abstract
Electrochromic devices (ECDs) comprising visible/near-infrared (NIR) transparent amorphous indium zinc oxide (a-IZO) outermost layers and novel NIR-emitting electrolytes are proposed for smart windows of buildings in cold climate regions. The electrolytes are composed of a di-urethane cross-linked poly(oxyethylene)(POE)/siloxane hybrid matrix (d-Ut(600), 600 is the average molecular weight of the POE chains in gmol-1), 1-butyl-3-methylimidazolium chloride ionic liquid, and the Er(tta)3(H2O)(2) complex (tta- is 2-thenoyltrifluoracetonate). The electrolytes, synthesized by sol-gel route, were obtained as transparent, flexible, and hydrophilic monoliths with nanoscale surface roughness, exhibiting emission in the NIR wavelength region. The first electro-optical tests, performed in 2019, with an archetypal ECD including amorphous tungsten oxide and crystalline nickel oxide as EC layers, a-IZO as outermost layers, and d-Ut(600)400Er(tta)3(H2O)(2)[Bmim]Cl (400 is the molar ratio of oxyethylene units/Er3+ ion) as the electrolyte, demonstrated rather low coloration efficiency (CEin/CEout) values of -4/+6 cm(2) C-1 at 555 nm. After 3 years of storage at rest in the dark and at room temperature, the same device demonstrates a huge performance enhancement, leading to CEin/CEout values about two orders of magnitude higher, apart from higher optical density, and improved cycling stability. In addition, this device offers a bright hot, and semi-bright warm dual modulation operation suitable for smart windows of skylights, roof lights, upper windows, inclined glazing, and privacy glazing of buildings located in cold climate regions.
keywords
ORGANIC-INORGANIC HYBRIDS; ENERGY-EFFICIENT; SMART WINDOWS; IONIC LIQUIDS; STABILITY; DEVICES; FILMS
subject category
Electrochemistry
authors
Pinheiro, D; Fernandes, M; Pereira, RFP; Pereira, S; Correia, SFH; Silva, MM; Fortunato, E; Ferreira, RAS; Gonçalves, MC; Bermudez, VD
our authors
Maria Rute de Amorim e Sá Ferreira André
Full professor
Sandra Filipa Henriques Correia
Assistant ProfessorProjects
Solar-Powered Smart Windows for Sustainable Buildings (SOLPOWINS)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was funded by project I&D&I OBTAIN, (NORTE-01-0145-FEDER-000084), co-financed by the FEDER through NORTE 2020, CENTRO2020 in the scope of the project PLANET, (CENTRO-01-0247-FEDER-181242), project SOLPOWINS (PTDC/CTM/4304/2020), CQ-VR that is supported by FCT (UIDB/00616/2020 and UIDP/00616/2020) and CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC). D. Pinheiro acknowledges OBTAIN for post-doc grant BIPD/UTAD/19/2021. R. Pereira and M. Fernandes acknowledge FCTU-Minho and FCT-UTAD, respectively, for the contracts in the scope of Decreto-Lei 57/2016 57/2017. S. Correia thanks FCT for the researcher contract (2022.03740.CEECIND).