In his publications, Destriau often referred to luminescence as Losev-Light.
In 1936, Georges Destriau observed that electroluminescence could be produced when zinc sulphide (ZnS) powder is suspended in an insulator and an alternating electrical field is applied to it. His research was distributed in Soviet, German and British scientific journals, but no practical use was made of the discovery for several decades. Russian inventor Oleg Losev reported creation of the first LED in 1927. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector. Green electroluminescence from a point contact on a crystal of SiC recreates Round's original experiment from 1907.Įlectroluminescence as a phenomenon was discovered in 1907 by the English experimenter H.
7.3 Data communication and other signalling.4 Organic light-emitting diodes (OLEDs).2 Physics of light production and emission.1.4 White LEDs and the illumination breakthrough.Īs a transducer of electricity into light, LEDs operate in reverse of photodiodes. LEDs usually need electronic support components to function, while an incandescent bulb can and usually does operate directly from an unregulated DC or AC power source. In contrast to LEDs, incandescent lamps can be made to intrinsically run at virtually any supply voltage, can utilize either AC or DC current interchangeably, and will provide steady illumination when powered by AC or pulsing DC even at a frequency as low as 50 Hz. In exchange for these generally favorable attributes, disadvantages of LEDs include electrical limitations to low voltage and generally to DC (not AC) power, inability to provide steady illumination from a pulsing DC or an AC electrical supply source, and lesser maximum operating temperature and storage temperature. LEDs have many advantages over incandescent light sources, including lower power consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. LEDs have also given rise to new types of displays and sensors, while their high switching rates are useful in advanced communications technology with applications as diverse as aviation lighting, fairy lights, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper, horticultural grow lights, and medical devices. Later developments produced LEDs available in visible, ultraviolet (UV), and infrared wavelengths, with high, low, or intermediate light output, for instance white LEDs suitable for room and outdoor area lighting. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. The first visible-light LEDs were of low intensity and limited to red. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. Īppearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons (Energy packets). A bulb-shaped modern retrofit LED lamp with aluminum heat sink, a light diffusing dome and E27 screw base, using a built-in power supply working on mains voltageĪ light-emitting diode ( LED) is a semiconductor light source that emits light when current flows through it.
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