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Abstract: CsPbX3 (X = halide, Cl, Br, or I) all‐inorganic halide perovskites (IHPs) are regarded as promising functional materials because of their tunable optoelectronic characteristics and superior stability to organic–inorganic hybrid halide perovskites. Herein, nonvolatile resistive switching (RS) memory devices based on all‐inorganic CsPbI3 perovskite are reported. An air‐stable CsPbI3 perovskite film with a thickness of only 200 nm is successfully synthesized on a platinum‐coated silicon substrate using low temperature all‐solution process. The RS memory devices of Ag/polymethylmethacrylate (PMMA)/CsPbI3/Pt/Ti/SiO2/Si structure exhibit reproducible and reliable bipolar switching characteristics with an ultralow operating voltage (<+0.2 V), high on/off ratio (>106), reversible RS by pulse voltage operation (pulse duration < 1 ms), and multilevel data storage. The mechanical flexibility of the CsPbI3 perovskite RS memory device on a flexible substrate is also successfully confirmed. With analyzing the influence of phase transition in CsPbI3 on RS characteristics, a mechanism involving conducting filaments formed by metal cation migration is proposed to explain the RS behavior of the memory device. This study will contribute to the understanding of the intrinsic characteristics of IHPs for low‐voltage resistive switching and demonstrate the huge potential of them for use in low‐power consumption nonvolatile memory devices on next‐generation computing systems. [ABSTRACT FROM AUTHOR]

Neuromorphic computing, which mimics biological neural networks, can overcome the high‐power and large‐throughput problems of current von Neumann computing. Two‐terminal memristors are regarded as promising candidates for artificial synapses, which are the fundamental functional units of neuromorphic computing systems. All‐inorganic CsPbI3 perovskite‐based memristors are feasible to use in resistive switching memory and artificial synapses due to their fast ion migration. However, the ideal perovskite phase α‐CsPbI3 is structurally unstable at ambient temperature and rapidly degrades to a non‐perovskite δ‐CsPbI3 phase. Here, dual‐phase (Cs3Bi2I9)0.4−(CsPbI3)0.6 is successfully fabricated to achieve improved air stability and surface morphology compared to each single phase. Notably, the Ag/polymethylmethacrylate/(Cs3Bi2I9)0.4−(CsPbI3)0.6/Pt device exhibits non‐volatile memory functions with an endurance of ≈103 cycles and retention of ≈104 s with low operation voltages. Moreover, the device successfully emulates synaptic behavior such as long‐term potentiation/depression and spike timing/width‐dependent plasticity. This study will contribute to improving the structural and mechanical stability of all‐inorganic halide perovskites (IHPs) via the formation of dual phase. In addition, it proves the great potential of IHPs for use in low‐power non‐volatile memory devices and electronic synapses. [ABSTRACT FROM AUTHOR]

Recently, halide perovskites (HPs), which exhibit resistive switching (RS) behaviors, are proposed as a promising candidate for next‐generation memory because of their low power consumption, low cost, and mechanical flexibility. However, HP‐based memories have crucial problems related to short endurance and vague switching mechanism. Here, the RS behaviors of switchable methylammonium lead iodide (MAPbI3) and nonswitchable rubidium lead iodide (RbPbI3) mixtures are reported and it is elucidated on the source of the switching phenomena. By controlling the ratio of rubidium iodide (RbI)/methylammonium iodide (MAI), five compositions of the mixture of RbPbI3 and MAPbI3 (Rb1−xMAxPbI3, x = 0, 0.31, 0.52, 0.71, and 1) films are fabricated. The mixtures of cubic MAPbI3 and orthorhombic RbPbI3 films exhibit excellent performances in Ag/polymethyl methacrylate/Rb1−xMAxPbI3/Pt cells, with endurance of 103 cycles, a high on/off ratio of 106, and an operation speed of 640 µs. Plausible explanations for the switching mechanism are provided based on Ag bridges by using the combination of conductive atomic force microscopy and energy dispersive X‐ray spectroscopy. It is suggested nonswitchable RbPbI3 contributes to the endurance enhancement by restraining the growth of Ag bridges. The unique approaches provide a new strategy to overcome the bottleneck of the HP‐based RS memories for next‐generation computing. A conducting bridge resistive switching behavior is found in mixtures of switchable (methylammonium (MA))PbI3 and nonswitchable orthorhombic RbPbI3 compared with that in MAPbI3. Using combined conducting atomic force microscopy measurement and energy dispersive spectrometer element mapping, plausible explanations for the switching mechanism are provided with the Ag bridge. Nonswitchable orthorhombic RbPbI3 restrains the conduction filament. [ABSTRACT FROM AUTHOR]