What is a “Quantum Dot?”

 
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Quantum Dots: Marketing Buzzword or Quantum Leap?

Nanosys’ proprietary Quantum Dot technology is changing the way we think about color for displays. Until recently, the best consumer displays could only reproduce about a third of the range of color the human eye can see. Today, with Quantum Dots, we’ve more than doubled that and we’re well on our way to a truly lifelike color experience for displays. 

You may already know that Quantum Dot displays deliver vibrant, lifelike color and brightness with great value but if you’d like to know more about what’s going on inside a Quantum Dot display, or to find out how can this tiny technology deliver premium performance at a commodity price, you’ve come to the right place!

 

SUPER SMALL 

The first thing to know about Quantum Dots is that they are incredibly small. At just 2-8 nanometers in diameter, or 10,000 times narrower than a human hair, Quantum Dots are so small they cannot even be seen by an optical microscope. Each dot is a tiny man-made crystal that behaves like a semiconductor. As a semiconductor, Quantum Dots can emit energy in the form of light when excited by either light or electricity.

There are trillions of these tiny crystals inside each Quantum Dot display.

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SUPER SMALL

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Being small in size gives quantum dots a unique superpower, not observable in macroscopic world. Their internal energy structure changes depending on the size. For example, 5nm and 8nm indium phosphide (InP) quantum dots have different enery levels, while 6 inch and 8 inch InP wafers would have the exactly same energy levels. This means 5nm InP Quantum Dot will produce a different color of light (green) an 8nm InP Quantum Dot, which emits red. It means we don’t need to find a set of different materials to generate different colors of lights but simply change the size of given Quantum Dots.

This color tuning ability is a real-world example of the laws of Quantum Mechanics at work and it is unique to Quantum Dots.   

When a Quantum Dot absorbs a photon, it generates an electron-hole pair that recombines to emit a new photon. Crucially, the color of this emitted photon depends on the size of the quantum dot: Bigger dots emit longer wavelengths, close to red (620 to 750 nm); smaller dots emit shorter wavelengths, closer to the violet end (380 to 450 nm) of the spectrum. Such “tunability” is unique to quantum dots. In other light-emitting materials, the wavelength of the emitted photon is a fixed property of the material and not affected by its dimensions. To create a quantum dot with a specific size, which determines the wavelength, Nanosys adjust the temperatures and the timing of the chemical reactions used in our automated production line.  

 

WHAT IS SPECIAL ABOUT QD FOR DISPLAYS?

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Nanosys’ proprietary technology enables to produce best quality crystal QD particles at a controlled size. The perfect crystal quality of Nanosys QDs guarantees highest brightness output and the controlled size leads to a sharp color spectrum of emission light. These features are the foundation for display innovation.  

Typical displays are made of millions of pixels, which are again composed of multiple smaller subpixels emitting red, green, and blue lights. At each pixel, billions of color shades are generated by mixing these three primary colors of subpixels. Accordingly, color purity of the primary colors determines color resolution accuracy among the billions of shades.  

 

Display technologies such as LED LCD and White OLED rely on a two-color (blue + yellow) light source. Color filters shave off this light source into red, green or blue primary color at each subpixel. This passive approach is very lossy because most of the energy from the yellow light source should be thrown away leaving only small portion of energy in either green or red. Also broad yellow spectrum of the light source only leads to broad green and red primaries through the color filter.  

What if we could make only the red, green and blue light that the display needed, without waste and with high purity? This is where Quantum Dots spectral super powers really shine. 

Nanosys Quantum Dots create a perfectly tuned spectrum of light with exactly the right red, green and blue that the display needs for accurate, lifelike color reproduction with high brightness. 

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LOW COST, HIGH VALUE MANUFACTURING

Through Nanosys’ proprietary solution chemistry, Nanosys Quantum Dots are manufactured in reactors bigger than thousand liters at high precision, high yield and high quality.  

Nanosys also focus not only on making best QDs but also on developing technologies to innovate displays applying QDs via cheap techniques, such as wet coating, printing and roll-to-roll process. This means our materials can be easily integrated into displays without extra capex investment such as ones for vacuum or vapor processes. 

 MORE ON QUANTUM DOTS

QUANTUM DOT PRODUCTS

Learn more about Nanosys Quantum Dot Products on the market.

NANOSYS QUANTUM DOT TECHNOLOGY ROAMAP

Learn how Quantum Dots are applied to displays today and what’s coming next as the technology makes the jump from LCD to OLED, microLED and beyond.

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IN-DEPTH VIDEO ABOUT NANOSYS QUANTUM DOTS

Go in-depth with Nanosys top Scientist Dr. Charlie Hotz in this over-an-hour-long lecture on all-things-QD.