Three researchers received the 2014 Nobel Prize in physics on Tuesday for the invention of this blue light-emitting diode (LED), a technology now used in high-speed networking, data storage, smartphones, water purification, and efficient home illumination.
The winners are Isamu Akasaki, a Japanese citizen and professor at Meijo University and Nagoya University; Hiroshi Amano, a Japanese citizen and professor at Nagoya University; and Shuji Nakamura, an American citizen and professor at the University of California in Santa Barbara.
The key advantage of their invention 20 years ago is the production of light with far less waste of electrical energy than with preceding technologies like incandescent and fluorescent lights, the Royal Swedish Academy of Sciences said in awarding the prize.
"A quarter of energy consumption goes to illumination," said Per Delsing, a physics professor at the Chalmers University of Technology in Sweden, during a press conference announcing the award. As a result, any increase in efficiency and consequent saving of energy "is really going to have a big impact on modern civilization," he said.
Nobel Prizes in physics often go to fundamental discoveries such as the Higgs Boson. But when the committee makes an award for an invention, "we really emphasize the usefulness of the invention," said Anne L'Huillier, an atomic physics professor at Lund University in Sweden, also speaking at the press conference. And the blue LED is nothing if not useful.
Recent Nobel prizes have been awarded for concepts that are very far from day-to-day human experiences -- giant magnetoresistance, Bose-Einstein condensates, superconductors and superfluids, and the accelerating expansion of the universe, for example. The blue LED -- something you can buy at the local home-improvement store -- seems downright mundane by comparison.
But it's anything but ordinary, said H. Frederick Dylla, chief executive officer of the American Institute of Physics, who called the work a "tour de force" because it required a combination of materials science, physics, and chemistry. Indeed, the invention of the blue LED was on a short list of his institute's candidates for the prize, he said.
"It's a very expensive technology requiring atomic-layer epitaxy, where layers are put down atomic layer by atomic layer at a very high vacuum," Dylla said. It's vastly more complicated than incandescent lights, he added. "Compare that to drawing tungsten wire and putting it into a blob of glass and blowing out the air with some argon, and you have a light bulb for a few cents."
Three colors of LED
The white light from the sun can be reproduced artificially by blending three colors of light: red, green, and blue. LEDs are very efficient at converting electrical energy into visible light, but blue LEDs proved much harder to engineer than red and green ones. It took more than a quarter century after red LEDs were invented in the early 1960s before semiconductor materials and fabrication techniques grew sophisticated enough to enable blue LEDs in the mid-1990s.
White LEDs work either by packaging trios of red, green, and blue LEDs or by using just blue LEDs whose light also excites phosphors that emit green and red.
Now those white LEDs are spreading rapidly across the globe, led by lighting applications.
Incandescent lights -- the traditional Thomas Edison-era light bulb -- work by heating up a filament until it glows. That approach produces light, but most of the energy is wasted as heat.
Fluorescent bulbs are more than four times more efficient, a big step forward. But LEDs are nearly twenty times as efficient as incandescent bulbs, and they aren't saddled with the risky mercury-related health risks of fluorescent bulbs. As an added bonus, LED lights last longer, too.
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