Layered lead-free perovskite memristors with ultrahigh on/off ratio

Abstract

Layered organic–inorganic hybrid halide perovskites hold promises for memristive and synaptic devices with ultralow power consumption. However, the lead-based layered perovskites often contain organic cations which are subject to thermal and optical instability. Here we report lead-free resistive switching devices incorporating nanostructured all-inorganic perovskite Cs₃Bi₂Br₉. Monocrystalline hexagonal microplates of Cs₃Bi₂Br₉ were synthesized via a solution method featuring layered structure and smooth morphology. Upon sandwiched by sliver and conductive glass, the microplate devices exhibit resistive switching behavior under forming-free bias below 0.2 V. Ultrahigh on/off ratio up to 10⁹ was recorded in these devices, favoring multi-level data storage capabilities within single memory units. The high switching ratio is attributed to the suppressed inter-layer electrical conductance of the microplates. In addition, the memristive devices demonstrate excellent stability over 20 months in ambient condition. This work offers insights into utilizing layered inorganic perovskite architectures for resistive switching devices with decoupled ionic and electronic transport.