biostudies-literatureSun FNational Research Foundation of Korea (NRF)9569https://www.ebi.ac.uk/biostudies/studies/S-EPMC12575868biostudies-literatureUnknown16(1)For dual-band electrochromic smart windows to achieve widespread adoption, challenges such as slow switching, poor stability, and high power consumption must be addressed. This study introduces a polyviologen|zinc mesh|WO₃ ⋅ 2H₂O electrochromic energy storage device (EESD) with a PEDOT: PSS layer to enhance conductivity and prevent polyviologen degradation. By utilizing a dual-cathode design, the EESD enables fast switching and operates in four distinct modes-transparent, visible colored, near-infrared colored, and fully colored-allowing adaptive light regulation (320-2500 nm) to optimize energy efficiency across different seasons and times of day. Its self-operating and energy recovery features achieve zero energy consumption while maintaining functionality similar to conventional glass. Simulations indicate that a large-scale deployment across the U.S. can save 66.87 billion MWh, amounting to $7.35 trillion, and reduce CO₂ emissions by 66.94 billion tons. With its rapid switching, long-term durability, and scalability, this device presents significant economic and environmental advantages for real-world applications.Nature communicationsFast-switching dual-cathode electrochromic smart windows for year-round building energy savings.PMC12575868RS-2023-00221396RS-2023-00208341Zhang WPal RJeong BSun FChoi JWEom SYPark JSfalseFast-switching dual-cathode electrochromic smart windows for year-round building energy savings.For dual-band electrochromic smart windows to achieve widespread adoption, challenges such as slow switching, poor stability, and high power consumption must be addressed. This study introduces a polyviologen|zinc mesh|WO₃ ⋅ 2H₂O electrochromic energy storage device (EESD) with a PEDOT: PSS layer to enhance conductivity and prevent polyviologen degradation. By utilizing a dual-cathode design, the EESD enables fast switching and operates in four distinct modes-transparent, visible colored, near-infrared colored, and fully colored-allowing adaptive light regulation (320-2500 nm) to optimize energy efficiency across different seasons and times of day. Its self-operating and energy recovery features achieve zero energy consumption while maintaining functionality similar to conventional glass. Simulations indicate that a large-scale deployment across the U.S. can save 66.87 billion MWh, amounting to $7.35 trillion, and reduce CO₂ emissions by 66.94 billion tons. With its rapid switching, long-term durability, and scalability, this device presents significant economic and environmental advantages for real-world applications.2025-01-01T00:00:00Z2025 Oct2026-06-05T07:23:00.605Z2026-05-14T03:12:29.125ZS-EPMC125758684116818310.1038/s41467-025-64962-2