3M reveals new quantum dot display material
Quantum dots could bring brighter, more vibrant colour to TVs, tablets, phones and other displays, according to Eric Nelson from the company 3M, talking this week at the 248th National Meeting & Exposition of the American Chemical Society (ACS).
Nelson was describing a new technology developed by his company quantum dot enhancement film (QDEF) that makes liquid crystal display (LCD) screens more richly coloured.
"Green grass just pops out at you from these displays," says Nelson, who helped create the plastic films that hold the quantum dots in a screen. "We believe this is the most efficient way to get to a high-colour display."
The QDs (made for 3M by Nanosys in this case) produce specific colours of light based on how big they are. In 3M QDEF displays, the LCD's white backlight is replaced with a blue one, and a sheet of plastic embedded with QDs that produce red and green light is placed over it. The display combines these three colours to produce all the colors the viewer sees.
One drawback of the dots is that they break down quickly when exposed to water and oxygen in the air. To address this challenge, Nelson helped create the plastic sheathing that protects them. They sandwiched the QDs between two polymer films, with the QDs embedded in an epoxy glue. "The polymer/quantum dot sandwich looks like a piece of plastic film," says Nelson. Coatings on the film provide further protection and enhance the viewing experience.
Because the QDEF displays need less light, says Nelson, they consume less electricity and help device batteries last longer than other high-colour solutions. He says 3M's tests have shown that the dots' heavy metals "” many of which are already found in today's electronics "” are entirely sealed inside the film. That means they won't leach out during the products' lifetime or as they languish in landfills if the displays aren't recycled.
3M hopes QDEF technology will compete well with more costly displays like those that use organic light-emitting diodes (OLEDs). Nelson explains that OLEDs produce similarly brilliant colors to the QDEF displays, but they use individual lights to make different colors. The drawback to OLEDs is that they are much more costly to manufacture.
Although QDEF displays are more expensive than conventional low-color LCDs, Nelson says the cost will come down as the technology becomes more widespread and as manufacturing costs come down with increased production scale. Several devices featuring QDEF are already on the market, and more are on the way.
