Stanford and SLAC
postdoctoral researcher Sean Andrews with an instrument used to spread
a thin layer of
conductive polymers onto a transparent film with a matchbook-sized silicon
blade.
The process,
called “solution shearing,” was used to make patterned electrodes for a solar
cell
and a sensor, and
shows promise for scaling up for use in industry. (SLAC National Accelerator
Laboratory)
(November 3, 2015) Stanford,
SLAC Process Has Potential for Scaling Up to Manufacture Solar Cells, Displays
and More
Scientists from Stanford University and the Department of
Energy’s SLAC National Accelerator Laboratory have shown they can make
flexible, transparent electrical conductors with record-high performance for
use in solar cells, displays and other devices by spreading polymers on a clear
surface with a tiny blade, like a knife spreading butter on toast.
The technique, reported Oct. 29 in the advance online
edition of Proceedings of the National Academy of Sciences, has already been
used to make patterned electrodes for touch sensors and organic solar cells,
and with further development could be a tool for manufacturing transparent
conductors on a large scale.
A close-up of the
solution shearing apparatus. Transparent conductors made with the technique
had record-high
electrical conductivity for this material, demonstrating that high performance
can be
achieved just by
controlling the way they are manufactured. (SLAC National Accelerator
Laboratory)
“We were able to achieve record-high conductivity with a
material people have known for years, just by tuning the coating process,” said
Zhenan Bao, a Stanford professor and member of SIMES, the Stanford Institute
for Materials and Energy Sciences at SLAC, who led the study. “That shows
there’s a lot of room for achieving high performance through controlling the
assembly and structure of materials at the molecular scale.”
Clear Conductors for
Flexible Gadgets
Bao’s group developed this “solution shearing” technique in
close collaboration with Michael Toney and Stefan Mannsfeld, staff scientists
at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), whose teams used
X-rays to look at the structures and properties of the finished films.
Transparent conductors are used where it’s important to get
light in or out of a device, such as in solar cells, electromagnetic shielding,
antistatic layers and lighting displays. Today these conductors are mostly made
with indium tin oxide, or ITO. But ITO is expensive to work with, and it isn’t
compatible with the flexible displays being developed for a new generation of
TV screens, computers and other electronics.