Sony Uses Quantum Dots In Latest Television Development

 Quantum Dots

Sony announced last week at the Consumer Electronics Show one of the first quantum dot television displays.  Made with QD Vision Color IQ quantum dot technology, the upcoming Triluminous television promises to bring the most vibrant color to large displays.

So far researchers working with nanoscale fluorescent particles called quantum dots only been able to guess at the groundbreaking achievements, such as ultra-efficient light-emitting diodes (LEDs) and solar cells, of the technology.  Now with the announcement last week that QD Vision, based in Lexington, Massachusetts, would supply Sony Corporation of Tokyo with quantum dots for flat-screen televisions that will transmit more richly colored images than other TVs on the market.

Created by QD Vision, Inc., Color IQ is an innovative semi-conductor nanocrystal technology that emits light very precisely. So when it’s used in LCD screens like TVs, you see a more dynamic range of colors and the true, natural palette encoded in the picture. According to QD Vision, Color IQ adds up to 50% more color into your TV picture.

Demand for quantum-dot displays, say industry watchers, could benefit quantum-dot companies, bring down the price of these nanomaterials and boost other applications that have stalled.

Quantum dots were initially discovered in 1981.  They are crystals about 10 nano­metres in diameter, made from a semiconductor material, commonly cadmium selenide. They are so small that their shape and size affect the quantum properties of their electrons, in particular their energy gap — the energy needed to kick electrons into a higher-energy band — which determines the color of light that the material can emit. While a bulk semiconductor is limited to emitting a single color of light, quantum dots can be tuned so that the precise color will absorb and re-emit by tailoring its size.

Until recently, the biomedical sector was responsible for US$48 million of $67 million in total quantum-dot revenues, with applications in fluorescent imaging labels for proteins and other biological molecules.

Now, quantum dots show much promise for electronics, too — for example in solar cells, in which a mix of quantum dots tuned to absorb different wavelengths of light could capture more of the energy in the solar spectrum. A big hurdle to their exploitation was their temperature sensitivity. Near the backlight of a liquid-crystal display (LCD), for example, temperatures can be around 100 °C. At this temperature, the dots lose efficiency and up to half of their brightness, says QD Vision co-founder and chief technology officer Seth Coe-Sullivan. He says that the company spent a long time tuning the chemistry of its quantum dots to make them stable at higher temperatures.

Sony plans to sell the new quantum dot televisions under the Tri­luminos brand name. The contrast with today’s flat screens begins with the light source. Conventional LCDs use a high-intensity blue LED backlight whose glow is converted by a phosphor coating to create a broadband, white light used to make the moving TV images.

The new Triluminos tele­visions instead pair an uncoated blue LED with a thin glass tube filled with quantum dots. Two kinds of quantum dots in the tube absorb some of the blue light from the backlight and re-emit it as pure red and green light. The resulting white light is more intense at the wavelengths of these three specific colours than the white light made by a phosphor-coated LED, so that more colour comes through in the images.

Another quantum-dot company, Nanosys of Palo Alto, California, is providing 3M with material for a similar product. 3M will make a polymer film seeded with quantum dots that does the same jobas QD Vision’s glass tube. The film is layered between the LCD’s stack of light filters, diffusers and polarizers, and similarly converts raw blue light into white light made up of pure colours. Nanosys and 3M announced their partnership in June 2012, but have not yet named any customers.




SOURCES  Source QD Vision, Nature

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