Electrochromic Harvester for All-Day Energy Savings in Buildings

Technologies that can simultaneously capture energy from outer space and the sun have garnered extensive interest in recent years. However, the utilization of these two energy sources is challenged by their conflicting spectral requirements, making it difficult to capture both in a single device or material. Here, an adaptive energy harvester coupling photothermal conversion and radiative cooling utilizing photonic metastructure electrodes in conjunction with reversible metal electrodeposition technology for all-day continuous energy harnessing is reported. The harvester demonstrates sustained bistability for over 30 days with large emissivity contrast (0.82 at 3–5 μm, 0.66 at 7.5–13 μm), robust environmental durability, and scalability (100 cm2) for switching between heating and cooling states. World-wide energy simulations show that it can significantly reduce energy consumption in buildings by up to 21.4%, amounting to a savings of 95.8 GJ year-round. This harvester offers a promising method to utilize heat source and heat sink, sun and outer space, to improve sustainability and reduce carbon foot print of the Earth.