%0 Journal Article %A Alesanco, Yolanda %A Viñuales, Ana %A Cabañero, Germán %A Rodriguez, Javier %A Tena-Zaera, Ramón %D 2016 %T Colorless to Neutral Color Electrochromic Devices Based on Asymmetric Viologens %U https://acs.figshare.com/articles/journal_contribution/Colorless_to_Neutral_Color_Electrochromic_Devices_Based_on_Asymmetric_Viologens/4055583 %R 10.1021/acsami.6b11321.s001 %2 https://acs.figshare.com/ndownloader/files/6530556 %K PVA-borax gel polyelectrolytes %K i.e %K application %K easy-to-make neutral-grayish color ECDs %K electrochromic devices %K electrochromic technology %K neutral-grayish colorations %K neutral-colored state %K device architecture %K Neutral Color Electrochromic Devices %K viologen %K Asymmetric Viologens Electrochromic materials %K study reports %X 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 (%Tb > 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. %I ACS Publications