Functional Ion Gels: Mechanically Robust, Highly Ionic Conductive Gels Based on Random Copolymers for Bending Durable Electrochemical Devices (Adv. Funct. Mater. 14/2018)

Abstract

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.

Semitransparent Energy‐Storing Functional Photovoltaics Monolithically Integrated with Electrochromic Supercapacitors

“…To investigate the EC response of the ECSs, we measured the response time required to achieve 90% of maximum transmittance contrast during coloration at −0.5 V and bleaching under short‐circuit conditions (Figure 3c). The coloration transition (≈22 s) was faster than the bleaching response (≈65 s), as observed in other gel‐based ECDs . Coloration efficiency (η) is defined as ΔOD / Δ Q , where ΔOD and Δ Q are the changes in optical density and the amount of injected charge, respectively, or log( T b / T c ) / Δ Q with transmittance values for bleached ( T b ) and colored ( T c ) states .…”

“…Figure 1b displays the molecular structures of the EC chromophores used in ECSs, including p ‐trifluoromethylphenyl viologen bis(hexafluorophosphate) [CF 3 ‐PV(PF 6 ) 2 ], (3‐fluoro‐4‐triflioromethyl)phenyl viologen bis(hexafluorophosphate) [CF 3 F‐PV(PF 6 ) 2 ], and diethyl viologen bis(hexafluorophosphate) [EtV(PF 6 ) 2 ] for indicating red‐, green‐, and blue‐colored states, respectively. These materials were selected due to their outstanding EC characteristics such as large transmittance contrast, high coloration efficiency, and low power consumption . Figure 1c shows a schematic illustration of the monolithically integrated energy‐storing functional photovoltaics, consisting of two parts: ST Q‐OPVs (energy harvesting) and ECS (energy storage).…”

“…Figure 3a displays the voltage dependence of the UV–vis absorption spectra of ECSs containing CF 3 ‐PV 2+ (EC chromophore). It is noted that dmFc was also added in the gel as a counter anodic EC material for low‐voltage operation . No characteristic peaks were shown up to −0.2 V, except for one broad absorption peak at ≈420 nm arising from the dissolved dmFc.…”

“…An ionic liquid, 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]), and electrochromic (EC) materials including p ‐trifluoromethylphenyl viologen bis(hexafluorophosphate) [CF 3 ‐PV(PF 6 ) 2 ], (3‐fluoro‐4‐triflioromethyl)phenyl viologen bis(hexafluorophosphate) [CF 3 F‐PV(PF 6 ) 2 ], and diethyl viologen bis(hexafluorophosphate) [EtV(PF 6 ) 2 ] were synthesized according to previous reports . The other chemicals were purchased from Sigma Aldrich.…”

Strain‐Visualization with Ultrasensitive Nanoscale Crack‐Based Sensor Assembled with Hierarchical Thermochromic Membrane

“…However, as such chromic material based sensors have a very long response and recovery time in the electrochromic (>5 s) and thermochromic (>10 s) cases, it is difficult to detect the rapid movement of targets and their mechanical stimulus with minute strain. Many research efforts have struggled to overcome this disadvantage while minimizing the thickness, yet show only subtle color changes according to the stimulus, so that users might have difficulty in distinguishing the colors, or use a mechanoresponsive intrinsic photonic crystal layer, polymeric chromic dye or block‐copolymer, which shows very limited color selectivity and sensitivity.…”