Flexible Threshold Switching Based on CsCu₂I₃ with Low Threshold Voltage and High Air Stability

Abstract

Halide perovskites featuring remarkable optoelectronic properties hold great potential for threshold switching devices (TSDs) that are of primary importance to next-generation memristors and neuromorphic computers. However, such devices are still in their infancy due to the unsolved challenges of high threshold voltage, poor stability, and lead-containing features. Herein, a unipolar TSD based on an all-inorganic halide perovskite of CsCu2I3 is demonstrated, exhibiting the fascinating attributes of a low threshold voltage of 0.54 V, a high ON/OFF ratio of 104, robust air stability over 70 days, a steep switching slope of 6.2 mV·decade–1, and lead-free composition. Moreover, the threshold voltage can be further reduced to 0.23 V using UV illumination to reduce the barrier of iodide ion migration. The multilevel threshold switching behavior can be realized through the modulation of either the compliance current or the scan rate. The TSD with mechanical compliance and transparency is also demonstrated. This work enriches TSDs with expanded perovskite materials, boosting the related applications of this emerging class of device families.

Robust Threshold-Switching Behavior Assisted by Cu Migration in a Ferroionic CuInP2S6 Heterostructure

“…Furthermore, the current rises sharply at the threshold voltage, yielding an ultrasmall SS value of less than 1.8 mV/decade, as shown in Figure g. A comparison of the threshold voltage and SS value with many other ionic conducting-based memory devices is presented in Figure h, where the Cu/CIPS/Gr device studied in this work shows outstanding performance, especially the low operation voltage and small SS value. − ,− This high performance is attributed to the particular mechanism of resistive switching in the Cu/CIPS/Gr structured device.…”

“…These results provide us with a visualized understanding of the inhomogeneity in layered CIPS induced by Cu ion migration, though it is difficult to resolve the exact locations of Cu ions under an electric field in the lattice microscopically. The widely distributed inhomogeneity inspired an ionic conducting-based resistive-switching device relying on the large nonresponsive areas rather than the randomly formed conducting filament as demonstrated in traditional oxide memory devices. − In this way, we expect to enhance the stability of the resistive-switching device.…”

Unraveling Dual Operational Mechanisms in an Air-Stable All Inorganic Perovskite for Nonvolatile Memory and Neuromorphic Computing

“…Figure S7b shows 50 consecutive I−V characteristics through voltage sweeps of 0 → 1 → 0 V with a compliance current of 10 −5 A, displaying consistent threshold switching behavior. 47 This further highlights the indispensability of the electroforming process for achieving nonvolatile RS behavior in our devices. To comprehensively evaluate the air stability of the devices over a two-month duration, the devices were placed in a sample chamber with controlled humidity (35% RH) at room temperature, as illustrated in Figure S8.…”

Recent Advances and Opportunities of Eco‐Friendly Ternary Copper Halides: A New Superstar in Optoelectronic Applications

“…However, the endurance of an overwhelming majority of TCHs‐based memristors is less than 10 3 cycles, far lower than that of conventional metal oxide memristors. [ 224 ] A thorough understanding of the resistance switching mechanism and the reason for cycling failure is the key to improving the reliability. Moreover, considering the environmental sensitivity and state retention of TCHs‐based memristors, it is recommended to reasonably evaluate the retention cycles at high humidity, high temperature, and high oxygen environment.…”