Nov 9 2017
Printed items, from textbooks to artwork to newspapers, are a part of everyday life. However, the ink used in printers today is limited in resolution and colors. Now in a new study reported in ACS' Nano Letters journal, researchers have discovered a method to expand the printable color spectrum with a new nanostructure system.
The current color range for printers and computers is based on the sRGB (standard Red Green Blue) color space, which was created in 1996 by Hewlett-Packard and Microsoft. However, the hues in the sRGB system only include a subset of colors that can be viewed by the human eye. Researchers have been trying to create a better system in order to surpass sRGB that would expand the printable color spectrum while preserving high resolution. For instance, they have employed metallic nanostructures for color printing, but this has led to images with vivid colors but lower resolution, or high-resolution images with less-rich colors. In addition, the use of metals like gold and silver would likely be very expensive for wide adoption. Therefore, researchers have turned to silicon as it has unique properties that may be favorable for expanding computer and printing colors at a reduced price. But until now, silicon color systems have displayed poor color saturation and range. Therefore, Joel Yang and colleagues wanted to develop a novel silicon nanostructure that could possibly overcome these limitations and contend with the sRGB system.
The researchers examined differently sized silicon nanodisks by controlling how close the structures were to each other. After figuring out the optimal disk sizes and distances between them, the researchers used the nanodisks in order to print an art piece on an anti-reflective layer-coated silicon substrate consisting of silicon nitride. This anti-reflective coated substrate was necessary to more closely imitate the color range visible to the human eye. The scientists concluded that the silicon nanostructures expanded the printable color range by 121%, while preserving both high resolution and color saturation. Although their design still has some limitations that have to be addressed, the researchers noted that the design has attained the largest color gamut for printing whilst preserving a print resolution better than 40,000 dpi.