The high-tech light-emitting diodes (LED) used in TVs, computer screens and billboards were invented in Illinois by Nick Holonyak, Jr.

Born in Zeigler in 1928, Holonyak received his undergraduate degree, masters degree, and Ph.D. from the University of Illinois. He was the first Ph.D. student of John Bardeen, the only person to have won the Nobel Prize in Physics twice. With the guidance of his mentor and consistent hard work, Holonyak created many useful inventions during his career.

Holonyak was noted for his work on light-emitting diodes and has been referred as "the father of the LED." He invented the first visible-spectrum LED in 1962 while working as a consulting scientist at General Electric. LEDs have many advantages over incandescent light sources, including lower energy consumption, longer lifetimes and smaller size.

Light-emitting diodes are now used in applications as diverse as aviation lighting, car headlights, advertising, general lighting, traffic signals and camera flashes. The inventor of LEDs made our world brighter and more colorful.

Learn more:
Want to know how light-emitting diodes work?  Read this article from HowStuffWorks.com.
Here is an interesting article about LED’s inventor, Nick Holonyak.