Three physicists have won the Nobel Prize for revolutionizing the way the world is lighted.
Isamu Akasaki and Hiroshi Amano of Japan and Shuji Nakamura of the University of California at Santa Barbara won the 2014 physics award Tuesday for "the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources."
Their work has spurred the creation of a new industry. The committee that chose the winners said light-emitting diodes, or LEDs, would be the lighting source of the 21st century, just as the incandescent bulb illuminated the 20th.
The three scientists, working together but separately, found a way to produce blue light beams from semiconductors in the early 1990s. Others had produced red and green diodes well before then, but without blue diodes, white light could not be produced, the Royal Swedish Academy of Sciences said in its prize citation Tuesday morning.
The three scientists will split a prize of $1.1 million, to be awarded Dec. 10 in Stockholm, Sweden.
Akasaki, 85, of Meijo University and Nagoya University and Amano, 54, of Nagoya University are Japanese citizens. Nakamura, 60, is an American. Awakened at 3 a.m. his time by a phone call from the Swedish academy, he described it in a news conference as "unbelievable."
In its announcement, the academy recalled Alfred Nobel's desire that his prize be awarded for something that benefited humankind, noting that one-fourth of the world's electrical energy consumption goes to producing light. This, it said, was a prize more for invention than for discovery.
Frances Saunders, president of the Institute of Physics, a worldwide scientific organization based in London, agreed. Noting in an email statement that 2015 is the International Year of Light, she said, "This is physics research that is having a direct impact on the grandest of scales, helping protect our environment, as well as turning up in our everyday electronic gadgets."
In Africa, for example, millions of diode lamps designed to run on solar power have been handed out to replace polluting kerosene lamps.
Light-emitting diodes are already ubiquitous - in the screens of smartphones, as well as in televisions, lasers and optical storage devices.
"The LED lamp holds great promise for increasing the quality of life for over 1.5 billion people around the world who lack access to electricity grids," the Nobel committee said. "Due to low power requirements, it can be powered by cheap local solar power."
Nick Holonyak Jr., of the University of Illinois, who invented the first red-light diode in 1962, has called the LED the "ultimate lamp" because "the current itself is the light."
The amount of information that can be packed into a light wave increases as its wavelength shortens, making blue - with its shorter wavelength - the color of choice for conveying information.
That is where the new laureates, working independently, came in. The key was to grow high-quality crystals of gallium nitride, a semiconductor for producing blue light - a process that had frustrated researchers.
Akasaki first tried to grow the crystals in the late 1960s as a young research associate at Matsushita Research Institute in Tokyo. It was not until 1986 that he and Amano, who was then his graduate student, succeeded in growing high-quality crystals on a layer of sapphire coated with aluminum nitride and found out that their properties were enhanced when they were scanned with an electron beam.
The royalties from their work subsequently funded the construction of a whole new research institute, the Nagoya University Akasaki Institute.
Meanwhile Nakamura, then at the Nichia Corp., a chemical engineering and manufacturing company, succeeded in growing his own crystals, improving on the other two scientists' method. In 1992 he went on to invent the first efficient blue-light laser, which is now the heart of Blu-ray players.
As is often the case with Nobel Prizes, not everybody was happy on Tuesday. The prize can be awarded to no more than three people, and Holonyak, the inventor of the red-light diode, expressed dismay that various American scientists who had laid the framework for the gallium nitride diodes were left out.
"We're always tugging and pulling," he said in a telephone interview from Illinois. "Nobody is smart enough to know all this."