The Nobel Prizes can often seem like they have little relevance to day-to-day life, especially the prizes in Physics.
However, the 2014 Nobel Prize in Physics, awarded jointly to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura, could not be more useful, especially with respect to the fight against climate change.
Background to the Award
In the early hours of the 7th October 2014, Professor Shuji Nakamura was woken up at his California residence by a phone call from Sweden. On the other end of line was Staffan Normark of the Royal Swedish Academy of Sciences calling to inform the sleepy professor on having been awarded the Nobel Prize in Physics [1]. He along with Professors Akasaki and Amano had all received the prize for “for the invention of efficient blue light-emitting diodes.” [2]
By all accounts the awarding of a Nobel Prize to three little known Japanese professors seemed a little out of character with the Academy. After all, the year before they had given the Nobel Prize to Peter Higgs and François Englert for their prediction of the Higgs Boson. After many years of expectation, the Higgs Boson had been found to great fanfare at the multi-billion dollar CERN research facility in 2012, and it came to no one’s surprise that the 2013 Prize went to Higgs and Englert.
So for the 2014 prize to be awarded for a niche invention of the efficient blue LED seemed a bit of a damp squib in comparison. Furthermore, why efficient? Why a blue LED? Why not red or green?
What Are LEDs?
Light Emitting Diodes (LEDs) are electronic components made from layers of semiconductors that emit a monochrome (single colour) light when an electric current is passed through them.
What we would recognise now as an LED was invented very soon after the transistor in the 1950s. The first LEDs emitted red light and were used as a replacement for incandescent bulbs as indicator lights or seven-segment displays on electronic equipment.
In those early applications the LED’s colour was not important and therefore the red LEDs were first used as they were the easiest to produce. Green LEDs were patented in the late 1950s [3], but the blue LED remained elusive for another three decades.
The Advantage of LEDs
Unlike conventional light sources, such as incandescent and halogen bulbs, LEDs last a lot longer and are incredibly efficient at turning electrical power into light, using up to 80% less energy [4].
Traditional bulbs, by contrast, waste a lot of energy as heat (95% is given off as heat [5]).
In order to make LED bulbs that rivaled traditional bulbs, however, scientists and engineers needed to produce white light. The easiest way to do that is to combine red, green and blue (RGB) LEDs.
Why Were Blue LEDs so Difficult to Make?
The first blue LEDs were manufactured in labs in the early 1970s using the semiconductor Gallium Nitride (GaN). After much early promise, these early examples produced very little light and by the late 1980s much of the research had switched over to Silicon Carbide (SiC) devices.
The SiC LEDs made it to market as the first commercially available blue LEDs, but they were still quite dim and very inefficient. Nowhere near good enough to be used as a replacement for traditional light sources.
In Japan, however, Akasaki and Amano at Nagoya University and Nakamura at Nichia – a chemicals company – were continuing independently of one another to investigate the use of GaN as a suitable material [6,8].
The problem with GaN blue LEDs was not necessarily the material itself, but the production and preparation of the material. Firstly, the crystals had to be of a high purity and quality; and secondly the material had to be ‘doped’ with the correct quantities of magnesium so that the LED would emit blue light efficiently.
The first issue was surmounted by using a process called ‘metalorganic vapour phase epitaxy’, which deposited a high purity layer of GaN onto a sapphire substrate. The two teams took different approaches over the second issue but ultimately they both succeeded in doping the GaN so as to make an efficient LED [8].
The bulk of the work took place in the first half of the 1990s, and efficient blue LEDs were commercially available by the turn of the millennium.
Crucially, that then allowed other scientists and engineers to take this innovation forward and create energy efficient LED lighting for the consumers and industry alike.
Conclusion
The awarding of the 2014 Nobel Prize in Physics was an elegant balance of scientific achievement and real world significance. In the eyes of the many, as well as the three recipients, it was an unexpected award [7] – especially when compared to the fanfare of the Higgs Boson the previous year.
By providing the last building block of white LEDs, Akasaki, Amano, and Nakamura contributed to an energy efficiency revolution. This has not only saved people money, but also significantly reduced the energy requirements for lighting and reducing carbon emissions.
In 1896, Alfred Nobel directed that the eponymous awards would be created upon his death. In his will he specified that his wealth shall create a series of awards that recognise achievements that confer “greatest benefit on mankind”.
The 2014 Nobel Prize in Physics certainly did just that.
References
- https://www.youtube.com/watch?v=aRn4_zDDxg4
- The Nobel Prize in Physics 2014. NobelPrize.org. Nobel Media AB 2020. Sun. 5 Jul 2020. https://www.nobelprize.org/prizes/physics/2014/summary
- https://www.electronicsweekly.com/news/products/led/50-year-history-of-the-led-2-2010-09/
- https://www.energy.gov/energysaver/save-electricity-and-fuel/lighting-choices-save-you-money/how-energy-efficient-light
- https://www.eta.co.uk/2018/03/15/green-your-home-energy-efficient-lighting/
- https://www.nature.com/news/nobel-for-blue-led-that-revolutionized-lighting-1.16092
- https://www.nature.com/news/nobel-for-blue-led-that-revolutionized-lighting-1.16092
- Takeda Foundation, Takeda Award 2002 Achievement Facts Sheet – Techno-Entrepreneurial Achievements for Social/Economic Well-Being, 2002, http://www.takeda-foundation.jp/en/award/takeda/2002/fact/pdf/fact01.pdf