light-emitting diode

Electronic component that converts electrical energy into light or infrared radiation in the range of 550 nm (green light) to 1,300 nm (infrared). They are used for displaying symbols in electronic instruments and devices. An LED is a diode made of semiconductor material, such as gallium arsenide phosphide, that glows when electricity is passed through it. The first digital watches and calculators had LED displays, but many later models use liquid-crystal displays.

In 1993 chemists at the University of Cambridge, England, developed LEDs from the polymer poly(p-phenylenevinyl) (PPV) that emit as much light as conventional LEDs and in a variety of colours.

A new generation of LEDs that can produce light in the mid-infrared range (300–1,000 nm) safely and cheaply were developed by British researchers in 1995, using thin alternating layers of indium arsenide and indium arsenide antimonide.