Editing Smart glass (section)

===Electrochromic devices===
[[Electrochromic devices]] change light transmission properties in response to voltage and thus allow control over the amount of light and heat passing through.<ref name="Nature">{{cite journal |last1=Xu |first1=Ting |last2=Walter |first2=Erich C. |last3=Agrawal |first3=Amit |last4=Bohn |first4=Christopher |last5=Velmurugan |first5=Jeyavel |last6=Zhu |first6=Wenqi |last7=Lezec |first7=J. |last8=Talin |first8=A.Alec |title=High-contrast and fast electrochromic switching enabled by plasmonics |journal=Nature Communications |volume=7 |pages=10479 |date=27 January 2016 |pmc=4737852 |pmid=26814453 |doi=10.1038/ncomms10479 |bibcode=2016NatCo...710479X }}</ref> In electrochromic windows, the material changes its [[opacity (optics)|opacity]]. A burst of electricity is required for changing its opacity, but the material maintains its shade with little to no additional electrical signals.<ref name="Mortimer">{{cite news |last1=Mortimer |first1=Roger J. |title=Switching Colors with Electricity |url=https://www.americanscientist.org/article/switching-colors-with-electricity |access-date=15 July 2022 |work=American Scientist |date=6 February 2017 |language=en}}</ref>

Old electrochromic technologies tend to have a yellow cast in their clear states and blue hues in their tinted states. Darkening occurs from the edges, moving inward, and is a slow process, ranging from many seconds to 20–30 minutes depending on window size. Newer electrochromic technologies eliminate the yellow cast in the clear state and tinting to more neutral shades of gray, tinting evenly rather than from the outside in, and accelerate the tinting speeds to less than three minutes, regardless of the size of the glass. Electrochromic glass maintains visibility in its darkened state and thus preserves visual contact with the outside environment.

Recent advances in electrochromic materials pertaining to [[Transition metal|transition-metal]] [[hydride]] electrochromics have led to the development of reflective hydrides, which become reflective rather than absorbing, and thus switch states between transparent and mirror-like.

Recent advancements in modified porous [[Nanocrystalline material|nanocrystalline]] films have enabled the creation of electrochromic display. The single substrate display structure consists of several stacked porous layers printed on top of each other on a substrate modified with a transparent conductor (such as [[Indium tin oxide|ITO]] or [[PEDOT:PSS]]). Each printed layer has a specific set of functions. A working electrode consists of a positive porous semiconductor such as titanium dioxide, with adsorbed [[chromogen]]s. These chromogens change color via reduction or oxidation. A [[Passivation (chemistry)|passivator]] is used as the negative of the image to improve electrical performance. The insulator layer serves the purpose of increasing the contrast ratio and electrically separating the working electrode from the counter [[electrode]]. The counter electrode provides a high capacitance to counterbalance the charges inserted/extracted on the SEG electrode (and maintain charge neutrality in the overall device). Carbon is an example of a charge reservoir film. A conducting carbon layer is typically used as the conductive back contact for the counter electrode. In the last printing step, the porous monolith structure is overprinted with a liquid or polymer-gel electrolyte, dried, and then may be incorporated into various encapsulation or enclosures, depending on the application requirements. Displays are very thin, often 30 micrometers. The device can be switched on by applying an electrical potential to the transparent conducting substrate relative to the conductive carbon layer. This causes a reduction of viologen molecules (coloration) to occur inside the working electrode. By reversing the applied potential or providing a discharge path, the device bleaches. A unique feature of the electrochromic monolith is the relatively low voltage (around 1 Volt) needed to color or bleach the [[Viologen|viologens]]. This can be explained by the small over- potentials needed to drive the electrochemical reduction of the surface adsorbed viologens/chromogens.

Most types of smart film require voltage (e.g. 110VAC) to operate, and therefore such types of smart films must be enclosed within glass, acrylic or polycarbonate laminates to provide electrical safety to users.{{ciation needed|date=August 2021}}