RESUMEN
Excessive electricity usage in buildings, notably for heating and cooling, accounts for over 30% of energy consumption, creating a pressing need for energy-saving solutions. Electrochromic Smart Windows (ECSW) aims to reduce energy use while maintaining comfort but faces high costs due to materials like tin-doped indium oxide (ITO) and thick electrochromic films. Moreover, achieving full opacity in the colored state of ECSW is a bottleneck for the industry to overcome privacy concerns. Herein, efforts are directed toward finding cost-efficient alternatives, with all-tungsten-based mesh networks showing promise due to enhanced stability. This newly developed ITO-free, all-tungsten ECSW displays minimal transmittance (≈3%) in the colored state using only 260 nm thick sub-stoichiometric tungsten oxide (WO3-x) film within a lithium-ion-based electrolyte. The ECSW device of size (25 cm2) also demonstrates areal capacitance of ≈13 mF cm-2 to power a liquid crystal display (LCD) for ≈25 min, showcasing its energy storage capabilities. Additionally, to confirm scalability and cost-effectiveness, a larger 15 × 15 cm2 ECSW utilized a single hybrid electrode, highlighting the potential for reducing costs when scaling up production processes. This advancement represents a significant stride toward accessible and energy-efficient smart window technology, offering broader applicability within modern architectural practices.
RESUMEN
Energy-efficient glass windows are pivotal in modern infrastructure striving toward the "Zero energy" concept. Electrochromic (EC) energy storage devices emerge as a promising alternative to conventional glass, yet their widespread commercialization is impeded by high costs and dependence on external power sources. Addressing this, redox potential-based self-powered electrochromic (RP-SPEC) devices are introduced leveraging established EC materials like tungsten oxide (WO3) and vanadium-doped nickel oxide (V-NiO) along with aluminum (Al) as an anode. These devices produce open circuit voltages (OCV) exceeding ±0.3 V, enabling autonomous operation for multiple cycles. The WO3 film exhibits 1% transmission and 88% modulation in the colored state at 550 nm with a mere 260 nm thickness. The redox interactions facilitate coloring and bleaching cycles without external power, while photo-charging rejuvenates the system. Notably, the inherent voltages of the RP-SPEC device offer dual functionality, powering electronic devices for up to 81 h. Large-area (≈28 cm2) device feasibility is demonstrated, paving the way for industrial adoption. The RP-SPEC device promises to revolutionize smart window technology by offering both energy efficiency and autonomous operation, thus advancing sustainable infrastructure.