A View from Kevin Bullis
Winners of the Nobel Prize for Physics Enabled Ultra-Efficient Lighting
The blue LED might save more energy than just about any other technology.
If you were to go to Best Buy and, while your friend did something distracting at the front of the store, dismantle one of the Sony 4K Triluminos TVs on display, you’d find a couple of remarkable materials inside. One of the materials is made of quantum dots—tiny crystals a few billionths of a meter in diameter that absorb light of one color and emit light of a very different hue and a very precise wavelength. They’re the basis, for example, for the brilliant red light you see in some medieval stained glass windows. And they’re the reason these Sony displays have some of the most stunning color you’ll see anywhere.
You’ll also find blue LEDs, a feat of science and engineering that took decades of concerted work to create. Like the quantum dots, they rely on quantum mechanics—they use ultrathin structures known as quantum wells to generate light efficiently. Without the blue LEDs, the quantum dots would be useless. The blue LEDs are the light source for the display. Some of the blue goes to lighting blue pixels in the display. The rest stimulates quantum dots to produce green and blue pixels. The red, green, and blue pixels together produce all the millions of colors the display can generate.
Today the inventors of blue LED lights—Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura—learned that they had won the Nobel Prize for physics. Sony’s Triluminos displays are just one of the latest technologies based on their invention. Blue LEDs are also used to produce the white backlight in many more conventional LCD displays, which produce red and green light using materials known as phosphors. The high color quality, compact size, and high efficiency of LED backlights made possible the ultrathin, vivid displays we have now in smartphones, tablets, and laptops.
And they’re the basis of the LED lightbulbs you can now buy for $5 to $10 that produce a beautiful glow indistinguishable from that of an incandescent bulb. Such lights use about a tenth the energy of an incandescent bulb, and LED lighting has the potential to use half to a third of the energy required by even highly efficient fluorescent bulbs (see “Bright Bulbs” and “LEDs Light the Future”).
If LED lighting catches on, it could be one of the greatest energy-saving technologies ever, since lighting accounts for 20 percent of the energy consumed in the United States. LEDs might also bring lighting to the more than one billion people in the world who aren’t connected to an electricity grid. Since LEDs use very little energy, it’s economical to power them with a small solar panel and battery. It’s one of the few cases where solar power has a clear economic advantage—the entire system costs a fraction of the amount people had been spending on kerosene for lamps (see “In the Developing World, Solar is Cheaper than Fossil Fuels” and “Solar Microgrids”).
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