Isamu Akasaki and Hiroshi Amano of Japan and U.S. scientist Shuji Nakamura won the Nobel Prize in physics on Tuesday for the invention of blue light-emitting diodes -- a new energy efficient and environment-friendly light source.

The Royal Swedish Academy of Sciences said the invention is just 20 years old, "but it has already contributed to create white light in an entirely new manner to the benefit of us all."

Akasaki, 85, is a professor at Meijo University and distinguished professor at Nagoya University. Amano, 54, is also a professor at Nagoya University, while the 60-year-old Nakamura is a professor at the University of California, Santa Barbara.

The laureates triggered a transformation of lighting technology when they produced bright blue light from semiconductors in the 1990s, something scientist had struggled with for decades, the Nobel committee said.

Using the blue light, LED lamps emitting white light could be created in a new way.

"As about one fourth of world electricity consumption is used for lighting purposes, the LEDs contribute to saving the Earth's resources," the committee said.

Nakamura, who spoke to reporters in Stockholm over a crackling telephone line after being woken up by the phone call from the prize jury, said it was an amazing, and unbelievable feeling.

On Monday, U.S.-British scientist John O'Keefe split the Nobel Prize in medicine with Norwegian couple May-Britt Moser and Edvard Moser for breakthroughs in brain cell research that could pave the way for a better understanding of diseases like Alzheimer's.

The Nobel award in chemistry will be announced Wednesday, followed by the literature award on Thursday and the Nobel Peace Prize on Friday. The economics prize will be announced next Monday, completing the 2014 Nobel Prize announcements.

Worth $1.1 million each, the Nobel Prizes are always handed out on Dec. 10, the anniversary of prize founder Alfred Nobel's death in 1896. Besides the prize money, each laureate receives a diploma and a gold medal.

Nobel, a wealthy Swedish industrialist who invented dynamite, provided few directions for how to select winners, except that the prize committees should reward those who "have conferred the greatest benefit to mankind."

Last year's physics award went to Britain's Peter Higgs and Belgian colleague Francois Englert for helping to explain how matter formed after the Big Bang.