Various coating methodologies of WO₃ according to the purpose for electrochromic devices

Solution-processable electrochromic (EC) materials have been investigated widely for various applications, such as smart windows, reflective displays, and sensors. Among them, tungsten trioxide (WO3) is an attractive material because it can form a film via a solution process and relative low temperature treatment, which is suitable for a range of substrates. This paper introduces the slot-die and electrostatic force-assisted dispensing (EFAD) printing for solution-processable methods of WO3 film fabrication. The resulting films were compared with WO3 films prepared by spin coating. Both films exhibited a similar morphology and crystalline structure. Furthermore, three different processed WO3 film-based electrochromic devices (ECDs) were prepared and exhibited similar device behaviors. In addition, large area (100 cm2) and patterned ECDs were fabricated using slot-die and EFAD printing. Consequently, slot-die and EFAD printing can be used to commercialize WO3 based-ECDs applications, such as smart windows and reflective displays.