All-inorganic halide perovskites are considered as favorable materials for various electronic applications because of their superior functionality and stability. In this study, the inorganic rubidium lead-bromide (RbPbBr3) perovskite has been integrated as a resistive switching (RS) layer in the Al/RbPbBr3/indium tin oxide/polyethylene terephthalate flexible structure and exhibits both bipolar (memory) switching and threshold switching functions. The threshold switching appears for a low compliance current (CC), whereas the memory switching is initiated by setting a higher CC. The resistive memory switching operations along with multilevel programming, moderate endurance, and retention performance show the reproducible and reliable nonvolatile high-density memory feature. The robustness and mechanical flexibility are established by uniform current–voltage curves under various bending diameters and flexing cycles. Also, the first principle density functional theory calculations demonstrate the contribution of each element in the conduction band and valence band of RbPbBr3 with a direct band gap (2.24 eV). Finally, a mechanism in combination with the formation/annihilation of a metal filament and a Br– ion vacancy filament is proposed to explain the RS behavior.

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Emulation of biological signal processing, learning and memory functions is essential for the development of artificial learning circuitry. Two terminal artificial synapses are supposed to be more feasible with biological system in terms of energy efficiency and processing. Here, we report on the fabrication of organic–inorganic hybrid perovskite based two-terminal artificial synapse in which the synaptic plasticity is modified by both voltage pulses and light illumination. The device emulates important synaptic characteristics, including analog memory switching, short-term plasticity, and long-term plasticity, analogous to the biological system. The change in conductance is attributed to the ion migration under external electric field. In addition, the improved post-synaptic current in optical exposer could be related to the generation of excitons and lowered Schottky barrier at perovskite/electrode interface under external electric field.

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In this work, a ZnO/NiO bilayer architecture is introduced to fabricate a transparent and flexible resistive random access memory device (Cu/ZnO/NiO/ITO) on polyethylene terephthalate substrate. The device exhibits excellent resistive switching (RS) characteristics, such as forming-free characteristic, low operating voltages, outstanding uniformity, long retention time (>10 4 s), high ON/OFF current ratio ~10 3 , reliable multilevel cell characteristics and excellent mechanical flexibility. The multilevel properties have been systematically evaluated by varying the compliance current and tuning the stopping voltage, which shows that the whole resistance state is distinguishable and remained stable without any considerable deprivation over 10 3 s. Intrinsic tailoring of RS mechanism has been well explained in the framework of electric field-induced formation and rupture of the reproducible Cu filaments in ZnO/NiO layer. Furthermore, the metallic nature of conducting filament has been confirmed by temperature-dependent variation of the high-and low-resistance states. Due to the increasing demand for flexible electronics, the mechanical robustness of the proposed device has been examined by varying the bending time and radius. The present RS device shows potential towards integration in many transparent, flexible and high-density storage devices, such as electronic skins and flexible displays.