Electroluminescent display

Electroluminescence (EL) is an optical and electrical phenomenon where a material emits light in response to an electric current passed through it, or to a strong electric field. Electroluminescent Displays (ELDs) are a type of display created by sandwiching a layer of electroluminescent material such as GaAs between two layers of conductors. When current flows, the layer of material emits radiation in the form of visible light.

EL was first observed in 1907 by Captain Henry Joseph Round in silicon carbide (SiC), although ELD thechnology was not made commercially available until the 1980s.

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Mechanism

EL works by exciting atoms by passing an electric current through them, causing them to emit photons. By varying the material being excited, the colour of the light emitted can be changed. The actual ELD is constructed using flat, opaque electrode strips running parallel to each other, covered by a layer of electroluminescent material, followed by another layer of electrodes, running perpendicular to the bottom layer. This top layer must be transparent in order to let light escape. At each intersection, the material lights, creating a pixel.

Application

ELDs are used as backlights in LCDs. They are also useful for creating soft ambient light, and for low-colour, high-contrast screens.

Abbreviations

• AMEL Active Matrix Electroluminescence
• TFEL Thin Film Electroluminescence
• TDEL Thick Dielectric Electroluminescence

See also

Electroluminescence

• Electroluminescence

Displays

• Liquid Crystal Display
• Cathode Ray Tube
• Field Emission Display

Lighting

• Lighting
• Luminescence
• Light emitting capacitor
• Electroluminescent wire