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This method involves coating LEDs of one color (mostly blue LEDs made of InGaN) with phosphors of different colors to form white light; the resultant LEDs are called phosphor-based or phosphor-converted white LEDs (pcLEDs). [32] A fraction of the blue light undergoes the Stokes shift, which transforms it from shorter wavelengths to longer.
Gallium nitride (Ga N) is a binary III/V direct bandgap semiconductor commonly used in blue light-emitting diodes since the 1990s. The compound is a very hard material that has a Wurtzite crystal structure.
LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors. LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on its surface.
LED phosphors can be placed directly over the die or made into a dome and placed above the LED: this approach is known as a remote phosphor. [27] Some colored LEDs, instead of using a colored LED, use a blue LED with a colored phosphor because such an arrangement is more efficient than a colored LED. Oxynitride phosphors can also be used in LEDs.
An organic light-emitting diode (OLED), also known as organic electroluminescent (organic EL) diode, [1] [2] is a type of light-emitting diode (LED) in which the emissive electroluminescent layer is an organic compound film that emits light in response to an electric current.
Lewis structure of a water molecule. Lewis structures – also called Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDs) – are diagrams that show the bonding between atoms of a molecule, as well as the lone pairs of electrons that may exist in the molecule.
Like the water found on the lunar surface, “on asteroids, water can also be bound to minerals as well as adsorbed to silicate and trapped or dissolved in silicate impact glass,” Arredondo said.
LED lamps are often made with arrays of surface mount LED modules. A significant difference from other light sources is that the light is more directional. An LED is a "Lambertian" emitter, producing a cone of light with half-power points about 60° from the axis. A laser diode is another form of LED emitter, but produces light by a different ...