Electroluminescence was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat’s-whisker detector. Russian Oleg Vladimirovich Losev independently reported on the creation of a LED in 1927. His research was distributed in Russian, German and British scientific journals, but no practical use was made of the discovery until later in the century.
LEDS were first used commercially as replacements for neon and incandescent lamps and for seven-segment displays. They replaced these lamps first in laboratory equipment and electronic testing equipment, then later they replaced lighting in such appliances as Radio’s T.Vs, calculators, telephones and watches. Early in their usage these lights were only bright enough for use as indicators, as the light output was so small it could not illuminate a large area.
Later though developments were made as other colours became readily available and they too appeared in similar appliances and equipment. Eventually, as the LED materials technology became more technologically developed, the light output was increased, while maintaining the efficiency and the reliability to a safe and acceptable level. The invention and development of the high power white light LED lead to use for illumination.