In many cities today, streets are lit by white lights, screens show vivid colors, and buildings glow with precise patterns of illumination, all depending on a small but important invention from the early 1990s: the blue light-emitting diode, or blue LED.
LEDs had been around for decades before that point. Red and green versions were invented in the 1960s and were widely used in electronics as indicators and displays. But without blue, the technology could not produce bright white light or the full range of colors needed for modern screens.
The main challenge was physical. To produce blue light, a semiconductor requires a much wider band gap than for red or green light. This means the electrons must be given more energy to jump across the gap and release light in the blue part of the spectrum. Gallium nitride was the most likely material to make this possible, but it was extremely hard to grow into crystals pure enough for efficient devices.
The crystals often contained too many defects, which trapped the electrons and wasted energy as heat instead of light. For years, labs around the world tried to overcome this barrier but could not make a device that was bright and efficient enough to be useful.
Shuji Nakamura, gallium nitride and the blue LED
By the late 1980s, many researchers had moved on to other approaches or had given up entirely. The problem was considered too costly and too uncertain to pursue. It was in this context that Shuji Nakamura, an engineer working for Nichia, a small chemical company in Tokushima, Japan, began his work on gallium nitride.
Nakamura had been with Nichia since 1979, but in 1988, he was sent to the University of Florida for a year to study advanced semiconductor fabrication techniques. While there, he worked with metalorganic chemical vapor deposition (MOCVD) equipment, the machines used to grow thin layers of semiconductor material atom by atom. He became familiar with their design and operation, knowledge that would later prove essential.
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By GlobalDataWhen he returned to Japan, Nakamura found that Nichia did not have the funds to buy a state-of-the-art MOCVD system. Instead, they had an older and less capable model. Rather than abandon the idea, Nakamura decided to modify the machine himself, using what he had learned in the US.
Over months of work, he rebuilt and modified large parts of the system to improve temperature control and gas flow, making it capable of producing much higher-quality gallium nitride layers. These modifications were risky and unconventional, but they gave him the platform he needed to push ahead when other researchers who didn’t know the machines like he did could not.
In 1993, after further experiments in crystal growth, doping techniques, and device structure, Nakamura produced a bright, efficient blue LED. His work built on earlier discoveries by Isamu Akasaki and Hiroshi Amano, who had developed methods for creating high-quality gallium nitride crystals and p-type doping, both essential steps toward a functional blue LED. The combined efforts of these scientists solved a problem that had stalled LED development for more than two decades.
A world of blue LEDs
The impact was immediate. With blue LEDs available, engineers could produce white light by coating the blue chip with a yellow phosphor, a process that blends the two colors in the human eye. These white LEDs were far more efficient than incandescent bulbs, consuming up to 90 percent less electricity and lasting many times longer. They also surpassed fluorescent lighting in both efficiency and lifespan, while avoiding the use of mercury.
The energy savings potential was enormous. The US Department of Energy has since estimated that switching entirely to LED lighting could save the country hundreds of terawatt-hours of electricity per year, equivalent to the output of dozens of power plants. On a global scale, the reduction in energy demand could significantly cut greenhouse gas emissions, since much of the world’s electricity still comes from fossil fuels.
The blue LED also enabled major advances in display technology. Every modern television, smartphone, and computer monitor that uses an LED or LCD panel relies on red, green, and blue LEDs to produce full-color images. Even displays that are not “LED screens” in the direct sense often use blue LEDs as a backlight, passing the light through filters to create different colors. Without blue LEDs, these products would simply not exist.
Specialised applications
Beyond lighting and displays, blue LEDs have found a place in many specialised applications. In medicine, they are used for phototherapy to treat newborn jaundice by breaking down excess bilirubin in the blood. They are also used in some sterilization systems to kill bacteria and viruses on surfaces or in water. In agriculture, blue light influences plant growth and flowering cycles, so LEDs that emit in this range are used in controlled-environment farms to optimise yields.
One of the most significant social impacts of the technology has been in areas without reliable electricity. In many rural regions of Africa and Asia, oil lamps once provided the only source of light after dark. These lamps are expensive to fuel, produce harmful indoor air pollution, and pose a fire hazard. Solar-powered LED lamps, made possible by the efficiency of the blue LED, have replaced kerosene in many communities. They provide brighter, cleaner light for evening work and study, improving education outcomes and reducing health risks.
By the early 2000s, LEDs began appearing in traffic lights, street lamps, and residential lighting. Costs dropped as manufacturing scaled up, and efficiency improved year after year. Today, in many countries, incandescent bulbs are no longer sold for general lighting, replaced almost entirely by LEDs.
In 2014, the Nobel Prize in Physics was awarded to Akasaki, Amano, and Nakamura “for the invention of efficient blue LEDs, which has enabled bright and energy-saving white light sources.” The Nobel committee noted that the blue LED was a rare example of a technology that had an immediate and clear benefit to society.
The blue LED story continues
The story of the blue LED shows how a single missing piece can hold back a technology for decades, and how solving that one piece can open up entirely new possibilities.
Red and green LEDs were important, but they could not revolutionise lighting without their blue counterpart. Once that gap was filled, the path was clear for energy-efficient lighting, modern display technology, and a wide range of new applications.
Today, LEDs are continuing to evolve. Research is focused on making them even more efficient, tuning their spectra for specific purposes, and integrating them into smart lighting systems that adjust automatically to the time of day or the presence of people. But all of that builds on the breakthrough of the early 1990s, when a combination of persistence, technical skill, and willingness to challenge conventional thinking made the color blue shine in a way it never had before.
