Room-temperature ferroelectricity in CuInP2S6 ultrathin flakes

TLDR

Two‑dimensional materials are promising for optoelectronics, yet cooperative phenomena such as ferroelectricity remain largely unexplored in the 2D limit. The study aims to demonstrate the potential of 2D ferroelectric CuInP₂S₆ by integrating it into functional devices. To this end, the authors fabricate a van der Waals ferroelectric diode using a CIPS/Si heterostructure that exhibits a memory‑like on/off ratio of about 100. They report room‑temperature ferroelectricity in ~4 nm CIPS flakes with a transition near 320 K, and show that this ferroelectricity enables high‑on/off memory behavior in the diode, opening avenues for sensors, actuators, non‑volatile memory, and other vdW heterostructures.

Abstract

Abstract Two-dimensional (2D) materials have emerged as promising candidates for various optoelectronic applications based on their diverse electronic properties, ranging from insulating to superconducting. However, cooperative phenomena such as ferroelectricity in the 2D limit have not been well explored. Here, we report room-temperature ferroelectricity in 2D CuInP 2 S 6 (CIPS) with a transition temperature of ∼320 K. Switchable polarization is observed in thin CIPS of ∼4 nm. To demonstrate the potential of this 2D ferroelectric material, we prepare a van der Waals (vdW) ferroelectric diode formed by CIPS/Si heterostructure, which shows good memory behaviour with on/off ratio of ∼100. The addition of ferroelectricity to the 2D family opens up possibilities for numerous novel applications, including sensors, actuators, non-volatile memory devices, and various vdW heterostructures based on 2D ferroelectricity.