Samples of the
correlated metals strontium vanadate (two squares on left) and calcium vanadate
(two squares on
right) with two uncoated squares in center. Image: Lei Zhang / Penn State
(December 15, 2015) A
new material that is both highly transparent and electrically conductive could
make large screen displays, smart windows and even touch screens and solar
cells more affordable and efficient, according to the Penn State materials
scientists and engineers who discovered it.
Indium tin oxide, the transparent conductor that is
currently used for more than 90 percent of the display market, has been the
dominant material for the past 60 years. However, in the last decade, the price
of indium has increased dramatically. Displays and touchscreen modules have
become a main cost driver in smartphones and tablets, making up close to 40
percent of the cost. While memory chips and processors get cheaper, displays
get more expensive from generation to generation. Manufacturers have searched
for a possible ITO replacement, but until now, nothing has matched ITO's
combination of optical transparency, electrical conductivity and ease of
fabrication.
A team led by Roman Engel-Herbert, assistant professor of
materials science and engineering, reports today (Dec 15) online in Nature
Materials a new design strategy that approaches the problem from a different
angle. The researchers use thin -- 10 nanometer -- films of an unusual class of
materials called correlated metals in which the electrons flow like a liquid.
While in most conventional metals, such as copper, gold, aluminum or silver,
electrons flow like a gas, in correlated metals, such as strontium vanadate and
calcium vanadate, they move like a liquid. According to the researchers, this
electron flow produces high optical transparency along with high metal-like
conductivity.