Flexible Phase Change Materials for Electrically‐Tuned Active Absorbers

Abstract

Phase change materials (PCMs), such as GeSbTe (GST) alloys and vanadium dioxide (VO2), play an important role in dynamically tunable optical metadevices. However, the PCMs usually require high thermal annealing temperatures above 700 K, but most flexible metadevices can only work below 500 K owing to the thermal instability of polymer substrates. This contradiction limits the integration of PCMs into flexible metadevices. Here, a mica sheet is chosen as the chemosynthetic support for VO2 and a smooth and uniformly flexible phase change material (FPCM) is realized. Such FPCMs can withstand high temperatures while remaining mechanically flexible. As an example, a metal‐FPCM‐metal infrared meta‐absorber with mechanical flexibility and electrical tunability is demonstrated. Based on the electrically‐tuned phase transition of FPCMs, the infrared absorption of the metadevice is continuously tuned from 20% to 90% as the applied current changes, and it remains quite stable at bending states. The metadevice is bent up to 1500 times, while no visible deterioration is detected. For the first time, the FPCM metastructures are significantly added to the flexible material family, and the FPCM‐based metadevices show various application prospects in electrically‐tunable conformal metadevices, dynamic flexible photodetectors, and active wearable devices.

Ultra-Stable, Endurable, and Flexible Sb2TexSe3–x Phase Change Devices for Memory Application and Wearable Electronics

“…In the last several years, flexible PCRAM has been widely perceived as a feasible solution for advanced data storage devices due to its excellent electrical properties, reliability, and power efficiency. − Meanwhile, flexible electronics are being developed at a tremendous pace and routinely used on many occasions, featured by superior bending stability, portability, compatibility, and light weight. However, the mechanical deformation is inevitable in flexible devices, such as compression, tension, and twist, which is unfriendly to the performance and properties of the flexible electronics.…”

Metasurface-Driven Optically Variable Devices

“…Developments of local heating systems and electromechanical systems enable electrical control of thermally and strain-responsive metasurfaces. Local heating systems are usually composed of thin metal films to generate heat from electrical resistance ,,, or plasmonic resonances . These microheaters are considered suitable for volatile PCMs, i.e., VO 2 , but not for nonvolatile PCMs, i.e., GST, as they require fast quenching.…”

Nanomaterials based on phase change materials for antibacterial application

“…Generally speaking, PCM refers to a special material that undergoes a phase change (melts or solidifies) at a nearly constant temperature. 17,28 PCM can store and release large amounts of heat during the process of phase change, which generally occurred within a narrow temperature range. PCM can be divided into three types, solid–solid phase transition, solid–liquid phase transition, and liquid–gas transition.…”