Bifunctional Silver-Doped ZnO for Reliable and Stable Organic–Inorganic Hybrid Perovskite Memory

Abstract

Halide perovskites (HPs) have possible uses as an active layer for emerging memory devices due to their low operation voltage and high on/off ratio. However, HP-based memory devices, which are operated by the formation of a conductive filament, still suffer from reliability issues such as limited endurance and stability. To solve the problems, it is essential to control filament formation in the active layer. Here, we present nanoscale HP-based memory devices that have a Ag-doped ZnO (AZO) layer on HP. The AZO layer is used as a Ag ion reservoir for filament formation in HP, and this reservoir enables control of filament formation. By adjusting the Ag concentration in the AZO layer, the controlled filament composed of Ag can be formed; as a result, the memory device has excellent endurance (3 × 10 4 cycles) compared to the device that uses a Ag electrode instead of an AZO layer (4 × 10 2 cycles). Also, an AZO layer can passivate HP, so the device operates stably in ambient air for 15 days with a high on/off ratio (10 6 ). These results demonstrate that the introduction of the AZO layer can improve the reliability of HP-based memory devices for high-density applications.

Oxide Passivation of Halide Perovskite Resistive Memory Device: A Strategy for Overcoming Endurance Problem

“…The ZrO x -passivated device exhibits the highest forming voltage of 1.85 V compared to the other oxide-passivated devices, it also shows a DC endurance of 57 000 cycles and a superior retention time of 7.8 × 10 4 s. These data demonstrate the correlation between the high forming voltage and the endurance property. As summarized in Table , our fabricated devices exhibit the highest endurance property compared to other studies on the HP-based RS memory devices. ,, …”

“…As summarized in Table 1, our fabricated devices exhibit the highest endurance property compared to other studies on the HP-based RS memory devices. 44,57,58 To understand the excellent endurance property of oxidepassivated devices, we simulated the cohesive energies of MAPbI 3 and other oxides (Table S1). 59 Table 2 clearly shows the correlation between the cohesive energy of materials, their forming voltage, and their DC endurance property.…”

“…25,26 These issues have been addressed through various measures such as defect control through an HP film with passivation layers, improving the morphology and crystallinity using the additive and solution coating method, and changing the structure from 3D to one-dimensional (1D) through monovalent cations and bivalent cations combination. 27−45 Also, the formation of heterojunction between zinc oxide based films and HP layers has been proposed to improve the resistive-switching memory properties 27,44 resistive switching, and stability did not have enough improvement in the RS properties.…”

“…The HPs with a three-dimensional (3D) ABX 3 structure consist of monovalent organic (CH 3 NH 3 ,CH 3 (NH 2 ) 2 ) or inorganic (Cs, Rb) cations at the A site, divalent metal cations (Pb, Sn) at the B site, and halide anion (I, Br, or Cl) at the X-site, The HP-based RS memory devices have an on/off ratio on the order of over 10 4 with multilevel resistive switching and low operating voltages. , However, these devices suffer from poor endurance, short retention, and stability for use as memory and artificial synapse, which requires over 10 6 endurance. , These issues have been addressed through various measures such as defect control through an HP film with passivation layers, improving the morphology and crystallinity using the additive and solution coating method, and changing the structure from 3D to one-dimensional (1D) through monovalent cations and bivalent cations combination. − Also, the formation of heterojunction between zinc oxide based films and HP layers has been proposed to improve the resistive-switching memory properties , Despite the many studies, low endurance, short retention, multilevel resistive switching, and stability did not have enough improvement in the RS properties.…”

Metal Halide Perovskite-Based Memristors for Emerging Memory Applications

“…Another multilayer structure can improve endurance by controlling filament formation of the filament. 62 A multilayer device with a structure of Al/Ag-doped ZnO/2D BA 2 PbBr 4 /Pt was proposed to improve the endurance properties of the RSM device. The Ag-doped ZnO layer served as a Ag-ion reservoir to control the concentration of Ag in the perovskite for filament formation.…”