Sol-Gel Derived Di-Ureasil Based Ormolytes for Electrochromic Devices

Two di-ureasils incorporating oxyethylene segments with average molecular weights Y = 600 and 900 g mol(-1), prepared by the sol-gel method, and doped with the ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and lithium tetrafluoroborate (LiBF4) salt were prepared. The as-obtained films are translucent, flexible, and hydrophobic, and have a low level of nanoscale surface roughness. The ionic conductivity values exhibited by an optimized sample are 8.10 x 10(-5) and 2.8 x 10(-4) S cm(-1) at room temperature and 55 degrees C, respectively. The main goal of the work was to employ the electrolytes in prototype electrochromic devices (ECDs) with the [glass/a-IZO/a-WO3/d-U(Y)LiBF4-[Bmim]Cl/c-NiO/a-IZO/glass], noted as ECD1 for Y = 600 and ECD2 for Y = 900, where a-WO3 and c-NiO stand for amorphous tungsten oxide and crystalline nickel oxide, respectively. At 555 nm the ECD1 device exhibited the highest coloration efficiency for coloring (CEin = -420.621 cm(2)center dot C-1), the highest optical density value ( increment (OD) = 0.13) and good cycling stability. In this article, the results of a preliminary evaluation of hybrid electrolytes, produced by a sol-gel process, as multi-functional components in prototype electrochromic devices are reported.

Automated summary

Two di-ureasils with oxyethylene segments were prepared by the sol-gel method, doped with ionic liquid and lithium salt. The resulting films were translucent, flexible, hydrophobic, and had low surface roughness. The optimized sample exhibited good ionic conductivity and was used in prototype electrochromic devices with promising performance.