Chemistry Center - Vila Real

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NIR-emitting Electrochromic Windows for Cold Climate Region Buildings

Publication . Pinheiro, Daniela; Fernandes, Mariana; Pereira, Rui F. P.; Pereira, Sónia; Correia, Sandra F. H.; Silva, M. Manuela; Fortunato, Elvira; Ferreira, Rute A. S.; Gonçalves, Maria Cristina; de Zea Bermudez, Verónica; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; WILEY-V C H VERLAG GMBH

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.

2024-02-01Artigo científico

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Entidade financiadora

Fundação para a Ciência e a Tecnologia

Programa de financiamento

6817 - DCRRNI ID

Número da atribuição

UIDP/00616/2020