Mechanism and Characteristics of Electroluminescence
– Electroluminescence is the result of radiative recombination of electrons and holes in a material, usually a semiconductor.
– Electrons and holes can be separated either by doping the material to form a p-n junction or through excitation by impact of high-energy electrons accelerated by a strong electric field.
– The excited electrons release their energy as photons, resulting in light emission.
– Electroluminescent technologies have low power consumption compared to neon or fluorescent lamps.
– EL technology is valuable to the advertising industry due to its thinness and precise control over illumination areas.
– EL film produces single-frequency light that is uniform and visible from a great distance.
– EL lamps can be made in any color, but commonly used greenish color matches peak sensitivity of human vision.
– EL lamps do not require extra circuitry to regulate current flow.
Examples of Electroluminescent Materials
– Inorganic electroluminescent materials include ZnS:Mn, powdered zinc sulfide doped with copper or silver, thin-film zinc sulfide doped with manganese, and certain semiconductors like InP, GaAs, and GaN.
– Organic electroluminescent materials include [Ru(bpy)(PF], where bpy is 2,2-bipyridine.
– Blue diamond with a trace of boron can also act as an electroluminescent material.
Practical Implementations of Electroluminescence
– EL devices can be composed of powder or thin films.
– EL panels can be used as night lights, backlights for instrument panel displays, and in advertising.
– Light-emitting capacitors (LECs) use electroluminescent panels as a dielectric between the outside plates.
– Electroluminescent automotive instrument panel backlighting was introduced in 1960 by Chrysler.
– Sylvania produced EL night lights and display panels for the Apollo Lunar Module and Command Module.
Display Backlighting with Electroluminescence
– Powder phosphor-based electroluminescent panels are commonly used as backlights for liquid crystal displays.
– EL backlights require high voltage, which can be generated by a boost converter circuit.
– Thin-film phosphor electroluminescence was commercialized in the 1980s, offering bright, long-life light emission.
– Timex introduced its Indiglo EL display on watches in 1992.
– Recent developments include blue-, red-, and green-emitting thin film electroluminescent materials for full-color displays.
New Applications and Related Concepts
– Electroluminescent lighting is used for public safety identification on vehicles.
– Electroluminescent lighting, especially EL wire, is used in clothing for the entertainment and nightlife industry.
– T-shirts with an electroluminescent panel, the T-Qualizer, gained popularity in 2006.
– Engineers have developed an electroluminescent skin that can stretch more than six times its original size while still emitting light.
– The stretchable electroluminescent skin has potential applications in healthcare, transportation, and electronic communication.
– Related concepts include OLED and the photoelectric effect. Source: https://en.wikipedia.org/wiki/Electroluminescence
This article needs additional citations for verification. (April 2014) |
Electroluminescence (EL) is an optical and electrical phenomenon, in which a material emits light in response to the passage of an electric current or to a strong electric field. This is distinct from black body light emission resulting from heat (incandescence), chemical reactions (chemiluminescence), reactions in a liquid (electrochemiluminescence), sound (sonoluminescence), or other mechanical action (mechanoluminescence).
