Low-power, deformable, dynamic multicolor electrochromic skin

Abstract

Active camouflage exhibited by certain creatures in nature such as cephalopods has inspired the fabrication of display devices for human-adaptive camouflage technologies. In order to realize that, electrochromic devices (ECDs) have attracted significant attention owing to their low-voltage operations and fast responses. However, the effective utilization of ECDs requires multicolor patterning, durable functioning, and wearable characteristics, simultaneously, but has not been explored. Here, we demonstrate a low-power, deformable, dynamic multicolor electrochromic skin (DMECS) that mimics the multicolor patterning and the active camouflage functionalities of the skins of cephalopods. The electrochromic polymers such as poly(3-hexylthiophene-2,5-diyl), poly[2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylenevinylene], and P4a (green color polymer) are used to create purple, orange, and green colors, respectively. An iontronic polymer pump composed of an ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) incorporated in thermoplastic polyurethane is used as a deformable and transparent solid-state electrolyte that enables low-voltage (+/- 3 V) operated DMECS with excellent cyclic coloration/bleaching stability (˃35,000 s), fast response (similar to 1.75 s), and high durability under repeated 10,000 cycles of compressive force (with a bending radius of 8 mm) and tensile strains (similar to 100% up to 15,000 s). We believe that our DMECS can offer user-controlled selective coloration/bleaching of arbitrary display patterns and open new avenues for next-generation wearable optoelectronics.