Electrochemical synthesis and investigation of poly(1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene) and its application in an electrochromic device

Colorless to Neutral Color Electrochromic Devices Based on Asymmetric Viologens

Electrochromic materials have extensively been investigated because of their potential fields of application, with a significant growing interest in expanding the provided colorations. However, among all palette of colors, colorless electrochromic devices (ECDs) that provide neutral-grayish colorations with a simple configuration remain a key challenge. The present study reports on the synthesis of asymmetrically 1-alkyl-1'-aryl-substituted viologens and their incorporation in PVA-borax gel polyelectrolytes for ECDs that constitute the simplest device architecture (glass/TCO/EC gel/TCO/glass). We demonstrate herein that these EC gels based on single asymmetric viologens provide more neutral-colored state than their corresponding symmetric viologens (a* and b* ≤ |15|), while maintaining satisfactory colorless bleached state (%T_b > 70% in the whole visible range), transmittance changes (i.e., ∼60%) and cyclability (i.e., ∼15 000 cycles). Additionally, the effect of the solvent on the observed coloration has also been investigated. This easy-to-make neutral-grayish color ECDs may significantly extend the potential of the electrochromic technology, because they adapt better aesthetically to the surrounding environment, as they are easier to implement in different applications.

Synthesis and characterization of donor–acceptor type conducting polymers containing benzotriazole acceptor and benzodithiophene donor or s-indacenodithiophene donor

Two D–A type copolymers were synthesized and characterized by a series of methods. Both copolymers showed high optical contrasts, fast response time and high coloration efficiency. In summary, they could be candidates for electrochromic applications.