Free-standing two-dimensional ferro-ionic memristor.

Lee, Jinhyoung; Woo, Gunhoo; Cho, Jinill; Son, Sihoon; Shin, Hyelim; Seok, Hyunho; Kim, Min-Jae; Kim, Eungchul et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Two-dimensional (2D) ferroelectric materials have emerged as significant platforms for multi-functional three-dimensional (3D) integrated electronic devices. Among 2D ferroelectric materials, ferro-ionic CuInP<sub>2</sub>S<sub>6</sub> has the potential to achieve the versatile advances in neuromorphic computing systems due to its phase tunability and ferro-ionic characteristics. As CuInP<sub>2</sub>S<sub>6</sub> exhibits a ferroelectric phase with insulating properties at room temperature, the external temperature and electrical field should be required to activate the ferro-ionic conduction. Nevertheless, such external conditions inevitably facilitate stochastic ionic conduction, which completely limits the practical applications of 2D ferro-ionic materials. Herein, free-standing 2D ferroelectric heterostructure is mechanically manipulated for nano-confined conductive filaments growth in free-standing 2D ferro-ionic memristor. The ultra-high mechanical bending is selectively facilitated at the free-standing area to spatially activate the ferro-ionic conduction, which allows the deterministic local positioning of Cu<sup>+</sup> ion transport. According to the local flexoelectric engineering, 5.76×10<sup>2</sup>-fold increased maximum current is observed within vertical shear strain 720 nN, which is theoretically supported by the 3D flexoelectric simulation. In conclusion, we envision that our universal free-standing platform can provide the extendable geometric solution for ultra-efficient self-powered system and reliable neuromorphic device.