Silver based reversible electrochromic (EC) devices which can be used for smart windows and information display are analysed to examine the factors that determine switching time, color, and scale-up. These devices demonstrate multiple colors: silver, black, magenta, yellow and dark cyan blue with switching time as low as 5 seconds. The usage of redox mediators, applied bias, in enhancing the kinetics of the color transformation while being constrained by the electrochemical window of the DMSO solvent was examined. By a judicious combination of these factors, fabrication of large-area electrochromic devices up to 77 cm(2) operating at -3.0 V for formation of mirror-like reflective state (similar to 100% reflectance) in less than 15 seconds; and reverse switching to transparency at 0.5 V in less than 30 seconds have been realised. Devices capable of transforming into different patterns are also demonstrated with similar switching performance. (C) 2017 Elsevier Ltd. All rights reserved.