A Smart Window Based on Reversible MetalElectrodeposition (RME) With Tin and Copper

Kurzfassung

The optical transmittance of smart windows can be modulated on demand, rendering them suitable for use in building facades, automobile mirrors, windows, display screens, and greenhouses. This study investigates reversible metal electrodeposition (RME) smart windows using a nontoxic, solid-like electrolyte based on tin and copper. Among the various switching methods, RME has been demonstrated to be cost-effective, scalable, and color-neutral. Solid-like electrolytes maintain electrode spacing over time and minimize leakage risks; however, they are typically composed of toxic substances. In this study, we present a nontoxic, solid-like electrolyte that exhibits a coulombic efficiency (CE) of 45.7%. To elucidate the alterations in transmittance, time-resolved measurements were conducted during the coloration and bleaching processes. The coloration rate was found to range from 39% to 55% per minute at a potential of −1.5 V compared to an indium tin oxide (ITO) electrode, applied for a duration of 60 s. The transmittance was measured from the ultraviolet (UV) to the near infrared (NIR) spectral range in both the initial state and the colored states. The average visual transmittance (AVT) between 380 and 750 nm ranges from 80.8% to 14.2%, with chroma ranging from 1 to 11, indicating color neutrality. Cyclic voltammetry measurements were conducted on a finished smart window to analyze the chemical reactions occurring during the coloration and bleaching processes. Further, the present study compares the self-bleaching mechanism (bleaching without applied voltage) of the RME window to recent studies in the field. Finally, the study also addresses reversibility and cycling stability deficiencies.