Dynamic Metal–Ligand Interaction of Synergistic Polymers for Bistable See‐Through Electrochromic Devices

Abstract

Bistable electrochromic materials are a promising alternative solution to reduce energy consumption in displays. Limited by the mechanism and lack of a design strategy, only a few electrochromic materials have truly been able achieve bistability. Herein, a novel strategy is proposed to design bistable electrochromic materials based on polymer‐assisted dynamic metal–ligand coordination. The mechanism and materials of such unconventional electrochromic systems are proved by sufficient characterization. Synergistic stabilization of polymerized switchable dyes and the ionic ligand polymer are attracted to each other by supramolecular forces. The color states of the dye molecules are controlled and stabilized by valence changes of the metal ions. Meanwhile, through the polymerization of the electrochromic material and the nearby metal–ligand material, the metal ions of the electroinduced valence change are tightly fixed, and the related diffusion problem of the active EC component is also almost completely suppressed. This strategy successfully enables preparation of the corresponding transparent electrochromic displays with good performances, such as, the display information is clearly visible for more than 1.5 h without consuming energy. Furthermore, the new way of dynamic coordination or dissociation bistable displays could likely prosper the development of the electrochromic area and inspire other fields.

Characterizing Electron Flow through Catechol‐Graphene Composite Hydrogels

“…To characterize the conductive redox electron transfer through the Cat-Gr-Chit composite hydrogel (central panel of Scheme 1c) we performed dynamic time series spectroelectrochemical measurements to detect redox-state switching of the conducting catechols while electrons are being transferred into/from the film. [64,84] To allow the measurement of optical absorbance, we used a transparent gold electrode and modified our electrodeposition conditions to deposit a thin (≈5 µm), partially-transparent Gr-Chit hydrogel film. Specifically, we electrodeposited using a chitosan solution (1%) with a lower level of graphene (0.2%) and imposed the cathodic current (0.6 mA cm −2 ) for a relatively short time (90 s).…”

A black energy-saving electrochromic device based on a dye copolymer–metal complex

“…2a and S2, † there are two doublet peaks at about 1435 cm −1 , 1456 cm −1 and 1558 cm −1 , 1575 cm −1 of M9, which can be conrmed as stretching vibrational absorption of the bipyridine skeleton through a previous work. 37 The shape and position of these doublets change aer cuprous coordination with bipyridine (M10) as shown in Fig. 2a.…”

“…For example, a higher optical tunability (74% transmittance change) can be obtained in a liquid device owing to the good solubility of the metal ions and switchable dyes, but intrinsic diffusion limits the bistability of liquid devices (no retention time). 36 Although a better bistability (1.5 h retention time) can be observed in a semi-solid device with a mixture of polymerized switchable dyes and the metal ionic ligand polymer, the intermiscibility of the two polymers restricted the optical tunability (about 21.4% transmittance change) 37 (Fig. 1b).…”

Emerging Electrochromic Materials and Devices for Future Displays

“…With the continuous advancement of modern display technologies, − the electrochromic (EC) display, a typical nonemissive (passive) display, has received extensive attention. − The working principle of EC displays is based on the electrochemically driven redox process of EC materials to produce color/transmittance/reflectivity changes and present the displayed content and information. Different from commercialized active light-emitting displays such as cathode ray tube (CRT) displays, liquid crystal displays (LCDs), light-emitting diode (LED) displays, , organic light-emitting diode (OLED) displays, , and quantum-dot light-emitting diode (QLED) displays, , and known nonemissive displays such as electrophoretic and dielectrophoretic displays, electrowetting displays, , interferometric modulator (IMOD) displays and photonic crystal displays, the current research and development (R&D) process of EC displays is still in the early stage.…”