Inorganic all-solid-state electrochromic devices (ECDs) hold significant application value in industrial fields due to their favorable chemical stability, high optical modulation rates, and excellent process compatibility. However, their monochromatic nature limits their development in display applications. Achieving dynamically tunable colors on inorganic all-solid-state ECDs represents a current frontier and hotspot in materials science research. Such colored inorganic all-solid-state ECDs also possess immense potential for future applications in areas like advertising, information transmission, and anti-counterfeiting.

Here, based on optical interference principles, we developed a composite electrode structure through precise optical design, simulation, and calculation. The optical cavity within this composite electrode structure causes incident light to undergo interference and diffraction, thereby presenting vibrant rainbow-like colors. Building on this, we fabricated a WO₃-based colorful all-solid-state electrochromic device (ECD) featuring both transparent and reflective switching modes. By leveraging the tunable optical constants of the electrochromic layer and the additive color mixing principle, an ultra-wide color gamut of up to 11.58% can be achieved with just a minimal bias voltage of ±1.5 V. This significantly expands the color gamut boundaries of all-solid-state ECDs and represents a major breakthrough in color rendering performance. It can be applied to large-size display applications such as billboards and also holds broad prospects in information transmission and anti-counterfeiting fields. This work provides a new approach to addressing the challenge of narrow color gamut in inorganic all-solid-state ECDs, breaking through their color limitations. Meanwhile, the dual-mode design makes it a candidate technology for "multi-scenario displays," opening new pathways for low-power consumption intelligent window displays based on electrochromism.

This research, entitled “Transparent-To-Reflective Multicolor All-Solid-State Electrochromic Devices for Next-Generation Intelligent Display Windows”, was published in Advanced Materials, with Jiankang Guo and Hanxiang Jia as co-first authors.

Link to original article:

https://onlinelibrary.wiley.com/doi/10.1002/adma.202500350

Color display and anti-counterfeiting applications of DMD color all-solid-state ECDs