NH₃PbI₃ micro/nanowire exhibits a wide and stable photoelectric response at low light intensities,mainly attributed to the existence of a large number of trap states induced by the QD hybridization that largely reduces the energy barrier at the electrode interface.The strong illumination dependence of electrical properties of the PbS QD@CH₃NH₃PbI₃ micro/nanowire can be applied in non-volatile information memory.