Preparation of a multicolored reflective electrochromic display based on monodisperse polymeric microspheres with N‐substituted viologen pendants

This article describes the preparation of multicolored reflective electrochromic displays (R‐ECDs) through the control of the substituents on viologen molecules. Cyanophenyl, salicylic, and alkyl groups were introduced onto 4,4′‐bipyridine. The synthesized viologen moieties were reacted with methyl chloride functional groups on polymeric microspheres, which were prepared by seeded polymerization. Then, R‐ECD cells were fabricated by the placement of a mixture of the viologen‐modified polymeric microspheres and an electrolyte between sandwiched indium tin oxide glasses. The R‐ECDs showed an inherent white background without potential because the micrometer‐range particles scattered the light, and the viologen was in a bleached state. From spectrophotometric results and visual appearances, it was confirmed that the devices showed red, green, and blue colors with respect to cyanophenyl‐, salicylic‐, and alkyl‐substituted viologen pendants when 2.7 V was applied to the device.