EVENTS, ADVANCES, AND NEWS
■ BY JEFF ECKERT
ANOTHER SOLAR CELL
Nanotechnologists at the University
of California, Riverside (www.ucr.
edu) have come up with a way to
control the color of a liquid by applying
a magnetic field. The liquid is just a
colloidal suspension of iron oxide
nanoparticles in water, but the particles
are “superparamagnetic,” meaning that
they have magnetic properties only in
the presence of an external magnetic
field. This is in contrast to “
ferromagnetic” materials, which retain their
magnetism after the field is removed.
If you vary the field strength applied
to the liquid, the particle arrangement is
altered, thereby changing what happens
when light passes through or is deflected
by the solution. According to researcher
Yadong Yin, “By reflecting light, these crystals (also called photonic crystals) show
brilliant colors. Ours is the first report of
a photonic crystal that is fully tunable in
the visible range of the electromagnetic
spectrum, from violet light to red light.”
Because the materials are cheap, nontoxic, and readily available, the technology could be used to create reflective color displays that use millions of the particles
for pixels. It also has possible applications
in erasable, rewritable electronic paper
and might even be used to make ink that
changes color electromagnetically.
PHOTO COURTESY OF UCSB.
■ Plastic tandem solar cells — which
use linked solar cells with different
absorption characteristics — use a
wider range of the visible spectrum.
as the 40. 7 percent achieved last year
by a Boeing Spectrolab (www.spectro
lab.com) device. However, “This is the
highest level achieved for solar cells
made from organic materials. I am
confident that we can make additional
improvements that will yield efficien-cies sufficiently high for commercial
products,” Heeger noted. He expects
the technology to be commercially
available within about three years.
PHOTO COUR TES Y OF DELL, INC.
■ Dell’s new Vostro notebooks and
desktops are aimed at small businesses.
A Vostro 200 is shown here.
■ A solution of iron oxide in water
changing color under a magnetic field,
with increasing field strength from left
Meanwhile, over on the other side
of L.A., a research team has been
working on a new type of plastic solar
cell with a noteworthy boost in efficiency. Nobel laureate Alan Heeger — a
physics professor at UC, Santa Barbara
www.ucsb.edu) — and associates have
come up with a “tandem” organic
device that, by virtue of its dual multilayer design, gathers a wider range of the
spectrum, at both shorter and longer
wavelengths. According to Heeger, the
cells “... can be fabricated to extend over
large areas by means of low-cost printing
and coating technologies that can simultaneously pattern the active materials on
lightweight, flexible substrates.”
At present, the tandem cells are
working at only about 6. 5 percent efficiency, which isn’t nearly as impressive
In July, Dell (
introduced a new lineup of PCs
designed for small businesses on a
budget. Consistent with market trends
that saw notebook sales up by 23 percent in the first quarter but desktops
pretty stagnant, the new brand at
introduction included four laptops but
only one desktop (although available in
either mini-tower or slim case versions).
Apparently, Dell has received a substantial number of complaints about PCs
that arrive bloated with trialware (also
known as “junkware” or “crapware”), so
the Vostro™ (Latin for “yours”) machines
come without it. They do include
“simple to use tools that address top-of-
PHOTO COURTESY OF YIN LABORATORIES, UCR.