Dynamic Information Transmission and Encryption by Stacked Electrochromic Device

ABSTRACT The development of information technology has escalated the demand for information security. The on‐demand coloration/bleaching characteristics enable electrochromic devices (ECDs) for controllable information encryption, yet achieving dynamic information transmission/encryption within a single ECD is still challenged by limited optical states. Herein, a stacked transmissive/reflective multi‐colored ECD is embodied via harvesting the synergy between (de)intercalation‐induced color switching in K + ‐doped vanadate (KVO) electrode and localized surface plasmon resonance in copper‐based reversible metal electrodeposition (Cu‐RME) electrode, with a copper mesh sandwiched in between. The KVO electrode shows enlarged interlayer spacing, realizing fast switching among green, yellow, and orange with a low activation energy of 23.4 kJ·mol −1 . Concurrently, the Cu‐RME electrode allows fast switching between multiple optical states (transparent, blue‐green transparent, purple‐red transparent, mirror state) via well‐tuned deposition voltage algorithms. Superimposing the KVO and Cu‐RME electrodes renders stacked ECD to switch between multi‐color transmissive mode and reflective mode, enabling non‐emissive displays, adaptive camouflage, infrared thermal management, and multi‐state information transmission in transmissive mode and dynamic information encryption in reflective mode (transmittance < 2% and reflectance > 30%). Integrating multiple optical states, fast response, and tunable transmissive/reflective modes, this stacked ECD offers an innovative solution for dynamic information encryption in the era of the Internet of Things.