What has the Nobel Prize in Physics ever done for me?

           (Karen Livesey’s article from The ABC NEWS AUS on 04 October 2023.)

Sometimes, however, physics research does have a practical goal all along. One such example is the quest for energy-efficient lighting.

Old-fashioned incandescent light bulbs are highly inefficient. Because they work by heating a wire until it glows, they waste a lot of energy as heat. In fact, less than 10 per cent of the energy they consume goes to producing light.

In the 1980s, scientists realised light emitting diodes, or LEDs — small electronic components that emit light of a specific colour — would make more efficient light sources. But there was a problem. Although red and green LEDs had been developed in the middle of the twentieth century, nobody knew how to make a blue LED.

LEDs are thin sandwiches of materials that respond to electricity in a very particular way. When an electron moves from one energy level to another inside the material, it emits light of a specific colour. All three colours of light (red, green and blue) would be needed to produce the kind of white light people want in their homes and workplaces.

In the early 1990s, in the culmination of almost 30 years of work by many groups, the missing blue LEDs were found. In 2014, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura received the physics Nobel for the discovery.

The layers of material chosen to make up the sandwich, plus the quality of each layer, had to be refined in order to make the first blue LED. Since the initial discovery, materials scientists have continued to improve the design and manufacture to make blue LEDs more efficient.

Lighting accounts for up to 20 per cent of total electricity consumption. LEDs use roughly one sixth as much energy as incandescent light bulbs. They also last much longer, with a lifetime of around 25,000 hours.

Why A Blue LED Is Worth A Nobel Prize

Three scientists have jointly earned the Nobel Prize in physics for their work on blue LEDs, or light-emitting diodes. Why blue in particular? Well, blue was the last — and most difficult — advance required to create white LED light. And with white LED light, companies are able to create smartphone and computer screens, as well as light bulbs that last longer and use less electricity than any bulb invented before.

LEDs are basically semiconductors that have been built so they emit light when they’re activated. Different chemicals give different LEDs their colors. Engineers made the first LEDs in the 1950s and 60s. Early iterations included laser-emitting devices that worked only when bathed in liquid nitrogen. At the time, scientists developed LEDs that emitted everything from infrared light to green light… but they couldn’t quite get to blue. That required chemicals, including carefully-created crystals, that they weren’t yet able to make in the lab.

Once they did figure it out, however, the results were remarkable. A modern white LED lightblub converts more than 50 percent of the electricity it uses into light. Compare that to the 4 percent conversion rate for incandescent bulbs, and you have one efficient bulb.

Besides saving money and electricity for all users, white LEDs’ efficiency makes them appealing for getting lighting to folks living in regions without electricity supply. A solar installation can charge an LED lamp to last a long time, allowing kids to do homework at night and small businesses to continue working after dark.

A modern white LED lightblub converts more than 50 percent of the electricity it uses into light. Compare that to the 4 percent conversion rate for incandescent bulbs.

LEDs also last up to 100,000 hours, compared to 10,000 hours for fluorescent lights and 1,000 hours for incandescent bulbs. Switching more houses and buildings over to LEDs could significantly reduce the world’s electricity and materials consumption for lighting.

A white LED light is easy to make from a blue one. Engineers use a blue LED to excite some kind of fluorescent chemical in the bulb. That converts the blue light to white light.

Two of this year’s prize winners, Isamu Akasaki and Hiroshi Amano, worked together on producing high-quality gallium nitride, a chemical that appears in many of the layers in a blue LED. The previous red and green LEDs used gallium phosphide, which was easier to produce. Akasaki and Amano discovered how to add chemicals to gallium nitride semiconductors in such a way that they would emit light efficiently. The pair built structures with layers of gallium nitride alloys.

The third prize-winner, Shuji Nakamura, also worked on making high-quality gallium nitride. He figured out why gallium nitride semiconductors treated with certain chemicals glow. He built his own gallium nitride alloy-based structures.

Both Nakamura’s and Akasaki’s groups will continue to work on making even more efficient blue LEDs, the committee for the Nobel Prize in physics said in a statement. Nakamura is now a professor at the University of California, Santa Barbara, although he began his LED research at a small Japanese chemical company called Nichia Chemical Corporation. Akasaki and Amano are professors at Nagoya University in Japan.

In the future, engineers may make white LEDs by combining red, green, and blue ones, which would make a light with tunable colors, the Nobel Committee wrote.

Press release (Nobel Prize) on 7 October 2014

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2014 to Isamu Akasaki (Meijo University, Nagoya, Japan and Nagoya University, Japan) and Hiroshi Amano (Nagoya University, Japan) and Shuji Nakamura (University of California, Santa Barbara, CA, USA) “for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources”

New light to illuminate the world: This year’s Nobel Laureates are rewarded for having invented a new energy-efficient and environment-friendly light source – the blue light-emitting diode (LED). In the spirit of Alfred Nobel the Prize rewards an invention of greatest benefit to mankind; using blue LEDs, white light can be created in a new way. With the advent of LED lamps we now have more long-lasting and more efficient alternatives to older light sources.

When Isamu Akasaki, Hiroshi Amano and Shuji Nakamura produced bright blue light beams from their semi-conductors in the early 1990s, they triggered a fundamental transformation of lighting technology. Red and green diodes had been around for a long time but without blue light, white lamps could not be created. Despite considerable efforts, both in the scientific community and in industry, the blue LED had remained a challenge for three decades.

They succeeded where everyone else had failed. Akasaki worked together with Amano at the University of Nagoya, while Nakamura was employed at Nichia Chemicals, a small company in Tokushima. Their inventions were revolutionary. Incandescent light bulbs lit the 20th century; the 21st century will be lit by LED lamps.

Professor Shuji Nakamura

White LED lamps emit a bright white light, are long-lasting and energy-efficient. They are constantly improved, getting more efficient with higher luminous flux (measured in lumen) per unit electrical input power (measured in watt). The most recent record is just over 300 lm/W, which can be compared to 16 for regular light bulbs and close to 70 for fluorescent lamps.

As about one fourth of world electricity consumption is used for lighting purposes, the LEDs contribute to saving the Earth’s resources. Materials consumption is also diminished as LEDs last up to 100,000 hours, compared to 1,000 for incandescent bulbs and 10,000 hours for fluorescent lights.

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: due to low power requirements it can be powered by cheap local solar power.

The invention of the efficient blue LED is just twenty years old, but it has already contributed to create white light in an entirely new manner to the benefit of us all. Prize amount: SEK 8 million, to be shared equally between the Laureates.