Recipe for Fabricating Optimized Solid‐State Electrochromic Devices and Its Know‐How: Challenges and Future

Abstract Electrochromism, a well‐defined phenomenon of bias‐induced reversible color switching, has led to real applications in several smart devices including smart windows and self‐powered batteries and solar panels. For these applications, the electrochromic (EC) materials need to be integrated as solid‐state devices. Deciphering ways to recreate a conventional device requires understanding of basic structure and its working. A thorough discussion is provided here regarding various materials that can act as chromophores when treated with some electric bias in addition to a few parameters that dictatehow fairly the device performs. The next important aspect is the device design, the skeleton of which usually includes conducting substrates, EC active materials, and an electrolyte. Step‐by‐step, various available device paradigms are discussed starting from a single EC electrode then joining a blank substrate to fabricate a monolayer electrochromic device (ECD) moving onto bi‐layer ECDs, and finally, all‐in‐one EC gel, which is devoid of any proper layered pattern. A thorough discussion regarding various application‐oriented structural modifications is provided. Challenges and the areas that need to be addressed in immediate future are discussed.