Electroluminescence - luminescence excited by an electric field .
It is observed in substances-semiconductors and crystal phosphors, the atoms (or molecules) of which pass into the excited state under the influence of a transmitted electric current or an applied electric field.
Content
Mechanism
Electroluminescence is the result of radiative recombination of electrons and holes in a semiconductor. Excited electrons release their energy in the form of photons. Before recombination, electrons and holes are separated — either by activating the material to form a pn junction (in semiconductor electroluminescent illuminators, such as a LED ) —or excitation by high-energy electrons (the latter are accelerated by a strong electric field) —in crystal phosphors of electroluminescent panels.
Electroluminescent materials
Usually, electroluminescent panels are produced in the form of thin films of organic or inorganic materials. In the case of crystal phosphors, the color of the glow is determined by the impurity-activator. Structurally, the electroluminescent panel is a flat capacitor. Electroluminescent panels require a sufficiently high voltage (60 - 600 volts); for this, as a rule, a voltage converter is built into the device with an electroluminescent backlight.
Examples of thin-film electroluminescent materials:
- Powdered zinc sulfide activated by copper or silver (blue-green glow);
- Manganese-activated zinc sulfide, yellow-orange glow;
- III — V semiconductors InP, GaAs, GaN ( light-emitting diodes ).
Application
Electroluminescent illuminators ( panels , displays , wires , etc.) are widely used in consumer electronics and lighting engineering, in particular, for illuminating liquid crystal displays, illuminating instrument scales and film keyboards, decorating buildings and landscapes, etc.
For military and industrial applications, electroluminescent graphical and sign - synthesizing displays are available . These displays are characterized by high image quality and relatively low sensitivity to temperature.
Literature
- Gershun A.L. ,. Electroluminescence // Brockhaus and Efron Encyclopedic Dictionary : 86 tons (82 tons and 4 extra). - SPb. , 1890-1907.