Dynamic windows based on reversible silver electrodeposition with improved resting stability and cyclability

Dynamic windows using reversible metal electrodeposition (RME) enhance the energy efficiency of buildings and control glare. Ag is competitive due to its single-electron reduction and high extinction coefficient. However, achieving both >24 h resting stability and >1,000 cycles is challenging. Here, we develop Ag-dimethyl sulfoxide (DMSO) windows enabling high optical contrast (∼75% clear-state and <0.1% dark-state transmission). While Cu promotes cyclability, Cu 2+ dissolves Ag films within 30 min in the dark state. Additionally, O 2 chemically dissolves Ag films in the presence of Br − . Without Cu, Ag windows cannot cycle >100 times because of Ag 2 O or AgOH formation. We introduce trifluoroacetic acid (TFA) into the electrolyte to prevent residue formation, enabling consistent optical properties over 7,500 cycles. We demonstrate that Ag films maintain <0.1% dark-state transmission for 80 days with a Cu-free electrolyte in the O 2 -free glovebox, and the device stays at <1% transmission for 24 h on the benchtop.