Dynamic windows, which switch between transparent and opaque states, are highly desirable in buildings, automobiles, and sunglasses. We describe dynamic windows based on the reversible electrodeposition of Cu alloys on glass electrodes coated with tin-doped indium oxide (ITO). The addition of a secondary metal in the electrodeposition bath gives rise to metal formation with a neutral transmission profile with respect to visible and infrared light. The presence of a self-assembled monolayer of Pt nanoparticles on the ITO surface significantly enhances the durability of the devices such that they can be switched at least several thousand times without degradation. Through surface characterization and optical modeling, we interrogate the relationship between electrodeposition parameters and the macroscopic and microscopic attributes of the metal electrodeposit. Three-electrode cyclic voltammetry experiments reveal that this system possesses high Coulombic efficiency, indicating that the metal electrodeposition and stripping processes are reversible. Two-electrode devices with gel electrolytes, which are advantageous for practical dynamic windows, possess high contrast ratios and minute-long switching times. Devices with large areas maintain high optical contrast and uniformity during metal electrodeposition, resulting in the formation of a mirror. This research indicates that future dynamic windows based on reversible metal electrodeposition may be more durable, aesthetically pleasing, and economical than those using traditional electrochromic materials such as transition metal oxides and polymers.

Dynamic windows based on reversible metal electrodeposition with fast switching, neutral color, and excellent durability

253rd National Meeting (2017)

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