NIR-emitting Electrochromic Windows for Cold Climate Region Buildings

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 cm2 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.

Descrição

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 & 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). Publisher Copyright: © 2023 The Authors. ChemElectroChem published by Wiley-VCH GmbH.

Palavras-chave

electrochromic windows erbium complex NIR emitting electrolytes visible/NIR transparent conducting oxides zero-energy buildings Catalysis Electrochemistry SDG 13 - Climate Action