What are quantum dots?
Quantum dots are tiny man-made crystals. They are so small that you can’t see them with a typical microscope. In fact, they’re 10,000 times narrower than a human hair. That’s incredibly small but don’t let their size fool you. Quantum dots are actually very powerful devices and it’s their size that gives them a unique ability: to convert light into nearly any color in the visible spectrum with very high efficiency.
Each quantum dot is actually a tiny semiconductor -- which means it can convert incoming energy. The electronic characteristics of quantum dots are determined by their size and shape. This means we can control the color of light given off by a quantum dot just by changing its size. Bigger dots emit longer wavelengths like red, while smaller dots emit shorter wavelengths like green. Think of a guitar string. When a guitar string is shortened, it produces a higher pitch and when it is lengthened, it creates a lower pitch. The tune of a quantum dot – the wavelength of the light it emits – behaves in a similar way.
Cool, so what can we do with quantum dots?
Quantum dots’ ability to precisely convert and tune a spectrum of light makes them ideal for LCD displays. From smartphones to tablets to TVs, we can make all the colors we see even better by remixing white light into red, green and blue components. Until now, the white light that LCDs have had to work with wasn’t very good, it contained a lot of blue and yellow but not very much red or green. This meant displays had to waste a lot of energy to make enough red and green for a bright display while also making for broad primary colors.
With quantum dots we can design an ideal spectrum of white light for an LCD, one that contains only the red, green and blue that the display needs to make a great image. The precise spectrum created by the dots makes colors pure. And since we’re only making the colors the display needs we can use less power. The result is a display that’s brighter, more power efficient and incredibly vibrant.
More on quantum dots
- See a video of how an LCD works from University of Illinois Professor Bill Hamack.