Tunable Photonic Applications Based on Electrochemical Mechanisms.

Reflective displays offer key advantages such as high energy efficiency, eye comfort, and excellent visibility, making them attractive for a wide range of applications. Recently, tunable photonics has focused on integrating electrochromic (EC) materials with optical resonant structures, enabling dynamic control of reflection spectra and intensity through enhanced light-matter interaction. Here, this review provides an overview of recent progress in electrochemically driven dynamic coloration devices, systematically categorized according to their tuning mechanisms and photonic design within the visible spectral range. We outline energy-efficient and reconfigurable optical modulation strategies enabled by EC materials that operate through ionic insertion, redox reactions, or reversible plating/stripping of ionic metals. Furthermore, by bridging electrochemistry and photonic structures, we highlight recent progress, challenges, and emerging applications in reflective displays, colorimetric sensing, optical memory, and active holography. This review concludes by addressing the key challenges and future directions of this rapidly evolving field, highlighting the scientific and technological significance of electrochemical photonics as a foundation for next-generation tunable optical systems.