For some applications, such as microprojection and augmented and virtual reality (AR/VR), researchers continue to chase ever-smaller pixel sizes (nanopixels) and higher pixel densities. And these efforts eventually run up against some practical limitations, particularly on pixel brightness, imposed by the 2D-patterning approaches commonly used to create display pixels.
Now, researchers have proposed a novel 3D-printing approach to manufacturing pixels for display, allowing much smaller nanopixels to be crowded in at far higher densities than possible with 2D-patterning methods. The approach rests on building up pixels vertically on free-standing nanopillars of a polymer spiked with luminescent nanoparticles, also known as quantum dots (QDs).
The 3D-printing process can produce 620-nm-wide pixels of pure color that are twice as bright as those made from 2D patterning. The method can lay down these nanoscale pixels at a “super-high density” some five times higher than the limits of current commercial technology.
The team decided on QDs as the luminescent material for the pixels because of their high quantum efficiency and long-term reliability. The scientists then added these luminescent nanoparticles to samples of a polystyrene polymer solution to produce three distinct polymer inks with dots radiating at various wavelengths: 650 nm (red), 540 nm (green), or 480 nm (blue).
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