Obtaining Reversible, High Contrast Electrochromism, Electrofluorochromism, and Photochromism in an Aqueous Hydrogel Device Using Chromogenic Thiazolothiazoles

Abstract

There have been an increasing number of materials developed that show multifunctional chromogenic properties (such as electrochromism, electrofluorochromism, or photochromism), but to date, few materials have shown all three properties. Materials that are electrochemically and optically active are attractive for a diverse set of applications that include smart‐windows, lighting, sensing, energy production, and conservation. This is especially attractive for building developers interested in adaptive or environmentally responsive façades. Achieving systems made from cost‐effective, readily synthesized materials will make them easy to utilize in a variety of fields. Low‐cost devices are developed using water‐soluble, chromogenic thiazolo(5,4‐d)thiazole (TTz) dyes that show high device performance in three areas: electrochromism, electrofluorochromism, and photochromism and are all contained within a highly fluorescent aqueous polyvinyl alcohol/borax hydrogel device. The dyes incorporate a rigid, heterocyclic TTz structure that enables the development of devices with excellent reversibility and stable cycling for 250 cycles. The TTz hydrogel‐containing devices also exhibit photochromism under illumination, which can be electrochemically cycled back to the colorless state. In addition, coupling photochromism with electrochromism lowers the power necessary for a comparable electrochromic color change. Last, the hydrogel‐containing devices also show electrofluorochromism, where fluorescence can be turned off by > 90%.

Dynamically Cross-Linked Hydrogel Electrolyte with Remarkable Stretchability and Self-Healing Capability for Flexible Electrochromic Devices

“…These results indicated that the introduction of borate had no negative effects on the intrinsic electrochromic performance of the ECD. The P­(GMA 2 -AAm 8 )-borate hydrogel electrolyte was compared with reported hydrogel systems for ECDs ,− and their properties are summarized in Table S2. Our hydrogel electrolyte and the flexible ECD showed better performance than reported works in terms of mechanical properties, self-healing performance, and electrochromic performance.…”

Advances in the Structural Strategies of the Self-Assembly of Photoresponsive Supramolecular Systems

“…Devices using water-soluble, chromogenic thiazolo(5,4-d) thiazole (TTz) dyes were developed by a research group headed by Michael Walter [ 35 ]. They synthesized viologens from TTz and these were later studied in PVA/borax hydrogel devices from which the ease-to-assemble and high oxidative stability in the air were highlighted.…”

Extending the 2D conjugated microporous polymers linked by thiazolo[5,4-d]thiazole for green light-driven selective aerobic oxidation of amines

“…Recently, considerable attention has been paid to CMPs linked by TzTz that could endow them with exceptional optoelectronic properties. 49–51 Nevertheless, the CMPs linked by the electron-deficient TzTz have been relatively underexploited for visible light photocatalysis. There were sporadic studies that revealed their great potential in H 2 evolution, 52 CO 2 reduction, 53 and dye degradation.…”