High-tech specks called quantum dots could bring brighter, more vibrant color to mass market TVs, tablets, phones and other displays. A new technology called 3M quantum dot enhancement film (QDEF), unveiled at the 248th National Meeting & Exposition of the American Chemical Society (ACS), has the potential to efficiently make liquid crystal display (LCD) screens more richly colored. That’s because quantum dot, or “QD,” displays need less energy compared to other high-color options. QDs are superconducting crystals so small that 10,000 could fit across the width of a human hair.
Almost all electronics sold today, from TVs to smartphones, use LCDs. A typical LCD works by shining white light through a series of filters that produce the colors the viewer sees. To achieve the best color, these filters need to be fairly dark. However, it takes a lot of energy to make the light bright enough for the viewer’s eye. The other problem is that the different colors, i.e. green, red, blue, etc., tend to leak into each other, preventing LCDs from rendering true colors in some instances.
Rather than filtering light, QDs change it into a different color. The dots — made for 3M by Nanosys, Inc. — produce specific colors 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 colors 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, scientists created a 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. The coatings on the film provide protection for the QDs and enhance the viewing experience.
Because the QDEF displays need less light, they consume less electricity and help device batteries last longer than other high-color solutions. Testing conducted by 3M 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.
It is hoped that QDEF technology will one day compete with more costly displays like those that use organic light-emitting diodes (OLEDs). 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.
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