Organometallic and all-inorganic halide perovskites (HPs), ABX3, where A is the organic (CH3NH3) or inorganic (Cs, Rb) cation, B is a metal cation (Pb, Bi, Sn), and X is a halide anion (Cl, Br, or I), are regarded as promising functional materials due to their exotic properties such as tunable bandgap, fast ion migration, facile majority carrier control, and super-flexibility as well as optoelectronic characteristics. With their unique property of current-voltage hysteresis caused by fast ion migration, they have begun to be actively applied to resistive switching (RS) memory devices beyond optoelectronics. Resistive switching random-access memory (ReRAM), which can be applied to memristors, neuromorphic technology, and logic-in-memory application, is considered to be a promising nonvolatile memory device due to its low power consumption, fast switching speed, and high integration density. In terms of RS mechanisms, it is clearly reported that HPs-based ReRAM with different top electrode materials (electrochemically active or inert) exhibits typical RS characteristics. Electrochemical metallization (ECM) and valence change mechanism (VCM) have distinct RS effect and trade-off relationship. Therefore, a combination of VCM and ECM provides an opportunity to engineer a device that can be switched with both low voltage and a high on/off ratio, by utilizing electrochemically active metal cations such as Ag and Cu to obtain a medium diffusion barrier in HPs. In this work, we successfully apply a lead-free all-inorganic Ag doped cesium bismuth iodide (Cs3Bi2I9) perovskite in RS memory device. The RS memory device has Au/polymethylmethacrylate (PMMA)/Ag doped Cs3Bi2I9/Pt/Ti/SiO2/Si structure. A pinhole-free and uniform perovskite film with a thickness of only 300 nm is synthesized on a platinum coated silicon substrate using low temperature all-solution process. Interestingly, the RS memory devices with Au electrode device based on Ag doped Cs3Bi2I9 perovskite exhibit bipolar RS behavior by doped metal cations. The devices with Au electrode exhibit filamentary RS behavior with ultra-low operating voltage (&lt;0.15 V) and high on/off ratio of 108. This study will contribute to combination of the RS mechanisms in HPs based ReRAM and suggests the possibility of the lead-free all-inorganic HPs for ultra-low operating voltage and high on/off ratio by preconditioned metal conducting filament.

Lead-free all-inorganic Ag doped cesium bismuth iodide perovskite for resistive switching with ultra-low operating voltage and high on/off ratio by preconditioned metal conducting filament

2019 Fall National Meeting

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