Voltage-tunable multicolor electrochromic devices (ECDs) are fabricated based on flexible ion gels consisting of copolymers and ionic liquids as an electrolyte layer. Dimethyl ferrocene (dmFc) is incorporated into the gel, which serves as an anodic species. In this study, two electrochromic (EC) materials, monoheptyl viologen (MHV) and diheptyl viologen (DHV), are employed and show significantly different EC behavior despite the similar chemical structure. Both MHV- and DHV-containing ECDs are slightly yellowish in the bleached state, whereas the colored states are magenta and blue, respectively. All devices have good coloration efficiency of 87.5 cm/C (magenta) and 91.3 cm/C (blue). In addition, the required power of ∼248 μW/cm (magenta) and ∼72 μW/cm (blue) to maintain the colored state put the ion gel-based ECDs in a class of ultralow power consumption displays. On the basis of the distinct difference in the coloration voltage range between MHV and DHV, and the rubbery character of the gel, flexible ECDs showing multiple colors are demonstrated. These results imply that voltage-tunable multicolor ECDs based on the gel are attractive to functional electrochemical displays.

Personal accessories such as glasses and watches that we usually carry in our daily life can yield useful information from the human body, yet most of them are limited to exercise-related parameters or simple heart rates. Since these restricted characteristics might arise from interfaces between the body and items as one of the main reasons, an interface design considering such a factor can provide us with biologically meaningful data. Here, we describe three-dimensional-printed, personalized, multifunctional electronic eyeglasses (E-glasses), not only to monitor various biological phenomena but also to propose a strategy to coordinate the recorded data for active commands and game operations for human–machine interaction (HMI) applications. Soft, highly conductive composite electrodes embedded in the E-glasses enable us to achieve reliable, continuous recordings of physiological activities. UV-responsive, color-tunable lenses using an electrochromic ionic gel offer the functionality of both eyeglass and sunglass modes, and accelerometers provide the capability of tracking precise human postures and behaviors. Detailed studies of electrophysiological signals including electroencephalogram and electrooculogram demonstrate the feasibility of smart electronic glasses for practical use as a platform for future HMI systems.

Mechanically robust, highly ionic conductive gels based on a random copolymer of poly[styrene-ran-1-(4-vinylbenzyl)-3-methylimidazolium hexafluorophosphate] (P[S-r-VBMI][PF 6 ]) and the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) are successfully prepared. The gels with either homo P[VBMI][PF 6 ] or conventional PS-block-poly(methyl methacrylate)-block-PS (SMS) show significant trade-off between ionic conductivity and mechanical resilience. In contrast, the P[S-r-VBMI][PF 6 ]-based gels exhibit both large elastic modulus (≈0.105 MPa) and ionic conductivity (≈1.15 mS cm −1 ) at room temperature. To demonstrate that these materials can be used as solid-state electrolytes, the ion gels are functionalized by incorporating electrochromic (EC) chromophores (ethyl viologen, EV 2+ ) and are applied to EC devices (ECDs). The devices show low-voltage operation, large optical transmittance variation, and good cyclic coloration/bleaching stability. In addition, flexibleECDs are fabricated to take advantage of the mechanical properties of the gels. The ECDs have excellent bending durability under both compressive and tensile strains. The versatile P[S-r-VBMI][PF 6 ]-based gel is anticipated to be of advantage in flexible electrochemical applications, such as batteries and electrochemical displays.

A facile random copolymer strategy based on poly(styrene-ran-methyl methacrylate) (PS-r-PMMA) is proposed for the preparation of highly conductive and mechanically elastic solid-state gel electrolytes.

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In article number https://doi.org/10.1002/adfm.201706948, Dong Gyu Seo and Hong Chul Moon describe mechanically robust, highly conductive ion gels based on random copolymers for electrochemical device applications. The versatility of the gels as a solid‐state electrolyte platform is demonstrated in electrochromic devices (ECDs). The resulting ECDs exhibit low‐voltage operation, large transmittance contrast, good cyclic coloration/bleaching stability, and high bending durability under both tensile and compressive strains.

We investigated the effect of process conditions on the electrochromic (EC) properties of tungsten trioxide (WO3) films. When WO3 films deposited using a sol-gel method were thermally treated in air at 150 °C, the majority of tungsten species in the films became W6+, which is important for the realization of an optically transparent bleached state. On the other hand, annealing in a vacuum required only 60 °C to induce a similar level of W6+ in the WO3 films. However, a cracked film morphology was observed at higher temperatures, regardless of whether the films were annealed in air or vacuum. Using the WO3 films prepared under various conditions, EC devices (ECDs) were fabricated to evaluate EC properties. We concluded that the optimal annealing conditions for WO3 films for ECDs are 60 °C in vacuum, at which the highest coloration efficiency, largest transmittance difference, and fastest bleaching/coloration dynamics were obtained. These mild fabrication conditions at a low temperature (60 °C) provide the opportunity to utilize flexible electrodes on plastic. Therefore, we successfully demonstrated a flexible WO3-based ECD.

Non-volatile, phase-transition, thermoresponsive smart gels directly indicating thermal status are proposed.