December 5, 2015

Nanoscale drawbridges open path to color displays

CAPTION: This animation illustrates the markedly different colors of light that are scattered
thanks to plasmonic shifts that occur when no metal bridges are present (left) and when
they are (right). CREDIT: C. Byers/Rice University

(December 5, 2015)  Rice develops first method for reversible color changes with metal nanoparticles.

A new method for building “drawbridges” between metal nanoparticles may allow electronics makers to build full-color displays using light-scattering nanoparticles that are similar to the gold materials that medieval artisans used to create red stained-glass.

“Wouldn’t it be interesting if we could create stained-glass windows that changed colors at the flip of a switch?” said Christy Landes, associate professor of chemistry at Rice and the lead researcher on a new study about the drawbridge method that appears this week in the open-access journal Science Advances.

CAPTION: This electron microscope image shows a dimer of silver plated
gold nanoparticles. A layer of silver connects the particles. CREDIT: C. Byers/Rice University

The research by Landes and other experts at Rice University’s Smalley-Curl Institute could allow engineers to use standard electrical switching techniques to construct color displays from pairs of nanoparticles that scatter different colors of light.

For centuries, stained-glass makers have tapped the light-scattering properties of tiny gold nanoparticles to produce glass with rich red tones. Similar types of materials could increasingly find use in modern electronics as manufacturers work to make smaller, faster and more energy-efficient components that operate at optical frequencies.

Though metal nanoparticles scatter bright light, researchers have found it difficult to coax them to produce dramatically different colors, Landes said.

This animation illustrates the green and orange hues of light that are scattered thanks
to plasmonic shifts that occur when metal bridges are present (bottom) and
when they are not (top). Credit: C. Byers/Rice University

Rice’s new drawbridge method for color switching incorporates metal nanoparticles that absorb light energy and convert it into plasmons, waves of electrons that flow like a fluid across a particle’s surface. Each plasmon scatters and absorbs a characteristic frequency of light, and even minor changes in the wave-like sloshing of a plasmon shift that frequency. The greater the change in plasmonic frequency, the greater the difference between the colors observed.

journal reference (Open Access) >>