Abstract
A di-urethane cross-linked poly(oxyethylene)/silica hybrid matrix (di-urethanesil, d-Ut(600)), sinthesized by the sol-gel process, was doped with lithium triflate (LiCF3SO3) and the 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid. The as-produced xerogel film is amorphous, transparent, flexible, homogeneous, hydrophilic, and has low nanoscale surface roughness. It exhibits an ionic conductivity of 3.64×10−6 and 5.00×10−4 S cm-1 at 21 and 100 oC, respectively. This material was successfully tested as electrolyte in an electrochromic device (ECD) with the glass/ITO/a-WO3/d-Ut(600)10LiCF3SO3[Bmim]Cl/c-NiO/ITO/glass configuration, where a-WO3 and c-NiO stand for amorphous tungsten oxide and crystalline nickel oxide, respectively. The device demonstrated attractive electro-optical performance: fast response times (1-2 s for coloring and 50 s for bleaching), good optical memory (loss of transmittance (T) of only 41% after three months, at 555 nm), four mode modulation (bright mode (+3.0 V, T = 77% at 555 nm), semi-bright mode (−1.0 V, T = 60% at 555 nm), dark mode (−1.5 V, T = 38 % at 555 nm), and very dark mode (−2.0 V, T = 11% and −2.5 V, T = 7% at 555 nm )), excellent cycling stability denoting improvement with time, and high coloration efficiency (CEin = −6727 cm2 C−1 (32th cycle) and CEout = +2794 cm2 C−1 (480th cycle), at 555 nm).
Highlights
The last decades have witnessed a considerable growth in energy consumption
In the last decade we focused our attention on the synthesis of polymer electrolytes based on natural host polymers, such as polysaccharides [chitosan (Alves et al, 2018), kappa-carrageenan (Nunes et al, 2017, 2019), gelatin (Alves et al, 2013), and gellam gum (Neto et al, 2015)] and proteins [deoxyribonucleic acid (DNA) (Leones et al, 2014) and silk fibroin (Pereira et al, 2016)]
The broad peak centered at 20.0-21.6◦ in the X-ray diffraction (XRD) patterns of the three di-urethanesils is attributed to the coherent diffracting domains of the siliceous framework (Carlos et al, 1999)
Summary
The last decades have witnessed a considerable growth in energy consumption. To curb this trend, Goal 11 of the United Nations Sustainable Development Goals for 2030 targets inclusive, safe, resilient, and sustainable cities, to ensure universal access to affordable, reliable, sustainable, and modern energy to everyone (Goal 11: Make Cities Inclusive, 2019). Smart windows [e.g., electrochromic (EC), thermochromic, and photochromic] have the ability to change a property (color) upon variation of the external environmental conditions [current/voltage, temperature, and ultraviolet (UV) radiation, respectively]. These dynamic systems have tremendous influence on the energy efficiency of a building, providing marked energy savings in terms of lighting, heating and ventilation
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