POSS based ionic liquid as an electrolyte for hybrid electrochromic devices

Abstract The main objective of this study was to broaden the assortment of I − /I 3 − redox ionic liquids using polyhedral oligomeric silsesquioxanes (POSS) acting as nanobuilding blocks for the construction of functionalized 1,3-alkylimidazolium iodide solid (melting temperature 150–200 °C) and room temperature (RT) ionic liquids. The structural characteristics of the synthesised final ionic liquids and the corresponding intermediates were determined using 1 H, 29 Si NMR and infrared spectroscopic measurements. Raman spectra were next reported, in order to demonstrate the presence of polyiodides formed after the addition of iodine and the formation of redox electrolytes. Ionic conductivity values obtained from the impedance (EIS) spectra were determined in the temperature interval from room temperature up to 100 °C. Finally, a hybrid electrochromic cell was constructed from room temperature MePrIm + I x − IO 7 T 8 POSS ( x =1, 1.2, 3 and 5) ionic liquids encapsulated between a lithiated WO 3 working and Pt counter-electrode, and colouring–bleaching changes assessed for cells cycled up to 1000 repetitive cycles.