Better, bolder printing with silicon nanostructures

From textbooks to artwork to newspapers, printed items are a part of our everyday life.

But the ink used in today's printers are limited in colors and resolution. Now in a new study in ACS' journal Nano Letters, scientists have found a way to expand the printable colour spectrum with a novel nanostructure system.

The current colour range for computers and printers is based on the sRGB (standard Red Green Blue) colour space, which was developed in 1996 by Microsoft and Hewlett-Packard. But the hues in the sRGB system only encompass a subset of colours that the human eye can see.

Researchers have been trying to develop a better system to surpass sRGB that would broaden the printable colour spectrum while maintaining high resolution. For example, they have used metallic nanostructures for colour printing, but this has resulted in either high-resolution images with less-rich colors, or images with vivid colours but lower resolution.

Also, the use of metals like silver and gold would likely be too expensive for wide adoption. So researchers have turned to silicon because it has unique properties that might be optimal for expanding computer and printing colours at a lower price.

But so far, silicon colour systems have shown poor colour saturation and range. So Joel Yang and colleagues wanted to design a novel silicon nanostructure that could potentially overcome these limitations and compete with the sRGB system.

The researchers tested differently sized silicon nanodisks, controlling how close the structures were to each other.

Once they figured out the optimal disk sizes and distances between them, the team used the nanodisks to print an art piece on silicon coated with an anti-reflective layer consisting of silicon nitride. This anti-reflective coated substrate was important to more closely mimick the color range visible to the human eye.

The researchers concluded that the silicon nanostructures expanded the range of printable colours by 121 per cent, while maintaining both high color saturation and resolution. The scientists note that although their design still has some limitations that need to be addressed, it has achieved the largest colour gamut for printing while maintaining a print resolution better than 40,000 dpi.