elektrochromer

An elektrochromer is a material or device that changes its optical properties, usually transmittance or color, in response to an electrical stimulus. This change is typically reversible and arises from redox reactions or ion insertion/extraction that alter the electronic structure and light-absorbing properties of the material. In a typical electrochromic device, a thin electrochromic layer is sandwiched between two transparent conducting electrodes, with an ion-conducting electrolyte or solid-state electrolyte bridging the layers. When a voltage is applied, ions move into or out of the electrochromic layer, triggering a change in color or transparency. Reversing the voltage bleaches the material.

Common electrochromic materials include inorganic metal oxides such as tungsten oxide (WO3), nickel oxide, and mixed tungsten-vanadium oxides, as well as organic polymers based on viologen or polyaniline systems, and hybrid organic-inorganic compounds. WO3, for example, darkens as protons or lithium ions are inserted, while removal of ions restores transparency. The performance of elektrochromers is described by metrics such as optical contrast (difference in transmittance between colored and bleached states), switching speed, coloration efficiency, and cycling stability.

Applications are dominated by smart windows and architectural glazing, which can modulate daylight and solar gain to save energy, as well as auto-dimming rear-view mirrors, information displays, and prospective flexible or wearable devices. Advantages include low steady-state power consumption, since the device holds its state without continuous power, and the potential for large area, scalable implementations. Challenges remain in material durability, long-term cycling, and the cost and compatibility of electrolytes and substrates.

See also: electrochromism, smart glass, electrochromic devices.