Jun 202012
 

LED 300x269 The Saga of the LEDLEDs are everywhere. Over past years they’ve crept into our cell phone screens, the headlights on our cars, the display boards in our favorite sports stadiums, and even into our household light sockets.  With their minimal energy consumption and extra-long rated lives, these babies are on the rise. But in this heyday of LED innovation, have you ever wondered how they came about?

Disclaimer: the history of LEDs is crazy.

(But what would you expect for a light source that we use to light our streets at night AND zap the tattoos off our arms?)

In the beginning was Henry J. Round, a British experimenter at Marconi Labs. In 1907 he was unsuspectingly at work on a cat’s whisker detector for radio made with carborundum (SiC) when suddenly he witnessed a yellowish light—and lo! it was electroluminescence. With increased voltage the light turned brighter yellow, then green, orange, and finally blue. Round was so stoked he wrote a letter to Electrical World about it, and then went back to his radio.

Next came the tragic tale of Russian scientist Oleg Losov. This dude was completely self-educated, and in the 1920s after witnessing light emission from SiC and zinc oxide detectors—let’s just say it was love at first light (ha). He spent years investigating the subject, published papers in Russia, England, and even Germany between 1924 and 1930. During the siege of Leningrad in 1941, poor Losov was working on what could have been a prelude to the transistor, but his work was lost when he later died of starvation.

In 1939, the outrageously named Zoltan Bay and Gyotgy Szigeti anticipated LED lighting in Hungary by patenting a device using SiC that emitted white, yellowish, or greenish white light.

The lasers came in 1962. Scientists at MIT first combined infrared LEDs with a gallium arsenide (GaAs) photodiode to transmit TV signals. Following on this work, Gunther Fenner at GE made the first semiconductor diode laser.

In October of that year, there was light. Nick Holonyak, Jr. made a visible version of GE’s laser with gallium arsenide phosphide (GaAsP—gasp!) and ta-da! he became the proud father of the light emitting diode. Holonyak’s LEDs were only bright enough to be used as red replacement indicator lights or in displays—not to illuminate a room.

Come 1967, LED researcher George Craford, inspired by Holonyak, invented orange, yellow, and green LEDs still using GaAsP.  Two years later, Craford headed a group that used aluminum gallium arsenide (AlGaAs) for bright red LEDs and gallium indium phosphide (AlInGaP) for bright green and orange.

By 1987, there was brighter light still. Finally AlGaAs LEDs created by HP shone intensely enough to replace incandescent break lights and traffic lights.

Jump to Japan: through the 1990s Nichia Corporation’s Shuji Nakamura headed innovations to commercialize blue and green LEDs and develop white LEDs. Eventually they discovered a colored LED could generate white light if coated with phosphor of a different color. Another way was to arrange red, blue, and green LEDs snugly together.

Today, LED and OLED technology thrives in many different forms. Scientists across the globe continue to burn the midnight diodes trying to create brighter, more efficient lights. As innovations progress, more cities, corporations, and families are making the switch to LED lights.

Excited to watch as the saga unfolds? Yeah, so are we.

As part of our series on the history of lighting, you can also check out the histories of fluorescent and incandescent lighting. 

by

Annie JoseyAnnie was the E-Commerce Marketing Specialist at Pegasus Lighting from June 2012 to October 2013. She has a background in English literature, and loves using language to help illuminate the world. So covering lighting news and tips naturally fit her interests. In her personal time she enjoys painting, biking, and reading.

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