Large-Area Flexible Electrochromic Devices with High-Performance and Low-Power Consumption Enabled by Hydroxyhexyl Viologen-Substituted Polyhedral Oligomeric Silsesquioxane

Abstract

In this work, we prepared octa-hydroxyhexyl viologen-substituted polyhedral oligomeric silsesquioxane (OHHV-POSS) as an organic−inorganic composite material applicable for large-area flexible electrochromic devices (FECDs). The organic−inorganic hybrid structure supported by the POSS cage and the enhanced interaction between hydroxyl end-groups and lithium salts can effectively increase the ionic conductivity of the ion gel films, thereby improving the electrochromic performance capabilities. Homogeneous ion gel was obtained with polyvinyl butyral and a lithium salt, and outstanding electrochromic properties were observed during electrochromic device operations. The FECDs of various sizes were fabricated for systematic evaluation, and the device of up to 22.5 × 19.5 cm 2 was successfully constructed using the simple doctor blade coating method. The prepared large-area FECDs achieved a large transmittance difference of 70.0% at 604 nm, fast switching times of 21.1 and 18.0 s, high coloration efficiency of 260.61 cm 2 /C, long-term cycling stability of up to 300 cycles, and low power consumption of about 250 μW/cm 2 . Furthermore, the device was maintained stably in various application tests for heat insulation and storage, UV resistance, and mechanical stability. High performance and low power consumption of OHHV-POSS prove suitable for large-area FECDs, suggesting promising potential for smart windows, wristbands, and eyewear products.

Flexing the Spectrum: Advancements and Prospects of Flexible Electrochromic Materials

“…These materials have special properties that distinguish them from others and make them an attractive choice in the field of electrochromics. One of their main advantages is the low operating voltage they require [108]. Viologen-based materials can undergo reversible redox reactions and exhibit significant color changes even at relatively low electrical voltages.…”

Heterocycle‐ and Amine‐Free Electrochromic and Electrofluorochromic Molecules for Energy‐Saving See‐Through Smart Windows and Displays

“…[31][32][33] Recently, our research group developed such thiophene-based electrochromes by functionalizing them with tetrabenzofluorene (TBF) core. [34] Besides thiophene derivatives, other heterocyclics such as pyrrole, [35,36] thiazole, [37,38] polyselenophene, [39] and amine derivatives like polyaniline [40,41] and viologen-based [42][43][44] molecular systems also showed the EC phenomenon. These entities produce steric repulsion across the molecular backbone, facilitate the mobility of the charge carriers, and help to enhance the conjugation length.…”

Performance Optimization for Multicolor Electrochromic Devices: Morphology and Composition Regulation of Inorganic Electrochromic Materials and Selectivity of Ions

“…It can meet the requirements of energy conservation and sustainability in human development and has been widely used in energy-saving buildings, intelligent displays, wearable devices, adaptive camouflage, and other fields. [1][2][3][4][5][6][7] Until now, the research on electrochromic (EC) technology has obtained great advances, optimizing the EC layer and electrolyte are the main methods to improve the performance of ECDs. [8,9] In recent years, some groups have found various EC materials that can exhibit multiple colors under different states (such as voltage and phase) in the ECDs.…”