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Quantum dots are nanoscale crystals that can emit different colors of light. Quantum dot-based display devices promise higher energy efficiency, brightness, and color purity than previous generation displays. Of the three colors (red, green, and blue) normally required to display a full-color image, the last has proven difficult to generate.
New methods based on self-assembled chemical structures offer a solution, and state-of-the-art imaging techniques to visualize these new blue quantum dots have proven essential for their fabrication and analysis.
If you look closely at your device’s screen, you may be able to see the individual image elements (pixels) that make up the image. Pixels can appear in almost any color, but they’re usually made up of red, green, and blue sub-pixels, so they’re not really the smallest elements on the screen. The variable intensity of these sub-pixels makes each individual pixel look like a single color from his billion-fold palette.
The underlying technology behind sub-pixels has evolved since the early days of color television, and there are now many possible options. However, the next big leap could be the so-called quantum dot light-emitting diodes or his QD-LEDs.
This means that blue quantum dots are often very complex and expensive to manufacture, and their quality is a key factor in any display. But now, a research team led by Professor Eiichi Nakamura of the University of Tokyo’s Faculty of Chemistry has found a solution.
Displays based on QD-LED already exist, but the technology is not yet mature and current options have some drawbacks, notably including blue sub-pixels. Of the three primary colors, the blue subpixel is the most important. It uses blue light to produce green and red light through a process called down conversion. For this reason, blue quantum dots require more tightly controlled physical parameters.