Electrochromy
The term electrochromism covers the ability of molecules and crystals to change their optical properties through an external electric field or a current flow. The basis is the influencing of electronic states ( redox reaction ). Typically, strong electrochromic effects are found with some transition metal oxides (e.g. tungsten oxide ), complex compounds (e.g. Berlin blue ) and with some conductive polymers . In the case of conductive polymers, the polymer structure can be reversibly oxidized and reduced electrochemically ; in the case of thin layers, the color of the conductive polymer depends on the oxidation state (examples are 3,4-polyethylene dioxythiophene ( PEDOT ) and polyaniline ).
Application examples
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Electrochromic is used, for example, in the energy management of houses in the form of thin layers on the window glass. These can vary their optical properties and, for example, darken depending on the ambient conditions (see electrochromic glass ).
Even in modern aircraft, the passenger windows can be darkened using an electrochromic process.
Electrochromic rearview mirrors are offered for motor vehicles, they reduce the glare of the driver at night.