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.