Elektrochrome

Elektrochrome, or electrochromic material, refers to substances that change their optical properties in response to an applied electric voltage. When a potential is applied, ions and electrons are inserted into or removed from an electrochromic layer, producing a reversible change in color or opacity. The effect is known as electrochromism, and devices that exploit it are called electrochromic devices (ECDs).

Materials commonly used include transition metal oxides such as tungsten oxide (WO3), mixed oxide composites, organic conducting polymers like poly(3,4-ethylenedioxythiophene) (PEDOT), viologen salts, and inorganic compounds such as Prussian blue. Practical electrochromics are typically thin films on a substrate with an electrolyte and a counter electrode. Coloration and bleaching are driven by small voltages, often less than a few volts.

Applications are diverse and include smart windows and skylights to modulate solar heat gain and glare, automotive dimmable mirrors, rear-view mirrors, display elements, and architectural glazing. A key advantage is the ability to maintain a colored or bleached state without continuous power consumption.

Performance is described by metrics such as the change in transmittance (ΔT), coloration efficiency, switching speed, cycle life, and optical memory. Durability and environmental sensitivity, including humidity and temperature, influence commercial viability.

Challenges remain in improving switching speed and uniformity, long-term stability, and cost, as well as integrating electrochromic layers with large-area substrates. Ongoing research seeks faster, higher-contrast devices, safer materials, and flexible or transparent substrates for broader adoption.