Nunes, Paulo JoaquimPereira, Rui Francisco PintoPereira, SóniaSilva, Maria ManuelaFortunato, ElviraBermudez, Verónica de ZeaFernandes, Mariana2023-03-172023-03-172022-12-301996-1073PURE: 56246936PURE UUID: 7250004c-1f7d-4ef5-8b67-7edb2fb5b993Scopus: 85145777156WOS: 000909275800001ORCID: /0000-0002-4202-7047/work/131067156http://hdl.handle.net/10362/150807M.F. and R.F.P. Pereira acknowledge FCT-UTAD and FCT-UMinho for the contracts in the scope of Decreto-Lei 57/2016—Lei 57/2017, respectively. Publisher Copyright: © 2022 by the authors.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 × 10−5 and 2.8 × 10−4 S cm−1 at room temperature and 55 °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 cm2·C−1), the highest optical density value (∆(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.123188328eng1-butyl-3-methylimidazolium chloridedi-ureasil electrolyteselectrochromic deviceslithium tetrafluoroboratesol-gelRenewable Energy, Sustainability and the EnvironmentBuilding and ConstructionFuel TechnologyEngineering (miscellaneous)Energy Engineering and Power TechnologyEnergy (miscellaneous)Control and OptimizationElectrical and Electronic EngineeringSDG 7 - Affordable and Clean Energyjournal article10.3390/en16010426https://www.scopus.com/pages/publications/85145777156