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Projeto de investigação
Chemistry Center - University of Minho
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Electrochromic windows based on luminescent acrylate/ionosilicas
Publication . Pinheiro, Daniela; Pereira, Rui F. P.; Gonçalves, Alexandra; Correia, Sandra F. H.; Silva, M. Manuela; Fortunato, Elvira; Gonçalves, Maria Cristina; Ferreira, Rute A. S.; de Zea Bermudez, Verónica; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Springer Science Business Media
Poly(methyl methacrylate) (PMMA)-based composite films doped with lanthanide-doped sol–gel derived imidazolium-based ionosilicas (IS-Ln) were recently proposed as active layers of luminescent down shifting (LDS) layers, but subsequent work demonstrated also their potential as electrolytes for electrochromic devices (ECDs) with foreseen application in smart windows of energy-efficient buildings. Nevertheless, some challenges remained to be addressed in the latter devices, the most critical one being the poor solubility of PMMA in the ionic liquid used in the formulation of these materials. To avoid this drawback, in the present work we propose novel lanthanide-containing acrylate/ionosilicas (AC/IS-Ln, Ln = Tb3+, Eu3+). The transparent, homogeneous, and luminescent hybrid materials synthesized are characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, atomic force microscopy, contact angle measurements, ionic conductivity, and photoluminescence spectroscopy. Optimized samples are successfully employed as electrolytes in luminescent ECD prototypes. The ECD device doped with AC/IS-Eu shows good cycling stability with reproducible bleaching/coloring over 50 chronoamperometry cycles, high coloration efficiency (CE) values CEin/CEout in the visible (−89/+98 cm2 C−1), and near-infrared (−126/138 cm2 C−1) spectral regions, and outstanding memory effect. Graphical Abstract: (Figure presented.)
Sol-Gel Derived Di-Ureasil Based Ormolytes for Electrochromic Devices
Publication . Nunes, Paulo Joaquim; Pereira, Rui Francisco Pinto; Pereira, Sónia; Silva, Maria Manuela; Fortunato, Elvira; Bermudez, Verónica de Zea; Fernandes, Mariana; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; MDPI - Multidisciplinary Digital Publishing Institute
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.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/00686/2020