Research team discovers new property of light

A research team headed by chemists at the University of California, Irvine has discovered a previously unknown way in which light interacts with matter, a finding that could lead to improved solar power systems, light-emitting ...

Enhancing solid-state phosphorescence in π-electronic molecules

Photoluminescent molecules, capable of absorbing and re-emitting light, play an important role in the development of technologies such as light-emitting diodes, sensors, and displays. Among them, ordered arrangements of π-electronic ...

LED lights, info treatments boost microgreen preference

Since microgreens entered the market in the 1980s and 1990s, their use has expanded far beyond being a garnish in high-end restaurants. They can now be found in casual dining establishments and private homes. They are used ...

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Light-emitting diode

A light-emitting diode (LED) (pronounced /ˌɛliːˈdiː/, or just /lɛd/), is an electronic light source. The LED was first invented in Russia in the 1920s, and introduced in America as a practical electronic component in 1962. Oleg Vladimirovich Losev was a radio technician who noticed that diodes used in radio receivers emitted light when current was passed through them. In 1927, he published details in a Russian journal of the first ever LED.

All early devices emitted low-intensity red light, but modern LEDs are available across the visible, ultraviolet and infra red wavelengths, with very high brightness.

LEDs are based on the semiconductor diode. When the diode is forward biased (switched on), electrons are able to recombine with holes and energy is released in the form of light. This effect is called electroluminescence and the color of the light is determined by the energy gap of the semiconductor. The LED is usually small in area (less than 1 mm2) with integrated optical components to shape its radiation pattern and assist in reflection.

LEDs present many advantages over traditional light sources including lower energy consumption, longer lifetime, improved robustness, smaller size and faster switching. However, they are relatively expensive and require more precise current and heat management than traditional light sources.

Applications of LEDs are diverse. They are used as low-energy indicators but also for replacements for traditional light sources in general lighting and automotive lighting. The compact size of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are useful in communications technology.

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