Intrinsically Electrochromic Deep Eutectic Solvents

Multi‐colored intrinsically electrochromic based Deep Eutectic Solvents (IEDES) have been firstly developed. IEDES composed by the suitable mixing between viologen salt derivatives as HBA and ethylene glycol (EG), glycerol (Gly) and poly(ethylene glycol) (PEG) as HBD have been prepared and characterized by thermal and electrochemical studies. A detailed electrochemical characterization of the IEDES using cyclic voltammetry studies in 2‐electrodes (ECDs) configuration cells were performed. The most promissory IEDES based on viologen salt derivatives can act simultaneously as electrolyte and electrochromic. Preliminary redox cycling studies showed a reversible and stable ECD composed by [(C5O2)2bpy]I2:EG at least until 1300 minutes. The coloration efficiency and reversibility can be tuned changing only the alcohol counterpart and/or the side chains and anion of the viologen derivatives. These IEDES can be explored as functional and efficient multi‐colored ECDs. Also, these innovative materials can open attractive applications for material science and energy devices. Intrinsically Electrochromic Deep Eutectic Solvents (IEDES) as functional and efficient multi‐colored electrochromic devices (ECDs) have been firstly developed. Suitable combinations between viologen salt derivatives as Hydrogen Bond Acceptors (HBA) and ethylene glycol (EG), glycerol (Gly) and poly(ethylene glycol) (PEG) as Hydrogen Bond Donors (HBD) are performed. The prepared innovative IEDES can be explored as versatile, functional and efficient multi‐colored materials.